IRRN GUIDELINES The International Rice Research Newsletter objective is:

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suggestions, please write the editor, IRRN, IRRI, P.O. Box 933, Manila, Philippines. We look forward to your continuing interest in IRRN.

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Guidelines for contributors

The International Rice Research Newsletter is a compilation of brief reports of current research on topics of interest to rice scientists all over the world. Contributions should be reports of recent work and work-in- progress that have broad, pan-national interest and application. Only reports of work conducted during the immediate past three years should be submitted.

Research reported in IRRN should be verified. Single season, single trial field experiments are not accepted. All field trials should be repeated across more than one season, in multiple seasons, or in more than one location, as appropriate. All experiments should include replication and a check or control treatment.

All work should have pan-national relevance.

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Limit each report to two pages of double-spaced typewritten text and no more than two figures (graphs, tables, or photos). Do not cite references or include a bibliography. Organize the report into a brief statement of research objectives, a brief description of project design, and a brief discussion of results. Relate results to the objectives.

analysis.

environment (irrigated, rainfed lowland, upland, deepwater, tidal wetlands).

Report appropriate statistical

Specify the rice production

Specify the type of rice culture (transplanted, wet seeded, dry seeded). Specify seasons by characteristic weather (wet season, dry season, monsoon) and by months. Do not use local terms for seasons or, if used, define them. Use standard, internationally recognized terms to describe rice plant parts, growth stages, environments, management practices, etc. Do not use local names. Provide genetic background for new varieties or breeding lines. For soil nutrient studies, be sure to include a standard soil profile description, classification, and relevant soil properties.

diseases, insects, weeds, and crop plants. Do not use common names or local names alone. Quantify survey data (infection percentage, degree of severity, sampling base, etc.). When evaluating susceptibility, resistance, tolerance, etc., report the actual quantification of damage due to stress that was used to assess level or incidence. Specify the measurements used. Use generic names, not trade names, for all chemicals. Use international measurements. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) or per specified length (in meters) row (g/ row) for small scale studies. Express all economic data in terms of the US$. Do not use local monetary units. Economic information should be presented at the exchange rate US$:local currency at the time data were collected.

abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Thereafter, use the abbreviation. Define any nonstandard abbrevia- tions or symbols used in a table or graph in a footnote or caption/ legend.

Provide scientific names for

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Categories of research published

GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality pest resistance

diseases insects other pests

stress tolerance drought excess water adverse temperature adverse soils

irrigated rainfed lowland upland deepwater tidal wetlands

seed technology

CROP AND RESOURCE MANAGEMENT soils soil microbiology physiology and plant nutrition fertilizer management

inorganic sources organic sources

integrated germplasm improvement

crop management integrated pest management

diseases insects weeds other pests

water management farming systems farm machinery postharvest technology economic analysis

ENVIRONMENT

SOCIOECONOMIC IMPACT

EDUCATION AND COMMUNICATION

RESEARCH METHODOLOGY

CONTENTS GERMPLASM IMPROVEMENT

Genetics 5 Contribution of IR crosses to improved cultivars for irrigated rice in Latin

America

Breeding method—hybrid rice 5 Photosynthesis and respiration in rice hybrids 6 Effect of low light on F 1 rice hybrids 6 Analysis of heterotic relationships among quantitative characters of hybrid

7 Restorers and maintainers for two cytoplasmic male sterile lines 7 Heterosis in physiological attributes of rice hybrids 8 Meiotic behavior of some WA cytosterile lines 9 Maintainers and restorers for WA cytoplasmic source (V20 A) 9 New CMS line Zaoxian A with incomplete dominance of short duration 10 Natural outcrossing on two cytoplasmic male sterile lines in northern India

Yield potential 10 Screening rice varieties and breeding lines for internode elongation ability

12 Elongation ability in deepwater rices

Pest resistance—diseases 12 Utilization of sources of resistance to bacterial blight (BB) in China 13 Resistance to tungro in some wild relatives of rice 13 Distribution of rice varieties resistant to bacterial blight (BB) in Yunnan,

14 Presence of rice tungro bacilliform virus (RTBV) in xylem cells of tungro-

rice

under field conditions

China

infected rice

Integrated germplasm improvement—up1and 14 Four rice varieties released in Sierra Leone

Integrated germplasm improvement—irrigated 15 ASD18, a blast (B1)-resistant rice variety for Tamil Nadu

Integrated germplasm improvement—rainfed lowland 15 Three new varieties of short-duration rice released in Cambodia

Integrated germplasm improvement—tidal wetland 16 Performance of short-duration rice varieties in tidal swamps of Indonesia

CROP AND RESOURCE MANAGEMENT

Fertilizer management 17 Influence of organic and inorganic amendments, modified urea, and

application methods on ammonia volatilization in saturated calcareous soil

Fertilizer management—organic sources 18 Effect of gypsum-enriched biogas sludge and farmyard manure on rice

yield

Fertilizer management—inorganic sources 18 Effect of irrigation and nitrogen on transplanted summer rice yield and

19 Improving applied phosphorus utilization by rice in Madagascar

Integrated pest management—diseases 19 Association of Fusarium moniliforme Sheld. with rice seeds and subsequent

20 Effect of grain discoloration in upland rice on some yield components

Integrated pest management—insects 20 Duration of diapause in white stem borer (SB) Scirpophoga innotata 21 Morphometric measurements of green leafhopper (GLH) Nephotettix

21 A new blister mite pest of rice in the Philippines 22 A quadrat insect sampler for direct seeded rice

Farming systems—deepwater rice 22 Cropping patterns for deepwater rice environments

Farming systems—irrigated rice 23 Transplanted rice-based cropping sequences in an irrigation canal command

23 Rice-based cropping systems for Andhra Pradesh

ANNOUNCEMENT 24 Tropical crops symposium postponed one year

water use efficiency

infection in Pakistan

nigropictus (Stål) head and body during development

area of Rajasthan

Heterosis in photosynthesis in F 1 rice hybrids is not well established; it is considered to be mostly cross-specific. We studied heterosis in photosynthetic rate (Pn) and maintenance respiration LMR) in IR54152 A/IR54 and V20 A/

IR36 at the vegetative (35 d after plant- ing) and flowering stages during the 1990 dry season. MR provides energy for the biochemical and physiological state of established tissues. It differs considerably among cultivars.

The hybrids, their restorers, and check variety Swarnaprabha were planted in pots. Pn in the second leaf at the vegeta- tive stage and in the flag leaf at flowering were measured by LI-6000 at full sunlight (about 1200 µE/m 2 per s). MR was

measured by differential respirometer as CO 2 evolution rate on excised leaves after incubation in the dark for 8 h.

The hybrids showed higher Pn and MR than their restorers at both growth stages (see table). Pn was similar, but MR was higher in the hybrid with IR36 than in the hybrid with IR54. Both hybrids had higher Pn and MR than Swarnaprabha.

