rice breeding with induced mutations ii · mutation induction in rice by radiation combined with...

TECHN ICAL REPORTS SER I ES No. 1 0 2

Rice Breeding with Induced Mutations II

JOINT FAO/IAEA DIVIS ION OF ATOMIC ENERGY IN FOOD AND AGRICULTURE

I N T E R N A T I O N A L A T O M I C E N E R G Y A G E N C Y , V I E N N A , 1970

RICE BREEDING WITH INDUCED MUTATIONS II

TECHNICAL REPORTS SERIES No. 102

RICE BREEDING WITH INDUCED MUTATIONS II

R E P O R T OF AN F A O / I A E A R E S E A R C H CO-ORDINATION MEETING ON THE USE OF INDUCED MUTATIONS IN RICE BREEDING,

HELD IN OISO, JAPAN, 12-14 AUGUST 1968

INTERNATIONAL ATOMIC ENERGY A G E N C Y VIENNA, 1970

RICE BREEDING WITH INDUCED MUTATIONS II IAEA, VIENNA, 1970

S T l / D O C / 1 0 / 1 0 2

Printed by the IAEA in Austria March 1970

FOREWORD

T h i s r e p o r t contains the p r o c e e d i n g s of the fourth meet ing of p a r t i c i -pants in the F A O / I A E A C o - o r d i n a t e d P r o g r a m of R e s e a r c h on the Use of Induced Mutations in R i c e B r e e d i n g , a p r o g r a m which was initiated in 1964. The three prev ious meet ings w e r e r e p o r t e d as f o l l o w s :

F i r s t : p r o c e e d i n g s publ ished in the International R i c e C o m m i s s i o n N e w s -le t ter , V o l . X V , No. 1 (1966) .

Second: r e p o r t p r e s e n t e d to the IRC W o r k i n g P a r t y meet ing at Lake C h a r l e s , Louis iana , 1 8 - 3 0 July 1966 (unpublished r e p o r t , document No. 6 6 / 4 4 6 8 , avai lable on reques t f r o m Joint F A O / I A E A Div i s ion of A t o m i c E n e r g y in F o o d and A g r i c u l t u r e , IAEA, P . O . Box 590, A - 1 0 1 1 , Vienna) .

T h i r d : p r o c e e d i n g s publ ished by the IAEA as T e c h n i c a l R e p o r t s S e r i e s No . 86 under the t i t le ' R i c e b r e e d i n g with induced mutat ions ' .

The fourth meet ing was held at O i s o , Japan, on 1 2 - 1 4 August 1968. C o - o p e r a t o r s f r o m nine countr i es attended, together with s c i en t i s t s f r o m f i v e other countr i es , the International R i c e R e s e a r c h Institute, the R o c k e f e l l e r Foundat ion, the International R i c e C o m m i s s i o n , and the F A O and IAEA. In addition, a number of s c i en t i s t s f r o m the host country w e r e p r e s e n t .

The p u r p o s e of the meet ing was to p r e s e n t r e p o r t s on r e s e a r c h re lated to o r c a r r i e d out under the c o - o r d i n a t e d p r o g r a m in 1 9 6 7 / 6 8 , to r e v i e w and c o - o r d i n a t e r e s e a r c h plans f o r 1 9 6 8 / 6 9 , and to draw up t e chn i ca l r e -c o m m e n d a t i o n s f o r future w o r k . With r i c e the staple diet of roughly half of mankind, the i m p o r t a n c e of this w o r k , a imed at b e t t e r - q u a l i t y gra in and higher y i e lds , g o e s without saying .

CONTENTS

Mutation induction in r i c e by radiat ion combined with c h e m i c a l pro tec tants and mutagens 1 A . A n d o D i s c u s s i o n 5

Induced mutation studies with B r a c h i a r i a br izantha Stapf. and s o m e indica r i c e v a r i e t i e s f r o m Ceylon 7 P . G a n a s h a n ' D i s c u s s i o n 12

P r e s e n t status of r i c e b r e e d i n g by induced mutations in Ta iwan , Repub l i c of China 13 C . H . H u , H . P . W u a n d H . W . L i D i s c u s s i o n , 18

R i c e b r e e d i n g with induced mutat ions in F r a n c e 21 R. M a r i e

Mutation breed ing in r i c e in India 25 M . S . S w a m i n a t h a n , E . A . S i d d i q , C . B . S i n g h an'd R . A . P a i D i s c u s s i o n 43

Haploid r i c e plants in mutation studies .• 45 S. T a n a k a D i s c u s s i o n 56

Induced mutations of r i c e f o r s h o r t - c u l m s e l e c t i o n s in M 2

generat ion 57 J . H . R e e D i s c u s s i o n 66

Improvement of r i c e v a r i e t i e s by induced mutations to i n c r e a s e y ie ld p e r a c r e and r e s i s t a n c e to d i s e a s e s and to i m p r o v e seed quality , 69 A . J . M i a h , I . M . B h a t t i , A . A w a n a n d G. B a r i D i s c u s s i o n 76

Breed ing f o r e a r l i n e s s , high y ie ld and d i s e a s e r e s i s t a n c e in r i c e by means of induced mutat ions 77 M . S . H a q , S . M . A l i , A . F . M . M a n i r u z z a m a n , A . M a n s u r a n d R . I s l a m

Induction and ut i l izat ion of mutations in r i c e 85 G . B . V i a d o , I . S . S a n t o s , E . C a d a , P . B . E s c u r o a n d J . D . S o r i a n o

Induction of mutations in Thai r i c e v a r i e t i e s and subsequent se l e c t i on and test ing of b e n e f i c i a l mutant l ines 105 S. D a s a n a n d a a n d P . K h a m b a n o n d a D i s c u s s i o n 110

R i c e s tem b o r e r s in Malaya : a p r o p o s a l to use mutation b r e e d i n g f o r their c o n t r o l '. I l l F". C. V o h r a

R e c o m m e n d a t i o n s 115 List of Par t i c ipants 121

MUTATION INDUCTION IN RICE BY RADIATION COMBINED WITH CHEMICAL PROTECTANTS AND MUTAGENS

A. ANDO Agricultural College, University of Sao Paulo, Sao Paulo, Brazil

Abstract

MUTATION INDUCTION IN RICE BY RADIATION COMBINED WITH CHEMICAL PROTECTANTS AND MUTAGENS. Seeds of the r ice variety "Dourado Precoce" were treated with different c o m b i -nations o f g a m m a rays, cysteine and EMS or g a m m a rays, cysteine and dES. Cysteine showed some protection against the effects o f g a m m a radiation and combined gamma-ray + chemica l treatments with regard to germination, seedling height and fertility. There are also indications of changes in the spectra o f chlorophyll mutations.

I N T R O D U C T I O N

T h e p r e v i o u s r e p o r t on mutat ion induct ion in r i c e [ l ] g i v e s the r e s u l t s o f e x p e r i m e n t s in w h i c h the s e e d s o f the B r a z i l i a n r i c e v a r i e t y " D o u r a d o P r e c o c e " w e r e t r e a t e d with d i f f e r e n t c o m b i n a t i o n s o f g a m m a r a y s , c y s t e i n e and e thy lene o x i d e o r g a m m a r a y s , c y s t e i n e and e t h y l e n e -i m i n e . The h i g h e s t c h l o r o p h y l l mutat ion f r e q u e n c i e s w e r e o b t a i n e d a f t e r the t h r e e - f a c t o r t r e a t m e n t s with the h ighes t rad ia t i on d o s e , c y s t e i n e and the r e s p e c t i v e c h e m i c a l m u t a g e n .

T h i s r e p o r t d e a l s with an e x p e r i m e n t in w h i c h e t h y l m e t h a n e su lphonate (EMS) and diethyl su lphate (dES) w e r e u s e d as the c h e m i c a l m u t a g e n s . T h e s a m e r i c e v a r i e t y w a s t r e a t e d . G a m m a i r r a d i a t i o n w a s c a r r i e d out in the r e a c t o r o f the A t o m i c E n e r g y Institute o f Sao P a u l o U n i v e r s i t y at an a p p r o x i m a t e d o s e - r a t e of 1000 R / m i n , and c h e m i c a l t r e a t m e n t s w e r e c o n d u c t e d i m m e d i a t e l y a f t e r i r r a d i a t i o n at about 27°C without pH c o n t r o l . The c o n c e n t r a t i o n and t r e a t m e n t t i m e of cys te ine , was 0 . 0 0 1 M f o r 24 h, o f dES 0 . 0 3 M f o r 3 h, and o f EMS 1.5% f o r 8 h and 0 .5% f o r T o h . T h r e e p a n i c l e s p e r plant w e r e h a r v e s t e d in the s e q u e n c e o f f l o w e r i n g .

1. G a m m a r a y s , c y s t e i n e and 1 .5% EMS

T a b l e I s h o w s the r e s u l t s o f the c o m b i n e d e f f e c t s o f g a m m a rad ia t i on , c y s t e i n e and 1.5% E M S on the r i c e s e e d s . T w o - y e a r - o l d s e e d s w e r e u s e d in this e x p e r i m e n t . T h e p r o t e c t i v e e f f e c t o f c y s t e i n e aga ins t g a m m a r a d i a t i o n , a s d e t e r m i n e d b y g e r m i n a t i o n , s e e d l i n g height and f e r t i l i t y , w a s v e r y o b v i o u s in a g e d s e e d s . In the t h r e e - f a c t o r t r e a t m e n t c o m b i -nat i ons , c y s t e i n e t r e a t m e n t i n c r e a s e d g e r m i n a t i o n but d e c r e a s e d f e r t i l i t y as c o m p a r e d with the t w o - f a c t o r t r e a t m e n t c o m b i n a t i o n s o f g a m m a r a y s and E M S . With r e g a r d to the c h l o r o p h y l l mutat i on f r e q u e n c i e s , it was d i f f i c u l t to draw any c o n c l u s i o n s b e c a u s e o f the s h o r t a g e o f p a n i c l e s in s o m e t r e a t m e n t c o m b i n a t i o n s .

1

T A B L E I . E F F E C T O F T R E A T I N G RICE SEEDS WITH D I F F E R E N T COMBINATIONS O F G A M M A RAYS, CYSTEINE M

A N D EMS (1.5% F O R 8 h)

Treatment Germination Seedling

height Fertility

No. of panicles

No. of chlorophyll mutations

per 100 panicles

O 100 .0 100.0 100.0 365 1 .09 OD 102 .2 103.6 102.3 411 0 . 2 4 OE, 16 .5 " 5 1 . 2 75 .4 77 19.48 ODE, 3 5 . 2 4 0 . 9 • 3 3 . 3 50 3 6 . 0 0

A 102.8 8 2 . 9 71 .1 374 6 . 4 2 AD 103.3 84 .9 ' 7 4 . 1 400 6 . 2 5 AEr 8 . 4 32 .8 19 .9 13 7 .69 ADE, 3 9 . 1 3 2 . 4 6 . 8 19 10 .53

B 46 .8 3 0 . 5 2 0 . 0 57 14 .02 BD . 102 .2 74 .0 3 8 . 1 264 7 . 2 0 BE ( 0 . 0 - - - -

BDE, 4 4 . 0 16 .2 • 2 . 5 . 3 100 .00

• C 0 . 0 - - - -

CD 4 3 . 5 2 0 . 3 12 .9 31 22 .58 CEj 0 . 0 - - - -

CDE, 1 .8 8 . 5 0 . 0

O : OR A : 10 000 R B : 20 000 R C : 30 000 R D : cyste ine , 1 X 1 0 " 3 M for 24 h Ej'. EMS, 1.5°1° for 8 h

T A B L E II. E F F E C T O F T R E A T I N G RICE SEEDS WITH D I F F E R E N T COMBINATIONS O F G A M M A RAYS, C Y S T E I N E A N D EMS (0.5% FOR 10 h) OR dES (0 .03M FOR 3 h)

Treatment Germination Seedling

height ' Fertility

N o . o f panicles

No. of chlorophyll mutations

per 100 panicles

0 100 .0 100 .0 100.0 720 0 .56 O D 97 .9 100.8 1 0 0 . 1 1594 0 .69 O E 2 99 .0 84 .8 4 2 . 7 734 26 .57 O D E 2 99.6 76 .7 6 8 . 0 482 24 .69 O E 3 9 7 . 1 8 3 . 0 9 6 . 3 732 3 .28 O D E 3 98 .7 78 .2 9 4 . 2 378 3 . 4 4

A 99 .6 101 .5 87-. 1 655 2 . 1 4 A D 9 9 . 4 9 6 . 4 8 9 . 3 2038 4. 02 A E 2 100.2 79 .8 2 8 . 6 217 19 .82 A D E 2 97.8 87 .6 53 .8 318 20 .69 A E 3 9 9 . 1 80 .6 8 9 . 7 450 5 .78 A D E 3 9 8 . 1 8 1 . 2 8 5 . 3 261 8 .43

B 99 .2 9 4 . 7 6 3 . 0 675 6 .07 B D 9 9 . 5 9 2 . 3 6 2 . 1 1606 8 .22 BE 2 98.8 79 .7 18 .5 266 2 2 . 6 2 B D E J 98 .2 79 .6 4 2 . 4 187 2 0 . 3 2 B E 3 98.3 68 .6 4 6 . 1 556 11 .33 B D E 3 98 .5 8 1 . 5 62.8 561 8 .20

c 98.8 78 .8 3 2 . 1 665 8 .29 C D 96.8 ' 61 .8 3 3 . 2 776 7 .86 C E 2 96 .5 5 2 . 4 6 . 3 85 21 .17 C D E 2 100.8 5 7 . 0 19 .3 252 2 1 . 8 2 C E 3 _ 9 6 . 1 5 7 . 4 2 7 . 6 253 9 . 0 9 C D E 3 ' 96 .7 63 .3 3 8 . 6 317 5 .68

0 : 0 R A : 10 000 R

B : 20 000 R C : 30 000 R

D : cysteine, E 2 : EMS, 0.

IX 10"3 M for 24 h 5°]o for 10 h

E 3 : dES, 0 03 M for 3 h

4 ANDO

TABLE III. CHLOROPHYLL MUTATION SPECTRA AFTER VARIOUS TREATMENT COMBINATIONS OF GAMMA RAYS, CYSTEINE AND EMS OR dES

Chlorophyll mutations Total

albina viridis xantha others Total

Gamma rays 63 14 10 19 106

EMS 103 33 15 44 195

dES 9 5 1 9 24

Gamma rays + cysteine 160 59 8 48 275

Gamma rays + EMS 67 22 7 25 121

Gamma rays •+ dES '51 21 5 35 112

Cysteine + EMS 56 18 11 34 119 '

Gamma rays + cysteine + EMS 77 40 5 37 159

Gamma rays + cysteine •+ dES 51 10 5 20 86

631 222 67 271 1197

Xz =47 .05 0 . 0 0 1 < P < 0 . 0 1

TABLE IV. COMPARISON OF THE CHLOROPHYLL MUTATION SPECTRA OF THE GAMMA-RAY AND GAMMA-RAY + CYSTEINE TREATMENTS IN 1967 AND 1968

Treatment

Chlorophyll mutations

Total X2-Treatment albina viridis xantha others

Total X2- P

Gamma rays 1967 224 59 21 92 396 3 .59 0 . 3 - 0 . 5

1968 63 14 10 19 106

Gamma rays + cysteine 1967 292 94 22 93 501 1.70 0 .5 - 0 . 7

1968 160 59 8 48 275

1967 Gamma rays 224 59 21 92 396 4 .76 0 . 1 - 0 . 2

Gamma rays-t-cysteine 292 94 22 93 501

1968 Gamma rays 63 14 10 19 106 9.66 0 . 0 2 - 0 . 0 5

Gamma rays + cysteine 160 59 8 48 275

.ANDO

2. Gamma rays, cysteine and 0.5% E VTS or 0.03M dES

5

The results of the different treatment combinations of gamma rays, cysteine and 0.5% EMS or 0.03M dES on the rice seeds are shown in Table II. When cysteine was applied between gamma irradiation and the application of EMS or dES the fertility generally increased compared with the two-factor treatment combination of gamma rays and EMS or dES. The three-factor treatment combinations did not cause any observ-able effects on the chlorophyll mutation frequency.

3. Chlorophyll mutation spectra

Table III shows the chlorophyll mutation spectra of various treatment combinations. This analysis was made on the data from the experiments with different combinations of gamma rays, cysteine and 0.5% EMS or 0.03M dES. Data for the cysteine and cysteine + dES treatments were excluded from the analysis because the plants had too few panicles. These results show that the chlorophyll mutation spectra are different for different treatments. A comparison of the chlorophyll mutation spectra between the treatments with gamma rays and gamma rays + cysteine was also made to see the post-treatment effect of cysteine. This comparison was based on the data from 1967 and 1968. As can be seen from Table IV, there was no significant difference in the types of chlorophyll mutation caused by the gamma-ray and gamma-ray + cysteine treatments between the two years. However, statistically significant differences between gamma-ray and gamma-ray + cysteine treatments were observed in 1968. This is particularly pronounced by the decreased frequency of xantha types of mutation in the gamma-ray + cysteine treat-ment compared with the gamma-ray treatment.

R E F E R E N C E

[ 1 ] ANDO, A . , in Rice Breeding With Induced Mutations, Technica l Reports Series No. 86, IAEA, Vienna (1968) 7.

D I S C U S S I O N

M.S.HAQ: Could you tell us (a) the name of the variety and (b) the moisture content of the seed during treatment? I also wonder why you got no germination after treatment with 30 000 R.

A. ANDO: (a) The variety used was Dourado Precoce, one of the leading varieties in the State of Sao Paulo, (b) The moisture content was 10-12% during irradiation. In the case of two-year-old seeds we found no survivals after the 30 000 R treatment.

K. MIKAELSEN: If I understood you correctly, ypu applied cysteine after the radiation exposure in your factorial treatments. Have you studied the effects when cysteine is applied before irradiation?

A. ANDO: Yes, we have done a series of preliminary experiments with pre- and post-treatment of cysteine, cysteamine and glutathion. However, there were no statistically significant differences between these treatments as observed on the basis of germination and seedling height.

INDUCED MUTATION STUDIES WITH Brachiaria brizantha Stapf. AND SOME indica RICE VARIETIES FROM CEYLON

P. GANASHAN Agricultural Research Station, Maha-Illuppallama, Ceylon

Abstract

INDUCED MUTATION STUDIES WITH Brachiaria brizantha Stapf. AND SOME indica RICE VARIETIES FROM CEYLON. Non- imbibed seeds of Brachiaria brizantha were irradiated with doses of 6 0 Co g a m m a rays ranging from 7. 5 to 75 kR and fresh stem cuttings containing three nodes were irradiated with doses ranging from 7 . 5 to.45 kR. Chromosome counts were made using the'Carn'oy method.

There was no germination at 75 kR,and 18% germination at 60 kR with no survival of the seedlings. At the other doses germination and seedling survival decreased from 56% and 100% respectively for the control to 42% and 46% respectively at 45 kR. There were no chlorophyll mutants at 7 . 5 kR, while a. few were observed among seedlings at the higher doses. In the stem cuttings establishment was poor and morphological variations were observed at all doses above 15 kR.

A mutant of desirable plant type was obtained from the 45-kR seed treatment with an erect growth habit, reduced pubescence, short internodes, profuse tillering and rapid regrowth compared with the parent.

Four indica r ice varieties, H - 4 , H - 8 , H-7 and Pachchaiperumal 2462 /11 (PP 2462 /11 ) , were . subjected to gamma rays, neutrons and ethyl methane sulphonate (EMS) treatments. The LD50 level for g a m m a rays was 50 to 60 kR, for neutrons 1600 R and for EMS-0.4%.

Germination and final plant stand in the M, generation were af fected only slightly by the neutron-treatments, but were greatly reduced by EMS, and g a m m a irradiation above 35 kR. The final plant stand of the variety PP 2 4 6 2 / 1 1 was most reduced by all the mutagens.

In the Mz generation there was segregation for chlorophyll mutants, of the albina, chlorina, xantha, virescens and zebrina types. Other macro-mutations observed were for grain size and shape, plant height, flowering date and sterility. Grass c lump types were found occasionally. .

I N T R O D U C T I O N

The use of mutagens in plant breeding in Ceylon was pioneered by Dr. S. Sakamoto (C-Plan advisor) in 1965. He treated rice seeds with 32P and irradiated them with 60Co gamma rays but did not obtain any variations from the original type. Experiments are now being conducted with rice as well as a pasture grass Brachiaria brizantha Stapf., using 60Co gamma irradiation, neutrons and ethyl methane sulphonate.

Brachiaria brizantha has been found to be the-best adapted pasture grass for Ceylon's dry zone [1], Its main disadvantages are a prostrate habit, elongated internodes, pubescence, and a low seed set and viability. As the attempts to improve this grass by conventional methods of plant breeding have not been successful, mutation breeding is now being tried.

The rice varieties generally grown in Ceylon have characteristically a tall growth habit, and lodge easily at high fertilizer levels. It has now

7

8 GANASHAN

been shown that the highest grain yields are associated with short stiff -strawed varieties [2]. The local hybridization program for short stiff-strawed varieties is of fairly recent origin and involves only a few varieties. Meanwhile it may be possible to transform the plant type of the varieties commonly grown by using mutagens and thereby further improve their yield.

A. EXPERIMENT WITH Brachiaria brizantha

Materials and methods

Seeds and stem cuttings of Brachiaria brizantha were irradiated with the following 6 ( to gamma-ray doses (kR):

Seeds: . (1) 0 (2) 7.5 (3).15 (4) 30 (5) 45 (6) 60 (7) 75. Stem cuttings: (1) 0 (2) 7.5 (3) 15.0 (4) 22.5 (5) 30.0 (6) 37.5 (7) 45.0

Non-imbibed seeds were used and fresh stem cuttings of equal size, with three nodes per cutting, that were taken from a well-studied clonal selection. The cuttings were planted immediately after irradiation in a germination box. Chromosome counts were made by means of the Carnoy method.

Observations and results

The germination percentage, survival percentage of seedlings and percentage of chlorophyll mutants are given in Table I. Table II gives the survival percentage of the cuttings.

TABLE I. EFFECT OF IRRADIATION ON SEEDS

Irradiation treatment

(kR)

Germination percentage "

Survival percentage of seedlings

Percentage of chlorophyll mutants

0 ' 56 , 100 i

- 0

. 7 .5 52 96 0

15.0 48 80 4

30 .0 44 60 7

45 .0 42 46 5

60 .0 18 0 -

75.0 0 _ _

9 GANASHAN

TABLE II. EFFECT OF IRRADIATION ON STEM CUTTINGS

Irradiation treatment

(kR)

Percentage of established

cuttings Initial growth

0 100 Normal

7 .5 75 Normal

15.0 100 Retarded growth, narrow leaves, light green streaks

22 .5 75 . Retarded growth, lean leaves, reduced pubescence

30 .0 50 Retarded growth, reduced pubescence

37 .5 40 Severely retarded growth, reduced pubescence and increase in lethality

45 .0 40 Severely retarded growth and increase in lethality

There was only a slight reduction in the number of seedlings at the lowest dose of irradiation but at the higher dosage levels seedling numbers were greatly reduced.' Chlorophyll mutants of the albina and chlorina types were observed at 15, 30 and 45 kR. Other types of morphological changes were also observed at 30 and 45 kR.

Stem cuttings that were irradiated with doses above 15 kR showed variations in leaf size and growth habit together with different types of chimaeras.

One mutant from the 45-kR seed treatment had.an erect growth habit with short internodes, narrow leaves and reduced pubescence.. This appeared to be the most promising mutant and was isolated for further study. Its chromosome number in pollen mother cells was 18, similar to the parent. Floral deformities and pollen sterility was also observed in this mutant.

B. EXPERIMENT WITH RICE

Materials and methods

Four indica varieties, H-4, H-8, H-7 and Pachchaiperumal 2462/11 (PP 2462/11), were treated with gamma rays, neutrons and ethyl methane sulphonate (EMS).

The doses were as follows:

Mutagen Doses

I. Gamma rays (kR) (1) 0 (2) 10 (3) 20 (4) .35 (5) 50 (6) 60 II. Neutrons (R) (1) 0 (2) 300 (3) 600 (4) 900 (5) 1200 (6) 1600

III. EMS (%) (1) 0 (2) 0.2 (3) 0.4 (4) 0.6 (5) 0.8 $

10 GANASHAN

Dry seeds were used in all treatments. Dehusked grains were used for the EMS treatment. In the M i generation the f irst three panicles at flowering-were se l f edby bagging and each panicle was harvested separately at maturity. The seed of each panicle was sown in a separate nursery and 25 seedlings on a line to a panicle basis were transplanted in the field at 20-21 days with a spacing of 15 cm and 30 cm between the lines.

Results

M j generation

Treated seeds showed different degrees of germination and the final stand was affected in some by delayed lethality. The dose giving 50% lethality in each variety under different mutagenic treatments is given in Table III.

TABLE III. LD50 VALUES

Mutagens Varieties Gamma rays Neutrons EMS

(kR) (R) ' (<?»)

1. H-4 . 60 1600 0 . 4

2. H-8 . 50 , ,1600 0 . 4

3. H-7 60 . 1600 ' 0 . 4

'4 . PP 2462/11 5 0 ' 1600 0 . 4

Different varieties exhibited different reactions to the treatments. Chlorophyll chimaeras and stunted and deformed plants were observed mostly in the variety PP 2462/11. There was also reduction of the final ' population in H-8 and PP 2462/11.

M2 generation

In the M 2 generation there were several lines segregating for chlorophyll mutants. More albina types were observed than chlorina, xantha, v irescens and zebrina. Table IV gives the percentage of the M2 'segregating lines for chlorophyll mutants in the different varieties of r i c e . '

The most frequent mutation was for seed size with short grain types being produced more than long grain types. In H-4 there was mutation for awnedness of varying degree. Awning was rare in the H-8 mutants and the awns were usually very short. Mutants producing abnormal spikelets with, elongated sterile lemmas, large lemma and normal palea, twisted spikelets, etc. were found in H-7 and PP 2462/11.

Several semi-dwarfs , • dwarfs and grass clump types were found in the taller varieties H-4 and H-8, along with a few taller type mutants. Grass

11 GANASHAN

TABLE IV. PERCENTAGE OF SEGREGATION FOR CHLOROPHYLL MUTATIONS

Mutagens ' Varieties

H - 4 H-8 H-7 PP 2462/11

1. Gamma rays (kR)

0 (Control) 0 .00 0 .00 0 .00 0.00

10 12 .51 4 .28 0 .00 6 .25

20 11 .11 10.52 1 .02 4 .02

35 7 .31 13.46 3 .07 1 .02

50 9.09 15.00 1. 06 0 .00

60 17 .14 • - 0 .00 -

2. Neutrons (R) 0 (Control) 0 .00 0 .00 0 .00 0.00

300 2 .63 9 .52 3.08 4 .26

600 6 .79 8 .73 4.68 3 .22

900 10.10 » 8 . 62 0 .80 3 .01

1200 9 .59 10.09 0 .00 5.62 '

1600 11.82 11.26 0 .00 0 .00

3. EMS (%) 0 (Control) 0 .00 0 .00 0 .00 0 .00

0 .2 1. 06 0 .64 0 .00 0.60

0 . 4 0 .00 0 .00 0 .00 0 .00

clump type mutants appeared only in the neutron treatments, whereas dwarfs were found mostly in gamma-irradiation treatments. Mutants with grass clump type characters did not flower and died in H-4, but in H-8 some flowered and produced seeds.

There was also mutation for sterility and date of flowering. In the short aged varieties PP 2462/11 (3 months) and H-7 (3| months) there were mutants of longer age. But the medium aged varieties H-4 and H-8 (4 to 4 j months) gave mutants of short and long aged types.

Only changes in seed size were observed in the EMS treatment, where-as the other two physical mutagens gave a wide spectrum of mutations and several mutated characters often appeared simultaneously.

DISCUSSION

These are the first set of results obtained and they relate mainly to the morphological changes.

12 GANASHAN

In the Brachiaria mutant the erect plant habit would permit the growth of an associated legume, while the lower pubescence would im-prove its palatability. The rapid rate of recovery after defoliation would permit grazing at a much earlier stage of growth. In the rice varieties mutants have been selected with short stature and different dates of flowering. Estimates of herbage production in the Brachiaria mutant and grain yields of the r ice mutants are still to be made.

A C K N O W L E D G E M E N T S

This work was made possible with the assistance of the International Atomic Energy Agency. Grateful acknowledgement is made to the Project Leader, Dr.J.W.L. Peiris, Deputy Director (Research), Department of Agriculture, Ceylon and to Dr. G.W.E. Fernando, Agrostologist, Agri -cultural Research Station, Maha-Illuppallama who was closely associated with the investigations on Brachiaria brizantha.

R E F E R E N C E S

[ 1 ] FERNANDO, G . W . E. , Grassland farming in the dry zone, Trop. Agric. Mag. Ceylon agric. Soc. 114 (1958) 183.

• [ 2 ] TANAKA, A . , KAWANOK, K. , YAMAGUCHI, J. , Photosynthesis, respiration, and plant type of the tropical rice plant, IRRI Technical Bulletin 7 (1966) 46.

D I S C U S S I O N

P.KHAMBANONDA: Could you tell us more about EMS treatments of dehusked grains of r i ce? Do you have difficulties in germinating de-husked seeds after EMS treatments? Do you think one can obtain the same mutation frequency with EMS without dehusking?

P. GANASHAN: We germinated the dehusked seeds after EMS treat-ments under controlled hydration in petri dishes. On the third day after the seeds had been kept in controlled hydration, they were planted in seedling boxes where optimum conditions were given for proper seedling growth. The seeds receiving the highest concentration of EMS did not ... germinate and they were attacked by an ashy-brown coloured fungus. In answer to the second question, we can use husked seeds as well for EMS treatments, but I feel that dehusked seed will permit more penetration of the chemical, and the mutagenic effect will be greater. However, a de-tailed study is required before making firm conclusions.

K.I.SAKAI: I understand that lodging is one of the most important problems in rice production in Ceylon. Did you succeed in obtaining any mutants resistant to lodging?

P. GANASHAN: Lodging resistance is one of the most important ob-jectives in our rice breeding program. From our radiation work we were very successful in isolating several lodging-resistant mutants. Lodging-resistant mutants were also obtained from the most popular variety of Ceylon, which has round grain (Samba type). Their yield potentials and

•resistance to diseases have yet to be tested.

PRESENT STATUS OF RICE BREEDING BY INDUCED MUTATIONS IN TAIWAN, REPUBLIC OF CHINA*

C . H . HU Taiwan Provincial Chung-Hsing University, Taichung, Taiwan and H.P. WU, H . W . LI Academia Sinica, Nankang, Taipei, Taiwan, Republic of China

Abstract

PRESENT STATUS OF RICE BREEDING BY INDUCED MUTATIONS IN TAIWAN, REPUBLIC OF CHINA. Since 1957, fourteen varieties, including both indica and japonica, have been treated with X-rays, gamma rays, thermal neutrons and EMS for inducing mutations. The object ives are: (1 ) To obtain erectoid mutants of good lodging resistance from the tall native varieties which can be adapted for intensive culture; (2) To obtain early maturing mutants with at least the same yield as the original variety, so that the multiple cropping system of Taiwan can be easily handled; and (3) To obtain disease-resistant mutants.

The results obtained suggest that after a useful gene such as erectoid has been obtained by induced mutation, it can be used immediate ly . But in general, it will be more useful to c o m b i n e this character into other genotypic backgrounds by cross-breeding. Henceforth, further breeding must be carried out by cross-breeding. A number of promising lines were selected from induced mutants after being crossed with loca l varieties and the advanced test of these lines is being carried on at present.

Since 1957, fourteen rice varieties, including indica and japonica, have been treated with X-rays , gamma rays, thermal neutrons and EMS to induce mutations. The objectives were: (1) To obtain erectoid mutants with good lodging resistance from the tall native varieties which can be adapted for intensive culture; (2) To obtain early maturing mutants with at least the same yielding ability as the original variety, so that the multiple cropping system of Taiwan can be easily handled; and (3) To obtain disease-resistant mutants. The progress reports of this breeding work have been published in various journals and the results obtained from the experiments done last year are reported in this paper.

1. Regional yielding trial of induced mutation lines in Taiwan

The X-ray-induced mutation lines of Sh 30-21 and KT 20-74 were tested in the island-wide regional tests sponsored by the District Agricultural Improvement Stations (DAIS) of Taiwan last year. The results showed that the grain yield of these two mutation lines was not

sp This is a co -operat ive project of Academia Sinica and Taiwan Provincial Chung-Hsing University.

13

14 SWAMINATHAN- et al.

TABLE I. RESULTS OF THE REGIONAL YIELD TRAILSa

( k g / h a , 1968)

Location Taipei Hsinchu Taichung Tainan Kaohsiong Average

Variety Yield Order Yield Order Yield Order Yield Order Yield Order Yield Order

YH 1 1 4116 7 4340 10 6177 7 6130 3 5055 16 5164 9

YH 1 II 3145 3 2570 4 4260 13 2905 13 3386 11 3253 7

K T 20-74 I 3846 14 4050 15 6287 5 5270 15 5205 12 4932 16

K T 20-74 II 2715 12 2195 8 4249 14 3150 7 3100 14 3082 11

Sh 30 -21 1 3959 12 4310 11 6070 9 5795 11 5075 15 5042 12

Sh 30 -21 II 1590 16 2130 9 4200 16 2775 16 3040 15 2727 15

IR 9 -60 1 3908 13 4900 4 6003 10 5505 13 5181 14 5059 11

IR 9 -60 II 2740 10 2080 10 4468 11 2850 14 3809 4 3189 8

4077 9 4060 14 6133 8 5365 14 5319 10 4995 14 Taichung-shen-yu 15

II 1810 14 1190 16 3850 18' 2935 10 3746 5 2706 16

I 4085 8 4960 1 6406 4880

1 5795 11 6125 5 5474 2 Taichung-shen-yu 16

II 2968 5 1645 13 6406 4880 5 2695 17 3410 10 3120 9

4493 2 4940 2 6306 4 6125 4 6014 6 5576 1 Taichung-shen-yu 17

II 2720 11 1765 12 4551 9 3135 9 4112 1 3257 6

3510 15 4450 9 5976 11 5805 10 5203 13 4989 15 Taichung-shen-yu 18

II 2050 13 1910 11 4229 15 2930 11 3337 13 2891 13

Taichung-shen-yu 19 4238 4 4500 7 5560 17 5900 9 5997 7 5239 7

Taichung-shen-yu 19 II 2740 10 1365 14 4109 17 2820 15 3499 8 2907 12

3112 16 4240 12 6256 6 5675 12 5912 9 5039 13 Taichung-shen-yu 20

II 1703 15 1350 15 4600 8 2925 12 3705 7 3110 10

4217 5 4230 13 5936 13 6100 5 6461 2 5387 5 Kaohsiung-shen-yu 2

II 2970 4 2400 6 5228 2 3470 3 3853 3 3584 2


II 2878 9 3080 1 5115 4 3365 5 3364 12 3560 3


II 2930 7 2545 5 4701 7 3235 6 3461 9 3374 5


II 3473 1 . 2600 2 4497 10 3630 2 . 3925 2 3625 1


II 2945 6 2575 3 5292 1 3145 8 3710 6 3533 4

3964 11 8

4610 5 6390 2 5925 8 5225 11 5223 8 Taichung Native No . 1

II 2900 11

8 2390 7 3040 15 2777 14

Taichung-shen-yu 7 I II

' 4313 12

Taichung-shen-yu 14 I II 4701 6

Taichung-shen 2 I II 3370 4

A i - c h i o - c h i e n I

II 3435 2

Min-Tang-Tsieh I II 5168 3

Chung-Lin-Chung I II 4150 1

3 Data from Department of Agriculture and Forestry, Taiwan Provincial Government, April 1968.

HU et a l . 1 5

higher than the other short-stature varieties which were offered by the DAIS. YH 1, a selected line f rom the hybrid of T(N) 1 X Sh 30-21, yielded more than its parents. The YH 1 yield exceeded that of T(N) 1 by about 3.5% in Taipei and Tainan in the f irst crop and by 17% in Taipei, Hsinchu and Kaoshung in the second crop. .But YH 1 was not the highest yielding variety in this trial (see Table I). These regional trials will be continued.

2. Extension of YH 1 and YH 2 trials by farmers in Chaiyi and Luckon

Before a new variety is recognized by the Government it must pass the above regional yielding trial for at least two years. The demonstra-tion of new varieties together with local ones will be taken up by the DAIS and/or by the Farmers ' Association of Taiwan (FAT). Although YH 1 is still on trial it has proven to be very successful in the Chaiyi area near the tropic of Cancer where it was grown on about one hectare of farmland. The data show that YH 1 yielded 7050 kg/ha in the second crop of 1967 and 8487 kg/ha in the first crop of 1968. These two crops out-yielded T(N) 1 (the check) by 30% and 19.4% respectively (see Table II). Because of the excellent results obtained, FAT in Chaiyi is going to extend YH 1 to about 50 hectares in the second crop of 1968.

YH 2 and YH 3, the selected lines f rom hybrids of T(N) 1 X KT 20-74 and T(N) 1 X Sh 30-21 respectively, were also grown on a small scale in Chaiyi. As shown in Table II the grain yield of YH 2 is almost the same as that of YH 1, whereas YH 3 yields less . But YH 3 is an early-maturing variety that 'matures 7 - 1 0 days before T(N) 1. YH 2 also grew well in Luckon, a coastal region near Taichung. This is a monsoon region with strong seasonal winds in the late fall, so the r ice yield never reaches 6000 kg/ha per crop. YH 2 was able to reach the goal with a yield as high as 6094 kg/ha in the first crop in 1967. The Farmers ' Association in Luckon is also planning to extend YH 1 and YH 2 in 1969.

TABLE II. RESULTS OF THE DEMONSTRATED TRIALS IN CHIAYI REGION a

(kg/ha dry seeds)

Variety T (N) 1

Variety YH 1 YH 2 YH 3

T (N) 1

Duplication YH 3

( check)

I 8208 8504 8056 6948

II 8568 8680 7996 7452

III 8280 8120 7292 7488

IV , 8892 8504 8668 6552

Average 8487 b 8452 b 8003 b 7110

% 119.6 118 .9 112.6 100.0

a Data from Farmers' Association in Chiayi . k Significant at l fo l eve l .

M . R . T . : D d ) = 680, 15 (3 ) = 660, 0 ( ^ = 628.

16 SWAMINATHAN- et a l .

3. Cross-breeding in Taichung

Taichung is the agricultural centre of Taiwan. The rice varieties from Taichung, e.g. Taichung 65, T(N) 1, have been developed by c ross -breeding a variety with a good performance and one with wide adaptability. Sh 30-21 and KT 20-74 were first developed in Taichung and are now used as parents for cross-breeding. The following hybrid lines are being tested in the experimental field of Chung-Hsing University.

/

F2 generation. 17 cross combinations were obtained with the particular aim to obtain resistance to blight disease. The resistant parent varieties were kindly supplied by Dr. T.T. Chang of IRRI, Philippines.

F3 generation. 182 lines were selected from the annual F2 populations of KT 20-74 X IR-8 and others. According to reports of IRRI and Chang [1, 2], IR-8 responds well to nitrogen fertilizer, has strong culms and wide adaptability in tropical countries. But IR-8 is too late and low yielding in sub-tropical zones such as Taichung, and is not cold resistant at the nursery stage. However, the F2 population shows a wide range of variation which enables selection of some early types with good tillering ability and resistance to leaf stripe disease.

F6-7 generation. 11 of 29 lines exceeded T(N) 1 in yield in the first crop of 1968. This trial will be continued in the second crop of 1968. Hence the grain yield of T(N) 1 is good for the first cropping season in Taiwan but not so good in the second cropping season. High yielding strains, particularly in the second cropping season, are being sought.

F3-9 generation. The advanced yielding trials were carried out in four places around Taichung. The results showed that the yield of 641-5121

exceeded T(N) 1 by 10.4 and 5.3% in Erh-Fen Pu and Erh-Lin respectively, but was less in the experimental fields of Chung-Hsing University. On the other hand the YH 2 yield was better in Luckon but less in the above two places. The early-maturing variety, YH 3, gave poor yields in these trials.

DISCUSSION

At the beginning of the radiation breeding work, it was believed that radiation might be useful to improve the weak characters of the existing rice varieties in one stroke, such as lodging resistance, disease resistance and early maturation, etc. As a result, the induced mutants with similar genotypes were considered to have the characters of the parent varieties, except the mutated characters. Also, the method seemed to be more attractive and effective than conventional breeding. The successful use of radiations by Gustafsson to induce favourable mutants in barley and by Gregory to induce resistance to leaf spot disease in peanuts gave us courage to enter this work. But we did not take into account the fact that the varieties used by the farmers

1 A selected line from the hybrid of Siam's King X Sh 30 -21 .

HU et a l . 17

TABLE III. YIELD OF indica ERECTOIDS IN THE REGIONAL TRIALS IN OUR PROGRAM (1st. crop, 1968)'

Location

Variety •

Chung-Hsing University

Luc kon Erh-Fen-Pu Erh-Lin Average

Taichung kg/ha 5476 6670 7053 7580 6694 .8 Native No . 1 Native No . 1 (as check) % . 100 .0 100.0 100 .0 100 .0 100 .0

YH 2 63 11-21123

% 101 .4 103 .0 9 9 . 4 97 .2 100 .4

YH 3 63 II -1441

% 94 .0 86 .5 9 7 . 8 7 9 . 5 89 .5

63 11-1642 1° 9 3 . 1 ' 94 .6 9 7 . 5 9 0 . 1 93 .8

64 1-512 % 9 2 . 9 100 .8 1 1 0 . 4 a 105 .3 102 .4

As-60 to 89 .7 9 4 . 2 ' 100 .2 9 0 , 8 93 .7

64 1-541 % 8 9 . 4 9 0 . 0 9 3 . 5 - 9 5 . 3 9 2 . 1

As-AK % 8 6 . 5 8 8 . 0 9 5 . 9 9 4 . 3 91 .2

63 11-1551 % 8 5 . 4 8 6 . 5 9 5 . 5 8 2 . 2 8 7 . 4

64 1-111 % 8 4 . 9 9 1 . 7 105 .4 9 3 . 8 94 .0

64 1-311 °lo 84 .2 9 8 . 5 101 .6 9 5 . 3 9 4 . 9

63 11-3672 % 8 1 . 8 . 91 .5 9 9 . 7 . 9 0 . 2 90 .8

a Significant at 5% l e v e l .

were also changeable. In Taiwan, because of the great improvement in agriculture and the farmers ' knowledge, the native varieties have now completely changed.- When we started the mutation breeding work, almost all the native varieties were tall, lodging and not intensive. We are seeking erectoid mutants of different varieties and frequently em-phasize this point. The short-stature variety, such as T(N) 1, and others were gradually but extensively taking over. The trait of lodging resistance is no longer sufficient for the farmers' needs. The intensive, early, disease resistant and high-yielding varieties are required. As a matter of fact, the farmers have put a lot of effort into seeking any new, good variety even without guarantees from the Government. The present situation is that we should study any possible method of breeding.

As previous papers have indicated [3,4] the semi-dwarf gene of in-duced erectoid mutants from different varieties, was considered to be at the same locus as that being found from spontaneous origins (Dee-geo-woo-gen, a parent of T(N) 1), but different yielding according to the

18 SWAMINATHAN- et a l .

genotype of other characters interacting with the same semi-dwarf gene. The component characters of grain yield, therefore, would be different. As a matter of fact the varieties in Table I are all the same type as T(N) 1, but with different grain yields. The induced erectoid mutant would be a good example for further trials in induced mutation breeding in the future, not only for direct field use but also for indirect use as parental material for cross-breeding.

SUMMARY

1. The induced mutants of Sh 30-21 and KT 20-74 were tried out in the Taiwan island-wide regional trials in 1967 and showed that the yield was a little less than that of the variety YH 1, a selected line from the hybrid of T(N) 1 X Sh 30-21. The yield from YH 1 exceeded T(N) 1 by 3.5% in Taipei and Tainan in the first crop and by 17% in Taipei, Hsinchu and Kaoshung in the second crop. But YH 1 was not the highest yielding variety in this trial. 2. YH 1 is particularly good in the Chaiyi area (between Taichung and Tainan). A comparison of the yields of YH 1 and T(N) 1 in this area by large-scale demonstration trials showed that the grain yield of the former was 7050 kg/ha in the second crop of 1967 and 8487 kg/ha in the first crop of 1968, which showed that the former out-yielded the latter by 30% and 19.4% respectively. The Farmers ' Association of Taiwan in Chaiyi city is going to extend YH 1 to 50 hectares in the second crop of 1968. 3. ' YH 2, a selected line from the hybrid of T(N) 1 X KT 20-74, has a similar grain'yield to YH 1 and proved to be particularly good in Luckon, a coastal area near Taichung. The Farmers ' Association of Taiwan in Luckon also plans to extend YH 2 in 1969. 4. Cross-breeding was carried out by using induced mutants of Sh 30-21 and KT 20-74 and other good performance varieties. The generations F2 to F1() are now being tested.

R E F E R E N C E S

[ 1 ] The International Rice Research Institute Ann. Rep. 1966, (1967) 65-66 . [ 2 ] CHANG, T. T . , The genetic basis of wide adaptability and yielding ability of rice varieties in the

Tropics, Int. Rice Commn Newsl. 1 £ ( 4 ) (1967) 4 . [ 3 ] LI, H . W . . HU, C . H . , WOO, S . C . , Further report on mutation breeding of rice in Taiwan since

1957, Bot. Bull. Acad , sin., Shanghai 6 (2) (1965) 131. [ 4 ] LI, H . W . . HU, C . H . , WOO, S . C . , Induced mutation breeding of rice in Taiwan, Ibid. 7(2)

(1966) 71.

D I S C U S S I O N

K.I. SAKAI: You mentioned that several semi-dwarf mutants induced by irradiation were the same as those resulting from spontaneous muta-tions. Is there any variation among those mutants with respect to dwarf-ness or other characters ? Are these mutant genes perhaps multiple alleles on the same locus?.

HU et al. 19

C.H. HU: One does find different characters among the semi-dwarf mutants obtained from different varieties. Diallel crosses have been made between T(N) 1 and induced semi-dwarf mutants, but no segrega-tion was found with regard to height. In the cross KT 20-74 X IR-8, about 0.2% of the F2 population consisted of tall plants. This suggests that different sites of the semi-dwarf gene may be present.

M.S. HAQ: Are the mutant varieties which lost short-day sensitivity, also insensitive to temperature?

C.H. HU: There was no change with regard to temperature sensitivity.

RICE BREEDING WITH INDUCED MUTATIONS IN FRANCE

R. MARIE Station d'Amelioration des Plantes, Institut National de Recherches Agronomiques, Montpellier, France

Abstract

RICE BREEDING WITH INDUCED MUTATIONS IN FRANCE. Mutation experiments with rice at . Montpellier yielded strains with improved lodging resistance, grain size, maturing t ime, mill ing quality and other characters. The general performance o f these mutant strains was tested in f ie ld trials. Further mutagenic treatments were made to improve the high-yielding short grain varieties with regard to grain quality and seed dormancy.

At the Plant Breeding Station of Montpellier (South of France), studies have been conducted on rice mutation since 1957.

The number of varieties able to ripen in the French Mediterranean region is relatively low compared with the number of rice varieties in the world, chiefly because of the photoperiodic response: most foreign varieties, being adapted to shorter day-lengths, cannot flower in our rice area (43° 25' to 43° 50' latitude N), and many of the varieties which can flower do not ripen. In 1968 our collection contained 130 varieties from 18 countries; these are the only varieties retained for further study after testing 2335 strains, originating from 48 countries of various lati-tudes, during 21 years.

Some of the objectives in our rice improvement program, i . e . yield,^ yield regularity and quality of the grain, have been reached by normal crossing and breeding methods. The first desired change by mutation was to produce a good resistance to lodging in the early varieties, which •• were all susceptible under our environmental conditions (Allorio, Maratelli, Precoce Corbetta, Bellardone, Ishikari-Shiroke). We began in 1957 to irradiate Allorio, Maratelli and Precoce Corbetta .with gamma rays. Our. most spectacular mutant, Allorio "Lambda" (named " Professor Lamarque"1) has a shorter culm, a better resistance to lodging and an increased yield (about 50%) in comparison with the starting variety Allorio 11. On the other hand, it ripens about 6 days later and its milling quality is in-sufficient: this interesting mutant encouraged us to continue with mu-tation. Maratelli gave only a chlorophyll mutant and Precoce Corbetta two erectoid mutant lines with a bigger grain, but not a superior yield.

The mutation program was extended to other mutagens (such as X-rays and EMS) and to other varieties: Cesariot, Stirpe 136 X Sesia, Americano 1600, Balilla 28 and Cigalon. Besides useful variations, which are a very small minority of the induced mutations, we detected in the progenies of treated seeds a great number of types of botanical interest, but without practical value for rice growers.

1 Professor P. Lamarque, head of the Centre de Lutte contre le Cancer , Montpell ier , has given us valuable help since 1957 with his assistant Dr. J. Garv-Bobo.

21

F A O / I A E A / I R R I UNIFORM Y I E L D T R I A L FOR I R R A D I A T E D japon i ca RICE M U T A N T S A N D H Y B R I D S E L E C T I O N S

R E S U L T S IN F R A N C E • ,

A . GENERAL DATA

Harvest year : 1967

Locat ion; No . 11

Location n a m e : Saujan (Gard) France

Annex o f Montpel l ier Plant Breeding Station.

Worker's n a m e : R. Marie

Seeding date : 6 May , 1 2 6 t h day o f the year •

Harvest date ; 18 October , 2 9 1 s t day of the'year

Experimental design; 4 randomized c o m p l e t e blocks

Plot area: 5 . 5 8 m 1 ( 1 . 2 0 X 4 . 6 5 )

Number o f seedlings per h i l l : 1 ( 2 grains sowed, then adjusted)*

Row distance: 30 c m

Hill d istance: 15 c m

Latitude: 43 degrees 44 minutes (N)

Longitude: 4 degrees 37 minutes (E)

Precipitations during the test period: 68 .6 m m - Irrigation: about 2000 m m

Fertil izer applied to the exper iment : NPK: 100, 144, 72

f o rm: ( N H 4 ) j S 0 4 ; C a ( P 0 4 ) 2 ; K , S 0 4

dates: for P and K: 1 2 Apri l ; for N: 27 April and in top dressing 17 June

appl i cat ion ; by hand

Seasonal c l i m a t i c condit ions: very g o o d .

No transplanting because o f the lack of water for a nursery.

B . RESULTS

1 . G e n e r a l b e h a v i o u r

Maturing characteristics Variety Country Date of heading

Average height ( c m )

Remarks on 18 Oct . (normal date o f harvesting)

Normal ( i ) Allorio 11 , Control France 1 Aug. 135 Harvested and tested

(2) Allorio Lambda Mutant from (1) • France 2 Aug. 90 Harvested and tested

(3) Balilla Local check France 14 Aug. 85 Harvested and tested

Late (4) R. 90 Mutant from (9) Japan 18 Aug. 95 Harvested and tested

Uncertain (5) Fukei 71 Mutant from (7) Japan 18 Aug. 65 Spikelet sterility: 20 to 30%. Harvested for a new trial in 1968

(6) Reimei Mutant from (7) Japan 19 Aug. 85 Irregular germination and growth. Harvested for a new trial in 1968

(7) Fujiminori Control Japan 17 Aug. 95 Irregular germination and growth. 90% unripe grains. Harvested for 1968

(8) San In 73 Mutant from.(12) Japan 20 Aug. 95 Irregular germination and growth. Harvested for a new trial in 1968

Not maturing 0 ) Koshihikari ' Control . Japan 10 Sept. 95 Hard dough stage

(10) From Taichung 65 Mutant Taiwan 11 Sept. 90 Soft to hard dough stage

(11) Tainan 3 Hybrid Taiwan 12 sept . 95 Soft dough stage

(12) Notin 22- Control Japan - 20 Sept. 100 Complete heading but spikelet sterility 100%

(13) FF 36 Hybrid Taiwan 2 Oct . 70 Half -headed

2 . O t h e r data o n r i c e v a r i e t i e s

Panicles/m* (4 blocks) (av . ) Panicles/plant ( a v . ) ' Yie ld g / p l o t (14 .5 % grain moisture) ( a v . ) Average yield

(g /ha )

Allorio 11 206 175 211 200 - 198 9 3 7 . 9 9 . 5 9 0 8 . 9 2305 1705 1970 2225 2051 3 9 . 3 Allorio Lambda 368 313 301 353 334 16 6 - - 1 4 . 1 13 .6 15 9 15 .0 . 3705 4100 3660 3300 3691 70 .7 Balilla 304 278 264 311 .', 290 13 7 • 12 .5 • 11 .9 14 0 - 13 .0 - 4285' 3495 3705 3550 3759 7 2 . 0 R. 90 422 412 420 387 411 19 0 1 8 . 6 18 .9 17 4 18 .5 3925 4395 3670 4000 3998 76 .6

L. •d. ( 0 . 0 5 ) 10 .0

24 MARIE

At the present time our Station possesses 195 mutant strains screened in these mother varieties and selected according to the following two criteria:

1. For characters of agricultural interest:

With X-rays : 4 mutants less sensitive to lodging, with larger grain, and earlier maturity.

With gamma rays: 84 mutants with shorter and stronger culms, more resistance to lodging, increased yield, earlier and later maturity, larger and slender grain, better milling quality, or better commercial quality.

With ethyl methane sulphonate: 7 mutants with shorter and stronger culms, more resistance to lodging, increased yield, earlier and later maturity, larger and slender grain, better milling quality, or better commercial value.

2. For characters without practical value;

100 mutant lines, obtained after treatments with X-rays, gamma rays and ethyl methane sulphonate. They are kept in the stock collection only for teaching purposes and theoretical studies.

Our first good mutant, Allorio Lambda was discarded in 1965 for its poor milling quality. On the other hand, in 1968 we began to test the performance of a larger grain mutant, induced in Cesariot in 1961 by gamma rays, which satisfies the present-day requirements of the French market.

The short grain varieties, which are much appreciated by the rice growers for their high yield, need to be improved in respect of their commercial value: they should be entirely vitreous or translucent and without chalky spot (white belly). We have worked towards this goal since 1963 and some strains without spot have been induced in the varieties Balilla and Cigalon. They are still under selection. We must point out that the "vitreous" mutants present, in addition, some changes in the grain size and shape and in the duration of the vegetative cycle.

Finally, we are carrying on a mutation program for inducing dormancy in the non-dormant variety Cigalon: this type of mutation is very easy to screen and interesting for a physiological study of dormancy in seeds.

MUTATION BREEDING IN RICE IN INDIA

M . S . SWAMINATHAN, E. A. SIDDIQ, C.B. SINGH, R.A. PAI Indian Agricultural Research Institute, New Delhi, India

Abstract

MUTATION BREEDING IN RICE IN INDIA. Mutation research was continued in rice with the fol lowing aims: (a) to enhance the frequency and spectrum of mutations in indica and japonica r i ce varieties; (b) to change the grain quality o f ' the japonica variety, Tainan-3 f into the indica type; ( c ) to improve the grain quality o f the indica variety, IR-8; (d) to increase the recombination frequency in japon i ca - ind i ca hybrids.

Both nitrosoguanidine and 5 - M e V fast neutrons gave a high mutation frequency. The japonica variety was more sensitive to all mutagens than the indica types. Chemica l mutagens had no particular advantage over ionizing radiations with reference to either mutation frequency or spectrum.

Mutants with indica type of grain occurred readily in Tainan-3 in all treatments. Such mutants had a larger grain length/ width ratio and were more resistant to alkali digestion.

Fine grain types with better cooking quality occurred in.the M 2 populations of IR-8. These mutants are likely to render this high-yielding variety more popular.

A wide range o f chlorophyll and viable mutations occurred in IR-8 and Ta inan-3 . Some of these, like those involving dwarfing and slow senescence, are of e c o n o m i c interest, besides those affecting grain quality.

Recombination frequency can be influenced in japonica X indica hybrids through the irradiation o f Fj sporocytes.

The precise influence varies with the stage at which the plant is irradiated, the dose given and the l o c i invo lved .

INTRODUCTION

The development of high-yielding semi-dwarf indica varieties in Taiwan and at the International Rice Research Institute, Philippines, by using the Dee-geo-woo-gen dwarfing gene has helped to dispel the old notion that japonica (ponlai) varieties alone are capable of responding well to the application of fertilizers. Dwarf indicas such as T(N)1 and IR-8, and several tropical japonicas like Tainan-3, Taichung-65 and Kaoshiung-68 have done well in India and have yielded from 5 to 9 tons per hectare. Despite their outstanding features like high-yielding po-tentiality, photo-insensitivity and synchronized tillering T(N)1 and IR-8 are becoming unpopular because of their coarse grain, inferior cooking quality and high susceptibility to bacterial leaf blight and tungro virus. Although the ponlai varieties like Tainan-3 possess a high degree of resistance to bacterial blight and can give high yields,' they are unpopular in India because their grains become sticky on cooking.

Since the release of IR-8 another culture, IR-5, which possesses a high head milling rice recovery with a relatively higher degree of resistance to various diseases and better cooking quality than IR-8, has been evolved at the IRRI. Extensive studies on IR-5 in India have shown that it matures very late. Keeip'ing in mind all the merits and demerits of these recent introductions, mutation breeding was initiated with the following objectives:

25

2 6 SWAMINATHAN- et al.

(a) Mutational rectification of grain size and cooling quality in IR-8 (b) Conversion of the grain quality of ponlai types (Tainan-3) to that

of the indica type (c) Induction of mutations for earliness in IR-5.

Besides taking up work on these applied aims, systematic studies were carried out on the maximisation of mutation frequency and spectrum in indica and japonica rices.

The non-recovery of desirable recombinations, which is presumably due to either cryptic structural differences or other genetical factors resulting in tight linkages, and also defective screening procedures ap-pear to be the main reasons for the failure of the indica X japonica hybridi-sation program sponsored by FAO in 1951. Since radiation can be used as a tool for increasing recombination, studies were undertaken to measure recombination frequency in F2 populations derived from irradiated Fj material.

MATERIAL AND METHODS

In studies on the maximisation of mutation frequency and mutational rectification of undesirable traits, three high-yielding varieties (two representing indica and one japonica subspecies of (X sativa) were used. The salient features of these varieties are given in Table I.

For studies on the influence of radiation and chemical agents on the recombination frequency in japonica X indica hybrids, the following ma-terial, kindly supplied by Dr. T . T . Chang, was used.

Parental combination Marker genes involved

1. N-45X IR-8 pusur (Japan) N-45 : d6 . - T o p leafed dwarf CBP- Chromogen A -Activator PI - Purple leaf

2. 1-45 CharnackX A-58, Kokushopento-2 ' A-58 Kokus (Japan) . CB - Chromogen

A -Activator Pr - Purple hull Ph - Phenol staining Pn - Purple node , Wx - Waxy glutinous

Similar studies were also taken up in reciprocal combinations of the following crosses which, however, do not have distinct markers:

(a) IR-8 Tainan-3 (b) T(N)1 X Tainan-3 (c) Basmati 370 X Tainan-3

Method

Seeds with 12 - 13% moisture content were treated with different doses of gamma rays, fast neutrons, ethyl methane sulphonate (EMS),

SWAMINATH AN et al. 27

nitrosomethylurea (NMU) and nitrosoguanidine (NG) at a constant tempera-ture of 28°C. In the chemical treatments, seeds pre-soaked for 5 h were immersed in the aqueous solutions of the mutagen with intermittent shaking for 8 h at pH 7. The M2 generation was grown from the seeds of selfed M1 plants. The M^ plant progenies and the M- spike progenies were kept separate.

RESULTS AND DISCUSSION

I. Mutation studies on indica and japonica varieties

A detailed study of the effects of physical (gamma rays and 5-MeV fast neutrons) and chemical (EMS, NMU and NG) mutagens was carried out on IR-8 (indica) and Tainan-3 (japonica).

To assess the relative efficiency and effectiveness of nitrosoguanidine, which is a new addition to the series of potent chemical mutagens, in comparison to that of gamma rays, EMS and NMU, a detailed study was made on IR-8. Data on the percentage of Mi survival indicated that the toxicity of NG and NMU -was very high, followed by that of gamma rays and EMS. The LDS0 seemed to be 30 kR with gamma rays and 0.5%, 0.015% and 0.010% with EMS, NMU and NG respectively (Table II).

Data on the frequency of chlorophyll mutations, as measured by the percentage of M2 families segregating, indicated that NG induced the most and NMU the.least at biologically equivalent doses. Although there was a positive correlation between lethality and mutation frequency in gamma-ray, EMS and NG treatments, it was quite the reverse in treat-ments with NMU (Table III). The order of mutagenic efficiency and effectiveness, as measured by the scheme suggested by Konzak et al. [1], of the mutagens used were as follows (cf. Table IV):

NG > NMU > EMS > gamma (Effectiveness)

NG > EMS > gamma > NMU (Efficiency)

Another characteristic of the NG treatments was the greater recovery of mutations, as expressed by a better fit to the expected segregation ratios (Table V).. Chemicals, compared with physical mutagens, tend to yield a lower segregation ratio, probably due to the operation of a less rigorous somatic sieve (cf. Ref . [2] ) . The percentage of mutations in segregating .families in NG treatments was about 23 as against about 17 and 19 in gamma-ray and EMS treatments respectively (Table V). This is probably due to a lower number of sector cells partaking in the for -mation of an Mj spike. . Thus, both for induction and recovery of mutations, NG seems to be quite valuable for use in rice.

Studies on fast-neutron treated material

Seeds of IR-8 and Tainan-3 were treated with 5-MeV fast neutrons ' through the help of the IAEA, Vienna. The percentage of survival showed almost a reverse trend beyond the dose level of 2400 rads in IR-8 and 1800 rads in Tainan-3 (Table VI).


The frequency of chlorophyll mutations in the M2 generation, as measured by the percentage of Mj spike progenies segregating, was 45. 2% in Tainan-3 and 28. 6% in IR-8. However, as in the case of sur-vival, the dose-reversal phenomenon also occurred with regard to mutation frequency (Table VII). This could be due to the onset of a more rigorous diplontic selection at doses higher than the optimum level.

Another interesting feature about the neutron treatment was its ability to induce a wider spectrum of chlorophyll mutations than other ionizing radiations and chemical mutagens (Table VIII). The data show that the frequency of albina was highest compared with the other types and that it was dose dependent. This may be due to the larger number of loci governing this phenotype. Varietal variation was evident from the relative frequencies of chlorophyll mutation types as shown in Table VIII.

Mutagenic potency indicated that the effectiveness was uniformly highest at lower doses and that the values seemed to be 7 - 1 0 times more than with gamma-rays and 2 - 3 times more than with EMS. Efficiency and dose were inversely correlated (Table IX).

Studies on the effects of neutrons on the spike initials as measured by the segregation ratio for albina seedlings indicated that the sector size was influenced by varietal difference. For instance, the ratio was nearer the expected value (25%) in IR-8, whereas the ratio in Tainan-3 • was half the value expected (Table X).

The frequency of chlorophyll and viable mutations in Tainan-3 and IR-8 after treatments with different doses of gamma-rays, EMS and NMU (Tables XI and XII) suggests that the frequency of chlorophyll mutations in Tainan-3 after gamma-ray and EMS treatments was more or less the same, whereas it was considerably lower after the NMU treatments. The trend in viable mutations was almost the same as in chlorophyll mutation. Unlike with Tainan-3, IR-8 showed the highest mutation frequency after gamma-ray treatments followed by NMU and then EMS. Although the chlorophyll mutation frequency after EMS treatments was the lowest, viable mutation frequency after these treatments was on par with that of gamma-ray treatment. NMU induced a relatively lower mutation frequency (both viable and lethal) compared with gamma-ray treatments. These findings are in agreement with our earlier results with rice that gamma-rays are as potent as any efficient chemical mutagen known.

Mutants of economic interest

The isolation of indica-like grain mutants in Tainan-3 and of fine grain types in IR-8 being the 'applied' objectives, the M2 population was carefully screened for grain characters. It is evident from the data in Table XIII that mutations for indica grain in gamma-ray treatments are as high as in EMS treatments. It is also apparent that the frequency of their occurrence has a tendency to be higher when dehusked seeds were treated. Alkali digestion tests of these mutants revealed that they are superior to their parents in having a moderate gelatinization tempera-ture. Apart from their economic value, the occurrence of such mutations lends further support to the view that the sub-specific differentiation in O. sativa has proceeded by the clustering of mutations probably under the influence of disruptive selection. The occurrence of fine grain mutants in IR-8, as judged by the increased L /B ratio, suggests that


mutation breeding can be a potent tool for altering the grain characters. The KOH test (2.4%) at 28°C for 24 h revealed that the fine-grain types withstand disintegration better than IR-8. Seeds are being multiplied for large-scale yield trials during 1968. A list of the major types of viable mutations recorded in IR-8 and Tainan-3 is given in Table XIV.

II. Enhancement of mutation frequency by synchronising the time of mutagen treatment with the DNA synthesis

Dehusked seeds of Tainan-3 and Taichung-65 were treated with 1% EMS for one hour after pre-soaking periods of 8 to 22 h (Tables XV and XVI). The data on the percentage of germination and survival show a drastic reduction in the seed lots presoaked for a period ranging between 18 and 22 h. The mutation frequency and spectrum in these treatments are being studied.

III. Increasing the diffusion rate of chemical mutagens

Dimethyl sulphoxide (dMSO) is considered to be an efficient carrier of chemical mutagens in higher plants. Earlier reports by various workers indicated that dMSO has no apparent inhibiting effect on the growth of the treated plants. The present findings in rice, however, show a marked effect of the chemical on germination and survival (Table XVI). The percentage of seedling lethality after dMSO treatment was as high as after EMS and dES treatments. Combined treatments of EMS (l%) + dMSO (5%) also showed the same levels of germination and survival as with dMSO (5%) alone. The effects of dMSO in combination with EMS on mutation frequency is being assessed.

IV. Promotion of crossing-over in indica X japonica hybrids

Studies were carried out on: (a) The effects of radiation and chemical treatments on chiasma

frequency and panicle fertility; and (b) The recombination frequency in the F2 progenies derived from

normal and irradiated F1 plants.

Studies on the immediate effects of the mutagenic treatments as measured by the chiasma frequency (Table XVII) revealed that there was a significant increase after radiation treatments. In general, the dose and the number of chiasmata were found to be inversely correlated, ex-cept for the doses 240 and 480 R (Table XVII).

To study whether the sensitivity is different at different stages of flower development and whether there are significant differences caused by a lapse of time between treatment and fixation, panicles were fixed at two different intervals, i . e . 24 and 48 h. The data show a decline in the chiasma frequency with an increased period between treatment and fixation.

The average panicle fertilities in the control as well as in treatments with X-rays and mitomycin C (MC) were nearly the same.


Recombination frequency

The recombination studies in the cross N-45X 1-68 (pusur) restricted to two genes, namely d6 and PI, revealed that the recombination per-centage was considerably increased after X-ray and MC treatments given at the pre-meiotic stages (Table XVIII). Treatments at the post-meiotic stage showed the same or a lower recombination percentage than the control. In the non-treated branches of the same plant there was a drop in the percentage of recombination, except at 240 R (Table XIX).

Similarly, in the second cross between I-45(Charnack)X A-58 (Kokushopento-2) recombinations for various markers located within and between linkage groups were calculated in the control and treated populations (Table XIX). It was observed that the response to radiation of the recombination frequency for different gene combinations differed significantly. The influence of mutagens on the recombination of genes within the linkage group was found to show an increase for genes CB and WX, whereas in the case of genes A and Pn, which are located on linkage group III in japonica, showed a decrease. Probably, the relative positions of these two genes are quite different in indicas, although they are located in the same linkage group in japonicas.

It appears from the data that the influence of mutagens on recombination values for genes located on different linkage groups is mediated through their effects on the segregation pattern. Treatments given at the pre-meiotic stage (zygotene-pachytene) led to either an increase or decrease in the recombination percentage. In the tillers, which were mostly'in the earlier stages, there was a decrease in the values thus indicating the influence of the mutagens to be stage specif ic .


T A B L E I. SALIENT F E A T U R E S OF T H R E E HIGH-YIELDING RICE VARIETIES

Variety Salient features

O. sativa subsp. indica *

(a) IR-8 A semi-dwarf (90-105 cm) high yielding (7-10 tons) variety with response to high levels of N 2 ; moderately,early maturing (110-120 days); photo-insensitive, moderate resistance to blight and tungro but susceptible to blast; low milling recovery ( 4 6 . 5 ) , Developed from the cross Dee-geo-woo-genV^Peta.