Heterosis over restorer was consis- tently higher in V20 A/IR36. Heterosis for Pn was higher at the vegetative stage than at flowering; differences in heterosis for MR were only marginal. Standard

K. S. Murty and S. K. Dey, Central Rice Research Institute, Cuttack 753006, India

Photosynthesis and respiration in rice hybrids

GERMPLASM IMPROVEMENT Genetics Contribution of IR crosses to improved cultivars for irrigated rice in Latin America

Federico Cuevas-Pérez, IRRI liaison scientist for Latin America, Apartado Aéreo 6713, Cali, Colombia

Adoption of modern semidwarf rice varieties in Latin America began in the late 1960s with the introduction of IR8. Although yield gains were impressive, grain quality was below regional stan- dards. This stimulated additional intro- ductions and breeding work to select locally adapted materials.

After nearly 20 yr of germplasm improvement work, modern semidwarf varieties are planted on 31 % of the rice area and contribute 56% of total Latin American rice production. For irrigated rice, 80% of the area and production are modern varieties. International collabora- tion through the International Network for the Genetic Evaluation of Rice (INGER, formerly IRTP) has been a major force behind these technological improvements.

To determine the contribution of IR materials to the improvement of irrigated rice in Latin America, the pedigrees of 143 cultivars released 1971-89 were ana-

lyzed: 85% had at least one IR line in their parentage.

Chile was the only country with no cultivar showing IR parentage, probably because of subtropical growing condi- tions. Other countries whose materials had low IR input were the traditional exporters, Surinam and Uruguay.

Table 1. IR breeding lines in the parentage of irrigated rice cultivars released in Latin America, 1971-89.

IR line Cultivar name Country, year of release

IR442 Huallaga Peru, 1972 BR2 Brazil, 1978

IR579 IR100 INIAP2

Nicaragua, 1973 Ecuador, 197 I

Navolato A7 1 Mexico, 197 I Brazil, 1976 IR665 IR665

IR822 CR1113 Costa Rica, 1974 IR837 Bamoa A75 Mexico, 1975

IR841 IR841 Piedras Negras A74 Mexico, 1974

Brazil, 1974 EMPASC 104 Brazil, 1985

IR930 BR-IRGA 408 Brazil, 1975 Chancay Peru, 1972 Cica 4 INIAP6

Colombia, 1971 Ecuador, 1972

Naylamp Peru, 1971 IR1055 N IR1529 IR1529

Guyana, 1975 Cuba, 1978

IR2058 Pesagro 102 Brazil, 1983 IR2153 Juma 62 Dominican Republic,

1986 IR4570 PA-3 Peru, 1984 IR5853 Saavedra Bolivia, 1987 IR8208 Pesagro 101 IR18348 INIAP11

Brazil, 1983 Ecuador, 1989

In rice varieties from the rest of the region, 24 cultivars were direct selections of IR lines (Table 1). About two-thirds of them were released 1971-78. IR930 was named in five countries. Navolato A71 (IR579) in Mexico and INIAP II (IR18348) in Ecuador are the most widely grown direct IR selections. Since 1978, most of the IR line contributions have been as parents in local crosses.

Fifty-two IR lines have been used in national breeding programs; the most frequently found were IR8, IR579, and IR930 (Table 2). Some 90% of the 2.1 million ha of irrigated favorable rainfed rice area of Latin America is currently planted to cultivars with IR8 in their parentage.

Table 2. IR lines most frequently found in the parentage of Latin American irrigated rice culti- vars, 1971-89.

Progenitor Genetic contribution per IR line of released cultivar a

cultivars Mean Maximum

IR8 76.2 0.36 0.75 IR262 26.6 0.50 0.50 IR579 36.4 0.29 1.00 1R66 1 9.1 0.22 0.50 IR665 34.3 0.28 1.00 IR84 I 16.8 0.17 1.00 IR930 51.0 0.38 1.00

a Assuming 50% contribution of each parent in a single cross. A contribution of 1.0 indicates that the IR line was released as a cultivar.

Breeding methods—hybrid rice

IRRN 16:4 (August 1991) 5

heterosis was also high in V20 A/IR36, standard heterosis over Swarnaprabha in Analysis of heterotic especially for MR at flowering. Pn/MR, especially at flowering. relationships among

marginal positive heterosis at the restorers to reduce MR and improve Pn hybrid rice vegetative stage and was negative at and Pn/MR would increase photosyn- flowering. Both hybrids showed negative thetic productivity.

Pn/MR in IR54752 A/IR54 showed These results suggest that selecting quantitative characters of

Peng Junhua and Tian Shoujun, Crop

Photosynthetic rate (Pn) and maintenance respiration (MR) a of F 1 rice hybrids in Cuttack, India, 1990 dry season. b tural Sciences, Chengdu 610066,

Institute, Sichuan Academy of Agricul-

Sichuan, China Vegetative Flowering

Hybrid Pn MR Pn/MR Pn MR Pn/MR In 1987, we used 6 male sterile lines and

IR54752 A/IR54 45.3 1.66 27.2 33.4 (24) (17) (6) (6) (19)

1.23

V20 A/IR36 46.1 1.80 25.6 34.7 1.46 23.7 Apr-Oct 1988 was laid out in a random- (–11)

(36) (25) (9) (26) (23) (2) ized complete block design with three Swarnaprabha 36.2 1.28 28.3 29.6 0.90

3.4 0.11 1.9 0.12 Standard heterosis and hill spacing was 17 × 23 cm. The

12 fertility restorer lines to make 72 F 1 27.1 hybrid combinations. A field experiment

LSD (0.05) 32.8 replications, with 30 plants per plot. Row

IR54752 A/IR54 25 29 V20 A/IR36 27 40

4 -10

13 36 17 62

-17 center five plants in each plot were -28 sampled.

a Pn and MR in mg CO 2 /dm 2 per h. b Figures in parentheses = heterosis over restorer.

Effect of low light on F 1 rice Effect of low light (50% of normal) from 40 dafter planting to harvest on dry matter and yield of F 1 rice hybrid restorers and check varieties. Cuttack, India.

hybrids

K. S. Murty and S. K. Dey, Central Rice Total dry Yield Research Institute, Cuttack 753006, lndia Cultivar matter (g/m2) (g/m2)

F1 rice hybrids are reported to be more productive than elite conventional Hybrid

Full Low Full Low light light light light

varieties even under such stresses as drought and salinity. Low light is another major constraint to rice production during the rainy season.

We studied tolerance for low light in hybrids IR54752 A/IR54 and V20 A/IR36 and their restorers, with standard checks Ratna and Swarnaprabha during 1990 dry season. The crop was grown in 1.2-m 2

field plots at 15- × 10-cm plant spacing and fertilized with 80 kg N/ha.

imposed from 40 d after planting to harvest by shading with wood screens. Controls were maintained under normal sunlight (about 420 cal/cm 2 per d). The experiment was laid out in a randomized complete block design with three replica- tions. Growth durations were 128 d in all treatments.

Low light (50% sunlight) condition was

The hybrids showed positive heterosis in total dry matter and yield over the restorer parent under low light only (see table).

Yield and heterosis in yield were higher for IR54752 A/IR54 than for V20 A/IR36.

IR54752 A/IR54 985 643 418 206 V20 A/IR36 853 471 345 167

Restorers IR54 993 IR36 853

Checks Ratna 803 Swarnaprabha 928

Mean 902 LSD (0.05) Variety Treatment Variety × treatment

Heterosis over restorer IR54752 A/IR54 –1 V20 A/IR36 0

Standard heterosis IR54152 A/IR54 vs

Ratna 22 Swarnaprabha 6

Ratna 6 Swarnaprabha 8

V20 A/IR36 vs

537 426 179 427 400 164

358 354 144 597 480 243 506 403 183

99 17 57 44 ns ns

19 –2 15 11 –13 2

79 18 43 8 –13 –15

33 –3 16 –20 –28 –31

This could be associated with the higher yield potential of restorer IR54. The hybrids also showed strong standard heterosis over Ratna under low light, but negative heterosis in yield over Swar- naprabha, a low light-tolerant variety.