(b) IR-5 A semi-dwarf but taller than IR-8 (130-140 cm) ; " late in maturity (130-145 days); weakly photo-sensitive; resistant to blight and susceptible to some races of blast; moderately lodging and better cooking quality. Developed from the cross.

O. sativa subsp. japonica

Tainan-3 Ideal plant type, but taller than the indica dwarf (120 cm) ; high yielding; photo-insensitive; high degree of resistance to bacterial blight; early maturing (110-115 days); poor cooking quality and hard threshing.

T A B L E II. P E R C E N T A G E OF S U R V I V A L IN IR-

Mutagen Dose No. o f seeds

treated No. of plants which survived

Percentage of lethality

Control

Gamma rays 15 kR 30 kR

200

500 500

50

82 59

0.00

34.00 51.80

EMS

NMU

NG

0 ;33% 0 .50%

0.01070 0 .015%

0 .005% 0.010%

500 500

500 500

500 500

102 90

61

64 59

18.40 28.00

47.20 51.20

48.80 52.80


T A B L E III. F R E Q U E N C Y OF C H L O R O P H Y L L M U T A T I O N IN I R - 8

No. of Mj No. o f M 2 families Percentage of Mj Mutagen Dose families segregating for plant progenies •

studied mutagen segregating

Gamma rays 15 kR 30 kR

82 56

29 21

35.36 37.50

EMS 0 .33% 0 .50%

90 81

24 20

26.66 24.69

0.010% 0.015%

66 61

13 12

19.69 19.67

0 .005% 0.010%

59 64

22

34 37.28 53 .12

T A B L E IV. EFFICIENCY AND E F F E C T I V E N E S S OF I R - 8

^ ^ D Efficiency Effectiveness Mutagen ose Mutated plants/lethality Mutated plants/kR or Cone, x t i m e

Gamma rays 15 kR 1.028 ' 2.357 30 kR 0 .724 1.250

EMS . 0 .33% 1.448 10.098 0 .50% 0 .882 6 .172

NMU 0.010% 0 .417 246.125 0.015% 0 .384 163.916

NG 0.005% 0 .764 ' 932.000 0.010% 1.006 664.000


T A B L E V . P E R C E N T A G E OF MUTATIONS IN ' SEGREGATING FAMILIES O F , I R - 8

/

Mutagen Dose Segregation ratio

Gamma rays 15 kR ' 8 . 6 4 ; : 30 kR 15.36 .

EMS 0.33% ' 0 .50%

^ . . 7 . 3 1 ' 8 .22

NMU 0.010% 0.015%

6 .76 6 .79

.. NG • ' 0 .005% 1 ' 0 .010%

' • ' 20 .04 'i 22 .45

T A B L E VI. P E R C E N T A G E OF SURVIVAL IN NEUTRON T R E A T M E N T

Variety Treatment

(rads) No. of seeds No. of seedlings Percentage of germinated survived survival

IR-8. Control-. 500- " 360 ' 100

2400 1800 765 . 59

3000 1775, 1030 ; ' 7 9

Tainan-3 Control 500; 173 100

1800 , ., 1030 355"' '74

2400 1030' • ,

i

366 • 77 -

T A B L E VII. F R E Q U E N C Y OF C H L O R O P H Y L L MUTATIONS ( M 2 )

Fast-neutron IR-8 .' ' Tainan-3

Fast-neutron dose

(rads) No. of spike

progenies

Percentage of spike progenies

segregating

r • Percentage of No. of spike •. °

; . spike progenies progenies - . r ° -

segregating

1800 . - 219 " ' • 45 .2

2400 385 28 .6 148 31 .1

. 3000 409 19.1-

T A B L E VIII. R E L A T I V E FREQUENCIES OF VARIOUS C H L O R O P H Y L L MUTATIONS (M2 )

Variety Fast-neutron Frequency (in °jo)

Variety dose .(rads) Albina Xantha Chlorina Alboviridis Striata Maculata Virido alba . Tigrina

IR-8 2400 .73 .90 0 .83 16 .72 - ' ' 7 .35 . 0 . 3 3 . 0 .33 • , 0.50 •

>. 3000 82.12 2 .53 9 .90 - - ' 4 . 95 - ,*• " ; 0 .48

Tainan-3 1800 ' 44 .70 - 8.6o . ; 35 .04 5 .60" ' ' 2 .10 13 .20 . - • '0 .53 -

2400 67.50 2 .50 24 .02 3 .80 1.90

T A B L E IX . M U T A G E N I C E F F E C T I V E N E S S AND E F F I C I E N C Y OF NEUTRON T R E A T M E N T S

Variety Fast-neutron -

dose (rads)

Effectiveness

(Mutated spike/krad)

Efficiency

Mutated spike/lethality • Mutated spike/pollen sterility Mutated spike/seed sterility

1R-8

Tainan-3

2400

3000

1800

2400

11 .9

8.0

18.8

12.9

0 .698

0.910

1.738

1 .352

0 .445

0 .284

0 .644

0 .388

0 .824

0 .461

1 .232

0 .730


T A B L E X . P E R C E N T A G E OF ALBINAS IN SEGREGATING FAMILIES (ALBINA) IN- M., ' '-' . . ..; : •

-.Fast-neutron , Variety - dose

' (rads) i .

No. of albina seedlings

No. of normal green seedlings

Segregation ratio

'•IR-8 2400 72 209 - 25 .6

' 3000 100 288 • 25 .8 '

Tainan-3. " * 1800 , 1 1 7 . 1302 8 . 2

' . 2400 64 • 341 ,'15.8

T A B L E XI . F R E Q U E N C Y OF MUTATIONS IN T A I N A N - 3 .

Treatment Chlorophyll ' Viable

Control 0 0

Gamma rays (kR)

. 2 0 42 .79 78.69

30 • 48.00 ; - 80.00

40 No survival

EMS (%) .

0 . 2 47 .83 72.73

0 .3 47.50 74.00

0 . 4 48 .84 41 .68

NMU {%)

0.025

0.050

0.100

35.16

39.18

50 .05

44 .45

45 .00

57.09


T A B L E XII. F R E Q U E N C Y OF MUTATIONS-IN I R - 8

Treatment Mutation frequency (°/o M2 families)

Treatment Chlorophyll Viable

Control 0 - 0

Gamma rays (kR)

20 43. 73 59 37

30 45. 94 60 93

40 42. 50 57 50

EMS (%)

- . . 0 . 2 23 08 53 84

0.-3 ' - " ' 27 45 62 74

0 ;4 38 00 - 58 00

' 0 .'5 33 33 60 00

NMU •(%)

0 .025 34 92 44 00 .

0 .050 58 02 56 68

0 .100 49 10 60 64

SWAMINATH AN et al. 3 7

T A B L E XIII. F R E Q U E N C Y OF indica MUTANTS IN TAINAN-3 '

Treatments Per 100' Mx

plant progenies' Per 100 Mt •

spike progenies

Control ,

Gamma rays'(kR) ' '

20 (with husk)

20 (without husk)

30 (with husk)

30 (without husk)

EMS (%)' '

0 .200 (with husk) ,

0 .200 (without husk)

0 :300 '

0 .400

NMU (%)• '. ,

0 .025 ^ '

• 0.050 (with husk) '

. . 0 .050 .(without husk)

0V100 '

14.75

18.75

14.00

12.50 .

'9.09

11.11

10.00

11.36

3 . 6 4

5 .22

3 . 0 4

2 .50

1 .96

2 .22

2 .55

5 .44

6 . 6 7 2 . 4 4

38 .SWAMINATHAN et.al.

T A B L E XIV. ' T Y P E S OF V I A B L E MUTATIONS

Variety Hab'it Leaf Panicle Grain

IR-8 • • 1. Dwarf 9. Broad leaf 17-. Open -habit 22. Fine

'2 . Tall 10. Narrow leaf 18. Compact habit 23. Coarse

. 3 . Bushy • 11. Boat leaf 19. Muffled ear 24. Japonica

4. Grass clump 12. Brittle 20. Hard threshing 25. Glabrous .

5 . Spreading 13. • Rolled flag leaf

21. Bifurcated ear 26. Beaked

6. Profuse tillering 14. Dark green 27. Elongated palea

7.

8.

Early ' "• .

Late

•15.

16.

Chlorina

Black spotted leaf

28.

29.

30.

Poly-husked

Double kernel

Large sterile glume

Tainan-3 1. Dwarf 12. Broad leaf - 19. Open habit 26.. White

2. Semidwarf -13: Narrow leaf 20. Compact habit ' 2 7 . Indica

3. Grass clump 14. Boat leaf '21. Clustered habit 28. Bold

. 4 . Bushy 15. Rolled leaf 22. Muffled ear 29. Short '

5 . Spreading 16; 'Dark green 23. - Free threshing 30. Awned

6. Trailing" type • 17. Chlorina 24. Shattering 31. Glabrous

7.

8.

Profuse tillering

Thin stem '

Mi- Black spotted 25. Bifurcated ear 32.

33.

Beaked -

Poly-husked

9. Erectoides 34. Elongated palea

10. Early 35.- Larger sterile glume

11. Late 36. Sessile

' SWAMINATHAN e t a l . . .• 3 9

I

' T A B L E X V . E F F E C T S O F P R E - S O A K I N G ' -

Variety Mutagen and dose

Pre-soaking (in hrs)

Germination

No. ofseeds . - Percentage . sown

• , Survival percentage

Tainan-3 .. . Control 16 ' . 500 •• 90. 0 t

41 .6

1 <?» EMS 16 500 : 47. A . -

5<7o dMSO 16 '500 ' . 36. ,0 • 29.8

EMS + 5% dMSO 16 500 , .35. ,0 28 .0

17 • . 500 , ; ' 32. .0 20.8

18 . 500 • ' '31. ,4" ' 14 .4

19 '' 500 - '. - •24. .4 22 .2

20 • 500 ;; ' 29. .2 19.6

Tainung-65 Control . 16 . , ' ^ ' • 'i

* ' 500. :',)••; •• '78, . 4 ' . '"••.35.6

EMS 16 500 v ' .'• - <-' 44, ,0 ' -

•' 5% dMSO 16 '-50b '• 41. ,6. '. 29.0

1 % EMS + S°Jo dMSO 16 r5oo ' ' 3 7 . .6 ' ' 30 .2

17 500; • ' 36. .0 ' - 25 .8 '

18 500 39. • o - ' ' .•• 3 3 . 4

19 - 500 • 35, ,0 14. 0

20 ' •. . 500 34, ,0 20.8

4 0 SWAMINATHAN- et al.

T A B L E X V I . P E R C E N T A G E OF SURVIVAL A F T E R EMS, dES AND dMSO T R E A T M E N T S A F T E R D I F F E R E N T PERIODS OF PRE-SOAKING (TAINAN-3)

Period of Percentage of survival pre-soaking

(hours) pre-soaking

(hours) EMS : - ' ' •1 d ES dMSO.

Control

8

• " 87.00

V 69 .3

87.00 -

96.0

87.00

. - 88.8

11 • 60.5- - 5 9 . 2 ' 51 .2

i 4 60 .5 79.8 45 .8 -

17 . - 47 .8 55 .2 51 .4

18 "43 .4 61 .4 47 .2

19 • 70.8 49 .6 42 .6

20 34 .0 45 .4 43 .8

21 47 .0 11 .4 41 .6

22 46 .9 48 .6 43 .2

T A B L E XVII . CHIASMA F R E Q U E N C Y IN CONTROL AND. X - I R R A D I A T E D PANICLES OF japonica X indica HYBRID

Material . Treatment No. of cells analysed •

Mean No. of chiasmata/ cel l

± S. E.

' ' 1-45 XA-58

1. Control 50 24.06 ±0 .15

2. Control 50 ' 24.18 ±0 .14

3. 240 R (24 h) 100 '24.86 ±0 .18

4. " " 480 R (24 h) 100 26.70 ±0 .19

5. 1200 R (24 h) 100 25.13 ± 0 . 1 3

6. 480 R (48 h) 100 25.09 ± 0 . 1 2

7. " » 1200 R (48 h) 50 24.62 ±0 .19

C . D. at 5% level for different combinations

1X3 = 0 .738 , 1 x 4 = 1 .14 ; 1 x 5 = 1 .07, 1 x6 = 0 .604 , 1 x7 = 0 . 8 6 7 , 1 x2 = 0 .617

SWAMINATH AN et al. 4 1

T A B L E XVIII. P E R C E N T A G E OF RECOMBINATION FOR D I F F E R E N T GENE COMBINATIONS WITHIN LINKAGE GROUPS; IN C O N T R O L A N D A F T E R X - I R R A D I A T I O N AND • MITOMYCIN C (MC) T R E A T M E N T A T D I F F E R E N T F L O W E R I N G STAGES

Recombination % , , Gene „, : Material . Treatment :

combinations Pre-meiotic Post-stage Other branches

1-45 x A-58 C B w x x c b W x Control 35 .08 35.08 35.08

240 R 40.00 40.00 37 .47

„ 480 R • - 40 .12 - 35.64

1200 R - 45 .24 - 33.33

' °A Pn xa pn Control 81 .54 - 81.54

„ 240 R 55 .46 - 78.68

480 R . 48 .57 - 81 .42

„ 1200 R 65 .64 _ - 69.64

0.001% MC 62.91 - 46.20


T A B L E X I X . P E R C E N T A G E OF RECOMBINATION F O R D I F F E R E N T GENE COMBINATIONS B E T W E E N LINKAGE GROUPS IN C O N T R O L AND A F T E R X - I R R A D I A T I O N AND MITOMYCIN (MC) T R E A T M E N T A T D I F F E R E N T F L O W E R I N G STAGES

Material Gene

combinations Treatment

Recombination %

Pre-meiotic Post-stages Other branches

N-45 X 1-6 PI X D6 pi Control

240 R

480 R

1200 R

0 .001% MC

30.29

36.75

44 .79

34 .14

37.70

30.

31.

23.

30.29

30 .77 .

14.50

19.99

16.67

1-45 X A-58 Pr wx X pr Wx Control

240 R

480 R

1200 R '

0.001% MC

34.88

16.00

39.33

65.46

59 .21

34.88 34.88

37 .69

52.65

39 .21

39.99

Pn wx x pn Wx Control 38.50

240 R 30 .29

480-R 35.43

1200 R 44 .44

0 .001% MC 37.59

38.50

A wx x a Wx Control

240 R

480 R

1200 R

1 2 . 3 1 '

16.00

16.09

20 .47

12.31

38.50

19.99

51 .04

11 ,85

38.23

12 .31

14 .04

12.70

11.11

Pr Pn X pr pn Control

240 R

480 R

1200 R

0 .001% MC

27.14

50.00

39.33

48.60

40 .12

27 .14 27 .14

30 .91

63 .57

48 .57

60 .34

C B Pn x c pn Control

240 R

480 R

1200 R

0.001% MC

81.21

55.46

48 .57

65 .64

62 .91

81.21 81.21

78.68

81 .42

' 69 .64

46 .20

SWAMINATHAN et al. 43

R E F E R E N C E S

[ 1 ] KONZAK, C . F . et a l . , in The Use of Induced Mutations in Plant Breeding (Rep. FAO/lAEA Tech. Meeting, Rome 1964) Pergamon Press (1965).

[ 2 ] SIDDIQ, E. A . , SWAMINATHAN, M . S . , RiceBreeding with'Induced Mutations, Tech . Reports Series No.86, IAEA, Vienna (1968) 25.

D I S C U S S I O N

G . T . SCARASCIA: What is the degree of synchronization of the meristematic nuclei of the presoaked seeds at the moment of the mutagen treatment?

M.S. SWAMINATHAN: It is fairly high, about 75 - 80% under constant conditions of temperature, light and humidity.

HAPLOID RICE PLANTS IN MUTATION STUDIES

S. TANAKA Institute of Radiation Breeding, Ministry of Agriculture and Forestry, Ohmiya, Ibaraki-ken, Japan . . , ' .

Abstract

HAPLOID RICE PLANTS IN MUTATION STUDIES. Studies were made on chlorophyl l -def ic ient ' sectors and d ip lo id - l ike sectors in haploid rice plants exposed to chronic gamma irradiation, and on germinal mutations in diploid strains derived from the haploid plants. The induction and el imination of somatic mutations.in haploid plants and the occurrence of drastic germinal mutations in diploid strains from haploid plants are discussed.

INTRODUCTION

Haploid rice plants are easily distinguished from diploid plants by their miniature features and almost complete sterility. Many papers have b'een published on the morphological and cytological studies of haploid rice plants and the spontaneous diploid strains from haploid plants [1-4]. Furthermore, when haploid plants are treated with muta-gens, induced mutations (most of which are recessive'to their wild types) are detected as mutated sectors on the irradiated haploid plants. By duplicating the .chromosome complement of haploid plants, pure di-ploid lines are obtained. Thus, haploid plants are suitable material for mutation studies. In the present experiments the appearance of somatic mutations, diploid-like sectors in haploid pla:nts and germinal mutations in diploid strains from haploid plants following chronic gamma irradia-tions were studied.

M A T E R I A L S AND METHODS

One haploid. rice plant of Norin No. 8 has been propagated in the Institute of Radiation'Breeding since 1962, and 563 haploid plants or i -ginating from this, haploid plant were obtained in the spring of 1964. These haploid plants were exposed to chronic gamma irradiation in the gamma-ray field of the Institute of Radiation Breeding in 1964. The dose-rates and duration of exposure to gamma rays are shown in Table I. Growth inhibition was so severe after irradiation at dose-rates of 400 and'450 R/day that irradiation was discontinued after 60 days.

• In 1964, chlorophyll-deficient sectors and diploid-like sectors were observed in haploid plants that.had been irradiated. Chlorophyll-deficient sectors were scored on the 25th of July and the 3rd of November 1964, 40 and 140 days respectively after the' start of the irradiation period. Chlorophyll-deficient sectors appeared in different sizes and those sec -tors which were larger than two thirds of a leaf length were recorded as mutated sectors. Plants or tillers with one or more leaves showing such chlorophyll-deficient sector(s) were recorded as mutated plants or tillers.

45

05

T A B L E I. SCHEME OF CHRONIC GAMMA IRRADIATION O F H A P L O I D P L A N T S

Treatment ' 1 2 3 4 5 6 7 ' - 8 9 '. • 10 11 12

Duration o f growth in the gamma-ray field (days) 142 69 69 142 ' 142 142 142 142 142 . 142 142 -

Irradiation times (days) 104 • 60 60 . 104 ' 1 0 4 . 104 104 .104 ' 104 104 104 -

Dose-rates (R /day) a - ' 500 450 400 350 • 300 250 200 150 100 , 50 25 0

Dose (.kR) 5 2 . 0 2 7 . 0 •24.0 3 6 . 4 ' 3 1 . 2 2 6 . 0 - 2 0 . 8 - 1 5 . 6 1 0 . 4 5 . 2 . 2 . 6 0 •

Note : Transplanting date : 5th June, 1964, ' Irradiation started on 15th June, 1964, and terminated on 15th October, 1964. ' •

• Gtowth inhibition was so severe after dose-rates of 450 and 400 R/day, that irradiation -was discontinued 60 days after it was started. Although i r r a d i a t i o n a t a d o s e - r a t e o f 5 0 0 R/day caused very severe growth inhibition irradiation was continued to investigate the lethality until-the autumn of 1964. -

a R /day was a 20 -h day due ' to administrative.reasons. . * • -

TANAKA 4 7

The occurrence of diploid-like sectors, which are easily, distinguished from haploid tissue by the size of the leaf, panicle, gimme, etc. were investigated on irradiated plants. Diploid-like panicles often produced seed(s). The number of panicles, both ha:ploid and diploid-like, were recorded and all the panicles with seed(s) were harvested in.the autumn of 1964. All the stems and leaves of the irradiated and non-irradiated haploid plants were cut off in September of 1964 and the stubbles were kept in a greenhouse until the spring of 1965.

In 1965, observations were made on the chlorophyll-deficient sectors and diploid-like sectors in the haploid plants propagated vegetatively in the spring of 1965. When new sprouts emerged, shoots of the'haploid plants in the greenhouse were separated and transplanted from pots to an experimental field. Plants derived from each- of the irradiated plants from the preceding year were grouped as individual clonal strains.

Chlorophyll-deficient sectors and diploid-like sectors observed on the above plants were larger than those on the progenitors in 1964. Observations on chlorophyll-deficient sectors were made on the 15th of August 1965, and on dipl'oid-like sectors on the 30th of October 1965 by the same methods as those used in 1964. All the diploid-like panicles with seed(s) were harvested and stored until the spring of 1967 together with the diploid-like panicles harvested in 1964. The pedigree method was used on germinal mutations of diploid strains derived from haploid plants.

The original haploid plant had been maintained and vegetatively propagated in the -National Institute of Agricultural Sciences. ' During the multiplication, ten spontaneous diploid strains were obtained. One of them has been used in mutation studies in the Institute of Radiation Breeding. "

In the spring of 1967, 325 panicle progenies from irradiated haploid plants; one strain from non-irradiated haploid plants; ten spontaneous diploid strains maintained in the National Institute of Agricultural Sciences and one spontaneous diploid strain which has been used in the Institute of Radiation Breeding were sown in a field nursery. Owing to the high sterility of the panicles obtained from irradiated haploid plants and the severe inhibition of germination of the seeds obtained from these panicles, only 93 diploid strains from irradiated haploid plants consisted of more than five plants, and 52 strains consisted of less than four plants. The other 180 strains did not germinate. The 93 strains were transplanted from the nursery to an experimental field together with ten spontaneous diploid strains maintained in the National Institute of Agricultural Sciences, and one spontaneous diploid strain which has been used in the Institute of Radiation Breeding as a control. The control strains were planted in every tenth row for comparison. Any visible, changes- observed on these strains were recorded.

RESULTS

The radiation damage induced by. chronic gamma irradiation on haploid plants was similar to.that observed on diploid plants, .although the. radio-sensitivity of the'haploid plants was higher than that of the diploid plants. Growth inhibition was very severe in those plants that were irradiated at dose-rates of 500, 450 and 400 R/day; severe at

T A B L E II. F R E Q U E N C I E S OF PLANTS. AND T I L L E R S WITH C H L O R O P H Y L L - D E F I C I E N T SECTORS INDUCED B Y CHRONIC GAMMA IRRADIATION OF H A P L O I D P L A N T S (July '1964)

Dose-rates (R /day) ? 500 450 400 350 . 300 250 - 200 150 100 50 ' 25 0 t

Total

N o . of plants irradiated _ 4 0 40 4 0 ' 4 0 4 0 " 4 0 40 40 . 40 40 •40 40 480 '

N o . of plants with ch lo tophy l l -de f i c ient sectors b

24 32 33 27 31 24 27 40 25 5 0 0 268

Frequencies o f plants with chlorophyl l -de f i c ient sectors (°jo)

6 0 . 0 80.0 82 .5 6 7 . 5 7 7 . 5 6 0 . 0 6 7 . 5 100 6 2 . 5 12 .5 0 0

No . o f tillers irradiated 357 ; 267 222 439 414 402 550 599 475 •451 512 427 5133

N o . of tillers with ch lorophyl l -de f i c ient sectors

.22 24 29 35 29 32 . 40 ' 91 39 9 0 0 • 350

Frequencies o f tillers with chlorophyl l -de f i c i ent sectors (^o)

5 . 9 9 .0 1 3 . 1 8 .0 7 . 0 8 .0 . 7 . 3 15 .2 8 .2 • 2 . 0 0 0 •

a See Table I . , Chlorophyll sectors which were longer than two-thirds of the lea f length were recorded.

T A B L E III. FREQUENCIES OF P L A N T S AND T I L L E R S WITH C H L O R O P H Y L L - D E F I C I E N T SECTORS INDUCED BY CHRONIC GAMMA IRRADIATION OF H A P L O I D P L A N T S (Nov. 1964)

Dose-rates (R /day ) a 500 450 400 350 300 250 200 150 100 50 25 0 Total

No . of plants irradiated 28 32 40 38 38 40 40 40 40 38 40 39 ' 454

No . of plants with chlorophyl l -de f i c ient sectors ^

13 25 38 16 19 18 21 37 28 28 24

Frequencies o f plants with chlorophyl l - ^ ^ g 5 _ Q ^ 5 Q _ 0 ^ ^ g 2 _ 5 7 Q _ 0 7 3 _ ? 6 0 _ Q ^ * g de f i c ient sectors (70) ^

> N o . of tillers irradiated 503 340 1023 824 1136 996 1633 1489 1053 957 1013 916 11885

N o . of tillers with chlorophyl l -de f i c ient sectors

Frequencies o f tillers with chlorophyl l -de f i c ient sectors (%)

21 45 126 34 31 30 40 113 50 68 50 4 612

4 . 2 13.2 12 .3 4 . 1 2 .7 . 3 . 0 2 . 4 7 . 6 4 . 7 7 . 1 4 . 9 0 . 4

See Table I. See Tab le II.

cd

T A B L E IV. F R E Q U E N C I E S OF HAPLOID P L A N T S WITH C H L O R O P H Y L L - D E F I C I E N T SECTORS, V E G E T A T I V E L Y P R O P A G A T E D A F T E R CHRONIC GAMMA IRRADIATION (August , 1965)

Dose-rates (R /day) a 500 450 400 . 350 300 250 200 150 100 50 25 0 Total

No. of tested plants 484 - - 801 1098 942 1592 1468 1002 963 992 892 10234

No. of plants with ch lorophyl l - 24 - - 20 20 3 21 9 5 3 7 0 112 def ic ient sectors

Frequencies of plants with ch lorophyl l - _ _ 2 _ 5 ^ Q _ 3 ^ 0 _ g Q _ 5 Q _ 3 Q _ 7 0 _ Q

def ic ient sectors (^o)

Plants irradiated at dose-rates of 450 and 400 R/day were not propagated because their growth was too severely inhibited. a See Tab le 1.

TANAKA 5 1

d o s e - r a t e s of 350 and 300 R / d a y ; marked at a d o s e - r a t e of 250 R / d a y ; sl ight at a d o s e - r a t e of 200 R / d a y ; v e r y slight at d o s e - r a t e s of 150 and 100 R / d a y ; and at d o s e - r a t e s of 50 and 25 R / d a y the growth of i r rad ia ted plants was a l m o s t n o r m a l .

C h l o r o p h y l l - d e f i c i e n t s e c t o r s appeared two o r three weeks a f ter the start of the i r rad ia t i on p e r i o d . The higher the d o s e - r a t e the e a r l i e r the appearance of such s e c t o r s . The s i ze of the c h l o r o p h y l l - d e f i c i e n t s e c t o r s i n c r e a s e d with growth and i n c r e a s e of total d o s e . The f r e q u e n c y of the plants and t i l l e r s with c h l o r o p h y l l - d e f i c i e n t s e c t o r s o b s e r v e d in July and N o v e m b e r of 1964 are presented in Tab les II and III. As shown in these tab les , the f r e q u e n c y *of the plants o r t i l l e r s with c h l o r o p h y l l - d e f i c i e n t s e c t o r s o b s e r v e d in July, 60 days a f ter the start of i r rad ia t i on at d o s e -rates of 50 and 25 R / d a y , w e r e d ist inct ly l e s s than those i r rad iated at d o s e - r a t e s of 100 R / d a y arid above . H o w e v e r , observa t i ons made in N o v e m b e r of 1964, 160 days a f ter the start of the i r rad ia t i on p e r i o d , indicated that there was no d i f f e r e n c e between the f r e q u e n c y of the plants o r t i l l e r s with c h l o r o p h y l l - d e f i c i e n t s e c t o r s a f ter i r rad ia t i on at high d o s e - r a t e s and low d o s e - r a t e s . The re lat ionship between the f r e q u e n c y of c h l o r o p h y l l - d e f i c i e n t s e c t o r s on plants o r t i l l e r s and the d o s e - r a t e o r total d o s e is m o r e c ompl i ca ted when growth takes p lace under c h r o n i c g a m m a i r rad ia t i on than under acute i r rad ia t i on . The induction and e l iminat ion of mutations in c e l l s of growing po ints , the death of c e l l s in growing po ints , the d i f f erent ia l r a d i o - s e n s i t i v i t y of those c e l l s and other f a c t o r s m a y be re lated to the appearance of c h l o r o p h y l l - d e f i c i e n t s e c t o r s on c h r o n i c a l l y i r rad iated haploid plants. Tab le IV shows the f r e q u e n c i e s of the haploid plants that f o r m e d c h l o r o p h y l l - d e f i c i e n t s e c t o r s a f t e r they w e r e vegetat ive ly propagated in 1965, s ix months a f t e r the end of the i r rad iat ion p e r i o d . Observat i ons made in August 1965, nine months a f t e r the end of i r r a d i a t i o n . p e r i o d , r e v e a l e d a tendency f o r the f r e q u e n c y of the plants with c h l o r o p h y l l -de f i c ient s e c t o r s to i n c r e a s e with i n c r e a s i n g d o s e - r a t e s o r total d o s e . This re lat ionship was not o b s e r v e d in the plants treated with c h r o n i c g a m m a i r rad iat ion in 1964. The s i z e of the s e c t o r s on vegetat ive ly propagated haploid plants was genera l l y l a r g e r than that of s e c t o r s o b -s e r v e d on haploid plants under c h r o n i c i r rad iat ion .

The f r e q u e n c y of haploid plants with d ip l o id - l ike s e c t o r s , a f ter c h r o n i c g a m m a i r rad ia t i on in 1964 and vegetat ive propagat ion in the spr ing of 1965, a r e s u m m a r i z e d in Tab les V and VI. The f r e q u e n c y of haploid plants with d ip l o id - l ike s e c t o r s i n c r e a s e d with i n c r e a s i n g d o s e -rates in 1964, and these s e c t o r s w e r e not o b s e r v e d on the haploid plants exposed to g a m m a rays at d o s e - r a t e s of l e s s than 250 R / d a y in 1964. H o w e v e r , the f r e q u e n c y of haploid plants with d i p l o i d - l i k e s e c t o r s a f ter vegetat ive propagat ion in 1965 was not par t i cu lar ly high a f t e r i r r a d i a -tion at liigh d o s e - r a t e s . The s i z e of the d ip l o id - l ike s e c t o r s ( i . e . the propor t i on of d i p l o i d - l i k e pan i c l es in the total pan i c l e s of the plants) growing in the g a m m a - i r r a d i a t e d f ie ld i n c r e a s e d r e m a r k a b l y with growth. This s e e m s to suggest that d ip l o id - l ike s e c t o r s a r e m o r e r a d i o - r e s i s t a n t and deve lop fas ter than haploid t i ssue under i r rad iat ion at high d o s e - r a t e s . The s i z e of the d i p l o i d - l i k e s e c t o r s under i r rad ia t i on in 1964 showed d i f ferent f e r t i l i t i e s ranging between 0% and 90%, the a v e r a g e being 30% in m o s t c a s e s . A f t e r vegetat ive propagat ion in 1965 m o s t of the d ip l o id -l ike pan i c l es p roduced s e e d s and the ir fert i l i ty was m o r e than 80%.

CJl to

T A B L E V . F R E Q U E N C I E S OF HAPLOID P L A N T S W I T H ' D I P L O I D - L I K E SECTORS INDUCED B Y CHRONIC G A M M A IRRADIATION (Oct. 1964)

Dose-rates (R /day) a 500 450 ' 400 350 300- 250' 200 150 100 50 25 0 Total

No. of plants which survived 28 32 . 40 38 38 '40 40 40 40 38 40 39 453

No . of plants with d ip lo id - l ike sectors

1 3. 3 " 2 1 0 0 0 0 0 0 0 10

Frequencies o f plants with d ip lo id - l ike sectors (°Jo)

3 . 6 9 . 4 7 . 5 5 . 3 2 . 6 - - - - - - -

N o . of tillers which survived 503 340 1023 824 1136 998 1633 1489 1053 957 1013 916 11885

N o . of tillers with d ip lo id - l ike sectors

43 15 ' 38 7 6 0 0 0 0 .0 0 0 109

Frequencies o f tillers with d ip lo id - l ike sectors (%)

8 . 5 4 . 4 3 . 7 0 . 8 0 . 5 - - - - - - -

Frequencies of d ip l o id - l ike tillers in the plants showing 4 2 . 9 2 6 . 3 6 0 . 3 13 .3 3 7 . 5 - - - - - - -

d ip lo id - l ike sectors (<7o) ^

N o . of panicles with seeds 10 0 0 0 1 0 0 0 . 0 0 0 0 11

a See Table I . k Plants which sprout both haplo id - l ike tillers and diplo id- l ike tillers.

T A B L E VI. FREQUENCIES OF HAPLOID P L A N T S WITH D I P L O I D - L I K E P A N I C L E S , V E G E T A T I V E L Y P R O P A G A T E D A F T E R CHRONIC GAMMA IRRADIATION (Oct . 1965)

Dose-rates (R/day) a 500 350 300 250 200 150 100 50 25 0 Total

N o . of c lonal strains propagated 28 38 38 40 40 40 40 38 40 39 453

N o . of c lonal strains which segregate 1 0 1 1 1 1 1 1 1 1 9 plants with d ip lo id - l ike panicles

N o . of plants propagated ^ g Q 1 i Q g g g 4 2 ^ ^ ^ g f ; 3 g g z g g g i ( m 3

vegetat ively

No . of plants with 1 0 1 6 4 5 " 1 3 4 4 2 40 d ip lo id - l ike panicles

N o . of d ip lo id - l ike panicles 73 1 145 42 36 1 55 37 28 11 429

N o . of panicles with seeds 64 1 130 31 22 1 47 5 24 1 265

a See Tab le I .

Plants irradiated at dose-rates of 450 and 400 R/day were not propagated because their growth was too severely inhibited.

T A B L E VII . MUTATIONS IN M 2 DIPLOID STRAINS D E R I V E D F R O M D I P L O I D - L I K E P A N I C L E S OF I R R A D I A T E D H A P L O I D P L A N T S (M x )

Dose-rates (R /day) a 500 350 300 250 200 150 100 50 25 0 Total Control b Spontaneous*3

N o . o f panicles with seed(s) in 1964 10 0 1 0 0 0 0 0 0 0 11

No . o f panicles with seed(s) in 1965 64 1 130 31 22 1 47 5 24 1 326

No . o f panic le progenies sown in 1967

74 1 131 31 47 337

N o . o f surviving panic le progenies

N o . o f strains tested c

N o . o f strains which segregate mutant plants

N o . o f strains f ixed

53

29

22

0 82

0 54

0 4

0 50

13

7

153

93

28

10

10 H > Z > >

N o . of strains not tested ^ 28 60

See Tab le I . k Control and spontaneous diploid strains were obtained from spontaneous duplication of chromosome c o m p l e m e n t of the original haploid plant during

vegetat ive propagation of haploid plants in the National Institute of Agricultural Sciences, and the control strain had been used in mutation studies at the Institute of Radiation Breeding.

c Progenies of d ip l o id - l ike panicles consisted of f ive or more plants. ^ Progenies of d ip l o id - l ike panicles consisted of four or less plants. Plants were grown in pots without observation and one panicle from each plant

was harvested to raise M , strains.

TANAKA 5 5

The v i s i b l e d ras t i c changes o b s e r v e d in diploid M 2 s t ra ins d e r i v e d f r o m i r rad ia ted haploid plants and spontaneous diploid s t ra ins or ig inat ing f r o m the s a m e haploid plant a r e r e c o r d e d in Table VII. F i f t y - e i g h t s t ra ins without any dras t i c changes and seven stra ins that w e r e pale g reen s e e m e d to be t r u e - b r e d s tra ins in the M 2 generat ion . T w e n t y - s i x s tra ins s e g r e g a t e d plants with one of the d ras t i c mutant types , such as dwar f ing , s h o r t - c u l m and e r e c t pan i c l e , and the other two stra ins s e g r e g a t e d both dwarf plants and plants with e r e c t p a n i c l e s . A l l the ch lorophy l l mutants o b s e r v e d in 1967 w e r e pale g r e e n . Most of the m o r p h o l o g i c a l mutants w e r e dwarf ing and a few of them w e r e shor t cu lms and e r e c t p a n i c l e s . In one s tra in , e a r l y heading plants (ten days e a r l i e r than the c ont ro l ) w e r e s e g r e g a t e d . Plants with changes of f e r -t i l i ty w e r e re lat ive ly , r a r e . The segregat i on f r e q u e n c y of these mutant plants within the mutant s tra ins was near ly 25% in m o s t c a s e s , which suggests a c h i m e r i c s t ruc ture of the panic les f r o m which these- s t ra ins w e r e d e r i v e d , o r inductions of mutations a f ter dupl icat ion of c h r o m o s o m e c o m p l e m e n t of haploid plants .

CONCLUSIONS

The f r e q u e n c y of the c h l o r o p h y l l - d e f i c i e n t s e c t o r s did not show a c l e a r dependence upon d o s e - r a t e s o r total d o s e . This suggests that many f a c t o r s are invo lved in the, appearance of mutated s e c t o r s on chron i ca l l y i rradiated haploid p lants . T h e s e factors ,should be invest igated to es tab l i sh e f f e c t i ve methods of ut i l izat ion of haploid plants in mutation studies .

The s i z e of the d i p l o i d - l i k e s e c t o r s under c h r o n i c g a m m a i r rad iat ion at high d o s e - r a t e s i n c r e a s e d r e m a r k a b l y with growth. This phenomenon m a y be caused by d i f f e rent ia l r a d i o - s e n s i t i v i t y between diploid s e c t o r s and haploid t i s s u e .

Diploid s t ra ins d e r i v e d f r o m i rradiated haploid plants unexpected ly s egrega ted dras t i c mutants . F ixed mutant s t ra ins with d r a s t i c changes such as dwar f ing , short cu lm and e r e c t panic le w e r e not o b s e r v e d in the M 2 generat ion . This fact s e e m s to suggest that the m o s t d r a s t i c muta -t ions induced in haploid plants a r e not transmitted to the next generat ion and that these d r a s t i c mutations o b s e r v e d in the M 2 generat i on w e r e induced a f ter dupl icat ion of the c h r o m o s o m e c o m p l e m e n t of the haploid plants .

These phenomena a r e v e r y important both t h e o r e t i c a l l y and e c o n o m i c a l l y .


The author w i s h e s to thank D r . H. Akemine f o r his use fu l suggest ions and Dr . T . Kawai f o r his helpful adv i ce .

R E F E R E N C E S

[ 1 ] MORINAGA, T . , KURIYAMA, H . , AOKI, M . , A sterile and extremely dwarf mutant occurred in a theoretically pure line of rice, Jap. J. Genet. 18 (1942) 297.

[ 2 ] HU, C . H . , Karyological studies in haploid rice I, lap. J. Genet. 32 (1957) 28 . [ 3 ] HU, C.H., Karyological studies in haploid rice II, Jap. J. Genet. 33 (1958) 296. [ 4 ] HU, C . H . , Karyological studies in haploid rice III, Jap. J. Breed. 9 (1959) 135.

5 6 TANAKA

D I S C U S S I O N

N. Y A M A D A : What p r a c t i c a l appl icat ions could resul t f r o m your r e s e a r c h , o r is it st i l l too p r e m a t u r e to draw c o n c l u s i o n s ?

S. T A N A K A : In the F 2 generat ion one can obtain pure and f ixed diploid l ines by duplicating the c h r o m o s o m e c o m p l e m e n t of the haploid plants . Such pure h o m o z y g o u s plants a r e v e r y use fu l in b reed ing . It is t oo e a r l y to draw c o n c l u s i o n s c o n c e r n i n g the appl icat ion of induced m u t a -t ions in this w o r k .

B. SIGURBjdRNSSON: I have heard of your s u c c e s s f u l resul ts in inducing an i n c r e a s e in the pro te in content of r i c e . Could you c o m m e n t on that?

S. T A N A K A : Y e s , pro te in analys is has been c a r r i e d out on a number of our mutants. Some of them p r o d u c e twice the prote in content of the m o t h e r var ie ty .

INDUCED.MUTATIONS OF RICE FOR SHORT-CULM SELECTIONS IN M 2 GENERATION""

J.H. REE Yungnam Crop Experiment Station, Office of Rural Development, Milyang, Korea

Abstract

INDUCED MUTATIONS OF RICE FOR SHORT-CULM SELECTIONS IN M 2 GENERATION. Seeds of a leading r ice variety Palkweng, japonica , were treated with X-rays and thermal neutrons to obtain mutations having short cu lm, earliness, resistance to lodging and blast disease, and a high yielding ability. 507 plants were selected for short-culm length; on the average they were also shorter in panic le length, lighter in weight of panicles, less in 100-grairi weight and earlier in days to heading. There was no strict correlation between cu lm length and panic le length. Some plants had longer panicles in spite of a distinct reduction in culm length, but the number of panicles, weight of panicle and days to heading were positively corre-lated with culm length in the selected plants. The length of each internode from the base of the panicle down to the basal internode was gradually reduced. The lodging index was lower than that of the original variety, and culm length was positively correlated with lodging index.

INTRODUCTION

The study r e p o r t e d h e r e was m a d e ' o n a leading r i c e var i e ty Palkweng, j apon i ca . Pa lkweng is an o ld v a r i e t y with a long cu lm, m e d i u m t i l ler ing and m e d i u m matur i ty , that i s suscept ib le to lodging, m o d e r a t e l y suscept ib le to b las t d i s e a s e , but high y ie ld ing and with good eating quality. It i s g rown on approx imate ly 34% of the total a r e a of paddy f ie lds in s o u t h - e a s t e r n K o r e a .

The s e e d s of Palkweng w e r e treated with X - r a y s and t h e r m a l neutrons to obtain mutations having short cu lm, e a r l i n e s s , r e s i s t a n c e to lodging and b las t d i s e a s e , and st i l l reta in the h igh -y ie ld ing abi l i ty .

The induction of s h o r t - c u l m mutat ions by radiat ion ' treatment may be one of the p r o m i s i n g m e t h o d s f o r r i c e b r e e d i n g as r e p o r t e d a l so by B e a c h e l l , Kawai , Tanaka and T o r i y a m a [ 1 - 6 ] . S ince s h o r t - c u l m plants obtained in this e x p e r i m e n t have not ye t been thoroughly examined , e s p e c i a l l y f o r their d e s i r a b l e a g r o n o m i c c h a r a c t e r s , this e x p e r i m e n t m a y a l s o b e worth continuing. ' • .

E X P E R I M E N T A L M E T H O D

This e x p e r i m e n t was init iated in 1966 and continued through 1967. In 1966, s e e d s of Palkweng w e r e given f ive d i f f e rent t reatments with 20 000 and 25 000 R of X - r a y s , and 5X 1 0 1 2 / c m 2 , 1 0 X 1 0 1 2 / c m 2 , 15 X 1 0 1 2 / c m 2 of thermal neutrons at the Institute of A t o m i c Energy A g e n c y , Seoul , K o r e a .

* This work was partly supported by the IAEA under Research Contract No. 547/RB.

57

5 8 REE

Mi plants were harvested separately. Data were recorded on germination and fertility of the M i panicles. In 1967, seeds of the second generation (M2) were sown directly on a raised seed bed on May 10, and all seedlings were transplanted in a paddy field on June 25. All the plants were grown spaced in 24X 15 cm lattices and ferti l izers were applied at 120-80-80 kg/ha of N, P 2 0 5 and-K20, respectively.

• In the M 2 generation, progenies of three or four panicles of each M! plant were grown as panicle progenies in rows. 3900 panicle progenies, with a total of 228 000 plants, were planted. The original variety Palkweng was planted as control at ten-row intervals.

During the growing period variations were observed in the agronomic characters, such as heading date, plant height, tillering and plant type. All plants that headed earl ier than the original variety were tagged. At maturity, the degree of sterility, grain size and.shape, spikelet density, and other characters of M2 generation.plants were also observed simul-taneously with the character of short culm.

Three different criteria were used in selecting short-culm variant types in the M2 generation; (i) distinctly shorter culm plants having other desirable agronomic characters; (ii) slightly shorter culm plants having other desirable agronomic characters; and (iii) plants which were regarded as belonging to the short-culm variant type but showing only slight di f fer-ences in agronomic characters. Those plants selected in the M2 generation will be tested in the subsequent generation in 1968. The extremely short-culm plants with distinctly poor yielding characters were discarded in the field selection.

Laboratory tests of bending moment, breaking strength and lodging index were made on plants randomly sampled from the field selections for short culm, as a basis for detecting lodging resistance. For analysis

TABLE I. RICE PLANTS AND LINES TESTED AND SELECTED FOR SHORT CULM IN THE M2 GENERATION IN 1967

Radiation dose

Lines tested

Number of

Plants tested

Lines selected

Plants selected

% of the plants

selected

X-rays 20 kR

25 kR

1200

900

72 000

60 000

61

51

265

133

0 . 3 7

0.22

Thermal neutrons 5 x l 0 1 2

n ( t h ) / c m !

700 36 000 29 0 . 0 8

10 x 10*'

15 X 101:

Total

700

400

3 900

36 000

2 4 0 0 0

228 000

25

15

191

36

44

507

0 . 1 0

0 . 1 8

0.22

REE 5 9

of y i e ld c o m p o n e n t s , such as number of pan i c l es p e r plant, weight of panic le p e r plant and weight of 100 gra ins , w e r e m e a s u r e d .

Data obtained f r o m the M2 generat ion plants w e r e a lways c o m p a r e d with those f r o m the o r i g i n a l v a r i e t y .

R E S U L T S .

In the M i generat ion , 1405 plants out of 17 901 w e r e s c r e e n e d in 1966, as p r e s e n t e d in the R e p o r t of Yungnam C r o p s E x p e r i m e n t Station [7] .

Out of 1300 M 2 s h o r t - c u l m plants s e l e c t e d on the b a s i s of o b s e r v a t i o n s in the f i e ld , 507 plants w e r e r e - s e l e c t e d in the l a b o r a t o r y by m e a s u r i n g certa in a g r o n o m i c c h a r a c t e r s . In this r e - s e l e c t i o n , those plants having s ter i l i ty o r m a l f o r m a t i o n and o ther c h a r a c t e r s which c l e a r l y i m p a i r y ie ld ing abil ity w e r e d i s c a r d e d . It was found that the treatment with 20 000 R of X - r a y s was the m o s t e f f e c t ive in shortening the cu lm in this e x p e r i m e n t (Table I) .

The 507 plants s e l e c t e d in the M 2 generat ion which had a shor t cu lm and n o r m a l fert i l i ty w e r e studied f o r o ther des i rab le a g r o n o m i c c h a r a c t e r s . A s shown in Tab le II, the mean c u l m length of the 507 plants s e l e c t e d was 80.8 c m c o m p a r e d with 96.6 cm f o r Pa lkweng . The mean panic le length was 17.9 c m c o m p a r e d with 18.8 c m f o r the o r i g ina l v a r i e t y . How-e v e r , the rat io of the panic le length to the c u l m length ( P L / C L X 100) in -c r e a s e d by 14% in the s e l e c t e d plants c o m p a r e d with the o r i g ina l one . This would suggest that panic le length does not a lways d e c r e a s e p r o -port ional ly to the shortening of the culm length. On the other hand, the mean value f o r the n u m b e r of pan i c l es per plant was 10.5 c o m p a r e d with 9.4 f o r the o r i g ina l o n e . H o w e v e r , the mean value f o r the panic le weight p e r plant was 22.5 g c o m p a r e d with 24.0 g f o r the o r ig ina l v a r i e t y , and the weight of 100 gra ins was 2.5 g c o m p a r e d with 2.7 g f o r the o r ig ina l v a r i e t y . T h e s e data indicate that the reduct ion in weight of the panic les

T A B L E II. M E A N V A L U E S A N D RATIOS OF C U L M LENGTH, PANICLE LENGTH, NUMBER OF PANICLES, PANICLE WEIGHT PER P L A N T , WEIGHT OF 100 GRAINS, AND DAYS T O HEADING OF 507 M 2 P L A N T S S E L E C T E D FOR SHORT CULM C O M P A R E D WITH THE ORIGINAL V A R I E T Y IN 1967

Culm length ( cm)

Panicle length ( c m )

Ratio of pan i c l e /

culm length

No. of panicles

Panicle weight per

plant (g)

Wt. of 100 grains

(g) Days to heading

Original variety, Palkweng

9 6 . 6 18 .8 19 .5 9 , 4 2 4 . 0 2 . 7 104; 3

Selected plants of M 2

80 .8 17 .9 2 2 . 2 10 .5 22. 5 2 . 5 9 9 . 5

Ratio of the original variety

84 95 114 112 94 93 95

T A B L E III. P E R C E N T A G E OF P L A N T S WHICH D E V I A T E F R O M THE C O N T R O L WITH R E G A R D T O C U L M A N D P A N I C L E L E N G T H , N U M B E R AND WEIGHT OF PANICLES P E R P L A N T , A N D 100 -GRAIN WEIGHT A F T E R S E L E C T I O N F O R S H O R T - C U L M LENGTH IN M 2

(Tota l N o . o f plants , 507)

Classi f icat ion 3

Deviat ion from control

Culm Panicle No. of W t . of 100-grain Classi f icat ion 3

Deviat ion from control length

07°)

length

(%) panicles

(%)

panicles (%)

weight (%)

significantly 42 0 0 0 53

keduced

slightly 55 16 1 16 17

Little d i f ference 3 52 83 76 22

slightly 0 27 13 ' 7 3

significantly 0 5 3 1 5

Mean and 96 .6 ± 5 .0 18.8 ± 1 . 5 9 . 4 ± 2 . 2 24. 0 ± 6 . 2 2 . 6 9 ± 0 . 0 7

standard deviation ( cm) ( cm) (g) (g)

a Based on mean value with standard deviation; l ittle difference falls within ± 1 S. D . , slightly reduced or increased fall within ± 2 S . D . , and significantly reduced or increased fall within ± 3 S . D .

REE 6 1

is affected by the reduction in the percentage of fertility and the kernel weight. In the number of days from seeding to heading, the selected plants for short culm headed, on the average, about 5 days earlier and the earliest plants headed 12 days earlier than the original variety.

Table III shows the frequency distribution in per cent of four characters of the 507 plants selected for short culm. In culm length 42% were significantly shorter, 55% were slightly shorter and 3% showed little difference compared with the original variety. In panicle length, 27% were slightly longer and 5% were significantly longer. On the other hand, 16% were slightly shorter and the rest showed little difference. However, in the number of panicles per plant, 3% of the 507 selected plants showed a significant increase, 13% a slight increase, 1% a slight reduction and the remainder showed little difference. In weight of panicles per plant, 1% were significantly heavier and 7% were slightly heavier, whereas 76% showed little difference and 16% were slightly lighter. It was shown that the weight of 100 grains in 17% of the 507 selected plants was slightly lighter and 53% was remarkably lighter compared with the original, whereas only 3% were slightly and 5% were remarkably heavier, r es -pectively.

As presented in F ig . l , the plants selected for short culm showed a smaller variation for panicle weight per plant than the original variety.

PANICLE WEIGHT (g)

F I G . l . Frequency curves for cu lm length and weight of panicles of plants selected for short cu lm in M z , compared with the original variety.

6 2 REE

In the plants selected for short culm, the correlations between culm length and panicle length, number of panicles, and weight of panicles per plant are presented in Figs 2, 3 and 4. No correlation was found between culm length and panicle length. Some plants had longer panicles in spite of a distinct reduction in culm length. On the other hand, the number of panicles was positively correlated with the culm length, with a coefficient of 0.1582. The weight of the panicles per plant was also positively c o r r e -lated with the culm length, with a coefficient of 0.4081, both significant at the 1% level.

In general, the weight and number of panicles per plant seemed to decrease with decrease in culm length. Some exceptional plants, however, had heavier panicles, more panicles per plant and longer panicles in spite of a distinct reduction in culm length. These results are similar to those obtained by Kawai [2], Such a combination of characteristics is highly promising in practical r i ce breeding. Therefore, it is advisable to continue the tests on the yield characters mentioned previously so as to determine whether they will persist in subsequent generations, similar to reports by Tanaka [3].

From the 507 plants selected for short culm, 111 plants were sampled at random to determine lodging resistance. The length of internode, bending moment ( = culm length (cm)X tiller weight (g)), breaking strength and lodging index (= bending moment/breaking strengthX 100) were measured.

The results in Table IV show that, in general, the length of each internode from the base of the panicle down to the basal internode was gradually reduced, and that particularly N3 (= the fourth internode from the base of the panicle) and N4 (= the fifth internode) internodes, which are c losely related to resistance to lodging, were remarkably shorter than those in the original variety.

26-

2 4 "

22-

20-

16-

K-63

1

1 4 3

2 1 3

1 2 11 2 1

2

2 1

67 71

2

1 1 3 2

3 5

6 10

1 1 2 2 1

1 1 5 1 2 2 4 2 1 1 1

6 4 10 3 6 5

6 . 9 13 6 5 8

9 9 9 12 12 11

9 10 12 8 12 15

4 10 11 7 4 9

7 2 5 10 3 1

1 6 3 7 3

1 3 2

2

75 79 83 87 91 CULM LENGTH ( c m )

FIG.2 . Correlation between cu lm length and panic le length of selected plants in M 2 .

REE 63

26

24-

22-

20

18-

16-

63 67

7 2 8 10

4 12 12 13 10 12 8 11 16 16 9 8 7 I E 10 I E 10 8 9 7 12 1 7 6 7 1 2

1 1 1 1 1

79 83 67

CULM LENGTH ( c m )

FIG. 3. Correlation between cu lm length and number of panicles per plant of selected plants in M 2

61 -

57 •

53 "

49 -

45 "

3 41 -

2 3 7 ' a. x 33 "

1 2 2 2 3 1 4 1 1 6 3 2

1 2 3 1 3 4 6 2 6 1 1 1 4 6 8 11 E e 9 3

1 2 2 4 5 7 E 9 7 11 7 5 3 4 4 5 7 4 15 14 21 10 9 2 3

3 3 3 8 14 15 15 17 12 9 7 b 1 2 7 E 9 7 10 14 E 4 2

1 63 66 69 72 75 78 81 84 87 90 93 96

CULM LENGTH ( c m )

FIG.4. Correlation between cu lm length and weight of panicles per plant of selected plants in M 2 .

T A B L E IV. L E N G T H OF C U L M AND INTERNODE, BENDING M O M E N T , B R E A K I N G S T R E N G T H , A N D LODGING INDEX OF 111 M 2 P L A N T S S E L E C T E D FOR SHORT CULMS

No. of plants tested

Culm iength ( cm)

Length of internode ( cm) Bending

moment'3

' (g x c m )

Breaking strength0

(g) Lodingj index

No. of plants tested

Culm iength ( cm) N? N, N, N 3 N4 Ns '

Bending moment'3

' (g x c m )

Breaking strength0

(g) Lodingj index

Original

variety, Palkweng 111

100

(98 .2 )

100

(41 .5 )

100

(21.4)

100

(15 .5 )

100

( 1 1 . 9 )

100.

( 6 . 1 )

100

( 2 . 0 ) *

. 100

(1. 087)

100

(981)

100

(110)

Short-culm

Mj plants 111 77 94 85 79 46 25 25 . 67 129 52

Note: Figures in brackets show the actual mean values.

aNQ = The.first internode from the base of the panicle down to the basal internode.

^Bending moment = Plant height x tiller weight.

CBreaking strengths Tested with a 5 - c m segment taken from the 4th internode.

d . , Bending moment Lodging index = r r " 0 r x 100.

° ° Breaking strength

REE 6 5

The bending moment of selected plants for short culm was less, whereas breaking strength was'heavier than that of the original variety, ' and accordingly the lodging index was 57.5 compared with 110.0 for the original variety. The data in Fig.5 show that culm length and the lodging index were positively correlated with a coefficient of 0.5290,• significant at the 1% level. These results indicate that the plants selected for short culm had resistance: to lodging.

120

£ 100-

80 -o o o 60

• • • . *

. " w** • ••• Jft . • V

60 65 70 75 80 85

C U L M LENGTH ( c m )

FIG. 5. Correlation between culm length and lodging index of 110 selected plants in M 2 generation.

In this experiment, the lodging index appeared to be a fairly good indicator of the plant type, tall plants vs . short ones. Most of the short-culm plants have an advantage over the tall ones in their resistance to lodging. These results agree well with those given in Ref. [8].

CONCLUSIONS

In the short-culm plants selected in the M2 generation, other agro-nomic characters were changed simultaneously. The mean culm-length of the 507 plants selected was 81 cm compared with 97 cm for the original variety. The plants selected were shorter in panicle length, less in weight of panicles per plant and kernel weight, earlier in days to heading and shorter in culm length. The variation in culm length and other desirable characters showed a wider range than in the original variety. No c o r r e -lation was found beween culm length and panicle length.

• Some plants were found in which the panicle length'was not shorter in spite of a distinct reduction in culm length. The number and weight of the panicles per plant were positively correlated with the culm length. Some exceptional plants, however, had heavier panicles and more panicles per plant. . :

The results obtained in this experiment indicate that each internode length of the plants selected for short culm was gradually reduced between the base of the panicle and the basal internode. In particular, the N3 and N4 internodes, which are closely related with resistance to lodging, were remarkably shorter than those in the original variety. The lodging index was lower than that of the original variety and the culm length was posi-tively correlated with the lodging index. These results indicate that the plants selected for short culm had resistance to lodging.

Such a combination of characters should give a very important reason for practical r ice mutation breeding by means of radiation, as also r e -ported by Kawai and Tanaka [2, 3]. As suggested in the recommendations

6 6 REE

of Ref.[ 9], the fact that a mutant strain possesses positive and negative characters with regard to its usefulness in plant breeding is not always due to pleiotropic action of a single mutant gene. It can also be due to the compound effect of two or more neighbouring absolutely linked genes, which changed simultaneously during the mutagen treatment.

The progenies selected for short culm having desirable agronomic characters must be tested in subsequent generations for the possibility of eliminating factors which impair yield components. In further studies in this project, not only the short-culm variants, bat also the slightly shorter ones which were not changed in other desirable agronomic characters, will be benefitial for practical breeding in r ice .

R E F E R E N C E S

[ 1 ] BEACHELL, H . M . , Newsletter (FAO) 6 (1957) 18. [ 2 ] KAWAI, T . , SATO, H . , MASIMA, I . , "Short -culm mutations in rice induced by P 3 ! " , Effects

of Ionizing Radiations on Seeds (Proc. Symp. Karlsruhe, 1960) IAEA, Vienna (1961) 565. [ 3 ] TANAKA, H . , Studies on artificial induced mutation in rice breeding. The report of g a m m a field

in Japan (1968) 83. [ 4 ] TORIYAMA, K . , FUTSUHARA, Y . , Studies on rice breeding by means of artificially induced

mutation. II. The breeding of the high yielding strain Fu. 53 by irradiation treatment with P 3 2 , Jap. J. Breed. 12 (1962) 148.

[ 5 ] TORIYAMA, K . , FUTSUHARA, Y . , Studies on r ice breeding by means of artificially induced mutation. IV. The breeding of the high yielding line Fr. 54 by X-ray treatment, Jap. J. Breed. 12_ (1962) 263.

[ 6 ] TORIYAMA, K . , FUTSUHARA, Y . , Breeding of new r ice variety "REIMEI" by gamma-ray irradi-ation, Jap. J. Breed. 17 (1967) 85.

[ 7 ] Yungnam Crops Experiment Station, The annual research report, O f f i c e of Rural Development (1966) 104.

[ 8 ] IRRI, Annual Report of the International Rice Research Institute, Manila, The Philippines (1963) 22. [ 9 ] Panel of Mutations in Plant Breeding,' in "Sc ient i f i c recommendations" (Proc. Panel Vienna, 1966)

IAEA, Vienna (1966) 260.

' D I S C U S S I O N

M.S.HAQ: Can you inform us about (a) the M2 population size, (b) the method of selection in Mj and M2 , and (c) whether the variety used is late in maturing?

J.H.REE: (a) The M2 population consisted of 17 900 plants, (b) In the Mi generation we discarded malformed plants; in the M2 population the main objective was to select for distinctly short culm and other desir-able agronomic characters, and (c) the variety is medium to late.

REE 6 7

RESULTS OF THE FAO/IAEA UNIFORM RICE MUTATION TRIALS IN 1967 FROM YUNGNAM CROPS EXPERIMENT STATION,

MILYANG, KOREA

1. In 1967 a yield trial was carried out with 12 mutant strains and Palkweng as the check variety.

2. The seed was planted on 26 June and transplanted on 20 July, but it was too late for seeding in our climatic conditions.

3. The trial gave the following results: (a) Among the 13 varieties, four produced more tillers and seven

attained earlier maturity than Palkweng, whereas three did not mature.

(b) The culm length was shorter than that of Palkweng in nine varieties and longer in three varieties. All the varieties were non-lodging except Allorio-11. In particular, we observed that the mutant variety Allorio lamda was 25% shorter in culm length and non-lodging, and that Reimei was 13% shorter in culm length than the original varieties Allorio-11 and Fujiminori, respectively.

(c) Only two mutants yielded more grain than the original variety. Allorio lamda yielded 15% more than Allorio-11 and Reimei yielded 4% more than Fu'jiminori.

(d) In' general, disease was seldom observed and there was no incidence of insects or pests.

IMPROVEMENT OF RICE VARIETIES BY INDUCED MUTATIONS TO INCREASE YIELD PER ACRE AND RESISTANCE TO DISEASES AND TO IMPROVE SEED QUALITY*

A.J. MIAH, I.M. BHATTI, A. AWAN, G.BARI Atomic Energy Agricultural Research Centre, • Tandojam^ West Pakistan

« • Abstract

IMPROVEMENT OF RICE VARIETIES BY INDUCED MUTATIONS T O INCREASE YIELD PER ACRE AND RESISTANCE TO DISEASES AND T O IMPROVE SEED QUALITY. Mutagen treatments of the variety Kangni-27 have given rise to short culm and early ripening strains. Experiments have been started with the varieties Dokri Basmati, Jajai-77, IR-8 and 370 Basmati using fast neutrons, gamma rays, EMS and dES as mutagens. Results obtained so far show a differential response of the varieties in their radiosensitivity and frequency of leaf colour mutations.

INTRODUCTION

Since joining the FAO/IAEA Co-ordinated Program of Research on the Use of Induced Mutations in Rice Breeding in 1964 our work has been directed at improving rice by means of induced mutations. This paper gives the results of experiments that were- carried out from 1967 to 1968.

EXPERIMENT NO. I

This experiment was initiated in 1964; the details are given in a previous paper by Miah and Bhatti published In Rice Breeding with Induced Mutations, Technical Reports Series No. 86, page 75.

Short-culm and early flowering mutants in Kangni-27

(a) Short-culm mutants

Out of 21 short-culm mutants isolated in the M2 generation, 19 lines were found to breed true in the M3 generation. The plant progenies of these mutant lines were grown in a randomised block design with four replications in the M4 generation. Observations were made plant height at maturity ' and yield per plant. The results are presented in Table I. From the data it is evident that all the mutant lines are shorter than the original variety. The minimum average plant height was recorded in the mutant line S-8 (126.4 cm) which is 16.8% less than the original variety. The data also indicate that there is more variability in plant height character in the mutant

* This work was conducted under the IAEA Contract No. 290/RB.

69

7 0 MI AH et al .

l ines than in the mother l ine. Delay in harvest ing due to shortage of labour resul ted in high shattering of the grains and hence the y ie ld data, though r e c o r d e d , are not r e l i a b l e .

(b) E a r l y f l ower ing mutants • •

T h i r t y - n i n e l ines w e r e se lec ted f r o m the M3 progen ies of six ear ly f l o w e r i n g mutants on the bas i s of ear l iness and higher plant y ie ld . The plant p r o g e n i e s of these l ines w e r e ra i sed in the M 4 generat ion in a r a n d o m -ised b l o ck des ign with f o u r replications1 . The f l ower ing date- and y ie ld w e r e r e c o r d e d on every individual plant. The resu l t s are s u m m a r i z e d in Table II.

F r o m the data it i s seen that a lmost all l ines f l o w e r e d e a r l i e r than the o r i g ina l var ie ty . It i s a lso to be noticed that the var iab i l i ty f o r f l o w e r i n g » t ime i s usual ly g r e a t e r in the mutant l ines than in the or ig ina l var ie ty . In •

T A B L E I. P L A N T HEIGHT AND YIELD OF 19 S H O R T - C U L M MUTANTS OF RICE C O M P A R E D WITH THE ORIGINAL V A R I E T Y KANGNI-27 IN

Mutant lines Plant height ( cm)

Mean Range

Plant yield (g)

Original variety 151 .9

•S-3 134 •9

S-4 135 .0

S -5 133 .7

S-6 140 . 5

S-7 130. .4

S-8 126 .4

, S-9 134 .3

S-10 .. 135. .5

S - l l 138. .3

S-12 132. .6

S-13 132. .8

S-14 132. .8

S-15 ' 131, ,7

S--16 • . 134. .9

S-17 • • • ' 134 .0

S-18< 135. .9

- S-19 . • • 134 .0

S-20 130 .4

S-21 129. .6

135.0 -

99 .0 -

9 6 . 5 •

8 6 . 0 -

107.0 •

9 7 . 5 •

•83.5 •

102 .5 •

106 .5 •

93 .0 •

102 .5 •

109.0 -

78 .0 •

1 0 2 . 0 -

92 .0 -

104 .5 •

102 .5 •

99'. 5 •

9 1 . 5 •

7 8 . 5 •

175 .5

172 .5

167 .5

163.5

171.0

166. 5

161 .5

1 6 1 . 0

170 .5

183 .5

169.0

169 .5

167.0

169.0

170.0

169.0

165 .5

163.0

167 .5

164. 5

60 .3

3 7 . 1

4 2 . 7

39 .0

4 0 . 8

4 1 . 9

29 .1

38 .6

. 3 7 . 5

4 0 . 0

3 8 . 5

4 2 . 1

4 0 . 2

3 9 . 7

4 1 . 5

3 9 . 7

4 0 . 8

4 5 . 1 .

3 7 . 5

' 3 1 . 8

MIAH et al .

T A B L E II. HEADING AND Y I E L D DATA OF 39 E A R L Y F L O W E R I N G MUTANT LINES OF RICE C O M P A R E D WITH THE ORIGINAL VARIETY ' KANGNI-27 IN THE M 4 GENERATION

No. of days Days earlier ' Plant yield

Mutant lines from sowing than original Range to heading variety

Original variety EF-1-7 EF-1-47 EF-1-69 EF-1-112

98.7 93 .4 97 .4 9 8 . 3 ' 97 .7

5 .3 J .3 0 . 4 1.0

96 - 104 85 - 99 92 - 100

. 9 5 - 108 95 - 100

39 .1 36.1 39 .1 39 .1 4 1 . 8

EF-2-9 EF-2-51 EF-2-73 EF-2-91

93 .6 94 .1 94 .5 95 .2

5 .1 4 . 6 4 . 2 3 . 5

87 - 99 85 - 98. 88 - 98 90 - 99

36 .4 37 .5 35 .1 36 .3

EF-3-2 EF-3-31 EF-3-68 EF-3-86

95 .2 93 .9 93.0 94. 5

3 . 5 4 . 8 '5 .7 4 . 2

89 - 99 88 - 104 86 - 97 90 - 100

4 0 . 9 38 .8 4 0 . 5 39 .0

EF-4-18 EF-4-46 EF-4-57 EF-4-86

93.1 95.7 95.3 • 95 .3

5 .6 3 .0 3 . 4 3 . 4

79 - 97

89 - 99 87 - 100

31 .3 3 9 . 8 29 .2 35 .3

EF-5-4 EF-5-7 EF-5-9 EF-5-10 EF-5-11

' EF-5-15 EF-5-23 EF-5-25 EF-5-27 EF-5-28 EF-5-30 EF-5-50 EF-5-57 EF-5-58 EF-5-77 EF-5-82 EF-5-85 EF-5-100 EF-5-108

91 .9 92 .5 91.0 93 .9 89 .8 91 .3 90 .3 52 .1

91.0 90.0 90.0 90 .6 91.1 92 .4 90 91 90

2 5 6

89.3

6.8 6.2

7 .7 4 . 8 8 .9 7 .4 8 .4 6.8

9 .6 7 .7 8 .7 8 .7 8.1 7.6 6 . 3 8 .5 7 . 2 8 . 1 9 . 4

85 - 9 8 80 - 97 85 - 95 87 - 98 85 - 96 86 - 108 82 98 83 - 98 83 - 95 80 - 96 83 -• 98 79 - 97 84 - ' 97 80 - 97 83 - 98 83 - 95 82 - 96 83 - 107 84 - 97

29 .1 37 .4 32 .5 33.0 30 .8 31 .6 27 .8 29 .6 29 .2 32 .0 28 .9 31 .2 30 .6 29 .7 33 .3 33 .6 38 .2 32 .6 31 .9

EF-6-1 EF-6-37 EF-6-67 EF-6-109

97 .2 97 .3 96.6 96 .8

1 . 5 1 .4 2 . 1 1 .9

94 - 104 94 - 101 95 - 103 94 - 1011

22.7 28.0

28.2

28.4

7 2 MIAH et al.

general, the yield per plant was reduced in the mutant lines but some lines had a yield potential at par.with the original variety.'