Eleven characters were analyzed (Table 1): days to heading (DH), culm number/plant (CN), panicle length (PL, cm), plant height (PH, cm), total spikelet number/panicle (TSN), filled spikelet number/panicle (FSN), filled spikelet percentage (FSP), 1,000-grain weight (GW, g), biological yield/plant (BY, g), grain-straw ratio (GSR), and grain yield/ plant (GY, 8). Heterosis was estimated for each character as

H = F 1 - ( P 1 + P 2)/2

Correlation coefficient and stepwise regression analysis were used to estimate relationships among characters.

Correlations vaned with character combinations; 31 were significant (Table 1). In the F 1 hybrids, correlations of DH to TSN and FSN; CN to BY; PL to PH, FSN, GW, and BY; PH to TSN, FSN, and BY; TSN to FSN and BY, FSN to FSP, BY, and GSR; FSP to GSR; GW to GSR; and CY to CN, PL, PH, FSN, FSP, GW, BY, and GSR were positive and significant; those of DH to GW, CN to TSN and FSN, and TSN to FSP, GW, and GSR were negative and significant.

Some of the character combinations had more or less the same correlation trends, except that more character combinations showed significant correla- tions in the F 1 hybrids than in the parents, particularly GSR, which had negative correlation (although nonsignificant) in the parents with PL, FSN, FSP, GW, and BY but showed positive correlation

6 IRRN 16:4 (August 1991)

Restorers and maintainers for two cytoplasmic male sterile lines

J. S. Bijral, T. R. Sharma, B. B. Gupta, K. Singh, and C. L. Raina, SKUAST, Regional Agricultural Research Station (RARS), R.S. Pura 181102, India

coefficient in the hybrids. It should be possible to increase GSR and BY simulta- neously in hybrids, but not in parents.

The multiple regression equation for GY heterosis was GY = 4.609 + 0.100 DH + 1.039 CN + 0.068 FSN + 0.429 GW + 0.312 BY + 27.286 GSR. This model was effective in predicting GY heterosis, accounting for 88% of the total variation (Table 2). Except for DH, the effect of the

regression was highly significant. Biological yield was the most important contributing character in the formation of GY heterosis.

Heterosis of GY depends on heteroses of BY, FSN, CN, PH, PL, FSP, GW, and GSR. It would be helpful in hybrid rice breeding to take into account the heterotic relationships among some metrical characters.

Table 1. Correlation coefficients for heterosis of F 1 and parents among 11 characters. a

Trait DH CN PL PH TSN FSN FSP GW BY GSR GY

DH P 1 –.20 –.06 .14 .37** .42** .22 –.35** .14 –.19 .13 F 1 1

CN P –0.2 1 F 1 –.38** 1

.08 .08 –.30* –.24* –.04 .09 .59** –.10 .50**

PL P .78** –.10 1 F 1 .43** –.27* 1 .65** .22 .40** .11 .23* .33** .19 .39**

PH P .81** .02 .92** 1 F 1 .57** –.20 .74** 1 .47** .49** –.07 .10 .43** .08 .41**

TSN P .49* –.37 .48* .52* 1 .72** –.30** –.27* .34** –.25* .23 F 1 .55** –.61** .34** .41** 1

FSN P .76** –.38 .76** .69** .68** 1 F 1 .57** –.60** .58** .44** .84** 1

.39** –.03 .49** .29* .57**

FSP P .44* –.14 .39 .23 –.20 .57* 1 F 1 .30** –.28* .59** .26* .15 .65** 1

.17 .12 .75** .38**

.21 .27* .31**

–.04 .86**

GW P .18 –.34 .25 .31 –.16 .12 .26 1

BY P .85** .18 .81** .84** .32 .68** .48* .37 1 F 1 .47** .14 .53** .53** .32** .52** .49** .43** 1

F 1 –.44** .11 .08 –.26** –.25** .11 .53** .15 .02 1 GY P .81** .19 .77** .80** .28 .71** .56* .36 .98** –.48 1

F 1 .40** .14 .54** .44** .23* .54** .65** .46** .91** .29 1

a Correlation coefficients for parents (P) and F 1 below the diagonal, those for heterosis above the diagonal. *,** = significant at 5 and 1% levels, respectively.

F 1 .14 –.11 .32** .27* –.21 .01 .30** 1

GSR P –.61** –.23 –.53* –.58** –.35 –.36 –.08 –.02 –.56* 1 .29*

Table 2. Statistical test for the model of grain yield heterosis. a

SV DF SS @ MS F R 2

DH 1 5.503 6 5.503 2.66 CN 1 21.734 3 21.734 10.49** FSN 1 18.942 4 18.942 9.14** GW 1 16.097 5 16.097 7.77** BY 1 47.109 1 47.109 22.73** GSR 1 37.017 2 37.017 17.86**

Error 65 134.722 2.073 Total 71 1111.090

Multiple regression 6 976.366 162.728 78.51** 0.8787

a @ = magnitude order of SS, ** = significant at the 1% level.

In a hybrid rice breeding program based on a cytoplasmic male sterility and fertility restoration system, identification of effective maintainers and restorers is of great importance. We crossed 10 short-, medium-, and long-duration rice cultivars with cytoplasmic male sterile lines Zhen Shan 97 A and V20 A in 1988 wet season

at Ranbir Singh Pura, Jammu, and Kashmir. The F 1 hybrids were evaluated for spikelet fertility during the 1989 wet season.

Varieties showing more than 80% spikelet fertility were classified as restorers; those with 30-79%, 1-29%, and less than 1% spikelet fertility were rated as partial restorers, partial maintainers, and effective maintainers, respectively.

All test cultivars except Dular, IET10770, and N22 were identified as restorers (see table). N22 partially restored the fertility of both cytosterile lines. IET10770 and Dular were classi- fied as effective maintainers.

Restorers and maintainers for 2 cytoplasmic male sterile lines identified at RARS, R.S. Pura, India, 1989 wet season. a

Spikelet fertility Variety

Zhen Shan 97 A V20 A

IR35454-18-1-2-2 R R IR25912-30-2-3-2 R R IR29692-99-2 R R IR9761-19-1-R R R B4227 E-KN- 10 R R IET10321 R R IET10770 M M IET1410 R R Dular M M N22 PR PR

a R = restorer (80% spikelet fertility), PR =partial restorer (30- 79% spikelet fertility, PM = partial maintainer (l-29% spikelet fertility), M = maintainer (less than 1% spikelet fertility).

Heterosis in physiological attributes of rice hybrids

K. S. Murty, S. K. Dey, and P. J. Jachuck, Central Rice Research Institute, Cuttack 753006, India

Heterosis in yield characters of F 1 rice hybrids from cytoplasmic genetic male sterile (CMS) lines has been well recognized. Information on the heterosis of physiological characters, however, is meager.