This year 12 out of the 39 M4 lines have been put to micro-yield trial with four replications (plot size 1 5 ft X 6 ft).

EXPERIMENT NO.'II

Improvement in Dokri Basmati and Jajai-77

Resting seeds of the rice varieties Dokri Basmati and Jajai-77 were treated with 1000, 1300, 1500 and 1800 rads of fast neutrons by the IAEA laboratory at Seibersdorf, Austria, and with 20, 30, 40 and 50 kR of gamma radiation from the 60Co source at-the Atomic Energy Agricultural Research Centre, Tandojam at a dose-rate of 8.5 kR/h. The Mx generation was grown in summer 1967 and observations were made on germination, plant height at maturity and seed fertility.

For chlorophyll mutation studies in the M2 generation, the longest spike from each Mj plant was sown, without threshing, as an M2 strain. Chloro-phyll mutants were scored when the seedlings were about 14 days old. Strains with less than 10 M2 seedlings were discarded while arranging experimental results. Mutation frequency was expressed as the number of mutations per 100 Mj spikes and also as the number of mutants per 1000 M2 seedlings. The segregation ratio for each treatment was a pooled one, i. e. expressed as a percentage of total mutants in total tested M2 seedlings in mutated M2 strains. Chlorophyll mutations were classified into four groups, i . e . albina (white), xantha (yellow), viridis (light green) and others (no definite pattern of chlorophyll destruction). Chlorophyll mutation studies were carried out in a field nursery from May to July, 1968.

M2 plants have been grown in the field for studies of viable mutations of economic importance.

The results of the Mj generation studies are presented in Table III. The results show that germination, plant height and seed fertility of the variety Dokri Basmati decreased after neutron and gamma irradiations, but the decrease was not proportional to the increase in dosage.

In Jajai-77, germination, plant height and seed fertility of the treated populations showed the same tendency as in Dokri Basmati, except for germination after gamma-ray treatments, which increased above the non-irradiated control.

From the data it is apparent that Jajai-77 is more radioresistant than Dokri Basmati.

Results of the chlorophyll mutation studies are presented in Table IV. In Jajai-77, both the number of mutations per 100 Mj spikes and the number of mutants per 1000 M2 seedlings, after neutron irradiation, increased with dose, but in the highest dose (1800 R), the mutation frequency dropped remarkably. On the other hand, after gamma irradiation the mutations per 100 Mi spikes decreased with the increase in dose. Mutant frequency per 1000 M2 seedlings increased up to 30 kR and then decreased at higher doses.

In the variety Dokri Basmati, mutation frequency on the basis of Mj spikes and mutant frequency per M2 seedlings were found to be highest after neutron irradiation with 1800 R, but at 1300 and 1500 R the mutation

VIADO et al. 73

TABLE III. DATA ON GERMINATION, PLANT HEIGHT AT MATURITY AND SEED FERTILITY OF Mx PLANTS OF RICE'VARIETIES DOKRI BASMATI AND JAJAI-77 AFTER IRRADIATION

Variety Treatment Germination (% of control)

Plant height (6/o of control)

Seed fertility of control)

Fast neutrons (R)

1000 77.0 96 .6 58.0 1300 84 .7 92 .3 4 2 . 5

' 1500 80 .9 93.1 . 4 3 . 5 • 1800 82 .5 ' 90 .4 36 .5 '

Dokri Basmati Gamma rays (kR)

20 95 .7 91.8 74.0 30 98 .4 88.8 59.4 40 89 .7 87 .2 48 .1 50 . 9 4 . 6 90.7 39 .6

Fast neutrons (K)

1000 94 .3 98 .2 71". 3 1300 105.7 97 .5 52.3

• 1500 110.3 95 .7 4 9 . 2 1800 104.6 95 .8 58.3

Jajai-77 Gamma rays (kR)

20 97 .3 98.1 75.2 30 95 .7 96 .5 57.9 40 97 .8 93 .5 55.0 50 82 .3 . - 9 7 . 9 45 .0

frequency was lower than at 1000 R. After gamma-irradiation, the mutation rate (calculated per 100 Mj spikes and per 1000 M2 seedlings) increased up to 30 kR and then decreased at higher doses. The data also indicate that neutron irradiation induced a higher frequency of chlorophyll mutations than gamma irradiation in both varieties. In both varieties, no linear increase • in segregation ratio could be observed after neutron or gamma-ray treat-ments. The segregation ratio showed almost the same tendency as the mutation frequency per 1000 M2 seedlings.

The mutation spectra obtained in different treatments with neutrons or gamma rays were pooled together and the results are reported in Table V. The data show that in both Dokri Basmati and Jajai-77, the appearance of albino mutations was maximum after neutron irradiation, followed by viridis in the case of Dokri Basmati and by xantha in the case of Jajai-77. On the other hand, after gamma irradiation, viridis was followed by albina in both the varieties.

TABLE IV. . CHLOROPHYLL MUTATION FREQUENCY IN M2 IN RICE VARIETIES DOKRI BASMATI AND JAJAI-77

Variety Treatment Mi spikes analysed

Mutations per 100 Mi spikes

Mg seedlings analysed

Mutants per 1000 Mj seedlings

Mean segregation ratio

(%)

Average M 2

seedlings per spike

Control 119 5468 - - 4 6 . 0

Fast neutrons ( R )

1000 104 16 .4 3468 2 1 . 9 1 5 . 4 3 3 . 4 1300 86 8 .1 2791 9 . 2 8 . 4 3 2 . 5 15 00 88 17. .0 2474 1 6 . 2 1 1 . 2 2 8 . 1 1800 .76 26, .3 2087 3 4 . 5 1 3 . 6 27. 5

Dokri Basmati

Gamma rays (kR)

20 49 22. ,5 1847 8 . 1 3 . 6 5 3 7 . 7 30 49 30 .6 1607 2 6 . 8 8 . 8 3 2 . 8 40 46 15 .2 1260 1 7 . 5 11 .4 2 7 . 4 50 69 23, .2 1608 2 4 . 9 1 0 . 7 2 3 . 3

Control 113 11. .5 9848 1 . 4 1 . 2 8 7 . 2

Fast neutrons (R)

1000 66 21, .2 4561 6 . 8 2 . 7 6 9 . 1 1300 98 32, ,7 5494 2 5 . 3 7 . 9 5 6 . 1 1500 88 33. ,0 5428 5 0 . 5 1 2 . 8 6 1 . 7 1800 98 19. 4 6098 1 2 . 0 7 . 1 6 2 . 2

Jajai -77 Gamma rays(kR)

20 93 35. 5 6362 14 .0 3 . 7 6 8 . 4 30 80 20. 0 4165 . 1 8 . 3 7 . 4 52 .1 40 85 16. 5 3998 17 .0 9 . 4 4 7 . 0 50 73 15. 1 3336 1 1 . 4 10 .4 4 5 . 7

VIADO et al . 7 5

TABLE V. SPECTRUM OF CHLOROPHYLL MUTATIONS (VALUES IN%) IN RICE VARIETIES DOKRI BASMATI AND JAJAI-77 AFTER NEUTRON AND GAMMA IRRADIATION

Variety Mutagen Albina Xantha Viridis Others Total No. of mutations

Dokri Basmati Fast neutrons

Gamma rays

63 .5

31 .7

12 .8 15.6

8 .3 4 1 . 7

8 . 1

18.3

211

120

Jajai-77 Fast neutrons 60.7 19.0 9 .7 10.6 517

Gamma rays 37 .3 17.0 38 .0 7 .7 271

T A B L E VI. G E R M I N A T I O N A N D P L A N T H E I G H T A T M A T U R I T Y O F M j P L A N T S O F RICE V A R I E T Y IR-8 A F T E R G A M M A I R R A D I A T I O N

Dose Germination Plant height ( cm) as (kK) (<yb of control) % of control

20 128.4 97 .5

30 111.9 96.7

40 111.0 95 .9

50 105.7 93 .3

EXPERIMENT NO. Ill

Improvement in IR-8 variety

Four doses of gamma radiations, i . e . 20, 30, 40 and 50 kR, were given to dry seeds of the rice variety IR-8 at the Research Centre, Tandojam. In the Mj generation grown in the summer of 1967 germination and plant height characters were studied. The data are presented in Table VI. From the data it is evident that germination increased in all the treated populations compared with the control. The increase was highest at 20 kR and then decreased with the increase in dose. The plant height, on the other hand, decreased with the increase in'dose. The M2 generation was raised in 1968 for the study of viable mutations of economic importance.

7 6 VIADO et al.

EXPERIMENT NO. IV

Improvement in 370 Basmati and IR-8

Dormant seeds of two rice varieties, namely 370 Basmati (fine grain) and IR-8 (coarse grain) were subjected to the following mutagenic treatments in May, 1968.

(a) Gamma-ray treatment

A60Co gamma source of the Atomic Energy Agricultural Research Centre, Tandojam was used at a dose-rate of 5.4 kR/h.

(b) Chemical treatment

Fresh solutions of EMS and dES were prepared with deionized water. After a 3-h presoaking, the seeds were treated with the chemicals for 20 h at room temperature and then washed thoroughly. Presoaking and post-treatment washing were also done with deionized water.

(c.) Doses given

Mutagen - Dose Gamma rays 25, 35 and 45 kR EMS ' 0. 1, 0. 3 and 0. 5% dES 0. 1, 0.15 and 0.2%

(d) Handling after treatment.

After the seeds had been treated with the mutagens they were sown in the nursery and the seedlings were transplanted in the field after 30 days of sowing. Seed fertility and morphological variations, if any, will be studied in the Mj generation.

D I S C U S S I O N

N. YAMADA: I wonder if one can expect a higher yield by reducing the plant height of any variety. If not, what is the criterion for selecting the mother variety for mutagen treatment?

A.J. MIAH: I think it is usually possible to increase the yield by reducing the plant height. In that case the starting material should be tall because if the starting material is already very short.there is very little possibility to increase the yield by further reducing the plant height.

On the other hand, if the objective is to increase the yield without decreasing the plant height, the starting material should be of good quality or have some other desirable character. And the increase in yield in that particular material should be aimed at by inducing polygenic'mutations in the yield components.

BREEDING FOR EARLINESS, HIGH YIELD AND DISEASE RESISTANCE IN RICE BY MEANS OF INDUCED MUTATIONS

M.S. HAQ, S.M. ALI, A.F.M. MANIRUZZAMAN, A. MANSUR and R. ISLAM Atomic Energy Centre, Dacca, East Pakistan

Abstract

BREEDING FOR EARLINESS, HIGH YIELD AND DISEASE RESISTANCE IN RICE BY MEANS OF INDUCED MUTATIONS. Ten varieties o f Boro, Aus and Aman rice were treated with 30 kR o f gamma rays from the 500-Ci 6 0 C o source o f the Atomic Energy Centre o f Dacca . In addition, two rice varieties were treated with EMS and dES. '

To suppress tillering, the seeds were sown late and at a high seed rate. 300 normal- looking fertile M t

plants from each variety were harvested at random. The M2 progenies were sown on a plant-to-row basis to select for high yie ld , earliness, blast resistance and response to large doses o f nitrogen fertilizer. Characters like plant height, number o f tillers, fertile tillers, length of panicle and t ime from sowing to maturity were checked . Asthe results showed great variability in the mutagen-treated material the chances for successful selection are promising.

INTRODUCTION

The present mutation breed ing work was initiated in D e c e m b e r 1966 with the ob ject of evo lv ing mutants of r i c e which a r e ear ly ' and high y ie ld ing , res is tant to blast d i s e a s e , and r e s p o n s i v e to heavy fer t i l i zat ion without being lodged by using a phys i ca l mutagen (gamma r a y s ) and c h e m i c a l mutagens (EMS and dES).

The impor tance of such breed ing p r o g r a m s needs no e m p h a s i s as the l o ca l v a r i e t i e s , which are all indica type, a r e lacking in m o s t of the above qual i t ies . The p e r a c r e y ie ld of r i c e is v e r y low (1500 lb) , the plants a r e tall with weak straw, incapable of uti l iz ing m o r e f e r t i l i z e r s and have the tendency to l o d g e . E a r l i n e s s is a v e r y d e s i r a b l e c h a r a c t e r f o r East Pakistan condit ions as it wi l l ensure a sa fe harves t b e f o r e the f l oods and wil l help in growing m o r e c r o p s in one y e a r in the s a m e f i e ld .

M A T E R I A L AND METHODS

In East Pakistan three d i f f erent g roups of r i c e a r e grown in three d i f f erent r i c e growing s e a s o n s : B o r o ( N o v e m b e r - D e c e m b e r to A p r i l - M a y ) , Aus ( A p r i l - M a y to July -August ) and Aman (July-August to D e c e m b e r -January) . T w o v a r i e t i e s of B o r o r i c e (Habiganj-II and Habiganj -VI ) , f our var i e t i e s of Aus r i c e (Kataktara, Mar ichbat i , Dular and Dharia l ) and four var i e t i e s of Aman r i c e (Nizersa i l , Lat i sa i l , Chi tra j and D A - 3 1 ) have been used in this p r o g r a m .

7 7

7 8 VIADO et al.

F r o m both l a b o r a t o r y and f ield exper iments 30 kR of gamma rays was found to be the most convenient working d o s e f o r all these v a r i e t i e s . I r rad iat ion was done f r o m a 500 -Ci 6 0 Co g a m m a s o u r c e of the A t o m i c E n e r g y Centre , D a c c a . Seed s a m p l e s w e r e mo i s ture stabi l ized ( 1 2 - 1 4 % ) b e f o r e i r rad ia t i on .

M ] generat ion

The B o r o seeds w e r e sown b r o a d c a s t and late at a higher s e e d - r a t e of 125 l b / a c r e instead of the usual rate of 82 l b / a c r e in o r d e r to s u p p r e s s t i l l e r ing . The usual p r a c t i c e with B o r o is to sow the s e e d s in the n u r s e r y bed in ear ly N o v e m b e r and transplant the seed l ings in the f ield in ear ly D e c e m b e r . The Aus var ie t i es w e r e sown broadcas t (which is the usual p r a c t i c e ) , late and with a higher seed rate f o r the s a m e r e a s o n s . The A m a n r i c e var ie t i es w e r e f i r s t sown in the nursery bed in late August and transplanted in the f ield in the later part of September , a l so to s u p -p r e s s t i l l e r ing .

The s i z e of the population was approx imate ly 100 000 plants f o r each of the v a r i e t i e s under each group of r i c e . At maturity , 300 n o r m a l - l o o k i n g f e r t i l e plants w e r e se l e c ted at random f r o m each var iety of B o r o , Aus and A m a n . Data relat ing to plant height, t i l l e r number , number of panic les , and s ter i l i ty percentage w e r e r e c o r d e d at maturity f o r each plant. The s e e d s of the se l e c ted plants w e r e kept separate ly . The seeds of the res t of the plant population w e r e bulked.

M 2 generat ion

In the second y e a r of the exper iment the 300 individual s e l e c t ed plants w e r e divided into three lots of 100 each, and the seeds f r o m each of the plants w e r e grown on a p l a n t - t o - r o w b a s i s . The three groups of 100 plants w e r e f o r the fo l lowing three e x p e r i m e n t s :

1. Se lect ion of ear ly and h igh-y ie ld ing mutants; 2. Se lect ion of b l a s t - r e s i s t a n t mutants; and 3. Se lect ion of mutants r e s p o n s i v e to large d o s e s of n i trogenous

f e r t i l i z e r .

In addition, the M 2 bulk population f r o m the bulk Mj seed w e r e grown f o r fur ther s e l e c t i o n w o r k .

1. Se lec t ion of ear ly and h igh-y ie ld ing mutants (Aus-, Aman and B o r o )

The seeds f r o m 100 s e l e c t e d Mi s ingle plants w e r e sown wel l spaced in 100 r o w s of 10 plants each in each rep l i cat ion , there being two r e p l i c a -t i o n s . The fo l lowing observa t i ons on a s ingle plant bas i s w e r e r e c o r d e d .

(a) Date of sowing (b) Date of f l ower ing (c) Plant height (d) No. of t i l l e r s (e) No. of f e r t i l e t i l l e r s .

VIADO et al. 7 9

2. Selection of blast-resistant mutants (Aus and Aman only)

For selection of blast-resistant mutants (Aus and Aman), seeds from 100 selected Mi single plants were exposed to infection by the uniform blast nursery trials' technique recommended by the IRC and IRRI. Boro seeds were not exposed to blast infection. It has been our observation that the incidence of blast in Boro rice is of minor importance. The Boro season is characterized by relatively dry weather, short days and low temperature.

3. Selection of mutants responsive to large doses of nitrogenous fertilizers (Aus, Aman and Boro)

The 100 selected Mi single plants from each variety were planted well spaced in 100 rows of 20 plants each. The land was fertilized at the rate of 120 lb N2 (urea), 60 lb P2 O s ( T . S . P . ) and 60 lb K 2 0 (muriat of potash) per acre. The plants were harvested on a single plant basis.

Treatment with chemical mutagens: (Mi)

Work was started with two rice varieties (Nizersail and Latisail Aman varieties) from late 1967. The treatment of pre-soaked seeds (soaking time 24 h) with freshly prepared mutagen solutions, which were prepared with de-mineralized water, was carried out at pH 7. 0 at a room temperature of 30°C. The pH was maintained with a buffer. The dES treatment time was 2 h for a 0.03M solution and the EMS treatment time was 24 h for a 0.03IVI solution. Large volumes of mutagen solution (1 ml/seed) were used and the solution containing the seeds was vigorously shaken by a mechanical shaker to give each seed the opportunity to absorb the same number of moles of mutagen.

Post-treatment washing was done in a buffer solution for about 1 h. With d'ES, the concentration was kept relatively constant by changing to fresh solutions after one fourth had been hydrolyzed. Sowings were made after post-treatment.

RESULTS AND DISCUSSION

M1 generation

Table I shows the Mj data for different characters of different varieties under Boro, Aus and Aman groups of rice. It may be mentioned that the Boro crop was raised out of season and sown broadcast. The Aus and Aman crops were sown late. In all cases the seed rate was higher' than the normal. These untimely, late and thick sowings seemed to be very effective in lowering the tiller numbers.

Chemical mutagens (Mj)

All the plants of the two varieties were harvested on a single plant basis for growing during normal time in the M2 generation.

8 0 HAQ et.al .

T A B L E I. A V E R A G E N U M B E R O F T I L L E R S P E R PLANT. O F C O N T R O L A N D I R R A D I A T E D M j RICE VARIETIES, 1966 - 1967

Rice group Variety Tiller No. per plant

(av.)

Tiller No. per .plant sown at

normal t ime (av . )

"Jo suppression in tillering

Boro Habiganj-II Control

3 . 1 10 -

1966-67 Habiganj-II Irradiated

3 . 9 - 61

Habiganj-VI 4 . 3 12 -

Control

Habiganj-VI 4 . 5 _ 62 .5 Irradiated

Aus Kataktara Control 2 .6 8

1967 Kataktara ; Irradiated •3.5 - 56.3

Marichbati Control 1 .7 • ' 6 -

Marichbati Irradiated 2 . 2 - 63.3

Dharial Control 1 . 9 8 -

Dharial • Irradiated 2 . 4 - 70.0

Dular Control 2 . 9 6 -

Dular Irradiated 3 . 4 - • 43.3

Aman Nizersail Control 8 . 5 12.3 -

1967-68 Nizersail Irradiated 6 .6 - 46.3

Latisail Control 7 .7 11.6

Latisail Irradiated 7 . 0 - 39.6

Chitraj Control 6 . 2 " 8 .4 -

Chitraj Irradiated 5 . 4 ' ' - 35.7

DA-31 Control 4 .7 6.7 -

DA-31 Irradiated 4 . 4 • - 34.3

VIADO et al. 8 1

M2 generation

The M2 generation of Boro was grown during'Nov. 1967 to May 1968. The M 2 Aus crop is in the field awaiting harvest and the M2 Aman crop will be sown next August. Table II shows the range of variation in the dif-ferent characters. The M2 results for Boro show a great variation in the mutant lines compared with the control (see Table II and Appendix.I). Marked variations are observed in the characters of plant height and number of total and fertile tillers. ' There are a few lines and plants which are comparatively short in height. If these lines and plants breed true'in the M3 generation they may be of value to us as these may be resistant to lodging and more responsive to nitrogenous fertilization.

As a result of circumstances beyond our control the experiment with Habiganj-VI (Boro) was abandoned.

TABLE II. RANGE OF DIFFERENT CHARACTERS FOR CONTROL AND IRRADIATED M2 HABIGANJ-II BORO VARIETY, 1967 - 1968

Habiganj-II(Boro) Plant height

(cm) Total No. o f tillers

Fertile tillers

Length of panicle

(cm)

Seeding to maturity (days)

Irradiated 68 - 123 5 / 5 - 4 8 . 0 3 . 5 - 4 3 : 0 1 8 - 2 7 1 4 4 - 1 6 0 (mean of lines)

Control (mean) 118.5 16 16 22 .4 144


The f inancia l and technica l a s s i s t a n c e of F A O and IAEA is grate fu l ly acknowledged .

Thanks are due to all the staff members of the Plant Breeding and Genetics Section of the Agriculture Division of Atomic Energy Centre, Dacca, for their co-operation and assistance.

The visit to the experimental plots and the discussion of the problems with the investigators by Dr. Lars Fredriksson, Uppsala, Sweden, and Dr. BjOrn SigurbjCrnsson, Joint FAO/IAEA Division of Atomic-Energy in Food and Agriculture are greatly appreciated.

8 2 VIADO et al .

APPENDIX I

HABIGANJ-II BORO MUTANT LINES Date of sowing 14.11.1967

Mutant Plant _ t , „ ., Panicle u • T o t a l Fertile , . .. t ,

line height . . „ length Date of flowering , ° tiller tiller , °

No. (cm) (cm)

1 120 22 .5 21 .5 21 .3 8 . 4 . 6 8

2 . 116 23 .0 11.0 26 .2 9 . 4 . 6 8

3 112 37 .5 30 .0 18.0 10 .4 .68

4 109 25 .2 16 .4 22.5 7 . 4 . 6 8

5 104 7 .0 4 . 0 22 .9 3 . 4 . 6 8

6 118 18.0 17.0 25 .7 7 . 4 . 6 8

7 112 14.2 12.7 23 .6 7 . 4 . 6 8

8 .103 18.0 18.0 19.5 9 . 4 . 6 8

9 • 111 33 .0 32 .0 21.5 3 . 4 . 6 8

10 112 24 .3 21 .6 22 .2 9 . 4 . 6 8

11 114 20 .0 18.0 23 .4 1 0 . 4 . 6 8

12 112 16.0 9.0 23.3 3 1 . 3 . 6 8

13 119 17.6 16.9 23 .3 2 . 4 . 6 8

14 117 16 .4 14.0 21 .4 4 . 4 . 6 8

15 118 17.6 16.6 22 .3 2 . 4 . 6 8

16 117 19.0 17.0 21.6 1 . 4 . 6 8

17 114 21 .0 19.0 22 .0 1 . 4 . 6 8

18 104 36.0 36.0 21 .0 1 . 4 . 6 8

19 111 24 .0 23 .0 22 .0 1 . 4 . 6 8

20 119 25 .0 21 .0 22.7 1 . 4 . 6 8

21 115 21 .0 12.5 21.7 1 . 4 . 6 8

22 68 16.0 15.3 23 .6 1 . 4 . 6 8

23 105 13.0 12 .6 21 .6 2 . 4 . 6 8

24 94 8 . 0 6 . 0 22 .6 3 . 4 . 6 8

25 108 16.0 15.6 19.5 3 . 4 . 6 8

26 100 14.0 13.3 20 .3 2 . 4 . 6 8

27 96 18.0 18.0 22.7 5 . 4 . 6 8

28 95 20 .2 19.0 21.3 3 . 4 . 6 8

29 91 20 .0 18.0 19.7 4 . 4 . 6 8

30 105 16.5 14.0 22 .8 2 . 4 . 6 8

VIADO et al. 83

Appendix I (cont. )

Mutant line No.

Plant height

(cm)

Total tiller

Fertile tiller

Panicle length

(cm) Date of flowering

31 110 19.0 13 .0 21 .1 4 . 4 . 6 8

32 97 16.0 6 .0 19.0 1 . 4 . 6 8

33 101 9.5 8. .0 21.0 5 . 4 . 6 8

34 114 22.3 22 .0 21.5 1 . 4 . 6 8

35 115 22 .0 18 .0 21 .3 7 . 4 . 6 8

36 113 26.0 24. .0 21 .5 4 . 4 . 6 8

37 123 35.5 30. .0 26 .4 1 .4 .68

38 111 35 .0 35. .0 22 .2 12 .4 .68

39 110 24 .5 23 .5 22.7 25 .3 .68 -

40 106 48 .0 43 .0 20 i 0 7 . 4 . 6 8

41 103 32 .5 30, ,5 23 .7 9 .4 .68

42 109 22.0 18.0 25 .3 6 .4 .68

43 112 20 .5 17 .5 • 23,. 7 19 .3 .68

44 118 28 .0 24, .0 21.5 6 .4 .68

45 111 20 .0 , 17. .5 23 .5 2 . 4 . 6 8

46 83 5 . 5 3, ,5 19.8 2 . 4 . 6 8

47 104 16.0 16. ,0 21 .8 2 6 . 3 . 6 8

48 117 32.0 32, .0 22.0 8 . 4 . 6 8

49 108 22 .5 20. .5 21 .6 27 .3 .68

50 93 32 .0 31. ,0 27.0 3 . 4 . 6 8

51 111 26 .0 21. 0 25.5 26 .3 .68

52 103 15.0 10, ,0 22 .5 2 0 . 3 . 6 8

53 110 27 .5 CO

CO

,0 23.0 3 . 4 . 6 8

54 102 13.0 9. ,0 23 .2 26 .3 .68

55 114 35 .0 34. ,0 20 .0 10 .4 .68

56 102 23.0 20. 0 23.5 1 .4 .68

57 107 28 .0 21. .5 22 .5 2 0 . 3 . 6 8

58 108 24 .0 21. 0 23.3 2 0 . 3 . 6 8

59 101 25 .0 23. 5 21 .9 3 0 . 3 . 6 8

60 103 27 .0 8. 0 22 .0

INDUCTION AND UTILIZATION OF MUTATIONS IN RICE *

G.B. VIADO1, I .S . SANTOS2, E. CADA3 , P.B. ESCURO4, J.D. SORIANO5

Abstract

INDUCTION AND UTILIZATION OF MUTATIONS IN RICE. Experiments at the Philippine Atomic Research Center with gamma-irradiated seeds of IR-8-2 88-3 showed a pronounced inhibition of germina-tion at 60 and 70 kR. The LD50 was calculated to be about 54 kR at 8 days from seeding. Fertility d e -creased with increase in gamma radiation dose in an approximately l inear ' fashion. Numerous types of variants have been obtained in the M 2 generation of which the' fol lowing may. be of particular interest: ( 1 ) Plant height slightly shorter and leaves darker green, narrower and more erect than IR-8; 99 days from seeding to harvest, fert i le . (2 ) Plant height distinctly shorter than IR-8, leaves dark green small and stiff, culms small, produced as many as 27 panicle-bearing culms, grains very narrow. (3) Typical ly IR-8 in early growth but at maturity exhibits long panic le exertion, longer grains than IR-8, 111 days from seeding to harvest, produced as many as 20 productive tillers.

At t h e U . P . Co l l ege of Agriculture, Los Banos 308 plants were 'selected from the M 2 generation of BE-3 and BPI-121, and 85 from the M'3 generation of Ben ga wan, Peta and In tan after irradiation with fast neutrons. All these selections were early to medium-ear ly and short to medium-short . More benef ic ial mutants were obtained with the.lower dose treatments of BE-3, BPI-121 and Bengawan.and with the higher dose treatments of Peta. Plant-progeny rows of these selections, except those from the photo -period-sensitive varieties BE-3 and BPI-121, are being grown this 1968 dry season for further evaluation.

In the M 4 generation of Peta a larger number of short.to medium-short and early to medium-ear ly plants were selected from the 35 to 45 kR gamma treatments and the 0 . 5 to 1 .0% EMS treatments. A total of 2430 plant selections were harvested and are now being grown in plant-progeny rows.

Seventy-three uniform lines were selected from the M 3 generation of Peta and Intan irradiated with fast neutrons and from the M 4 generation of Peta treated with gamma rays, mixed radiations and EMS. Al l these lines were earlier and mostly shorter than the Peta c h e c k . .They are now growing in a twOT replicate preliminary test with.the control . . , •

Work at the Maligaya Rice Research and Training Center has included (1 ) further selection of mutants in the M 3 of several- varieties after different mutagenic treatments, and (2) field tests and observations on 12 indica and 15 japonica mutants. From BPI-121, 140 non-seasonal l ines .were selected. The range of maturity of the selected lines was 120 - 125 days from sowing to harvesting; From BE-3, 547 lines were selected for non-seasonal characteristics with a-range o f maturity from 125 to 140 days. Of these selections 12 from BPI-121 and 28 from BE-3 were practical ly uniform and are now being tested for preliminary yield trials during the 1968 dry season.

In the field trials four of the indica mutants gave higher yields than the c h e c k . All the indica mutants were non- lodging and relatively early. The japonica mutants did not perform as well as the indica mutants. All were non-lodging but only the irradiated Taichung 65 Mut. gave a higher yield than BPI-76 ( c h e c k ) .

* Supported by FAO/IAEA research contract No . 2 8 . 1 Philippine Atomic Energy Commission, . Manila, Philippines

2 Philippine Atomic Research Center, Dili man, Quezon City, Philippines

3 Maligaya Rice Research and Training Center, Munoz, Nueva Ecija, Philippines

4 U. P. Co l l ege of Agriculture, Co l lege , Laguna, Philippines

5 University of the Philippines, Dil iman, Quezon City, Philippines

85

8 6 VIADO et a l .

A study on the-selection for eating quality in M 2 IR-8 rice at the College of Arts and Sciences, University of the Philippines indicated that improved eating quality may be induced in IR-8 by mutagenic agents.

I. MUTATION E X P E R I M E N T S AT TI-IE PHILIPPINE ATOMIC RESEARCH C E N T E R , DILIMAN, QUEZON CITY

A . STUDIES ON RADIOSENSITIVITY

1. Mater ia l and methods

F 7 s e e d s of I R - 8 - 2 8 8 - 3 (IRRI), with a m o i s t u r e content of 11.9%, w e r e g iven acute e x p o s u r e in a i r to 10, 20, 30, 40, 50, 60 and 70 kR of g a m m a radiat ion f r o m the 6 0 C o g a m m a i r rad iat ion fac i l i ty of the Phi l ippine A t o m i c R e s e a r c h Center .

Two -hundred s e e d s w e r e used in each treatment . F o r the i r r a d i a -tion each lot of s e e d s was divided and p laced in two un i f o rm l a y e r s on two p i e c e s of ce l lophane tape , 1. in. X 3 in. each .

The i r rad iated s e e d s w e r e soaked in d ist i l led water f o r two hours b e f o r e they w e r e sown in seed b o x e s containing garden s o i l . In al l the plant ings , each treatment was rep l i cated f our t i m e s . Only 10 random plants f r o m each rep l i ca t i on w e r e used f o r data in T a b l e s I and II.

In the seed l ing stage of observat i ons w e r e made on:

The p e r cent germinat i on and p e r cent abor t ive germinat ion ; The seed l ing height at 8 days f r o m seeding; The n u m b e r of seed l ings showing m o r p h o l o g i c a l abnormal i t i e s ; The p e r cent surv iva l to 21 days (transplanting) ; and The LD5o (at 8 days f r o m seed ing ) .

T A B L E I. RADIATION E F F E C T S ON THE GROWTH OF I R - 8 - 2 8 8 - 3 SEEDLINGS F R O M G A M M A - I R R A D I A T E D SEEDS Based on 40 plants p e r d o s e

Germination „ . , - , Survival

. , . Seedling height , > morphologically Dose Total germination 7° abortive germination ° ° to 21 days , r , , .

° ( > control) . , defective seedlings (kR) (°/o control) 07° control) 5

0 100 0 100 100 4 . 0

10 98 .9 0 . 5 100 100.2 22 .8

20 97.3 2 . 1 91 .7 100.7 20 .5

30 100.5 0 85 .4 89.8 33 .5 '

40 96.3 7 .0 50 .0 78 .7 51.0

50 91.4 28 .0 50 .0 61 .1 86.5

60 71.1 78.0 33 .3 24 .5 98 .2

70 50.3 100 - - -

VIADO et a l . 8 7

T A B L E II. E F F E C T O F G A M M A R A D I A T I O N O N M j P L A N T S O F IR-8-288-3 Based on 40 plants per dose

Dose (kR)

Average No. of panicle-bearing

culms per hill

Average No . of branches per hill

Average No. of days from sowing

to heading

Average pollen fertility

Average seed set

0 14.2 0 .3 97.6 91.0 76.5

10 16.5 1.0 96.8 77.6 64 .1

20 17.0 7.0 95.8 70.2 4 6 . 7

30 15.8 8 .2 97.8 50 .8 4 2 . 8

40 17.2 12.3 98.6 • ' 3 1 . 4 33 .5

50 14.4 13.2 98 .8 20 .3 18.0

60 a a a 9 .6 b

a Very few plants,

k Very few seeds formed.

In the mature stage of M^, observations were made on:

The per cent pollen fertility according to the iodine test; The per cent seed set based on the first three panicles that emerged; The number of panicle-bearing culms per hill; and The average number of days from sowing to harvesting.

2. Observations 011M1 seedlings

Data taken during the seedling stage are summarized in Table I. The data show that the early stage of germination was not inhibited by doses up to 40 kR. At 50 kR, inhibition is perceptible, and at 60 and 70 kR it is pronounced. The completion of germination appeared to-be severely inhibited at 50 kR and higher doses.