We studied standard heterosis over check Jaya of seven F 1 hybrids (six from CMS line IR54752 A and one from Madhu A) during 1989 wet season (Jul- Oct). The hybrids and Jaya were trans- planted (25 d after seeding) at 20- × 15-cm spacing, one seedling/hill, in a

IRRN 16:4 (August 1991) 7

randomized block design with three replications. Fertilizer (80 kg N/ha) was applied in 3 equal splits: at transplanting, 20 d after transplanting, and at panicle initiation.

4.5 h of bright light/d. Periodic samples were taken for leaf area index (LAI), total dry matter (TDM), and crop growth rate (CGR). Photosynthetic rates (Pn) of the second leaf before flowering and the flag leaf at flowering were measured with LI- 6000 Portable Photosynthesis System; maintenance respiration (MR) was measured by Gilson differential respi- rometer. Crop photosynthesis is assumed to be Pn × LAI.

The season was cloudy, with less than

Yield and yield attributes were recorded at harvest. Given a high frequency of sterile plants in the hybrids, 20 normal fertile plants were taken for yield assessment. Standard heterosis was calculated over check Jaya.

Considerable standard heterosis was apparent in Pn, LAI, and Pn × LAI at 30 d after planting and in post-flowering CGR, TDM, and yield (see table). Heterosis of MR was negative. Panicle number and grain number/m 2 exhibited high heterosis. The hybrid with Madhu A showed good heterosis in Pn, MR, and Pn/MR at flowering (F).

Swarna and IR54 hybrids combined Among the hybrids with IR54752 A,

Meiotic behavior of some WA cytosterile lines

R. K. Mandal and S. Saran, Botany Department, Patna University, Patna 800005; and V. N. Sahai, A.R.I. Mithapur farm, Patna I, India

The meiotic behavior of CMS lines IR46827 A, IR46828 A, IR46829 A, and IR46830 A was studied to ascertain chromosomal abnormality associated with pollen abortion or sterility.

Meiosis of microsporogenesis showed 12 regular, well-developed bivalents at diakinesis and metaphase I with a normal 12: 12 separation of chromosomes at anaphase I; 3 secondary associations of 2 bivalents each in a large number of

8 IRRN 16:4 (August 1991)

Standard heterosis for physiological characters and yield of rice hybrids, Cuttack, India, 1989 wet season.

Standard heterosis (%) of hybrids over

Character a Standard IR54752 A Jaya check Jaya IR54 IR54 IR27- Prabhat Swarna Pratiba Madhu A/

(UAS) (CRRI) 31.5 IR15324

Pn at 30 d (mg CO 2 / 28.1 22 8 20 12 8 9 17 dm 2 per h) Flowering 34.6 4 5 –11 –11 –14 4 23

MR at flowering 2.6 –9 4 –14 –7 –14 –14 12 Pn/MR at flowering 8.9 0 3 0 –17 –7 4 18 Pn × LAI (F) gCO 2 /m 2 11.3 35 22 11 –2 3 –13 19 LAI at 30 d 0.92 39 31 4 19 42 6 3

Flowering 3.28 42 16 25 9 20 –9 4 SLW at flowering 520 8 11 12 –2 4 18 –14

(mg/dm 2 ) Flag leaf area (cm 2 ) 29.3 22 19 17 11 26 14 4 FL SLW (mg/dm 2 ) 541 2 7 5 8 3 9 TDM at 30 d (g/m 2 ) 88 30 39 –2 4 22 9

–9

870 –2

Flowering 23 11 40 –16 40 14 –26 Harvest 1051 60 62 66 26 54 28 13

CGR at 0-30 d 2.93 30 39 –2 4 24 9 –2 (g/m 2 per d) 50 d tooflowering 14.7 15 3 15 48 6 –10 8 Flowering-harvest 6.0 243 311 190 226 123 96 203

Yield (g/m 2 ) 384 68 73 77 2 71 17 7 Yield (g/m 2 per d) 2.9 59 62 59 0 55 7 14 Panicles/m 2 177 53 52 52 33 33 28 23

Grains/panicle (no.) 87.7 3 4 9 –21 45 –16 –7 Grains/m 2 (×10 2 ) 155 56 45 65 4 94 7 –25 1000-grain wt (g) 26.3 4 –7 6 0 –11 –7 –22 HI (%) 36 6 8 8 –17 11 –8 4

a Pn = photosynthetic rate, MR = maintenance respiration rate, LAI = leaf area index, TDM = total dry matter, CGR = crop growth rate, SLW = specific leaf wt, FL SLW = flag leaf specific leaf wt

strong heterosis in LAI, TDM, and yield, hybrids might be improved by combining but heterosis in Pn at flowering and CGR them with photosynthetically effective at reproductive growth was poor. restorers. Heterosis for photosynthesis in these

Meiotic behavior of chromosomes in 4 CMS lines.

Pollen CMS line mother cell Diakinesis Metaphase Anaphase Remarks

scored (no.) I I

IR46827 A 50 12 II 12 II 12:12

Chromatin becomes feeble in anaphase I and dis-

IR46828 A 50 12 II 12 II 12:12 integrates completely in IR46829 A 50 12 II 12 II 12:12 telophase I. IR46830 A 50 12 II 12 II 12:12

preparations; a variable number and type. In this type, meiosis initially behavior of nucleoli; and a gradual progresses normally, but the microspores disintegration of chromatin setting in at tend to abort. Total absence of chromatin anaphase I, resulting in its complete dis- matter at telophase I is a new report of a appearance by late telophase I (see table). cytological basis for pollen abortion in

Complete sterility of microspores in CMS lines. Imbalance of synthesis and all CMS lines showed that they belonged degradation of auxins could be the reason to the CPA (complete pollen abortion) for pollen abortion and complete sterility.

Maintainers and restorers for WA cytoplasmic source (V20 A)

S. B. Pradhan and P. J. Jachuck, Cetral Rice Research Institute (CRRI), Cuttack 753006, Orissa, India

Screening locally adapted elite breeding lines for genetically diverse maintainers and restorers for different cytoplasmic male sterile (CMS) lines is important in developing new CMS lines.

We used 37 National Screening Nursery entries as pollen parents for crossing with stable WA-type CMS line V20 A. The F 1 hybrids were grown in a well-puddled field. During anthesis, anthers from 10-15 spikelets each of 3 panicles of individual F 1 plants were collected at random. They were examined under a microscope, using Lugol’s iodine solution, and pollen sterility estimated. Spikelet fertility was estimated on two to three panicles that had been bagged on each hybrid plant.

Varieties were classified as effective maintainers (spikelet fertility less than l%), weak maintainers (spikelet fertility less than 25%), partial restorers (spikelet fertility 25-79%), and effective restorers (spikelet fertility more than 80%). IET10158, IET10428, IET10849, IET10851, IET11721, IET11811, IET11668, and IET10503 were effective maintainers; IET10830, IET9819, IET10458, IET9979, IET9798, IET11O57, IET10462, IET10463, IET10435, and IET11722 were effective restorers for V20 A (see table). The effective maintainers will be used to develop new CMS lines possessing WA cytoplasm with different nuclear back- grounds, using recurrent backcrossing procedures.

New CMS line Zaoxian A with incomplete dominance of short duration

Liu Biaoxi, Peng Junhua, and He Yuezhong, Crop Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China

Fertility restoration of National Screening Nursery varieties in test crosses with V20 A of wild abortive source. CRRI, 1990.

V20 A (F 1 )

Genotype Parentage Pollen Spikelet M/R a

fertility fertility (%) (%)

IET10158 Swarnadhan/NLR9674 0 0 M IET10428 IR4219-35-3/IR4.570 0 0 M IET11350 Bas370/CRR88-1-7-1-3 10.0 9.6 WM IET10849 CR157-392/OR 67-21 0 0 M IET11062 b B29826/SR62-31-4 54.6 49.9 PRIM IET12020 Sona/Basmati 370 9.1 7.0 WM IET10851 Samridhi/IR36 0 0 M IET11721 0 0 M IET11811 IR36/TR17 0 0 M

IET11668 Co. 37/6551 0.6 0 M IET10881 c Ryllored/Palman 64.8 61.5 PRIM IET10983 d WGL23022/Surekha 73.8 71.7 PRIM IET10503 Sona/IR28 0 0 M IET10451 T90/IR8//RPW 6-13/// 8.2 6.0 WM

IET9994 Sona/ARC14529 15.0 13.1 WM IET10763 IR36/IET7916 24.8 21.1 WM IET9831 Prasanna/IR50 23.0 15.3 WM IET9292 CO13/IR26 16.0 12.6 WM IET11004 ES280/1-2/Ptb 33 49.7 29.6 PR IET11785 69.1 61.8 PR IET10516 Phalguna/TKM6 45.3 40.8 PR IET9824 Rasi/Dular 70.1 63.8 PR IET11001 IR36///Suphala/PR3880// 32.9 28.6 PR

IET10508 IR50/IET7918 50.0 44.7 PR IET9288 Jaya/Ptb 33 60.6 44.5 PR IET9961 IR8 mutant 70.0 63.9 PR IET9586 IET4141/CR98-7216 58.6 29.9 PR IET10830 CR157-392/OR57-21 94.7 80.0 R IET98 I9 Ratna/Zagar 96.8 91.5 R IET10458 IET2886/Annapuma 92.1 81.0 R IET9979 Phalguna/IR50 87.3 84.5 R IET9798 Pusa 186-10-45/Pusa 2-21 84.9 83.2 R IET11057 Rasi/IET7332 86.4 81.5 R IET10462 Nam Sagui 19/IR4215// 91.6 89.5 R

IET 10463 92.1 91.1 R IET10435 Sel. from IRTP 12140 89.7 87.4 R IET11722 IET7615/RP79-5 94.1 83.5 R

Siam 29/Mahsuri

CR222/Parijat

IR9219-209-3-2

a M = maintainer, R = restorer, P = partial, W = weak. b IETI1062: 40% of F 1 plants completely sterile. c IET10881: 66.7% of F 1 plants highly sterile (96.8-99.1% pollen sterility). d IET109X3: 20% of F 1 plants completely sterile.

IET11062, IET10881, and IET10983 heterozygous fertility restoration genes; were both effective maintainers and they interacted differently with CMS line partial restorers for V20 A. This indicates V20 A. that these three varieties might have

The growth duration of hybrid combina- tions used in commercial rice production in China (Shanyou 63, Weiyou 64) is mainly determined by restorer lines. To shorten the growth duration of hybrid rices for a cropping system of rice - wheat - rice or rice - rape - rice and to extend hybrid combinations derived from long-duration restorer lines to short-

duration rice regions and to mountainous, high altitude regions, we developed a CMS line with incomplete dominance of short duration.

In 1985, we crossed Zhenshan 97 B with a shorter duration plant selected from the F 2 of O. longistaminata / Liuzhou wild rice ( O. sativa L. f. spontanea ). Zhenshan 97 A was backcrossed with

IRRN 16:4 (August 1991) 9

that short-duration line for eight genera- Days to heading of CMS lines, restorer lines, and F 1 s, and growth duration and grain yield of F 1 s. a

tions. A new CMS line was named Grain yield Zaoxian A in 1989. Days to heading Growth

Zaoxian A is still classified as a WA Hybrid combination duration t/ha Percentage compared to

type. It is semidwarf (68 cm tall), averages value Check Check Check 104 spikelets/panicle, with a 1,000-grain weight of 26.0 g. It also has long (1.62 m),

Zaoxian A/R 2

Zaoxian A/R 1 78 111 94.5 90 127 9.6 112 121 113 78 113 95.5 92 128 9.4 110 119 111

well-exserted (73.5%) stigma, and its Zaoxian A/R 3 78 115 96.5 92 128 9.2 108 116 108 outcrossing rate is high (55.3%). Zhen Shan 97 A/R1 (check 1) 75 111 93.0 112 148 8.6 100

three long-duration restorer lines, and

P 1 P 2 Mid-parent F 1 (d)

1 2 3

In 1990, we crossed Zaoxian A with V20 A/R5 (check 3) Zhen Shan 97 A/R4 (check 2) 75 88 81.5 92 130 8.0 100

75 87 81.0 90 127 8.5 100

tested yield capacity in a field experiment check 3 are the national checks of China and check 2 is the provincial check of Sichuan Province in the regional test of hybrid rice. a R 1 = Minghui 63, R 2 = 086, R 3 = Mingdian 501, R 4 = Zhalyeqing 8, R 5 = Ce 64. P 1 = CMS line, P 2 = restorer line. Check I and

in Chengdu. Plots (2.5 m 2 ) were laid out in a randomized complete block design with three replications.

The period to heading of F 1 s related to Zaoxian A was about 20 d shorter than those of the restorer lines and shorter than the mid-parent values (see table). The period to heading of F 1 s related to other CMS lines was about 10 d longer than the mid-parent values and longer than those of the restorer lines.

This indicates that days to heading of restorer lines is dominant over that of CMS lines Zhenshan 97 A and V20 A. Days to heading of Zaoxian A was incompletely dominant over that of the restorer lines.

Grain yields of hybrid combinations derived from Zaoxian A were higher than yields of national check Shanyou 63, although hybrid growth durations were

about 20 d shorter than that of Shanyou 63. Yields were significantly higher than those of Shanzhai 8 and Weiyou 64, which had almost the same growth durations as the hybrids.

appears to be incompletely dominant over the long duration of restorer lines, making Zaoxian A valuable for rice production and for hybrid rice breeding.

The short duration of Zaoxian A

Natural outcrossing on two Seed set on 2 cytosterile lines at RARS, R.S. Pura, India, 1989 wet season.

cytoplasmic male sterile lines in northern India

Grains/panicle (no.) Total Mean A line B line Planting grains seed set

ratio Filled Unfilled (no.) (%)

J. S. Bijral, T. R. Sharma. B. B. Gupta, RR988 A CH988 1:1 68 850 918 7.4 K. Singh, and C. L. Raina, SKUAST, RR39 A K39 1:1 142 1101 1243 11.0

Regional Agricultural Research Station (RARS), R.S. Pura 181102, India

We studied the extent of outcrossing in cytoplasmic male sterile (A) lines RR988 A and RR39 A (CMS-WA cytoplasm developed at Pura, Jammu, and Kashmir). The cytosterile lines were surrounded by a single row of their

respective maintainer (B) lines (CH988 and K39). Plant spacing was 20 × 30 cm.