On the basis of seedling height, Table I shows that IR-8-288-3 tolerates gamma radiation without sustaining severe reduction up to 30 kR. Morphologically distorted and defective seedlings were observed even in the lowest dose level used (10 kR) and their number markedly increased with increase in dose. Survival of the seedlings to 21 days C (up to the time of transplanting) was reasonably high except at 60 and 70 kR. The LDg0 was calculated to be approximately 54 kR at 8 days from seeding.

3. Observations on mature Mj plants.

There is a slight indication that the radiation treatment might have caused a certain increase in the number of panicle-bearing culms. Another effect observed at this stage of growth was the production of

88 VIADO et a l .

secondary branches at the nodes of many culms which were also • panicle bearing. A count of the number of branches produced per hill revealed that this branching effect increases with increase in dose level (Table II). The number of days from seeding to emergence of the inflorescence did not appear to.be affected by the radiation treatment. However, both the percentage of fertile pollen and the percentage of filled grains decreased with increase in gamma ;radiation dose in an approximately linear-fashion (Table II).

B. MUTANTS IN THE M2 GENERATION

From each treatment dose 4 X 10 plants were harvested (first 3 panicles per plant). The seeds of the 40 lines were bulked and a sample of about 2400 seeds from each treatment was planted in June 1.967 for M2 observation. Heavy rat infestation, however, reduced the number of plants. The plants were checked for the following characters:

(a) At seedling stage: "Colour

(b) At growth stage: ' . Relative height Colour, shape and size of leaves Degree of tillering and variations in the culms Days from seeding to heading

(c) At maturity:' " • ' ' - 1

Number of productive tillers Fertility ' ' 1

Panicle characteristics ' Grain characteristics.

M2 observations have not yet been completed. Only partial results from M2 plantings can be reported at pres:ent, and the descriptions, can be regarded as tentative until checked and confirmed in the M3 and com-pared with those reported in the literature.

The characteristics of'typical IR-8-288-3 are: high tillering ability, short stature (90 - 105 cm), moderately early maturity (120 days from ' seeding to harvest), insensitivity to photoperiod, 'susceptible to bacterial leaf blight, highly susceptible to certain races of rice blast prevalent in the Philippines, medium-sized and chalky grain. ;

Types of variants observed in the M2 • 1 ' ' . '

Besides the albino, xantha and.mottled leaf seedlings, the", following types of variants have been observed:.-" ... . . . .

1. Leaf wide and more erect than typical IR-8, blunt leaf apex, base of plant very compact, culm stout, grains rounded.

2. Loose plant habit, leaves light green, 'le'af blade narrow and folded at midrib, panicles long, grains long and very narrow with very strong attachment, 139 days from seeding to harvest.

3. Very compact plant habit,' 104'days from' seeding to harvest, pro-duce as many'as 41'panicle-bearing, culms; semi-sterile. '

VIADO et a l . ,89

4. IR-8 plant habit, 173 days from seeding to harvest (probably photo-period sensitive), dense panicle,' large peduncles, tendency to shatter. : • >. .

5. Very short plant, leaves onion-like (fine and-rolled), culms very, small, grains smaller. • . . '•

6. Leaves narrower and longer than typical IR-8,- taller with long internodes,. duration as long as 172 .days from seeding to harvest (probably photoperiod sensitive),- glumes streaked with brownish, pigmentation. : i

7. Slightly shorter than IR-8, dark green, leaves narrower and more erect, 99 days from seeding to harvest, fertile.

8. Plant habit that of IR-8, tillers with chimeral yellow variegation. -9. Similar to (8) but white variegation. 10. Plant habit like IR-8 but the colour of,the leaves distinctly yellow

green.. • . . . 11. Plant habit like IR-8, grains much smaller in length and width. 12; Distinctly shorter than IR-8, leaves smaller and more erect, culms

also small. • • 13. Distinctly shorter than IR-8, leaves dark green, -small and stiff, •

culms small, produce, as many as 27. panicle-bearing culms, grains very narrow.

14. Extremely small (30 cm height), grass-like in appearance. 15. Shorter than control, .leaves somewhat folded, grains long. 16. Leaves longer and narrower than .control, very tall, lodging, bushy

habit, culms branching at the nodes, branches also panicle-bearing, 172 days from seeding to harvest of main culms (probably photo-period sensitive).

17.. Typically. IR-8 in early growth, but a mature stage plant exhibits long panicle exertion, longer grains than IR-8, 111, days from seeding to harvest, produces as many as 20 productive tillers.

18. Early growth is indistinguishable from IR-8, at transition to flowering stage plant habit becomes spreading, panicle lax with long

.exertion., grains very long, 111 days from seeding to harvest. 19. Morphologically similar to IR-8, except for narrower leaves, grains'

•very long, 111 days to harvest. 20. Early growth habit similar to IR-8, beak or claw-shaped grains,

opaque kernels, 111 days to harvest, semi-sterile-. 21. Morphologically similar to control but grains; are rounded. 22., Leaves narrower than control, folded or cupped, semi-steri le . 23.- Plant habit-indistinguishable from control but 105 days to harvest,

semi-sterile. , " - -24. Leaves distinctly narrow, base of plant very compact, purplish in

colour,; tillers many, panicles do not fully emerge, spikelet possesses only one functional glume the other being modified into a long awn-, like structure, kernel is exposed, very low seed set. • '

25. Shorter than control, leaves also.smaller, semi-steri le . 26. Relatively tall with long internodes, grain with.purple'apiculus; very

low fertility. '. ; . i . • 27. Morphologically normal, semi-sterile (probably approximately 50%

seed set). 28.- Morphologically.normal, very low.fertility (seed set probably only 5%). 29. Morphologically normal but completely sterile. .

90 VIADO et al.

30. N o n - t i l l e r i n g , usual ly s t e r i l e . 31. Smal l , with s m a l l l eaves and c u l m s , s t e r i l e . 32. L e a v e s l ighter g reen than cont ro l , n a r r o w e r and l o n g e r , late heading,

panic les do not e m e r g e c o m p l e t e l y , no g ra ins . 33. Small st i f f plants, leaf blade has prominent ve ins , few t i l l e r s , no

panic le e m e r g e d a f ter boot ing , p robab ly s t e r i l e . 34. L e a v e s long, l o o s e growth habit, later c r a w l s in g r a s s - l i k e manner

produc ing shoots and roo t s at nodes , low fer t i l i ty . 35. L o o s e plant habit, no un i f o rmi ty in growth, 219 days to matur i ty .

C. SELECTION IN L A T E R GENERATIONS

Seeds of variants o b s e r v e d in the M 2 w e r e planted f o r the p u r p o s e of checking the her i tabi l i ty of the var ia t i ons . The plants are at p resent in the seedl ing stage .

About 3300 mutant l ines w e r e sent to the U.P . Co l l ege of A g r i c u l t u r e , C o l l e g e , Laguna, Phi l ipp ines , and are at present being s c r e e n e d f o r blast r e s i s t a n c e . M o r e plant l ines wi l l be tested f o r blast d i s e a s e r e s i s t a n c e as soon as m o r e seed m a t e r i a l can be p r o c e s s e d .

II. E X P E R I M E N T S A T THE U.P. C O L L E G E OF A G R I C U L T U R E , C O L L E G E , LAGUNA

1. D e s c r i p t i o n of work

(a) Cultivation of M 2 and M3 generat ions of lowland r i c e s e e d s i r rad iated with fast neutrons

M 2 s e e d s harvested f r o m the 1966 w e t - s e a s o n planting of treated s e e d s of r i c e var i e t i e s Bengawan, Peta and Intan (weakly p h o t o p e r i o d -sens i t ive var i e t i e s ) w e r e sown in an ord inary wet bed on January 9, 1967. The seed l ings w e r e transplanted s ingly in hi l ls in 6 - m p lant -progeny r o w s in the lowland f ield 18 days a f t e r sowing . The hi l ls w e r e 30 c m X 20 c m apart . T e n r o w s of p r o g e n i e s of untreated s e e d s w e r e a l s o grown b e s i d e the M 2 plants of each var ie ty .

No f e r t i l i z e r was applied in the exper imenta l f ie ld b e c a u s e of the high native fer t i l i ty of the s o i l as a result of p rev ious f er t i l i zat ion . During the past rainy s e a s o n , even without f e r t i l i z e r , the l o c a l var i e t i e s lodged badly . Insect pests like s t em b o r e r s and leaf hoppers w e r e c ont ro l l ed with two appl icat ions of g a m m a BHC granules at 3 kg a . i . p e r ha and b i -weekly spraying of "Sev in" i n s e c t i c i d e at 2 kg a . i . per ha within two months f r o m transplanting. The weeds w e r e adequately contro l l ed by r o t a r y weeding f o l l owed by hand weeding .

At matur i ty , e a r l y and s h o r t - s t a t u r e d plants w e r e s e l e c t e d . Plants and r o w s with c h a r a c t e r s s i m i l a r to those of the c o n t r o l w e r e d i s c a r d e d . Sixty-f ive plant se l e c t i ons f r o m Bengawan, 93 f r o m Peta and 22 f r o m Intan w e r e harves ted .

During the fo l lowing rainy s e a s o n , the M3 generat ion of these s e l e c -tions was sown in an o rd inary wet bed on July 8, 1967, and transplanted s ingly in hi l ls in 2 . 7 5 - m p r o g e n y rows on August 1. The hi l ls w e r e

VIADO et al. 9 1

30 cm X 25 cm apart. Progenies of untreated seeds of each variety were grown after every 20*h row.

The M2 generation of three varieties (BPI-121, BE-3 and Raminad Strain 3), which were not grown during the preceding dry season because of their photoperiod sensitivity, were sown in an ordinary wet bed on July 9 and were transplanted in the same manner as the M3 materials using 6-m rows. •

Recommended cultural practices were followed. Grass weeds were controlled by spraying them with "Treflan" herbicide at 1 kg a.i. per ha within a week after transplanting followed by a 2, 4 -D spray about three weeks later to control broad-leaf weeds. Remaining weeds were hand pulled. Stem borers 'were controlled with Diazinon granules at 3 kg a.i. per ha applied at monthly intervals. When leaf hoppers became abundant in neighbouring areas later in the season, the field was sprayed with Sevin insecticide at 2 kg a.i. per ha.

(b) Cultivation of M3 and M4 generations of mutagen-treated Peta and Intan

Seeds of 526 M2 plant selections were sown as lines in an ordinary wet bed on January 8, 1967. Most of these (453 lines) were selections from progenies of EMS-treated Peta. Twenty days later the seedlings were transplanted singly at 30 cm X 20 cm spacing in plant-progeny rows, 6 m long. Recommended cultural practices, similar to those followed for the M2 fast-neutron treated plants stated above, were followed.

Plant selections were practised as the plants matured. Those se -lected within the first week were considered early and those selected within the second and third weeks, but not exceeding the maturity of the check, were classified as medium-early selections. Short-statured selections were those with plant heights shorter than 120 cm and medium-statured selections were those with heights between 120 cm but not ex-ceeding 150 cm (height of the check Peta). Chlorophyll mutations, plants with sterile florets, and plants that were photoperiod sensitive occurred rarely. A total of 979 plant selections were harvested from the dry-season planting.

The M4 plant-progeny selections were sown in an ordinary wet bed on July 8-9, transplanted on August 1 and cultured in the same manner as the M3 material described above.

2. Results

The number of selected plants and types of selections from the M2 and M3 generations of progenies of rice seeds irradiated with fast neutrons are indicated in Table III. Three hundred and eight plant selections from the M3 generation of BE-3 and BPI-121, and 85 from the M3 generation of Bengawan, Peta and Intan were selected. These are all early to medium-early and short to medium-short statured plants. More beneficial mutants were obtained with the lower doses of neutrons on BE-3, BPI-121 and Bengawan, and with the higher doses on Peta. Plant-progeny rows of these selections, except those from the photoperiod-sensitive varieties (BE-3 and BPI-121) are being grown this 1968 dry season for further evaluation of their agronomic characters.

9 2 VIADO et a l .

T A B L E III. N U M B E R O F S E L E C T E D P L A N T S A N D T Y P E S O F S E L E C T I O N S F R O M P R O G E N I E S O F RICE VARIETIES I R R A D I A T E D W I T H F A S T N E U T R O N S 1967 w e t - s e a s o n harves t

Generation Variety and treatment No . of plants

selected

Types of selections

Generation Variety and treatment No . of plants

selected Short

statured Medium statured

Early Medium-

early

M , BE-3

6 .6 X 1 0 " n / c m 2 55 35 20 - 55 •1.32 X 1 0 u 45 45 - 1 44 . .1.78 X 1011 130 - 130 - 130 1.98 X 1 0 n 8 - 8 - 8 2 .64 X 1 0 u 5 - 5 - 5

Total 243 80 163 1 242

BPI-121

6 . 6 X 1010 n / c m 2 25 3 22 - 25 1.32 X 1011 24 3 21 - 24 1.78 X10 1 1 5 5 5 1.98 X10 1 1 5 - 5 - 5 2 . 6 4 X 1 0 " 6 3 3 - 6

Total 65 9 56 - 65

M 3 Bengawan

6 .6 X 1 0 " n / c m 2 . 10 3 7 7 3 1 . 3 2 X 1 0 " 7 - 7 7 1 . 7 8 X 1 0 " 8 - 8 4 4 1 . 9 8 X 1 0 " - - - - -

2 .64 X 1 0 " 8 - 8 8- -

Total 33 3 30 26 7

•.. peta

6 .6 X 1 0 " n /cm 2 2 - 2 2 1.32 X 1 0 " 9 - 9 8 1 1.78 X 1 0 " - - - - -

1 . 9 8 X 1 0 " 8 - 8 3 5 • 2 . 6 4 X 1 0 " . 17 - 17 10 7

Total 36 - ' 36 . 21 15

Intan

1.32 X 1010 n / c m 2 16 9 7 13 3

Total ~16

Grand total 393 101 292 61 332

VIADO et a l . 93

TABLE IV. NUMBER OF SELECTED PLANTS AND TYPES OF SELECTIONS FROM M4 PROGENIES OF VARIETY PETA IRRADIATED WITH GAMMA RAYS AND MIXED RAYS OR TREATED WITH EMS 1967 wet-season harvest

No. of plants selected

Types of selections

Treatment No. of plants

selected Short

statured Medium statured

Early Medium-early

Gamma rays(kR)

1 .0 - - - - -

f o . o 12 - 12 12 -

20 .0 48 - 48 48 -

35 .0 112 29 83 112 -

45 .0 115 - 155 155 -

Total 327 . 29 298 327 -

Reactor mixed radiations (rads)

100 65 - 65 65 -

500 4 - 4 - 4 1000 82 - 82 82 -

2 000 19 16 3 16 3 3 500 60 - 60 60 -

5 000 21 - 21 21 -

10 000 4 - 4 - 4

Total 255 16 239 244 11

EMS (%)

0 .0078 61 - 61 55 6 0.0625 28 - 28 28 -

0.125 67 - 67 67 -

0 .25 35 - - 35 - ' 35 1 .5 117 15 102 55 62 1 .0 1540 6 1534 1497 43

Total 1848 21 1827 1702 146

Grand total 2430 66 2364 2273 157

In the M4 generation of Peta (Table IV) a larger number of short to medium-short and early to medium-early plants were selected from the higher doses of gamma rays (35 to 45 kg) and EMS (0.5 to 1.0%). There is no definite trend in the number of beneficial mutants as affected by different doses of mixed rays. A total of 2430 plant selections were harvested. These materials are now being grown in plant-progeny rows this dry season for further evaluation.

Seventy-three uniform mutant lines were selected from the M3 generation of Peta and Intan after neutron irradiation and from the M4 generation of Peta after treatment with gamma rays, mixed radiation and EMS. These lines are all earlier and mostly shorter than the Peta variety (time to heading for the lines was 91-116 days, for Peta 120 days; plant height of the lines was 106-170 cm, for Peta 158 cm). Further tests are being made with the check varieties.

CD

T A B L E V. D A Y S T O M A T U R I T Y , A V E R A G E H E I G H T A N D A V E R A G E N U M B E R O F T I L L E R S O F E A R L Y M A T U R I N G A N D N O N - S E A S O N A L LINES S E L E C T E D

Variety Treatments No. of lines

No. of lines selected a Total of

Range of maturity Average height Average No. of

Remarks Variety Treatments planted

fot further study for preliminary trial lines selected Range of maturity

( c m ) tillers per hill Remarks

BPI-121 1 kR y -rays 62 50 6 62 120-125 119.6 8 .2 Control variety BPI-121 flowered

2 . 5 kR y-rays 78 50 6 78 120-125 138.2 10.0 earlier than the treated ones. This is due to late planting which

Control. 118 139.0 7.6 indicates sensitivity to photoperiod.

Sum 140 100 12 140 - -

5 kR y-rays 197 50 8 159 125-130 104.4 12.6

7 . 5 kR yvrays 17 50 6 77 130-136 . 130.4 11 .8 No uniform lines from BE-3

BE-3 10 .0 kR y - tays 83 60 - 70 136-140 136.0 9 .0 treatment with 10 kR were ob -

35 .0 kR y-rays 140 50 6 140 125-130 143.0 11 .8 tained for preliminary yield trial.

1 0 0 0 rads mixed rays 101 50 8 101 125-130 118.0 6 .8

Control - 135 135 10 .2

Sum - 598 260 28 547

Grand total 738 360 40 687

3 Planted for further study and preliminary yield trial during this "palagad" season.

VIADO et al . 9 5

III. EXPERIMENTS AT THE MALIGAYA RICE RESEARCH AND TRAINING CENTER, MUNOZ, NUEVA ECIJA

The research program consisted of two parts: (a) Selection and testing of possible mutations obtained by treatment

of the varieties BE-3, BPI-121, Raminad str.3, Elon-elon and Wagwag with gamma rays from 60Co, mixed radiations from the nuclear reactor, and ethyl methyl sulphonate (EMS).

(b) Field tests of japonica and indica mutants from Taiwan and India.

RESULTS Experiment 1

Early maturing selections were made from gamma-ray and mixed-radiation treated BPI-121 and BE-3. The early maturing lines from BPI-121 and BE-3 were sown in the seed-bed on August 2, and trans-planted on August 31, 1967.

Table V shows the number of lines selected from plantings of early maturing lines from BPI-121 and BE-3 obtained after treatment with gamma rays and mixed radiations. From a total of 140 lines of BPI-121 from gamma-ray treatments with 1 and 2.5 kR, 100 lines were selected for further study. From BE-3, 260 lines were selected out of 547 lines obtained from 5.0, 7.5, 10 and 35.0 kR of gamma rays and from 1000 rads of mixed radiations. A total of 360 lines from these varieties were se-lected and planted during the 1968 dry season as M5 lines for further study of their photoperiodic sensitivity.

From the two treatments of BPI-121 and the five treatments of BE-3, 12 and 28 early maturing lines respectively (i.e. a total of 40 lines) were selected and planted for preliminary yield trials as M5 during the 1968 dry season.

The range of maturity, average height and average number of tillers per plant of the 140 lines of BPI-121 and 547 lines of BE-3 are also indicated in Table V. The 140 BPI-121 lines matured in 120 to 125 days. It may be noted that the selected early maturing lines of BPI-121 seemed to mature later than the control plants. This may be explained by the fact that the original BPI-121 used as control was a photosensitive variety so that when planted late in the season its length of maturity was considerably shortened. Hence, it was shorter in maturity than the non-seasonal selected lines.

It is also interesting to point out that 62 lines out of 140 of BPI-121 were very much shorter than the control plants. The tillering capacity of the 140 lines was higher per plant than the control.

The BE-3-lines selected from 5 and 35 kR and 1000 rads were earlier by 5 to 10 days than the control plants. Those that were obtained from the 7.5 and 1-0 kR treatments matured practically at the same time as the control. This is also due to the photosensitivity of the parent or control variety BE-3.

In height, the 159 lines from the 5-kR treatment were very much shorter than the control plants. The lines obtained from the 5-kR treatment had the highest number of tillers among the selected plants while the lowest number of tillers per hill was obtained from the 1000-rad treatment.

T A B L E VI. LINES P L A N T E D , S E L E C T I O N M A D E A N D R A N G E O F M A T U R I T Y O F LINES IN E A C H V A R I E T Y '

BPI-121 : 8E-3 . ' E l o n - e l o n - Raminad Str. 3 Wagwag

N o . of N o . o l . N o . of N o . of N o . of .. Treatment

Lines Panic les Range

Lines Panicles Range

Lines pan i c l es Range



planted se lec ted of maturity planted selected

o f maturity planted "se lected

• o f maturity planted se lec ted

of maturity planted se lected

o f maturity

2 . 0 35 59 1 6 2 - 1 6 7 30 36 1 7 6 - 1 8 0 24 44 1 8 0 - 1 8 8 24 35 1 6 4 - 1 9 3

1 . 0 4 5 45 145 -148 35 58 ' 1 6 2 - 1 6 3 24 60 _ 1 7 5 - 1 8 0 24 31 1 7 3 - 1 8 4 - - -

• 0 . 5 4 0 69 156-160 ' 3 5 62 1 6 2 - 1 6 3 24 32 1 7 9 - 1 8 0 24 59 , - - 18 37 1 9 8 - 2 0 2

0 . 2 5 4 0 • '42 145 -160 - ' ' 4 0 59 1 6 2 - 1 6 3 24 28 1 7 6 - 1 8 3 24 - 37 1 8 1 - 1 8 6 30 28 1 8 2 - 1 9 8 '

EMS 0 . 1 2 5 • 60 56 157 -160 '40 69 1 6 6 - 1 6 9 24 27 • 1 6 6 - 1 8 0 24 26 1 8 0 - 1 8 3 24 32 1 9 7 - 2 0 4

m 0 . 0 1 5 6 35 47 148-160 . 35 . 56 1 6 6 - 1 7 1 24 30 1 6 9 - 1 8 0 24 26 1 8 0 - 1 8 4 24 36 1 8 2 - 1 9 7 m

' 0 . 0 3 1 2 4 0 65 130-160 35 64 1 7 6 - 1 7 9 24 50 1 6 9 - 1 8 0 24 ' 4 5 1 7 3 - 1 8 4 24 35 1 9 7 - 2 0 2

0 . 0 6 2 5 - - - ' 35 35 1 7 6 - 1 8 0 24 26 . 1 7 5 - 1 8 0 - - - 24 34 1 8 2 - 1 9 4

0 . 0 0 7 8 25 ' ' 27 147-160 45 37 142 -166 . 33 1 7 3 - 1 7 9 24 . 68 1 8 0 - 1 8 4 " -

Contro l 6 - 163 -166 6 " 1 8 0 - 1 8 6 6 " 1 8 0 - 1 8 5 ' 6 ' 1 8 0 - 1 8 8 6 2 2 5 - 2 2 9

1 . 0 25 34 149-156 25 42 1 6 8 - 1 7 3 40 35 - 1 7 8 - 1 7 9 35 . 43 183 -186 30 • 51 ., 1 9 6 - 1 9 8

2 . 5 25 36 156 -159 30 56 1 6 5 - 1 6 8 45 30 ' 1 7 0 - 1 7 5 15 54 1 8 4 - 1 8 6 45 57 1 9 8 - 2 0 3

5 . 0 2 5 " .26 153-156 25 30 1 6 9 - 1 7 1 ' 30 36 1 6 3 - 1 7 9 30 6 1 1 7 9 - 1 8 6 35 40 1 9 6 - 2 0 2

G a m m a rays , 7 . 0 . 25 .26 . 1 5 3 - 1 5 6 25 33 1 5 3 - 1 6 3 30 ' 45 - ' 1 7 2 - 1 7 9 . 3 0 30 183 -186 35 ' 65 1 9 6 - 2 0 4

(kR) ' 1 0 . 0 2 5 ' 42 " 159 -163 35 . 45 1 6 9 - 1 7 4 30 28 1 6 9 - 1 7 9 30 36 1 7 9 - 1 8 4 30 33 1 9 6 - 1 9 9 (kR) ' 2 0 . 0 3 0 37 ' 156 -159 30 50 • 1 5 9 - 1 7 0 ' 30 ' 37 1 7 8 - 1 7 9 • 35 40 1 8 1 - 1 8 6 35 44 196 -202

3 5 . 0 - 30 • . 4 7 " 163 -170 15 31 1 7 3 - 1 7 9 30 4 8 1 7 9 - 1 8 0 35 39 1 7 9 - 1 8 6 35 27 1 9 6 - 2 0 8

Control 6 " 163-168 . 6 " 1 8 6 - 1 8 9 6 " 1 9 1 - 1 9 2 ' 6 " 189 -190 - 6 " 2 2 2 - 2 2 6

100 30 39 155 -159 30 36 1 6 2 - 1 6 5 4 0 31 1 6 9 - 1 7 7 30 60 1 8 2 - 1 8 5 35 37 1 8 9 - 1 9 1

' 200 " 35 45 157 -159 30 39 '• 1 6 7 - 1 7 2 35 19 ' ' 1 7 1 - 1 7 8 30 36 1 8 4 - 1 8 7 40 29 1 8 6 - 1 9 0

500 "35 " " ' 3 0 • 1 5 3 - 1 5 9 30 44 1 6 5 - 1 7 2 . 30 28 1 6 9 - 1 7 2 35 26 181 -186 40 32 1 8 9 - 1 9 2

1 0 0 0 4 0 '38 158-162 35 49 1 6 9 - 1 7 2 30 ^ 38 1 7 1 - 1 7 6 . 3 5 4 1 1 8 3 - 1 8 8 35 41 . 1 8 4 - 1 8 8

' 2 000 30 > 1 155-162 30 38 1 7 1 - 1 7 4 30 35 1 7 5 - 1 7 8 35 44 1 8 6 - 1 8 8 35 35 189-191-

Mixed radiations 3 500 30 32 ' 155 -160 30 4 1 1 6 4 - 1 6 9 •30 39 1 6 9 - 1 7 8 35 32 1 7 8 - 1 8 4 30 .. 64 1 8 6 - 1 8 9

( tads) 5 0 0 0 30 52 158-162 30 37 1 6 5 - 1 7 7 37 63 . 1 6 5 - 1 7 8 35 32 1 8 2 - 1 8 8 35 4 3 1 8 9 - 1 9 1 ( tads) 7 500 35 50 156-159 30 44 1 6 8 - 1 7 4 30 31 1 7 0 - 1 7 8 40 61 1 8 0 - 1 8 5 30 57 1 8 9 - 1 9 2

. 10 000 15 46 156 -159 35 ' 34 1 6 2 - 1 7 2 • 30 36 1 7 1 - 1 7 6 35 ' - 76 . 1 7 9 - 1 8 3 40 67 1 8 2 - 1 8 7

15 000 30 35 ' . 156-159 40 35 1 6 5 - 1 7 2 30 ^ - 3 1 1 7 3 - 1 7 8 35 36 1 8 3 - 1 8 7 . 40 ' 43 1 8 9 - 1 9 2

Contro l 6 ' - 157-159 j " 6 1 7 2 - 1 7 7 6 , - - 1 7 3 - 1 8 0 6 " 1 8 9 - 1 9 4 6 2 2 6 - 2 2 8

VIADO et al. . 9 7

Experiment 2. Selections from M3 after EMS and radiation treatments

The M3 seeds were sown from June 19.to 23, 1967. Transplanting began on July 18, 1967. The distance between the plants and the rows was 20 cm. The crop was fertilized with 80-50-50 kg/ha and top dressed with 20 kg N/ha.

The number of selected panicles and the range of maturity of the lines from each dose of EMS, gamma-rays and mixed radiations are shown in Table VI. Further laboratory studies of the grains of each panicle will be made on these field selections. Very early maturing lines were obtained from BPI-121, BE-3 and Wagwag, and earlier maturing lines were also observed from the two other varieties.

The differences in the length of maturity between the selected lines and the control for BPI-121,. BE-3 and Wagwag was about one month with the EMS treatment. Marked differences in length of maturity between treated lines and the control were not observed among the varieties treated with gamma rays and mixed, radiation, although the treated lines in most of the doses of each treatment matured earlier than the control.

Observations were made on the number-of tillers, the plant height, length of panicles, weight of grains and sterility for all the selected M3 plants. These agronomic characters will be followed up in the next generation.

Experiment 3. Field tests of japonica and indica mutants from Taiwan and India 1

The plots in the yield trial of the indica group were replicated four times and the experimental design was the randomized block system. The japonica mutants were replicated twice. In both tests BPI-76 was used as the check variety.

The results obtained in the yield trial and in the observational trial of indica and japonica mutants are presented in Tables VII and VIII respectively. The data represent the average of the replicates. To identify the strains and compare their performance see Rice Breeding with Induced Mutations, Technical Reports Series No.86, IAEA, Vienna (1968).

(a) -Yield trial of the indica group (Table VII)'

The, mean number of tillers of the mutants ranged from 8.7 to 14.1-per hill. Three of the varieties produced 14.0 to 14.1, while the majority produced 12 tillers per hill.

In length of maturity, IR-154-77-2 was"the earliest with 82 days, followed by NH-X-^-131 mut. with 105 days from sowing the seeds. The majority of the varieties matured in-109 days. BPI-76 (NS), IR-8-288-3 and CP 231 X SLO 17 were the latest, all maturing in 124 days.

The mean -height of the plants showed that a number of the indica group had short straw - the majority of the varieties did not grow higher than 1 metre, whereas the rest were taller (139.4 to 151.2 cm high). None of the varieties, in spite of tallness in some, lodged at maturity.

CO OO

TABLE VII. YIELD TRIAL OF indica MUTANTS DURING THE WET SEASON 1967-68

Variety Mean N o . of tillers Maturity (days)

Mean plant height ( c m )

Lodging characteristics Spikelet fertility Grain

wt /100 grains

<S>

Plot yield <g> Diseases Pests

1. Taichung (N) 1 14 .0 109 85 .2 Non-lodging 4 7 . 3 7 2 . 1 9 280 .3 BLB

2 . CP 231 dwar f (Muc . ) XRex 8 .7 111 67 .3 46 .53 1 .91 87 .3 BLB. tungro Rats

3. CP 231 dwarf ( M u l . ) XTP 11.4 111 94 .8 57 .86 1 .79 3 2 6 . 5 BS, BLB

4 . CP 231 X SLO 11 10.8 124 80 .1 53 .29 1 .98 137 .8 BS. BLB

5 . 1R-8-288-3 12 .9 . 124 87.4 4 0 . 4 7 2 . 7 0 255 .3 BS, BLB

6 . 1R-154-77-2 12.2 102 82 .7 64 .05 2 . 0 8 2 4 1 . 8 BS. BLB

7. N M - N , - 4 (Mut . of 9) 11 .8 109 143.0 77.57 3 . 2 7 285 .5 BS, BLB

8. N M - X i - 1 3 1 ( M u t . o f 9 ) 9 . 8 105 139.4 63 .14 3 .17 2 2 2 . 5 BS, BLB

9. Nahng Mon S -4 12.0 109 151.2 87 .02 3 . 4 0 2 7 5 . 5 BS, BLB

10. NP 130 Mut. S - l 14 .1 109 92 .9 60. 70 3 . 7 5 115.0 BLB Rats, stem borer

11. NP 130 Mut. S -3 14 .1 109 93 .1 53.77 1 .81 118 .5 BS, BLB, SB tungro

Stem borer

12. Yuang-Hsing 1 a 13 .3 109 84.0 61 .50 2 . 2 0 290 .3 BLB Stem borer

13. I-Kungbau 4 - 2 ( M u t . ) 13.0 109 76 .6 37 .92 2 . 0 9 166 .8 BS, BLB Stem borer

14. Shung-Chiang 30-21 (Mut . ) 12 .9 109 82.6 62 .36 2 . 2 2 211 .8 BS. BLB

15. K e h - T z e 20-74 ( M u t . ) 12 .9 109 84 .3 55 .85 2 . 1 8 268 .3 BS, BLB

16. BPI-76 (NS) 12 .0 124 108.2 70.48 2 . 0 0 2 4 1 . 3 BS, ELB

Diseases: B: Blast

BLB: Bacterial leaf blight BS: Bacterial stripe SB: Seedling blight

Top dressing: 2 0 - 0 - 0 kg/ha

Date sown: July 13, 1967 Typhoons: Date transplanted: August 9, 1967 Trining: Oc t . 16, 1967 Area: 720 m 2 (y ie ld trial and observational trial) Strong .

* , Wei mine: Nov . 3, 1967 Distance of planting: 30 c m x 20 c m . ° bn/h« VerV SU011g

a Selection from [ T a i c h u n g ( N ) 1 x Shung-chiang 30-21 (Mut . ) ]

T A B L E VIII. P E R F O R M A N C E OF japonica M U T A N T S IN T H E O B S E R V A T I O N A L T R I A L , R E G U L A R W E T SEASON 1967 -68

Variety Mean No. of tillers Maturity (days)

Mean plant height ( c m )

Lodging characteristics Spikelet fertility

( »

Grain wt/100 grains

(S>

Plot yield ( g ) . Diseases Pests

1. Tainan 3 11 .2 115 105 .4 Non-lodging 84 .3 2 . 5 4 7 5 . 5 BS, BLB

2 . FF 36 12 .7 109 83 .9 56 .3 2 . 2 313 .5 BS Stem borer

3 . Irrad. Taichung 6 5 ( M u t . ) - 2 1 . 9 109 94 .1 • 92 .9 2 . 7 368 .5 BS. BLB, tungro

4 . Fujiminori 8 .6 101 73.5 85 .6 2 . 6 197.5

5. Fvikie 70 (Mut , of 4) 1.1 101 69 .0 91 .4 2 . 5 154 .5 BS, BLB. SB

6. Fukie 71 (Mut . of 4) 7 .2 101 4 1 . 9 4 8 . 8 2 . 3 91 .0 BS, BLB, tungro

7. Koshihikare 10 .4 101 61 .9 83 .3 2 . 4 130.5 BS, BLB

8. Norin 22 8 .0 101 56 .2 „ 6 7 . 2 2 . 5 74 .0 BS, BLB

9. R-90 (Mut . of 7) 10.6 101 61 .7 83 .2 2 . 4 105.5 BS

10. San-in 73 (Mut. of 8) 8 . 8 101 66 .4 81 .4 2 . 8 127.5 BS, BLB, tungro

11- 'Allorio 11 Temoin 6 . 4 102 104.2 Lodging r 71 .4 ' 2 . 9 113.0 BS. BLB

12. Allorio Lambda ( M u t . o f l l ) 9 .4 101 76 .1 Non-lodging 78 .6 2 . 9 141.0 BS, BLB, SB

13. BPI-76 (NS) 11 .5 124 53 .5 6 8 . 5 1 . 9 322 .0 BS

Date sown: July 13, 1967 Date transplanted: August 9, 1967 Area: 720 m 2 (yield trial and observational trial) Distance of planting: 30 c m X 20 c m Fertilizer applied: _ , rn . „ r r Basal: 80 -50-50 kg/ha

Top dressing: 20 -0 -0 kg/ha

Typhoons: Tciiung-.. Oc t . 16, 1967

Strong Welming: Nov . 3, 1967

Very strong

Blast Bacterial leaf blight Bacterial stripe Seedling blight

1 0 0 VIA DO et al .

The highest f i gure f o r spikelet f e r t i l i ty (87.02%), was obtained f r o m v a r i e t y Nahng Mon S - 4 . This was f o l l owed by var i e ty N M - N i - 4 mut . with sp ike let f er t i l i ty of 77.57%. B P I - 7 6 (NS) Ck gave only 70.48% spike let f e r t i l i ty , and f our of the test v a r i e t i e s p roduced l e s s than 50%.

. The seed weight p e r 100 gra ins showed var iab i l i ty . A s shown in Tab le VII, the weights f o r three var i e t i e s w e r e 3 .40 , 3.27 and 3.17 g p e r 100 s e e d s . On the other .hand, f ive v a r i e t i e s .had seeds weighing f r o m 1.75 to 1.98 g per 100 g ra ins , w h e r e a s the m a j o r i t y of the var i e t i e s gave gra ins that weighed 2.00 g p e r 100 g ra ins . It is interest ing to note that Nahng Mon S - 4 , the var i e ty that had the highest spikelet f e r t i l i ty , has a l s o the highest seed weight p e r 100 g r a i n s .

The y ie ld p e r plot of 1.5 m 2 shown in Table VII may have been a f f e c ted by the two typhoons , Tr in ing and Welming , which o c c u r r e d on O c t o b e r 16, 1967 and N o v e m b e r 3, 1967, r e s p e c t i v e l y . The data on y ie ld p e r plot of the 16 entr ies in the test of indica mutants show that eight w e r e c o m p a r a b l e in product iv i ty with the check var ie ty , B P I - 7 6 (NS). In fac t , s even of the eight v a r i e t i e s produced h igher y ie lds than the check v a r i e t y , par t i cu lar ly CP 231 dwarf X Rex with a y ie ld of 326.5 p e r plot c o m p a r e d with 241.3 g p e r plot of B P I - 7 6 (NS).

The d i s e a s e s that w e r e c o m m o n in m o s t of the var ie t i es w e r e b a c t e r i a l leaf blight and b a c t e r i a l s t reak . Apart f r o m these d i s e a s e s , tungro was o b s e r v e d in two v a r i e t i e s , NP 130 -mut S - 3 and C P 231 dwarf X R e x . Rats and s t e m - b o r e r s w e r e a l s o found attacking the plants. NP 130-mut S - l and C P 231 dwarf X Rex w e r e m o r e s e v e r e l y attacked by rats than the other v a r i e t i e s .

(b) Observat i ona l t r ia l of j apon i ca mutants

The resu l t s of the o b s e r v a t i o n a l t r ia l of japonica mutants during the wet s e a s o n are presented in Tab le VIII. M o r e japonica mutants had l e s s t i l l e r s p e r hi l l than the indica mutants . The l owest number of t i l l e r s among the japonica mutants was 7.4 and the highest was 21 t i l l e r s p e r h i l l . '

The length of maturi ty f o r 9 of the 12 mutants was 101 and 10 2 days f r o m sowing the s e e d s in the s e e d - b e d .

The m e a n plant height of the v a r i e t i e s ranged f r o m 41.9 to 105.4 c m . Only A l l o r i e 11 T e m o i n , which was 104.2 c m , lodged at matur i ty .

The sp ike let f er t i l i ty was g e n e r a l l y h igher among the japon i ca mutants than among the indica group . Eight of the 12 mutants had h igher sp ike let f e r t i l i ty than the check var i e ty - it ranged f r o m 71.43 to 92.94% c o m p a r e d with the check B P I - 7 6 which had only 68.51% fert i l i ty . .

T h e r e w e r e no appl i cable d i f f e r e n c e s in the grain weight among the mutants . The yield of the d i f f e rent mutants var ied c o n s i d e r a b l y . The l owes t y i e l d e r , Norin 22, gave only an average yie^ld of 74.0 g p e r plot whi le the highest y i e l d e r , Tainan 3, p roduced 475.5 g. Of the twelve mutants only two produced h igher y ie lds than the check var i e ty .

S imi lar to the indica mutants in the y ie ld t r ia l , the japonica group showed in fect ion by b a c t e r i a l leaf bl ight and b a c t e r i a l s t reak . S o m e of the mutants w e r e a l s o infected by tungro .

VIADO et al. 1 0 1

S U M M A R Y

One hundred and for ty n o n - s e a s o n a l l ines w e r e se l e c ted f r o m B P I - 1 2 1 , t reated with 1 and 2.5 kR. The range of maturity of the s e l e c t e d l ines was 120 - 125 days f r o m sowing to harves t ing . In B E - 3 , 547 l ines w e r e s e l e c t e d f o r n o n - s e a s o n a l c h a r a c t e r i s t i c s with a range of matur i ty f r o m 125 to 140 days . Of these se l e c t i ons twelve f r o m B P I - 1 2 1 and twenty-e ight f r o m B E - 3 , which w e r e of p r a c t i c a l un i f o rmi ty , w e r e e l e -vated to the p r e l i m i n a r y yield test during the 1968 dry s e a s o n .

F r o m the d i f f erent var i e t i e s .treated with d i f ferent mutagens a l a rge number of pan i c l es has been s e l e c t e d f o r further s tud ies . Some of these s e l e c t i o n s w e r e e a r l y in matur i ty c o m p a r e d with the c o n t r o l plants .

Observat i ons on s o m e of the important c h a r a c t e r s , p a r t i c u l a r l y the number of t i l l e r s , height, length of panic le , seed weight and per centage of s t e r i l i ty w e r e a l s o m a d e . Data on these c h a r a c t e r s show that there s e e m s to be no def inite trend on the e f f e c t s of the three t reatments in re lat ion to the dosage used .

F i e ld t r ia l s with mutants of indica and japonica r i c e f r o m Taiwan and India gave the fo l l owing r e s u l t s :

(a) T w o of the indica mutants had a higher per centage of sp ike let f e r t i l i ty than the check B P I - 7 6 (NS). •

(b) Eight of the indica mutants w e r e c o m p a r a b l e in y ie ld with the check var ie ty B P I - 7 6 (NS). In fact , seven produced h igher y ie lds than the check v a r i e t y . •

(c ) The range of matur i ty of the indica mutants was f r o m 102 to 124 and all. of them w e r e non - l odg ing . Al l the mutants in the test as we l l as the check v a r i e t y w e r e a f f e c ted by d i s e a s e s , p a r t i c u l a r l y b a c t e r i a l leaf blight and b a c t e r i a l s t reak . Tungro d i s e a s e was a l s o o b s e r v e d in two mutants.

(d) In the observat i ona l t r ia l , the. range, of matur i ty of the japonica mutants was 101 to 109 days; the height of the plants var ied f r o m 41.9 to 105.4 cm; all mutants w e r e non - l odg ing , except A l l o r i o 11 T e m o i n which lodged at matur i ty . Two of the mutants, F F 35 and i rradiated Taichung 65 Mut. , p roduced h igher y ie lds than the check var ie ty .

IV. E X P E R I M E N T S A T THE C O L L E G E OF A R T S AND SCIENCES, UNIVERSITY OF THE PHILIPPINES, DILIMAN, Q U E Z O N CITY

Select ion of eating quality in Mg I R - 8 r i c e ( E x p e r i m e n t No. 067213)

The IR -8 r i c e var i e ty , popular ly ca l led " m i r a c l e r i c e " , is about the best r i c e plant in the w o r l d today due to its high y ie ld and dwarf growth habit. T h e s e two qual i t ies o v e r s h a d o w its highly s p e c i f i c cultural r e -qu i rements , l ike n i t r o g e n - r i c h s o i l s , plenty of i r r i g a t i o n water and e f f e c t i ve weed and pest c o n t r o l . Its main drawback , h o w e v e r , is its p o o r eating quality which makes this var ie ty a s e cond c l a s s c o m m e r c i a l r i c e on the m a r k e t . H e n c e , the reason f o r this p r o j e c t to i m p r o v e the eating quality of the IR -8 var ie ty through induced mutation and s e l e c t i o n .

1 0 2 VIADO et a l .

Method

G a m m a i rradiat ion of the seeds and growth of the M i generat ion have been d e s c r i b e d in prev ious r e p o r t s . This paper deals with the se l e c t i on test f o r eating quality in the M 2 generat ion . The M 2 c r o p was planted in a t h r e e - s e e d s per Mi plant plan.

The plants w e r e harvested l ine by line and the yield p e r l ine was threshed by hand and s tored f o r three months in label led paper bags . A f te r the s torage p e r i o d , the grains w e r e divided into two lots of equal amounts . One lot was used f o r the cooking test and the other f o r M 3

planting. The gra ins f o r the cooking test w e r e c leaned by pounding them by

hand in a wooden m o r t a r and pest le as the r i c e m i l l s re fused to c lean s m a l l amounts of s e e d s . When m o s t of the grains of the M 2 l ines had been c leaned , the cooking test began. The kerne ls w e r e cooked in s m a l l pots o v e r earthen e l e c t r i c a l b u r n e r s . As far as p o s s i b l e , c a r e was taken to make the cooking condit ions the s a m e with r e s p e c t to cooking t e m p e r a -ture , duration of cooking, amount of water f o r boi l ing the r i c e and per iod of coo l ing the cooked r i c e f o r the test .

The eating quality test (EQ) was done when the cooked r i c e got c o ld , b e c a u s e the coo led cooked r i c e of IR-8 d i f f e r s f r o m the ord inary c o m -m e r c i a l v a r i e t i e s . T h e r e is hardly any d i f f e r e n c e in eating quality in newly cooked r i c e . Eating quality was s c o r e d as soft (s) , med ium hard (s+) and hard (+). These qual it ies w e r e based on the quality of the s tandard , the Peta var ie ty , and that of the n o r m a l , unirradiated IR-8 r i c e .

T A B L E IX. EATING Q U A L I T Y AND COLOUR OF COOKED RICE IN M 2

IR-8 V A R I E T Y

Gamma-ray dose Colour of ^ , . , , No. of M2 lines Eating quality Culture No. and variety on Mi ° cooked rice

, tested (kR)

142 Peta 0 102 102 0 0 102 0

143-1 IR-8 0 180 0 0 100 0 180

143-2 IR-8 10 203 2 0 201 4 199

143-3 IR-8 20 264 1 3 260 1 263

143-4 IR-8 30 236 1 2 233 6 230

143-5 IR-8 40 285 1 5 279 2 283

143-6 IR-8 50 207 2 1 207 3 204

Legend: s - soft ccld cooked rice s+ - medium hard cooked rice (cold) + - hard cold cooked rice

- white cooked rice - light or pale brown cooked rice

VIADO et al . 1 0 3

The c o l o u r of the IR-8 cooked r i c e was a l s o tested . The r i c e was e i ther pale to light brown o r white . This test is only appl i cable to hand-mi l l ed r i c e . With m a c h i n e - m i l l e d I R - 8 , the c o l o u r of the cooked r i c e is white like the c o m m e r c i a l v a r i e t i e s .

Observat i ons and resu l t s

As shown in Table IX, out of 1192 M 2 l ines tested s o f a r , only about 0.59% had so f t c o l d - c o o k e d r i c e c o m p a r e d with the Peta standard. A p -p r o x i m a t e l y 0.89% had m e d i u m - h a r d c o l d - c o o k e d r i c e , and the res t had an eating quality like the n o r m a l I R - 8 var ie ty . The 7 l ines with so f t cooked r i c e and 11 l ines with m e d i u m - s o f t r i c e w e r e obtained at random without any par t i cu lar M i radiat ion d o s e a s s o c i a t i o n o r c o r r e l a t i o n . This m a y be due to the fact that not al l the M 2 l ines have been accounted f o r .

Future plans

The few se l e c ted l ines with soft c o l d - c o o k e d r i c e and white c o l o u r of cooked r i c e w i l l be grown in the M 3 generat ion during the regu lar r i c e growing season in J u n e - D e c e m b e r , 1968. Planting of these " g o o d " l ines is d e s i r a b l e in re lat ion to p r o b l e m s of adaptabil ity and highest yield under n o r m a l r i c e growing condi t ions .

INDUCTION OF MUTATIONS IN THAI RICE VARIETIES AND SUBSEQUENT SELECTION AND TESTING

. OF BENEFICIAL MUTANT LINES

S. DASANANDA, P.'KHAMBANONDA Ministry of Agriculture, Bangkok, Thailand

Abstract

INDUCTION OF MUTATIONS IN THAI RICE VARIETIES AND SUBSEQUENT SELECTION AND TESTING OF BENEFICIAL MUTANT LINES. Ionizing radiations were first used in the Thaiiand Rice Breeding Program in 1955 when seeds o f two recommended varieties were sent to the United States of America for treatment. As a result, f ive promising mutant lines are at present in regional yield tests where" they are being considered for recommendation to rice growers. During the period 1960-1961 an unsuccessful attempt was made to induce resistance to blast.in three susceptible varieties by exposing seeds to a l oca l source of ionizing radiation.

In 1964, after an elapse o f about 4 years, anqther.-attempt was made to utilize ionizing radiations in the breeding program by treating seeds o f two recommended varieties. In 1965, a co-ordinated rice mutation breeding program was initiated under the auspices of the Joint FAO/IAEA Division o f Atomic Energy in Food-and .Agriculture which resulted in treating seeds o f twelve different rice varieties with both ethyl methane • sulphonate arid gamma'rays from a 6 0 C o gamma c e l l .

The results so far indicate that mutagenic agents have been successful in producing genetic variability. Differences in heading date, mature plant height and plant type are frequently observed in the M? and M 3

generations. Several lines obtained from two of the-irradiated varieties have exhibited a higher degree o f resistance to blast than the parental material, . From 15-kR treatments,of non-glutinous varieties, mutants with glutinous endosperm have been obtained. Not all varieties gave the same response to treatment.

INTRODUCTION ' ' : ;

Thai r i c e is c h a r a c t e r i z e d by its long s l ender and c l e a r gra in which, when cooked , b e c o m e s f lu f fy and r e m a i n s soft f o r a r e la t ive ly long t i m e . Hence , Tha i r i c e has b e c o m e noted throughout the w o r l d f o r i ts s u p e r i o r quality. Although a number of v a r i e t i e s with exce l l ent gra in quality ex is t there i s a need to i rhprove the plant by deve lop ing types with shor ter ' s t raw, be t ter r e s i s t a n c e to d i s e a s e and bet ter r e s p o n s e to f e r t i l i z e r s . Attempts to e f f e c t ' v a r i e t y i m p r o v e m e n t have been m a d e through i r r a d i a -tion in addition to the convent i ona l ' b reed ing p r o g r a m . •

In 1955, r i c e s e e d s of two r e c o m m e n d e d Thai v a r i e t i e s w e r e sent to the United States of A m e r i c a to b e t reated with X - r a y s and t h e r m a l neutrons in an attempt to obtain s u p e r i o r v a r i e t i e s by mutation b r e e d i n g . A s a resul t , f i ve p r o m i s i n g mutant l ines of the two i r rad iated v a r i e t i e s a r e at p r e s e n t included in advanced y ie ld t r i a l s b e f o r e being c o n s i d e r e d f o r r e -l e a s e . The mutant l ines have exhibited be t t e r s t raw strength and higher | y ie ld than the two parent v a r i e t i e s in p r e l i m i n a r y t es t s ! In addition, e x -p e r i m e n t s w e r e initiated in 1960 to induce b last r e s i s t a n c e in three s u s c e p t -ib le v a r i e t i e s by i r rad ia t i on of seed with g a m m a r a y s at K a s e t s a r t U n i v e r -sity , Bangkok, Thai land. Unfortunately , induction of b last r e s i s t a n c e was not achieved at that t i m e b e c a u s e of s o m e te chn i ca l p r o b l e m s . Since 1964,

1 0 5

106 DASANANDA and KHAMBANONDA

af ter an e lapse of about 4 y e a r s , r i c e s e e d s of s e v e r a l v a r i e t i e s w e r e again treated with g a m m a r a y s at the Thai R e s e a r c h R e a c t o r No . 1.

In 1965, a c o - o r d i n a t e d r i c e mutation p r o g r a m was initiated in T h a i -land under the a u s p i c e s of the Joint F A O / I A E A Div i s i on of A t o m i c E n e r g y in F o o d and A g r i c u l t u r e . G a m m a r a y s f r o m a 6 0Co s o u r c e contained in a c e l l w e r e u s e d to t reat r i c e s e e d s at the Thai A t o m i c E n e r g y f o r P e a c e in 1966. Induced mutations b y the use of c h e m i c a l mutagen, ethyl methane sulphonate, to t reat r i c e s e e d s w e r e started in 1966. Thus , the p r e s e n t joint p r o g r a m , which was started in 1964, is s t i l l in p r o g r e s s .

M A T E R I A L S AND METHODS

E x p e r i m e n t I. Started in O c t o b e r 1964. I rrad iated v a r i e t i e s : Nahng-Mon S - 4 and M e u y - N a w n g 62 M . M o i s t u r e content of s e e d s : About 14%. Ionizing radiat ion: G a m m a r a y s f r o m 2 3 5 U s o u r c e of

Thai R e s e a r c h R e a c t o r No . 1. D o s a g e ; 15 and 30 kR at 1 kR p e r minute .

E x p e r i m e n t II. Started in July 1965. I rrad iated v a r i e t i e s : N i a w - S a n - P a h - T a w n g , K h a o - D a w k -

Mal i 105, L e u a n g - P r a t e w 28, K h a o - T a h - H a e n g 17 and Nahng-Phaya 132.

Ionizing radiat ion: G a m m a r a y s f r o m 235U s o u r c e of Thai R e s e a r c h R e a c t o r No . 1.

D o s a g e : 15, 20, 25 and 30 kR at 5 kR p e r minute .

E x p e r i m e n t III. Started in August 1966. I rradiated v a r i e t i e s : K h a o - T a h - H a e n g 17 and Leuang

Awn 29. Ionizing radiat ion: G a m m a r a y s f r o m 2 3 5 U s o u r c e of

Thai R e s e a r c h R e a c t o r No. 1. D o s a g e : 15, 30 and 45 kR at 5 kR p e r minute .

E x p e r i m e n t IV. Started in September 1966. I rradiated v a r i e t i e s : Bang -Khen 293, K h a o - D a w k - M a l i 105,

and K h a o - P a h k - M a w 17. Ionizing radiat ion : G a m m a rays f r o m 60 Co s o u r c e of

the g a m m a c e l l at the Thai A t o m i c E n e r g y f o r P e a c e .

D o s a g e : 8, 16, 32, 48 and 64 krads at about 15 krads p e r minute .

E x p e r i m e n t V . Started in O c t o b e r 1966. T r e a t e d v a r i e t i e s : N i a w - S a n - P a h - T a w n g , K h a o - D a w k -

Mal i 105 and Nahng-Phya 132. C h e m i c a l mutagen: EMS (ethyl methane sulphonate) T r e a t m e n t s : 0 . 1 , 0 . 2 , 0 . 3 , 0 . 4 and 0 . 5% so lut ion f o r

6 and 18 h.


P r e t r e a t m e n t s : Soaking .brown r i c e in water at r o o m t e m p e r a t u r e 4 h f o r 6 - h EMS treatment and 3. 5 h f o r 18-h EMS t rea tment .

E x p e r i m e n t VI . Started in January 1968. T r e a t e d var i e ty : I R - 8 . C h e m i c a l mutagen: EMS T r e a t m e n t s : 1 and 2% solut ion at 22°C f o r 20 h . P r e t r e a t m e n t : Soaking in water f o r 24 h at 3 0 ° C b e f o r e

EMS t rea tment .

Mi generat ion

1. Seed ( b r e e d e r seed) that had b e e n exposed to p h y s i c a l ( ioniz ing radiation) and c h e m i c a l t rea tments was sown in pots o r in s e e d - b e d s and transplanted one plant p e r hi l l in pots o r f i e ld with c l o s e spac ing of 10 c m X 25 c m a p a r t ' s o that only a f e w t i l l e r s were , obtained. Untreated seed of the s a m e s e e d s o u r c e was g r o w n as a c o n t r o l e v e r y tenth r o w . Survival ra tes at seed l ing and heading s tages w e r e r e c o r d e d f o r both t reated and untreated s e e d .

2. P a n i c l e s should be c o v e r e d with pol l ination bags b e f o r e sp ike le ts start opening; h o w e v e r , bagging is a l a b o r i o u s job so the Mi was g r o w n in an i so lated f i e ld s e v e r a l m e t r e s f r o m other v a r i e t i e s .

3. P a n i c l e s w e r e bulked f r o m each plant but plants w e r e kept s e p a -ra te ly . Ster i l i ty p e r c e n t a g e was r e c o r d e d as the rat io of the n u m b e r of s t e r i l e sp ike le ts to the total number of sp ike le ts in the p a n i c l e .

M 2 generat ion

1. Seed f r o m each M j plant was g r o w n in an upland s e e d - b e d ( short row) to test f o r b last r e s i s t a n c e . Since s o m e of the M j plants m a y p r o -duce a c o n s i d e r a b l e amount of s e e d , s e v e r a l short r o w s f r o m each Mi plant m a y be sown, but a l l the seed was planted.

2. Only those seed l ings that w e r e b last res i s tant w e r e saved and transplanted in the f i e l d at one seed l ing p e r hi l l with a spac ing of 25 c m X 25 c m . The untreated v a r i e t y was grown e v e r y tenth r o w . A f t e r the seed l ings had b e e n transplated f o r one month, al l the plants that showed y e l l o w - o r a n g e leaf v i r u s s y m p t o m s w e r e d i s c a r d e d .

3. At harves t t i m e , the plants that had good plant type and other d e s i r a b l e c h a r a c t e r i s t i c s w e r e saved . Se lec ted plants w e r e kept s e p a r a t e . Thus , in the M 2 generat i on , w e expec t to save only those plants that have both v i r u s and b las t r e s i s t a n c e and which exhibit good a g r o n o m i c c h a r a c t e r -i s t i c s . A f e w s e e d s of each s e l e c t e d plant should b e grown in tjie d ry s e a s o n to d e t e r m i n e whether mutat ions have o c c u r r e d f o r photoper i od insens i t iv i ty .

1 0 8 DASANANDA and KHAMBANONDA

M 3 generat ion . • , .

1. The upland short r o w test f o r b las t was repeated as in the M2 generat ion , but only 8 g of M 3 seed f r o m each s e l e c t e d M 2 plant was u s e d . Only those seed l ings which w e r e res i s tant to b last w e r e transplanted at a spac ing of 10 c m X 25 c m , with one plant p e r h i l l . Y e l l o w - o r a n g e leaf d i s e a s e s y m p t o m s w e r e o b s e r v e d one month after transplanting in the f i e l d . One r o w of the untreated check was g r o w n e v e r y tenth r o w .

2. Each row that was u n i f o r m was harves ted in bulk. If plants w e r e segregat ing in the r o w s , they w e r e harves ted separa te ly and grown as p e d i g r e e plant r o w s in the next generat ion . Plant height and heading date w e r e r e c o r d e d in this generat i on . P r o m i s i n g mutant l ines w i l l b e g iven a s e l e c t i o n n u m b e r in the o r d e r of heading date and height, r e s p e c t -i ve ly .

3. E s p e c i a l l y p r o m i s i n g l ines which showed n o n - s e g r e g a t i o n w e r e ' put in the u n i f o r m y ie ld t r i a l and grown at s e v e r a l stations to obtain in -f o r m a t i o n on their p e r f o r m a n c e .

R E S U L T S

E x p e r i m e n t I. The M 4 generat ion of both i r rad iated v a r i e t i e s was planted in the 1967 wet s e a s o n . Se lect ion f o r be t ter b last and y e l l o w - o r a n g e leaf v i r u s r e s i s t a n c e was p r a c t i c e d during the test p e r i o d . F o r Muey -Nawng 62 M, s c r e e n i n g f o r ga l l m i d g e r e s i s t a n c e was a l s o made at the Sakolnakorn E x p e r i m e n t Station, l ocated in the Northeast of Thailand where ga l l m i d g e is usual ly a threat to r i c e produc t i on . Se lec t ion of d e s i r a b l e c h a r a c t e r i s t i c s and good plant type with in termediate height f o r M5 planting was m a d e as f o l l o w s :

V a r i e t y No. of M4 s e l e c t i o n s planted No. of s e l e c t i o n s saved

N a h n g - M o n S - 4 543 r o w s 33 l ines M u e y - N a w n g 62 M 315 r o w s 123 l ines

The l ines of both v a r i e t i e s wi l l b e planted in ' o b s e r v a -t ion n u r s e r i e s ' to study the y ie lding abi l i ty and other p e r f o r m a n c e in m o r e detai l in the next wet s e a s o n . S o m e s e l e c t e d l ines of N a h n g - M o n S - 4 mutants showed g o o d plant type with s l ightly s h o r t e r s traw and e a r l i e r matur i ty than the o r i g ina l v a r i e t y . A l l the late matur ing types w e r e d i s c a r d e d f r o m both i r rad ia ted populat ions .

E x p e r i m e n t II. The M 3 generat ion of the f i v e i r rad iated v a r i e t i e s w e r e planted in f i v e r i c e exper iment stations in v a r i o u s r e g i o n s of the country . Mutants with good plant type and other d e s i r a b l e c h a r a c t e r i s t i c s f r o m each i r rad iated v a r i e t y w e r e s e l e c t e d f o r e i ther p l a n t - t o - r o w o r o b s e r v a t i o n n u r s e r y in M 4 , depending upon whether the s e l e c t e d M 3


r o w s appeared u n i f o r m in height and heading. D i s p o s i -tion of the m a t e r i a l was as f o l l o w s :

V a r i e t y

Niaw- San- P a h - Tawng K h a o - D a w k - M a l i 105 ' L e u a n g - P r a t e w 28 K h a o - T a h - N a e n g 17 Nahng-Phya 132

R i c e exper iment

station

Sanpahtawng P i m a i K o k s a m r o n g Supanburi Kuangut

No . of M 3

plants grown

737 r o w s 2 141 r o w s 1 386 r o w s 1 502 r o w s

781 r o w s

No. of s e l e c t i o n

saved

97 l ines 2 141 l ines

690 l ines 286 l ines

53 l ines

T w o l ines se l e c t ed f r o m the i r rad ia ted v a r i e t y N i a w - S a n - P a h - T a w n g headed approx imate ly 2 w e e k s e a r l i e r than the o r i g ina l var i e ty . Severa l other mutant l ines of this v a r i e t y exhibited wide var iat ion in height and heading dates .

T h r e e l ines of K h a o - D a w k - M a l i 105 f r o m the 15 kR treatment m a y have mutated f o r e n d o s p e r m c h a r a c t e r i s t i c s resul t ing in a change f r o m non-glut inous to glutinous r i c e . T h e s e glutinous mutant s e e d s wi l l be i n c r e a s e d and evaluated m o r e thoroughly in the next s e a s o n . Since m o s t of the plants did not exhibit genet i c var iat ion al l l ines of this

' i r rad ia ted var i e ty wi l l be replanted in the 1968 wet s e a s o n . S e v e r a l K h a o - T a h - H a e n g 17 and Nahng-Phya 132

mutant l ines showed be t te r b las t r e s i s t a n c e than the o r i g ina l v a r i e t i e s . Nine K h a o - T a h - H a e n g 17 mutant l ines a lso have glutinous e n d o s p e r m .

E x p e r i m e n t III. The M 2 generat ion of the two i r rad iated v a r i e t i e s was planted in the 1967 s e a s o n . The number of plants c o l l e c t e d f o r M 3 planting w e r e as f o l l o w s :

Var i e ty

K h a o - T a h - H a e n g 17 Leuang -Awn 29

No. of plants grown

62 r o w s 6 5 r o w s

No. of plants s e l e c t e d

16 plants 30 plants

V e r y f e w r o w s of e i ther i r rad iated v a r i e t y exhibited ev idence of s ter i l i ty a n d / o r a b n o r m a l p lants . Some genet i c var ia t ion in height and heading dates was o b s e r v e d among and within the r o w s .

Exper iment IV. The M 2 generat ion of three i r rad ia ted v a r i e t i e s was grown in the 1967 s e a s o n and the f o l l owing n u m b e r of s e l e c t i o n s

• w e r e m a d e f o r M3 planting:

V a r i e t y

B a n g - K h e n 293 K h a o - D a w k - M a l i 105 K h a o - P a h k - M a w 17

No. of plants grown

200 r o w s . 141 r o w s 169 r o w s

No. of plants s e l e c t e d

65 plants 24 plants 29 plants


A f e w r o w s exhibited ev idence of s ter i l i ty a n d / o r a b n o r m a l plants , except in the i r rad iated var i e ty Bang-Khen 293 which showed a high ster i l i ty and a heavy infect ion of sheath blight d i s e a s e . Some genet ic var iat ions in height and heading dates o c c u r r e d among and within the r o w s .

E x p e r i m e n t V . The M 2 generat ion of the three var i e t i e s treated with EMS was planted in the 1967 season , and the f o l l owing w e r e s e l e c t e d f o r M3 planting:

V a r i e t y No . of plants g r o w n No . of plants s e l e c t e d

N i a w - S a n - P a h - T a w n g K h a o - D a w k - M a l i 105. Nahng-Phya 13 2

16 r o w s 26 r o w s 24 r o w s

3 plants 3 plants

V e r y little genet ic var ia t ion was o b s e r v e d in this m a t e r i a l . Only three plants f r o m each of the two i r rad iated v a r i e t i e s w e r e saved f o r further studies in the M3 g e n e r a -t ion. The c h e m i c a l mutagen treatment f o r r i c e should be conducted again with var i ous treatment techniques and a l so on a w i d e r s c a l e .

E x p e r i m e n t VI. The M^ generat ion of the EMS treated var i e ty was planted in the 1968 dry season . The fo l l owing w e r e c o l l e c t e d f o r

V a r i e t y

M 2 planting:

No. of plants grown

No. of transplanted seed l ings

No. of plants c o l l e c t e d

IR- 600 1 1 2 70

T h e r e w e r e no d i f f e r e n c e s in s ter i l i ty p e r c e n t a g e of the treated and untreated plants of I R - 8 . H o w e v e r , the surv iva l r a t e s at seedl ing and heading s tages of the treated seed w e r e m a r k e d l y r e d u c e d .

D I S C U S S I O N

K . I . SAKAI: You have d e s c r i b e d that in one exper iment you fa i led to f ind mutants res is tant to b last d i s e a s e , while in the second e x p e r i -ment you s u c c e e d e d . Can you te l l m e what is the r e a s o n f o r the fa i lure in the f i r s t exper iment and the s u c c e s s in the second?

P . KHAMBANONDA: The s u c c e s s of the second exper iment m a y be due to the bet ter s c r e e n i n g techniques a n d / o r the b i g g e r s i ze of the M j plant population than the one used in the f i r s t exper iment . In the second e x p e r i m e n t we used al l the s e e d s f r o m the M2 plant and sowed them in an upland s h o r t - r o w seed bed . Plants with good type and bet ter b last r e s i s t a n c e w e r e se l e c ted in the M 2 and M 3 g enera t i ons . M 4 s e e d s of each s e l e c t e d plant w e r e tested f o r b last r e s i s t a n c e in the M 4 generat ion . W e have found s e v e r a l mutant l ines with a h igher d e g r e e of b last r e s i s t a n c e than that of the o r ig ina l v a r i e t y .

RICE STEM BORERS IN M A L A Y A

A proposal to use mutation breeding for their control

F.C . VOHRA University of Malaya, Kuala Lumpur, Malaysia

Short communication

1. The p r o b l e m of r i c e stem b o r e r s

A m o n g the var i ous p r o b l e m s in the r i c e c r o p the l o s s caused by the l a r v a e of l ep idopterous stem b o r e r s s e e m s to be v e r y s e r i o u s . In s o m e d i s t r i c t s of the Kurian area , the rate of damage has been as much as 100% [ 1]. It i s not unlikely that the stem b o r e r threat will b e c o m e w o r s e with the i n -t roduct ion of double c ropp ing in many a r e a s .

R e s e a r c h into s tem b o r e r s and e f f o r t s f o r their c o n t r o l date back to 1930 when Pagdon [ 2] publ ished his paper " A p r e l i m i n a r y account of three r i c e stem b o r e r s " . Severa l la ter p a p e r s d e s c r i b e d natural p a r a s i t e s of s tem b o r e r s and great ly e m p h a s i z e d their use f o r b i o l o g i c a l c o n t r o l of the b o r e r s . Thus T r i c h o g r a m m a namum Zehnt was t r i ed but with l i tt le s u c c e s s . Another fut i le attempt was m a d e with an i m p o r t e d s p e c i e s of a Tachinid f ly P a r a -t h e r e s i a c lar ipa lp i s de wulp a f ter the war in 1951. Since then the c o n t r o l of s tem b o r e r s has mainly been through the appl icat ion of v a r i o u s i n s e c t i -c i d e s , namely DDT, BHC, Endrin, d ie ldr in and g a m m a - B H C , and this has met with a c e r t a i n amount of s u c c e s s .

The c h e m i c a l method of c o n t r o l , h o w e v e r , i s not ful ly sa t i s fa c to ry b e c a u s e of :

(a) The high r e c u r r e n t c o s t in appl icat ion; (b) The danger of hazard to man by r e s i d u e s ; (c ) The t ox i c e f f e c t s to f i sh and m a m m a l s in the paddy f i e l d s [ 3]; (d) The po isoning of the natural p a r a s i t e s of the b o r e r s ; (e) The d i f f i cu l t i es f o r p r o p e r appl icat ion, exact c oncentra t i ons e t c . by

untrained f a r m e r s ; and (f) The probabi l i ty f o r deve lopment of i n s e c t i c i d e r e s i s t a n c e in stem b o r e r s .

Apparently there is an urgent need f o r s o m e c o n t r o l f r e e f r o m c h e m i c a l h a z a r d s . Sc ient ists in var i ous c o u n t r i e s have turned to b reed ing f o r v a r -ietal r e s i s t a n c e , among other a p p r o a c h e s , to save the c r o p f r o m damage by stem b o r e r s . The deve lopment of a var i e ty of r i c e res i s tant to stem b o r e s wi l l p r o v i d e an e f f e c t i v e contro l opera t ive at all l e v e l s of insec t population without additional c o s t and inconven ience to the f a r m e r . .