To synchronize flowering and prolong the pollen supply, maintainer lines were seeded 3 d earlier and 4 d later than the cytosterile (A) lines. All lines were transplanted at the same time, at 2 seedlings/hill. The flag leaves of the

cytosterile lines were not clipped. The main panicles of 10 randomly

selected plants of each cytosterile line were harvested individually and filled and unfilled grains/panicle counted. Outcrossing rate was low, probably because of poor panicle exsertion of cytosterile lines (see table).

Yield potential We evaluated 155 varieties and experi- Seventy-four entries failed to produce

Screening rice varieties and mental lines for internode elongation grain. Among surviving entries, 17 breeding lines for internode ability under field conditions. Entries produced 9-12 internodes, with total elongation ability under field were seeded 13 Apr 1989 in two 5-m internode lengths of 126-215 cm (see

conditions rows, 25 cm apart. table). These lines also had much better Water depth reached 190 cm the first kneeing ability.

R. V. Singh, Crop Research Station week of Oct. Plant height, number and Maturity ranged from the last week of (CRS), Ghagharaghat, Bahraich 271901, length of internodes, kneeing ability, Nov to the first week of Dec. Locally Uttar Pradesh (UP); J. L. Dwivedi maturity, and phenotypic acceptability popular variety Jalmagna matured the (present address: Plant Breeding, were observed. Maximum length of three first week of Dec, 233 d after seeding. Genetics, and Biochemistry Division, consecutive elongated internodes was While Jalmagna was highest in total IRRI); and O. P. Verma, CRS, Ghaghar- derived from the sums of three adjacent internode elongation, four other entries aghat, Bahraich 271901, UP, India internodes. exceeded its maximum three consecutive

10 IRRN 16:4 (August 1991)

internode elongation (see figure). Length of maximum elongating three adjacent internodes ranged from 54 to 93 cm. It took an average of 13.6 d for one internode to form (computed as number of days between start of flooding and flowering, divided by total number of elongated internodes). An estimate of

number of days required for maximum elongation of three adjacent internodes is 41 d. These internodes were probably formed during the highest water stagna- tion period starting the first week of Oct.

The maximum elongation of three adjacent internodes gives an indication of capacity for elongation in a prolonged

Performance of promising lines under natural field conditions in Uttar Pradesh, India.

Promising lines Plant Internodes height Days to Date of

Designation Parentage (cm) no. Length maturity maturity (cm)

IR45478-B-3 Baisbish/IR 19245-76-2- 1-3-3 167 12 126 239 8 Dec NDGR87-2 Jalmagna/Sona 217 9 126 237 6 Dec NDGR87-2-1-3 Jalmagna/Sona 220 9 127 245 14 Dec NDGR87-104-2-1 Jalmagna/Sona 232 9 139 234 3 Dec NDGR87-2-1-1 Jalmagna/Sona 232 9 142 237 6 Dec NDGR87-104-2-3 Jalmagna/Sona 225 9 143 237 6 Dec IR45478-B-4 Baisbish/IR19245-76-2-1-3-3 223 10 146 239 8 Dec IR45468-15-GR-5 Baisbish/IR56 232 10 149 238 7 Dec NDGR1045-125-103 RP/LMN111 238 10 160 236 5 Dec NDGR87-104-1-3 Jalmagna/Sona 238 10 166 234 3 Dec IR45468-B-10 Baisbish/IR56 237 10 168 240 9 Dec IR45468-B-11 Baisbish/IR56 248 11 180 240 9 Dec IR45468-B-12 Baisbish/IR56 245 12 180 240 9 Dec RP2078-58-74-1 Mansarovar/CO 14 268 10 186 231 6 Dec RF'2078-63-81-1 Mansarovar/CO 14 250 10 191 236 5 Dec RP2078-56-71-39 Mansarovar/CO 14 269 10 195 237 6 Dec Jalmagna Pureline selection 290 13 196 233 2 Dec NDGR1045-38-127- RP/LMN111 255 11 215 228 21 Nov

113

period of rapidly rising water, in this case 190-200 d from seeding. Elongation of the central internode of the longest three internodes (position 3-5 counting from the top of the figure) may correspond to the onset of water 40 d before flowering and/or to the extra stimulus to internode growth at panicle initiation, which was also 30-40 d before flowering. Further experiments using a group of varieties with a wider spread of flowering dates may help distinguish between these two causes.

Number of elongated internodes and maximum elongating three adjacent internodes may be used to assess promis- ing lines for elongation ability. Further study is needed to determine the relation- ship between elongation ability and yield potential.

Surveys of disease or insect incidence/severity in one environment are useful only if the information is related to other variables (e,g., climatic factors, crop intensification, cultivars, management practices, etc.). By itself, information on incidence in one environment does not increase scientific knowledge.

Internode length and three maximum elongating internodes.

IRRN 16:4 (August 1991) 11

Elongation ability in deepwater rices

O. P. Verma, Crop Research Station (CRS), Ghagharaghat, Bahraich 271901, Uttar Pradesh (UP); J. L. Dwivedi (present address: Plant Breeding, Genet- ics, and Biochemistry Division, IRRI); and R. V. Singh, CRS, Ghagharaghat, Bahraich 271901, UP, India

We studied the elongation ability of 12 deepwater rice varieties and 24 advanced breeding lines during 1989 wet season. Entries seeded in pots were submerged in 120-cm-deep water 42-49 d after seeding.

Internode, leaf sheath, and leaf blade lengths were measured on 10 plants before and after flooding. Recovery or submergence tolerance was scored 10 d after water was drained.

By and large, the traditional floating rices had higher total elongation than did the breeding lines (see table). Total plant elongation after 7 d water treatment ranged from 8.5 cm (entry ACC33745 was rejected and is not in the table) to 66.5 cm (TCA4).

TCA4 had the highest internode

Plant elongation and regeneration ability of rices with different deepwater survival strategies. a

Elongation (cm) Variety

Internode Leaf Leaf Submergence

tolerance score sheath blade

TCA4 51.5 7.6 7.4 7 NDGR401 NDGR406

49.0 2.7 3.7 42.7

5

NDGR404 5.0 5

42.3 3.7 16.4 5 ACC38876 34.3 9.4 7.3 5 Jalmagna 31.3 5.0 6.0 9 NDGR402 28.4 920356

6.3 18.6 3 22.0 4.7 20.3 3

IR11141-6-1-4 16.9 8.4 18.7 5 Nam Sagui 19 13.1 9.6 2.7 3 IR39657-4-502-1-3-2 12.0 4.7 12.0 5 TCA7819 11.0 20.3 10.0 5

ACC18973 4.0 15.7 4.0 5 2.0

FR 13A 16.0 5.0 3

0.4 20.6 4.0 3 a Underlining indicates relatively high reliance of the plant on the corresponding survival strategy.

8.0

IR39657-B-B-1

elongation, followed by NDGR404 and sudden submergence. NDGR406. Higher elongation values indicate

Leaf sheath and leaf blade elongation as relatively high reliance on the corre- high as 15.7-20.6 cm were recorded in sponding survival strategy. Some 920356, ACC18973, TCA7819, varieties rely on internode elongation, NDGR402, IR39657-B-B-1, and FR13A. leaf (sheath, blade) elongation, and/or Since leaf elongation ability is limited, submergence tolerance. Breeding these entries might be suitable for areas strategies could incorporate some or all that have sudden floods of limited depth. of these survival characters, depending

scores 1-3 will be helpful in areas prone to Varieties with submergence tolerance on the target area.

~.

Pest resistance—diseases Disease incidence was scored 21 d after

Utilization of sources of resistance to bacterial blight (BE) in China

Shen Ying, Zhu Peiliang, and Yuan Xiaoping, China National Rice Research Institute (CNRRI) Hangzhou 310006; He Hui and Zhu Jinwen, Plant Protection Department, Zhejiang Agricultural University, Zhejiang 310029, China

We screened 99 rice cultivars and lines against BB caused by Xanthomonas oryzae pv. oryzae (Xoo) at CNRRI Experiment Station during Apr-Oct 1990.

Thirty-day-old seedlings were transplanted in two rows of 14 hills each at 20- × 20-cm spacing, with two replica- tions. One row each of local susceptible check Jin-Gang 30 and resistant check IR26 were transplanted between each entry and around the experimental field.

The plot was fertilized with 75-37.5- 25 kg NPK/ha.

Seven pathogenic groups of Xoo with varying virulence, based on their reaction on five Chinese differentials, were pro- vided by Yin Shangzhi, Jiangsu Academy of Agricultural Sciences (Table 1).

Test plants were clip-inoculated with a concentration of 3 × 108 CFU/ml from maximum tillering to initial booting stage.

inoculation. Eight varieties showed resistance to

the pathogenic groups (Table 2). They have good agronomic traits and high yield potential, and have been used as resistance sources for breeding.

the BB pathogenic groups and the rice varietal types appropriate for different rice cropping regions, Xa-3 resistance sources are best in japonica rice cropping

Given the geographical distribution of

Table 1. Pathogenic groups of Xoo in China.

Reaction a on indicated differential varieties Pathogenic Representative

group isolate Jin-Gang 30 Tetep Nan-Jing 15 Java 14 IR26

I JS97-2 S R R R R II KS-1-21 S S R R R III JS158-2 S S S R R IV Zhegiang 173 S S S S R V 1358 S S R R S VI OS-198 S R S R R VII JS49-6 S R S S R

a R = resistant, S = susceptible.

12 IRRN 16:4 (August 1991)

Table 2. Resistance of rice cultivars (lines) to 7 pathogenic groups of BB in China 21 d after inoculation. inoculation.

Reaction a to pathogenic group One accession of O. officinalis

Variety (line) Origin Use (105365) showed high antibiosis to GLH I II III IV V VI VII and resistance to both RTBV and RTSV

Milyang 23 1 5 3 5 3 5 5 Korea Hybridization DV85 5 7 3 3 1 5 3 Bangladesh Hybridization O. nivara (102175, 105333), two of O.

infection (see table). Two accessions of

IR54 3 3 3 3 5 3 3 IRRI Hybridization IRBB 7 3 1 1 1 3 1 1 IRRI Resistance source

C702015 Resistance source

1 3 3 3 3 3 5 Taiwan (China) Resistance source C722355 1 3 3 5 5 3 3 Taiwan (China) Resistance source Suwon 339 1333351 Korea Resistance source

BR568-15-4-2-2-3 3 3 3 1 3 3 3 Bangladesh

a By the Standard evaluation system for rice scale 0-9.

regions of the northern part beyond the Yangtze River. Xa-4, xa-5, and Xa-7 Yangtze River. Xa-3, Xa-4, xa-5, Xa-6, or resistance sources are needed in indica Xa-7 resistance sources are best in indica- rice cropping regions in the south China japonica rice cropping regions along the coastal area.

Resistance to tungro in some wild relatives of rice

N. Kobayashi, R. Ikeda, and D. A. Vaughan, IRRI; and S. Shigenaga, Kyoto University, Japan

We tested 16 accessions of wild rice Oryza spp. for antibiosis to green leafhopper (GLH) Nephotettix virescens Distant, resistance to rice tungro bacilli- form virus (RTBV) and rice tungro spherical virus (RTSV) infection, and tolerance for tungro.

To test for antibiosis, a 10-d-old seedling of each accession was placed in a test tube with five GLH nymphs (2d instar), with 10 replications. Antibiosis of each accession was rated on a 1-5 scale by counting surviving GLH nymphs every day for 3 d. Those same seedlings (15-d-old) were inoculated with 10 viruliferous GLH adults/seedling for 4 h. Leaves were individually sampled 3 wk after inoculation, and tested for RTBV and RTSV by enzyme-linked immuno- sorbent assay. Disease severity of each accession was scored at 4 wk after

Reactions of wild species of rice to GLH and tungro disease.

IRGC

no. to GLH a (no.) B+S B S

Anti- Plants Infected plants b (%) Average Genome Species acc. Origin biosis tested severity c

AA O. nivara 102463 Bangladesh 5 38 74 26 0 3 102175 India 1 18 0 78 0 5 105333 India 1 49 2 59 0 2 105409 Sri Lanka 5 39 69 18 3 2 105417 Sri Lanka 4 18 50 11 6 2 105456 Sri Lanka 4 3 67 33 0 5

BB O. punctuta 103896 Tanzania 1 17 0 53 0 2

BBCC O. minuta

CC O. eichingeri CC O. officinalis

CC O. rhizomatis

CCDD O. latifolia AA O. sativa

ARC11554 Utri Merah TN1 IR22

105158 101126 101141 105414 105365 105394 105660 105448 100914

21473 (check

16680

Kenya Philippines Philippines Sri Lanka Thailand China Sri Lanka Sri Lanka Mexico

varieties) India Indonesia Taiwan Philippines

2 1 1 2 1 3 1

1

1 5 5 5

49 20 36 47 27 32 13 4

23

54 54 53 57

0 5 0

47 0 9

15 50 57

2 2

96 90

37 0 3 50 0 3 56 0 5 43 0 5

0 0 2 81 0 3/7 d

31 8 5 25 0 3

0 13 3

39 0 3 52 0 3

4 0 9 10 0 9

punctata (103896, 105158), and two of O. minuta (101126, 101141) showed high antibiosis to GLH and resistance to RTSV infection. Even with low antibiosis to GLH and severe infection with RTBV and RTSV, three accessions of O. nivara (102463, 105409, 105417) showed low scores for symptom severity, indicating tolerance for tungro.

These results suggest that a number of new sources of resistance to both RTBV and RTSV may be found among the wild rices.

Distribution of rice varieties resistant to bacterial blight (BB) in Yunnan, China

Chen Yong and Xinhua Liao, Yunnan Academy of Agricultural Sciences, Kunming 650205; Yuefeng Xie and Duanpin Zhang, Huazhong Agricultural University, Wuchang, China

We screened 4,091 Yunnan rice varieties for resistance to BB caused by Xanthomonas oryzae strain Jiangling 691: 6% were resistant, 84% were susceptible, and 10% were moderately resistant. The frequency of resistance differed within rice classifications (Table 1).

glutinous rices.

among japonica-irrigated-glutinous, japonica-irrigated-nonglutinous, and japonica-upland-glutinous rices. Mean

Table 1. Distribution of BB-resistant rices in Yunnan, China.