I l l

1 1 2 VOHRA

2. The r e s e a r c h p r o j e c t - -

T o ach ieve this ob j e c t i ve a r e s e a r c h p r o j e c t has r e cent ly been started as a c o - o p e r a t i v e venture at the School of B i o l o g i c a l S c i e n c e s , Univers i ty of Malaya, Kuala Lumpur . This p r o j e c t wi l l invo lve : " •

(a) Detai led e c o l o g i c a l studies of b o r e r s in d i f ferent v a r i e t i e s of r i c e grown c o m m o n l y in the var i ous par ts of the country ;

(b) A study of p a r a s i t e s of b o r e r s f o r p o s s i b l e b i o l o g i c a l c o n t r o l ; and (c) P r o d u c t i o n of r i c e v a r i e t i e s res i s tant to stem borers.. .through induction

of mutations and hybr id izat ion with l o c a l l y used types . '

In Malaya only the f o l l owing f our l ep idopterous s tem b o r e r s are i m p o r -tant [ 4 , 5] : Sesamia in fe rens (Wlk); Chilo s u p p r e s s a l i s (Wlk); Chi lo t raea p o l y c h r y s a ( M e y e r ) ; and T r y p o r y z a incer tu las (Wlk).

Var ious f a c t o r s pertaining to the m o r p h o l o g y , phys io l ogy and c h e m i c a l nature of the r i c e plant are poss ib ly r e s p o n s i b l e f o r the stem b o r e r r e s i s -tance . Care fu l ly planned e x p e r i m e n t s have to evaluate their contr ibut ion to r e s i s t a n c e b e f o r e s u c c e s s f u l b reed ing p r o g r a m s can be undertaken. A wi ld s p e c i e s of r i c e in Malaya , Oryza r id l ey i Hook, i s said to-be highly res i s tant [ 6 ] . S imi lar ly , s e v e r a l cult ivated v a r i e t i e s are c l a i m e d to o f f e r c o n s i d e r a b l e r e s i s t a n c e , but none of them can be r e c o m m e n d e d f o r c o m m e r -c i a l planting b e c a u s e of unsat i s fac tory y ie ld , grain s i z e and appearance , and nutrient and cook ing value . T h e r e f o r e , in o r d e r to deve lop a valuable r e s i s -tant var ie ty one would have to i m p r o v e all the a:bove c h a r a c t e r i s t i c s . Muta -t ion b r e e d i n g with a high standard var ie ty m a y be m o r e p r o m i s i n g than a l o n g - t e r m c r o s s - b r e e d i n g p r o g r a m and should, in the opinion of the author, a l so be attempted in other c o u n t r i e s . ' '

3. W o r k in p r o g r e s s ••

Through the c o - o p e r a t i o n of the authorit ies of the Serdang A g r i c u l t u r e Co l l ege , the use of the ir paddy f i e l d s f o r observa t i on and exper imentat ion has b e e n s e c u r e d . P r e l i m i n a r y w o r k to a s s e s s the type of b o r e r and i n f e s -tation in the m o s t c o m m o n r i c e v a r i e t i e s namely Mahsuri , Mal inja and Ria i s a l ready in p r o g r e s s . This i s essent ia l b e c a u s e m o s t of the p r e v i o u s work on stem b o r e r s in Malaya has been c a r r i e d out on o lder v a r i e t i e s which are not much favoured e i ther by the government o r by the peop le . A l l the f o u r s p e c i e s ment ioned e a r l i e r have been found attacking the new v a r i e t i e s at Serdang. At present , the data are too m e a g r e to warrant any def inite c o n -c l u s i o n s , but the fo l l owing p o s s i b i l i t i e s are indicated by the f i e ld o b s e r v a t i o n .

(a) Some s p e c i e s of b o r e r s are m o r e c o m m o n in one l o ca l i ty than other-s p e c i e s . ,

(b) In a par t i cu l e r l o ca l i ty there s e e m s to be a quantitative host, var ie ty p r e f e r e n c e .

(c ) T h e r e i s no indicat ion of a re la t i onsh ip between the b o r e r infestat ion and the habit of the plants .

(d) Some v a r i e t i e s are p o s s i b l y m o r e vu lnerab le during younger s t a g e s . (e) T h e r e i s an indicat ion of one s p e c i e s of b o r e r being m o r e abundant

during e a r l y s tages of the plant and another one during la ter s t a g e s . (f) T h e r e are many b o r e r s p e r t i l l e r during the ear ly s tages of paddy

plants , but only one o r two at l a t e r ones . .

VOHRA 113

T h e s e o b s e r v a t i o n s indicate s o m e p o s s i b i l i t i e s f o r r e s i s t a n c e b r e e d i n g which wi l l s oon b e tested on new s tra ins in the f i e ld and in the l a b o r a t o r y . F o r i m p r o v i n g s c r e e n i n g techniques on l a rge plant populat ions , e x p e r i m e n t s are be ing c a r r i e d out to i m p r o v e methods of m a s s breed ing of s tem b o r e r l a r v a e in the l a b o r a t o r y . B e s i d e s th is , the c o l l e c t i o n of p a r a s i t e s of s t em b o r e r s i s be ing attempted.

R E F E R E N C E S

[ 1 ] KAWASI, D . , "Rice pests and their control" , Rice Culture in Malaya, Symposium series No. 1, The centre for Southeast Asian Studies, Kyoto University (1965) 50.

[ 2 ] PAGDON, H . T . , A preliminary account of three rice stem borers, Sci . Ser. Dept. of Agr i c . , Straits Settlements and Federated Malay States, Bulletin N o . l (1930).

[ 3 ] PATHAK, M . D . , Ecology of common insect pests of rice, A . Rev. Ent, 13 (1968) 257. [ 4 ] KOK, L. T . , VERGHESE, G . , Yield losses due to lepidopterous stem borer infestations of Padi

(Oryza sativa). Trap. Agr i c . , Lond. (1965) 69. [ 5 ] YUNUS, ROTHSCHILD, C . H . L . , "Insect pests of r ice" , The Major Insect Pests of the Rice Plant

(Malaysia Symp.) IRRI (1967) 617. [ 6 ] VAN, T . K . , GOH, K . G . , The resistance of Oryza ridleyi Hook, to padi stem borer attack, Malay,

agric. J. 42 (1959) 207.

D I S C U S S I O N

K. I. SAKAI: With r e g a r d to y o u r e c o l o g i c a l studies on the r i c e stem b o r e r , can you tel l m e if there i s an e c o l o g i c a l d i f ferent iat ion in f o r m s , s u b s p e c i e s o r other subdiv is ion of the stem b o r e r ?

F . C. VOHRA: T o m y knowledge there are no d ist inct s u b s p e c i e s of s tem b o r e r s . The f o u r s p e c i e s c o m m o n l y o c c u r r i n g in Malaya do exhibit s o m e e c o l o g i c a l d i f f e r e n c e s which are at present under detai led study.

H. ISHIKURA: In connect ion with your statement that the dominant s p e c i e s of the f o u r s t em b o r e r s in Malaya d i f f e r f r o m p lace to p l a c e , I would l ike to point out that the dominance of a given s tem b o r e r s p e c i e s s e e m s to be re lated to the genera l env ironmenta l condi t ions , avai labi l i ty of a l ternat ive hos t s ( including c r o p s other than r i c e ) and the type of r i c e cult ivat ion. A m o n g these , the type of r i c e cult ivat ion i s expec ted to change r e m a r k a b l y in many r i c e - g r o w i n g a r e a s by the introduct ion of double c r o p -ping and f e r t i l i za t i on at high l e v e l . I suspect that Chilo may b e c o m e d o m i n -ant o v e r T r y p o r y z a in a r e a s where double c ropp ing of r i c e m a y be adopted. This a l ready happened in Taiwan s o m e t i m e ago .

Observat i ons have been m a d e in v a r i o u s c ountr i e s on the way in which severa l , s p e c i e s of s tem b o r e r s b o r e into the r i c e plant t i s s u e . T h e s e o b -se rva t i ons indicate that the method of attack depends on the r i c e s p e c i e s and on the deve lopmenta l s tage of the r i c e plant. In t ry ing to b r e e d r i c e v a r i e t i e s that are res i s tant to s t e m - b o r e r attack, it would i>e n e c e s s a r y to take these d i f f e r e n c e s into c o n s i d e r a t i o n . Some exist ing v a r i e t i e s , which are s u s c e p -t ib le to the s tem b o r e r in t e r m s of p e r c e n t a g e of c u l m s in fes ted , do not give r e d u c e d y i e l d s .

RECOMMENDATIONS

R O L E OF INDUCED MUTATIONS IN RICE BREEDING

It was e m p h a s i z e d that induced mutations play a s igni f i cant r o l e in r i c e breed ing .

The advantages of mutation breed ing are :

1. Favourab le s p e c i f i c changes in individual c h a r a c t e r s , without a l ter ing the r e s t of the genotype, can be obtained in an es tab l i shed v a r i e t y . Such c h a r a c t e r s m a y be short c u l m s , r e s i s t a n c e to lodging, r e s i s t a n c e against d i s e a s e s , r e s i s t a n c e against insec t pes ts , i m p r o v e m e n t in grain quality (prote in and amino acid content) , and e a r l i n e s s , e t c .

2. P o l y g e n i c changes f o r the i m p r o v e m e n t of quantitative c h a r a c t e r s , l ike y ie ld , can be induced.

3. Addit ional var iab i l i ty 'and s y n e r g i s t i c e f f e c t m a y be obtained by sub jec t ing the F j seed to mutagenic t reatment , par t i cu lar ly in i n t e r - r a c i a l c r o s s e s .

The disadvantages of mutation b r e e d i n g are :

1. D i rec t i on and nature of induced var ia t ion are sti l l l a r g e l y at random. 2. It i s not p o s s i b l e to expect d e s i r a b l e changes in m o r e than a f ew

c h a r a c t e r s at a t i m e in the s a m e individual un less the c h a r a c t e r s are contro l l ed p l e i o t r o p i c a l l y .

3. Mos t induced mutations are of negative se l e c t i on value and hence a large population is needed f o r the detect ion of d e s i r a b l e mutat ions .

4 . Induced mutations and hybr id izat ion methods are both important in r i c e breed ing p r o g r a m s , although in s p e c i f i c c a s e s one o r the combinat ion of the two m a y . b e p r e f e r a b l e , depending on the b r e e d i n g goal and the genet ic var iat ion in the breed ing m a t e r i a l .

OBJECTIVES OF RICE MUTATION BREEDING P R O G R A M S

I. Mutation breed ing p r o g r a m s should aim at the deve lopment of s u p e r i o r v a r i e t i e s with the f o l l owing c h a r a c t e r i s t i c s :

1. High y ie ld ing abil ity: the high y ie ld ing abil ity of a r i c e v a r i e t y depends p r i m a r i l y upon its n i t r o g e n - r e s p o n s i v e n e s s and lodging r e s i s t a n c e . The f o l l owing plant c h a r a c t e r i s t i c s constitute b a s i c r e q u i r e m e n t s f o r such a var ie ty : a. short stature b. s t rong s t raw c . e r e c t , dark g reen and thick l e a v e s of in termedia te length and

width d. e a r l y vegetat ive v igour e . s l ow leaf s e n e s c e n c e f . high grain densi ty and high grain weight .

115

1 1 6 RECOMMENDATIONS

2. Grain shape and quality: grain shape and cooking quality should be acceptab le to the c o n s u m e r s of the d i f f erent c o u n t r i e s . An e f f o r t should also be made to i m p r o v e the nutrit ional value of the r i c e by i n c r e a s i n g the prote in content and i m p r o v i n g the amino acid c o m p o s i t i o n .

3. Res i s tance to d i s e a s e s and i n s e c t s : v a r i e t i e s res is tant to the f o l l owing d i s e a s e s and insec t pests should be evo lved : a. blast b. var i ous v i rus d i s e a s e s c . var i ous bac ter ia l d i s e a s e s d. s tem b o r e r s e . plant hoppers f . gall m i d g e . It has been shown that genetic r e s i s t a n c e to these plant a d v e r s a r i e s can be developed by breed ing .

4. Other c h a r a c t e r i s t i c s : a. d i f ferent matur i ty durations b. r educed sensi t iv i ty and insens i t iv i ty to photoper iod c . seed d o r m a n c y d. r e s i s t a n c e to grain shatter ing e . drought r e s i s t a n c e f . sal inity r e s i s t a n c e .

II. The best available v a r i e t i e s with wide adaptability should be used in mutation breed ing p r o g r a m s .

III. Exchange of b reed ing m a t e r i a l and mutants between d i f ferent b r e e d e r s should be encouraged .

IV. Mutation breed ing should be used along with conventional b reed ing methods , depending upon the ob j e c t ive of the breed ing p r o g r a m .

M E T H O D O L O G Y

Mutagen treatment

1. Ionizing radiat ions

Dormant seeds with a water content of about 10 - 14% should be used .

a. X - and gamma radiat ion The opt imum dose range wi l l n o r m a l l y be as f o l l o w s : F o r indie a v a r i e t i e s : 15-30 krads F o r japonica v a r i e t i e s : 15 -25 krads

b. Neutron radiation Both fast and t h e r m a l neutrons can be used . The dose range f o r r i c e i s approx imate ly 1 / 1 0 of the g a m m a dose in r a d s . Neutron radiation s e r v i c e s are avai lable at the IAEA L a b o r a t o r y at S e i b e r s d o r f . P r e l i m i n a r y resu l t s f r o m neutron i r rad ia t i on in r i c e look p r o m i s i n g and the group felt that a c o - o r d i n a t e d study

RECOMMENDATIONS 117

fc»

on c o m p a r a t i v e e f f e c t s of fas t neutrons and g a m m a radiat ion should be c a r r i e d out. The radiat ion t reatments should be done at the S e i b e r s d o r f L a b o r a t o r y and the part ic ipants should send s a m p l e s of one v a r i e t y which would be given 3 d o s e s of fast neutrons and g a m m a radiat ion .

2 . C h e m i c a l mutagen t reatments

Ethyl methane sulphonate has proved to be a highly e f f i c i ent mutagen in r i c e . The use of diethyl sulphate should also be c o n s i d e r e d in p r a c t i c a l mutation breed ing p r o g r a m s .

The s e e d s should p r e f e r a b l y be p r e s o a k e d in d ist i l led water b e f o r e mutagen t r e a t m e n t s . The t reatment t ime can thus be reduced and l e s s in jur i es o r p h y s i o l o g i c a l damage to the M j plants are p r o d u c e d . No bu f f e r ing of mutagen so lut ion i s n e c e s s a r y , but p o s t - w a s h i n g in running water i s r e c o m m e n d e d .

3.. Combined radiat ion and c h e m i c a l t reatments

• Although in teres t ing resu l t s have c o m e out of c o m b i n e d t reatments , it was fe l t that m o r e invest igat ions are needed b e f o r e combinat ion t r e a t -ments can be r e c o m m e n d e d in p r a c t i c a l r i c e b reed ing p r o g r a m s .

4 . Handling of the t reated m a t e r i a l and s u c c e s s i v e generat ions

A m i n i m u m of 500 s e e d s should be used in each t reatment . T h e y should be seeded in a n u r s e r y o r seed ing box and transplanted in the f i e ld . The s i ze of the M i population depends on the breed ing ob j e c t i ve but, in general , a m i n i m u m of 250 - 300 plants should be used .

The f i r s t three p a n i c l e s should p r e f e r a b l y be bagged to prevent out -c r o s s i n g , o r each v a r i e t y should be i so lated f r o m other v a r i e t i e s .

F r o m each M x panic le , 15 - 2 5 seeds should be planted out in r o w s f o r ana lyses and s c r e e n i n g of qualitative, v i s i b l e mutants in M 2 . If m o r e var iab i l i ty i s r e q u i r e d , the number of M j plants should be i n c r e a s e d , and the M j panic le s e l e c t i on and the number of plants to be grown in the M 2 on M j plant bas i s could be suitably r e d u c e d . When quantitative po lygene mutations are d e s i r e d , s p e c i a l s c r e e n i n g methods should be appl ied.

I M P R O V E M E N T OF F O R M E R L Y P O P U L A R L O C A L VARIETIES (RESTORATION)

The group r e c o g n i z e d that m o s t emphas i s should be p laced on i r rad iat ion of new v a r i e t i e s which are de f i c i ent in a f ew c h a r a c t e r i s t i c s . C h a r a c t e r i s -t i c s of the v a r i e t y under cons idera t i on should be c a r e f u l l y studied b e f o r e undertaking a mutation p r o g r a m . If the var i e ty i s de f i c ient in many c h a r a c t e r s it should not be used . The fo l l owing steps w e r e suggested :

1. C a r e f u l l y s e l e c t the m o t h e r var ie ty on the b a s i s of w e l l - d e f i n e d o b j e c t i v e s .

2. R e c o g n i z e that c h a r a c t e r s other than the ones under cons iderat i on wi l l be changed. This m e a n s that a conste l la t ion of d i f f erent

RECOMMENDATIONS i

c h a r a c t e r s wi l l be e x p r e s s e d . T h e r e f o r e , it wi l l be n e c e s s a r y to g row a large population in o r d e r to s e l e c t those containing the m o s t d e s i r e d t ra i t s . C o n s i d e r ut i l iz ing only those c h a r a c t e r s re la t ive ly unaf fected by environment , e . g. matur i ty , height, d i s e a s e - and insec t r e -s i s tance , and grain quality.

It i s r e c o g n i z e d that c e r ta in v a r i e t i e s have b e c o m e wide ly accepted by f a r m e r s and that the p r i m a r y r e a s o n why they are no l onger grown i s the de f e c t s in one or a f ew c h a r a c t e r s . It i s s o m e t i m e s d i f f i cu l t to change the f a r m e r s ' p r e f e r e n c e s despite a new var ie ty being high y ie ld ing . The quality, plant c o l o u r , height, and s m e l l of cooked grain, f o r example , tend to attract cer ta in groups of f a r m e r s . A l s o , there are s p e c i a l c o n -dit ions, such as deep water a reas , where only f loat ing v a r i e t i e s can be grown. Under cer ta in c i r c u m s t a n c e s the induction of a c h a r a c t e r , such as r e s i s t a n c e to v i rus o r product ion of short straw, m a y save an o t h e r - . w i se popular , we l l -adapted var ie ty .

Q U A L I T Y I M P R O V E M E N T

1. A m o n g c e r e a l s , r i c e has the best pro te in quality f r o m the point of v iew of lys ine content and the a m i n o - a c i d p r o f i l e . H o w e v e r , the c u r r e n t l y grown r i c e v a r i e t i e s have a low prote in quantity, ranging only f r o m about 5 - 10%. I n d i c a v a r i e t i e s usual ly have a l ittle higher prote in content than japon i ca s t ra ins . A l s o , the concentrat ion of prote ins in the a leurone l a y e r l eads to a c o n s i d e r a b l e l o s s of prote ins during mi l l ing . Any i m p r o v e -

, ment m a d e in the quantity and quality of prote ins in r i c e wi l l be a s i g n i -f i cant contribution t owards br idg ing the rap id ly widening gap between the supply and requ i rement of pro te ins in the w o r l d .

2. The var iab i l i ty found in natural populations is usual ly the resu l t of s e l e c t i on , natural and human, act ing upon random mutations and r e -c o m b i n a t i o n s . Pro te in quantity and a m i n o - a c i d c o m p o s i t i o n are new p a r a -m e t e r s in human se l e c t i on . Hence , the natural var iab i l i ty f o r such c h a r a c t e r s is not l ike ly to be wide, as i s a l ready indicated by the s c r e e n i n g f o r lys ine c a r r i e d out at the International R i ce R e s e a r c h Institute. H o w -e v e r , where use fu l natural s o u r c e s of high prote in and high lys ine content o c c u r , these should be ut i l ized in b reed ing . It would be use fu l if the Joint F A O / I A E A Div is ion r e c e i v e d f r o m the IRRI a l ist of p r o m i s i n g high prote in and high lys ine cu l tures as soon as they are detected at the IRRI so that a l ist could be c i r cu la ted among the part ic ipants and other r i c e mutation b r e e d e r s .

3. Mutation b r e e d i n g o f f e r s the greates t s c o p e where the s e l e c t i o n c r i t e r i o n used r e p r e s e n t s a new need by w o r l d agr i cu l ture . The induction of mutat ions in high y ie ld ing and photo - insens i t i ve r i c e s tra ins f o r prote in quantity and quality may , t h e r e f o r e , lead to v e r y b e n e f i c i a l r e su l t s as is a l ready c l e a r f r o m the p r e l i m i n a r y work done in Japan and India. Such work can be undertakein at c e n t r e s where competent b i o c h e m i c a l help and f a c i l i t i e s are avai lable f o r s c r e e n i n g l a rge populations f o r lys ine and prote in .

4 . Mutation b r e e d i n g f o r pro te in quantity and quality should be c a r r i e d out without s a c r i f i c i n g y ie ld . F o r the i m m e d i a t e future it would be w o r t h -while to concentrate on i m p r o v i n g prote in quantity without any a d v e r s e a l terat ion of the a m i n o - a c i d c o m p o s i t i o n .

1 1 8

3.

RECOMMENDATIONS 119

5. E x p e r i m e n t s should be started on a s s e s s i n g t h e s c o p e f o r a mutat ional a l terat ion of prote in distr ibut ion in the r i c e grain. It would be v e r y valuable if the prote in gets distr ibuted in the ent ire e n d o s p e r m rather than r e m a i n s l a r g e l y r e s t r i c t e d to the a leurone l a y e r and e m b r y o .

6. It would be use fu l if data on the in terac t i on between v a r i e t y and l o cat i on and season , with r e f e r e n c e to prote in c h a r a c t e r i s t i c s , could be c o l l e c t e d f o r the important r i c e v a r i e t i e s . ' Th i s aspect could be taken into c o n -s iderat ion by the International R i c e R e s e a r c h Institute, which obtains in -f o r m a t i o n on y ie ld ing p e r f o r m a n c e of the s a m e v a r i e t i e s f r o m many l o ca t i ons in South East A s i a . The IBP adaptation t r ia l s in r i c e can a lso be used f o r this p u r p o s e . It would be d e s i r a b l e if in format ion could be obtained on the interact ion between var ie ty , f e r t i l i z e r appl icat ion, p l a c e m e n t and t ime .

7. The R i c e Mutation Group congratu lates the Joint F A O / I A E A Div i s ion f o r taking the init iative to o r g a n i z e a Panel Meet ing in Sweden, in June 1968, on new a p p r o a c h e s to b reed ing f o r better plant p r o t e i n s . The P r o -ceed ings of this Panel would great ly st imulate and aid the genet ic up -grading of pro te in quality and enhancement of total pro te in product ion .

8 . Mutation b r e e d i n g has a l ready p r o v e d to be an e f f i c i ent and speedy method of changing the phys i ca l and c h e m i c a l p r o p e r t i e s of s tarch , such as a m y l o s e content, gela'tinization t e m p e r a t u r e , and h a r d n e s s of e n d o s p e r m . T h e r e f o r e , even good japon i ca v a r i e t i e s can now be m a d e use of in indica a r e a s a f ter the a l terat ion of the p r o p e r t i e s of s tarch , and v i c e v e r s a . Th i s has b e c o m e an exce l l ent substitute f o r the j apon i ca X indica hybr id izat i on p r o g r a m s p o n s o r e d by F A O . The high y ie ld ing indica v a r i e t y IR-8 can be m a d e m o r e acceptab le through the mutational r e c t i f i c a t i o n of its grain quality.

LIST OF PARTICIPANTS

C O - O P E R A T O R S

ANDO, A .

GANASHAN, P .

HAQ, M . S .

HU, C . H .

KHAMBANONDA, P .

MIAH, A . J .

REE, J . H .

SWAMINATHAN, M . S .

T A N A K A , S.

VIADO, G . B .

Agr i cu l tura l C o l l e g e , Univers i ty of Sao Paulo , P i r a c i c a b a , S . P . , B r a z i l

A g r i c u l t u r a l R e s e a r c h Station, Maha-I l luppal lama, C e y l o n

Pakistan A t o m i c E n e r g y C o m m i s s i o n , A t o m i c E n e r g y Centre , P . O . Box 164, Ramna, D a c c a , East Pakistan

Genet i c s L a b o r a t o r y , Department of A g r o n o m y , C o l l e g e of A g r i c u l t u r e , Taiwan P r o v i n c i a l Chung-Hsing

Univers i ty , Taichung, Taiwan, Republ i c of China

B r e e d i n g Div is ion , R i ce Department , Min i s t ry of A g r i c u l t u r e , Bangkok, Thailand

Plant Genet i cs Sect ion, A t o m i c Energy A g r i c u l t u r a l R e s e a r c h

Centre , Tando jam, West Pakistan

Yungnam C r o p E x p e r i m e n t Station, O f f i c e of Rural Deve lopment , .Milyang, K o r e a

Indian Agr i cu l tura l R e s e a r c h Institute, New De lh i -12 , India

Institute of Radiation Breed ing , Min i s t ry of A g r i c u l t u r e and F o r e s t r y , Ohmiya , Ibarak i -ken , Japan

Phi l ippine A t o m i c E n e r g y C o m m i s s i o n , 727 Herran Street , Manila , Phi l ippines

1 2 1

1 2 2 LIST OF PARTICIPANTS

P A R T I C I P A N T S

AKEMINE, H.

FUTSUHARA, Y .

HARN, H.

ISHIKURA, H.

ITO, R.

K A W A R A , K .

L E TRUNG L A P

M A R I E , R.

MATSUO, T .

MURAKAMI , K .

OGURA, T .

Department of P h y s i o l o g y and Genet i c s , National Institute of A g r i c u l t u r a l

Sc i ences , . Nishigahara, Ki ta -ku , Tokyo , Japan

Facul ty of Agr i cu l ture , Nagoya Univers i ty , F u r o - c h o , Chigusa-ku , Nagoya, Japan

Radiation Agr i cu l tura l R e s e a r c h Institute, Seoul, K o r e a

A g r i c u l t u r e , F o r e s t r y and F i s h e r i e s R e s e a r c h Counci l ,

M i n i s t r y of Agr i cu l ture , K a s u m i g a s e k i , Chiyoda-ku , Tokyo , Japan

National Centra l A g r i c u l t u r a l E x p e r i -ment Station,

Konosu 1227, Sa i tama-ken , Japan

K o y a n a g i - c h o 3 - 1 1 - 3 0 , Fuchu, Tokyo , Japan

Vie tnam E m b a s s y , M o t o - Y o y o g i 50, Tokyo , Japan

Centre de R e c h e r c h e s A g r o n o m i q u e s du Midi ,

Station d ' A m e l i o r a t i o n des P lantes , Montpe l l i e r (Herault) , F r a n c e

Facu l ty of A g r i c u l t u r e , T o k y o Univers i ty , Yayo i , Bunkyo-ku, T o k y o , Japan

D i v i s i o n of Genet i c s , National Institute of A g r i c u l t u r a l

S c i e n c e s , Hiratsuka, Kanagawa-ken , Japan

A g r i c u l t u r e , F o r e s t r y and F i s h e r i e s R e s e a r c h Counci l ,

M i n i s t r y of A g r i c u l t u r e , K a s u m i g a s e k i , Chiyoda-ku , Tokyo , Japan

123 LIST OF PARTICIPANTS

OSONE, K .

P A R K , L . A . I .

RAJAN, S . S .

SAKAI, K . I .

S C A R A S C I A - M U G N O Z Z A , G . T .

SMITH, H . H .

T O R I Y A M A , K .

VOHRA, F . C .

YAMASAKI, Y .

Facu l ty of Agr i cu l ture , Tokyo Univers i ty , Yayo i , Bunkyo-ku, Tokyo , Japan

Yungnam C r o p E x p e r i m e n t Station, O f f i c e of Rural Deve lopment , Mi lyang, K o r e a

Indian A g r i c u l t u r a l R e s e a r c h Institute, New D e l h i - 1 2 , India

National Institute of Genet i c s , Yata 1111, M i s h i m a , Shizuoka-ken, Japan

Centro di Studi Nuc l ear i de l la C a s a c c i a , C . N . E . N . , Sa. Mar ia di Galer ia , R o m e , Italy

Department of B io l ogy , B r o o k h a v e n National L a b o r a t o r y , Upton, L . I . , New Y o r k 11973, United States of A m e r i c a

National Chugoku A g r i c u l t u r a l E x p e r i -Ment Station,

Higashifukatsu 540, Fukuyama, H i r o s h i m a - k e n , Japan

School of B i o l o g i c a l S c i e n c e s , Univers i ty of Malaya, Kuala Lumpur , Malays ia

Nihon Univers i ty , S h i m o u m a - c h o 3 - 4 9 , Setagaya-ku, Tokyo , Japan

INTERNATIONAL ORGANIZATIONS

JACKSON, R .

KHUSH, G . S .

R o c k e f e l l e r Foundation, P . O . Box 2453, Bangkok, Thailand

International R i ce R e s e a r c h Institute, Manila Hotel , Mani la , Phi l ippines

MIKAELSEN, K . Div i s i on of R e s e a r c h and L a b o r a t o r i e s , International A t o m i c E n e r g y Agency , 1010 Vienna, Austr ia

124 LIST OF PARTICIPANTS

Y A M A D A , N. F A O Regional O f f i c e f o r As ia and the F a r East ,

Mal iwan Mansion, Phra Atit Road, Bangkok, Thailand

SCIENTIFIC S E C R E T A R I A T

SIGURBJORNSSON, B .

K A W A I , T .

Joint F A O / I A E A Div i s ion of A t o m i c E n e r g y in Food and A g r i c u l t u r e , •

International A t o m i c Energy A g e n c y , 1010 Vienna, Austr ia

D i v i s i o n of Genet i cs , National Institute of A g r i c u l t u r a l S c i e n c e s , Hiratsuka, Kanagawa-ken , Japan

I A E A S A L E S A G E N T S A N D B O O K S E L L E R S

Orders for A g e n c y publ i cat ions c a n b e p l a c e d with your bookse l l er or any o f the addresses l isted b e l o w :

ARGENTINA Comis i f in N a c i o n a l de Energla A t S m i c a A v e n i d a del Libertador 8250 Buenos Aires

A U S T R A L I A Hunter Publ icat ions 23 M c K i l l o p Street Me lbourne , C . 1

A U S T R I A Publishing Sect ion International A t o m i c Energy A g e n c y Karntner Ring 11 P . O . Box 590 A - 1 0 1 1 Vienna

B E L G I U M O f f i c e International de Librairie 3 0 , A v e n u e Marnix Brussels 5

C A N A D A Canadian Government Printing Bureau, International Publ icat ions Main Stores, R o o m 2738 , Second Floor, Sacred Heart Boulevard, Hul l , Q u e b e c

C . S . S . R . S . N . T . L . Spo lena 51 NovS Mesto Prague 1

D E N M A R K Ejnar Munksgaard Ltd. 6 Norregade D K - 1 1 6 5 Copenhagen K

F R A N C E O f f i c e International de D o c u m e n t a t i o n et Librairie 4 8 , Rue Gay-Lussac F - 7 5 Paris 5e

G E R M A N Y , Fed . Rep . R. Oldenbourg Verlag Rosenheimer Strasse 145 D - 8 Munich 80

H U N G A R Y Kultura Hungarian Trading C o m p a n y for Books and Newspapers P . O . Box 149 Budapest 62

I S R A E L Hei l iger & C o . 3 , Nathan Strauss Str. Jerusalem

I T A L Y A g e n z i a Editoriale C o m m i s s i o n a r i a A . E. I . O . U . V ia Merav ig l i 16 1 -20123 Mi lan

J A P A N M a r u z e n C o m p a n y , Ltd. P . O . Box 5 0 5 0 , 1 0 0 - 3 1 T o k y o International

M E X I C O Librerfa Internac ional , S . A . A v . Sonora 206 Mfexico 11, D . F .

N E T H E R L A N D S Martinus Ni jho f f N. V . Lange Voorhout 9 P . O . Box 269 T h e Hague

P A K I S T A N Mirza Book A g e n c y 65 , Shahrah Q u a i d - E - A z a m P . O . Box 729 Lahore - 3

P O L A N D Ars Po lona Centrala Handlu Z a g r a n i c z n e g o Krakowskie P r z e d m i e s c i e 7 Warsaw

R O M A N I A C a r t i m e x 3 - 5 13 D e c e m b r i e Street P . O . Box 1 3 4 - 1 3 5 Bucarest

S P A I N Libreria Bosch Ronda Univers idad 11 Barcelona - 7

S W E D E N C . E . Fritzes Kungl . H o v b o k h a n d e l Fredsgatan 2 S t o c k h o l m 16

S W I T Z E R L A N D Librairie Payot Rue Grenus 6 C H - 1 2 1 1 G e n e v a 11

U . S . S . R . Mezhdunarodnaya Kniga S m o l e n s k a y a - S e n n a y a 3 2 - 3 4 M o s c o w G - 2 0 0

U. K . Her Majes ty ' s Stat ionery O f f i c e P. O . Box 569 London S. E . 1

U . S. A . UNI PUB, I n c . P . O . Box 433 New York , N . Y . 10016

Y U G O S L A V I A Jugoslovenska Kn j iga T e r a z i j e 2 7 Belgrade

IAEA Publ icat ions c a n also b e purchased reta i l at the Uni ted Nations Bookshop at United Nations Headquarters, N e w Y o r k , f r o m the news -s tand at the Agency ' s Headquarters, V i e n n a , and at most c o n f e r e n c e s , sympos ia and seminars o r g a n i z e d by the A g e n c y .

In order to f a c i l i t a t e the distribution o f its pub l i ca t i ons , the A g e n c y is prepared to a c c e p t p a y m e n t in UNESCO coupons or in l o c a l currenc ies .

Orders and inquiries f r o m countr ies not l isted a b o v e m a y b e sent to i

Publishing Sec t i on International A t o m i c Energy A g e n c y Karntner Ring 11 P . O . Box 590 A - 1 0 1 1 V i e n n a , Austria

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1970

PRICE: US $4.00 Austrian Schillings 104,-(£1.13.4; F.Fr. 22,20; DM14,70)

SUBJECT GROUP: I Life Sciences/Induced Mutations

rice breeding with induced mutations ii · mutation induction in rice by radiation combined with...

Documents