Resistance was more frequent among

Table 2 shows more resistant varieties

Varieties Resistant varieties

(no.) no. % Classification tested

Indica 2186 83 3.8 Japonica 1905 159 8.4 Irrigated 3233 202 6.2 Upland 858 40 4.7

a Scale of 1 (resistant) to 5 (susceptible). b Infected with both RTBV and RTSV (B+S), with RTSV (S), or with RTBV (B). c Scale Nonglutinous 3183 159 5.0 1 (no symptoms) to 9 (more than 50% plant height reduction and yellow to orange leaf discoloration), using Nasanuddin et al scale. Glutinous 908 83

d Segregating. 9.1

IRRN 16:4 (August 1991) 13

resistance scales of these types are signifi- cantly lower than that of other types. In terms of average resistance, Yunnan rices could be classified into three significantly different resistance groups.

Presence of rice tungro bacilliform virus (RTBV) in xylem cells of tungro- infected rice F. C. Sta. Cruz and H. Koganezawa, Plant Pathology Division, IRRI

Earlier studies have shown that RTBV and rice tungro spherical virus (RTSV) are restricted to the phloem tissues of infected plants, and it has been suggested that only phloem feeding by green leafhopper (GLH) causes tungro infec- tion. On GLH-resistant cultivars, how- ever, it has been observed that GLH feeds mainly from the xylem and transmits primarily RTBV. We examined the location of RTBV in host cells in relation to tungro transmission.

Rice seedlings (1 5 d old) of tungro- susceptible cultivar TN1 and GLH- resistant cultivar ASD8 were inoculated with rice tungro viruses (RTVs) using adult GLHs. The leaf blades of infected plants were collected 30 d after inocula- tion for electron microscope study.

RTBV particles were found in xylem parenchyma cells as well as in phloem

Table 2. Distribution of resistant varieties in 8 classes and the significance level test of mean resistance scales.

Total Resistant varieties (no.) resistance Classification

Mean

no. % scale”

Indica-irrigated-nonglutinous Indica-irrigated-glutinous Indica-upland-nonglutinous Indica-upland-glutinous Japonica-irrigated-nonglutinous Japonica-irrigated-glutinous Japonica-upland-nonglutinous Japonica-upland-glutinous

Total

1832 303

31 20

679 419 641 166

4091

a Means followed by the same letter are not significantly different.

65 17 0 1

70 50 24 15

242

3.55 5.61 0 5.00

10.31 11.93 3.74 9.04 5.92

8.02 b 7.76 b 8.35 a 7.80 b 7.38 c 7.26 c 7.96 b 7.39 c

cells of tungro-infected TN1 and ASD8 These results suggest that GLH can (see figure). RTSV was observed only in transmit RTBV directly to xylem cells, phloem cells and around the boundary where the virus multiplies and causes between xylem and phloem tissues. In infection. They also support the observa- initial observations, RTBV in xylem cells tion that GLH feeds mainly from the were found in the third and fourth leaf xylem of GLH-resistant cultivars and position of infected plants. transmits predominantly RTBV.

RTBV in xylem parenchyma cells of rice cultivars TN1 (a) and ASDS (b). R = ribosomes.

Integrated germplasm improvement—upland

Four upland rice varieties Table 1. Mean performance of 4 newly released varieties in Sierra Leone.

released in Sierra Leone Height Duration Panicles Mean grain

Variety Original name (cm) (d) (no./m 2 ) yield (t/ha) A. H. Hilton-Lahai, S. S. Monde, and M. S. Mansaray, Rice Research Station, ROK17 LAC23 119 138 186 3.1 Rokupr, Sierra Leone ROK 18 IDSA-6 96 117 174 2.9

ROK 19 FARROX 299 116 115 172 2.8

The uplands account for about 70% of the ROK16 rice area in Sierra Leone. In 1988, four

ROK20 IRAT161 103 118 178 3.0 NGOVIE (local) 128 132 183 2.6

new varieties (ROK17, ROK18, ROK19, ROK20), all foreign introductions, were In varietal trials conducted for two ROK17 is a local japonica selection released for upland planting (Table 1). seasons in farmers’ fields in three from Liberia. It is a medium-duration These varieties surpassed check variety villages in the North-Western Region, the cultivar, with bold grains much like ROK16 in overall performance and new varieties consistently outyielded ROK16. It is, however, more resistant to farmer acceptability in field tests over local check ROK16. Table 2 shows grain diseases and lodging than ROK16 and is four seasons. yields and some properties of the soils. suited to the high rainfall areas of East

14 IRRN 16:4 (August 1991)

Table 2. Yield of 4 new upland rice varieties in farmers’ fields in Kambia District, Sierra Leone.

1986-87 Variety

1987-88

Kamaranka Funkia Petifu Mean Gberika Rochain Rochint Mean

ROK 17 2.2 1.9 2.1 2.1 2.9 2.4 2.4 2.5 ROK18 2 .0 2.8 2.3 2.4 2.8 2.8 2.3 2.4 ROK19 2.8 2.3 2.0 2.2 2.4 2.0 2.3 2.2 ROK20 2.4 2.1 2.3 2.3 2.7 2.2 ROK16 (check) 1.8

2.4 2.3 1.6 1.8 1.7 1.5 1.3 1.7 1.5

CV (%) 12.2 14.6 18.2 15 19.7 22.9 LSD (0.05)

14.4 19 8.2 8.2 8.2 8.2 8.2 8.1 8.2 8.2

Soil Sandy Loam Gravelly Clay Sandy Loam

pH (water) loam 5 0 4.9 5.1 5.5 4.8

CEC (meq/100g) 11.4 5.0

10.2 13.2 15.1 9.9 Organic C (%)

11.1 1.2 0.9 1.4 2.1 0.8 1.8

Total rainfall (mm) 2,156 2,256

clay loam loam loam

and South Sierra Leone. ROK17 is preferred by North Sierra Leone farmers because it is awnless, which makes threshing with the feet less painful. It also has better cooking and eating qualities.

ROK18, ROK19, and ROK20 are short-duration varieties superior to ROK16 in plant type, disease resistance, and phenotypic acceptability. They are recommended for the low rainfall areas of the north. Grain size ranges from slender to medium bold, as preferred by northern farmers.

Integrated germplasm improvement—irrigated ~

ASD18, a blast (BI)-resistant Table 1. Reaction of ASDl8 to major diseases in Tamil Nadu, India.

rice variety for Tamil Nadu Reaction a

M. Rangaswamy, K. Mohanasundaram, P. Shanmugasundaram, K. Ganesan, T. Sundaram, M. Subrammian, D. Alice, and M. Velusamy, Rice Research Station (RRS), Ambasamudram, Tamil Nadu 627401, India

Bl-resistant, short-duration, medium- slender rice culture AS34011, selected from the cross ADT31/IR50, was released as ASD18 by the Tamil Nadu G.D. Naidu Agricultural University in Jan 1991. It is recommended as an alternative to IR50 and TKM9 for summer (Mar-Jun), first season (Jun- Sep), and second season (Nov-Feb) planting.

ASD18 is 90 cm tall with 105-110 d growth duration. Mean grain yield was 7.3 t/ha over 6 yr at RRS, 5.7 t/ha in multilocation trials over 2 yr at seven research stations throughout Tamil Nadu, and 5.9 t/ha under Adaptive Research Trials (ART) in 52 farmers’ fields. Total dry mass was 18.2 t/ha (8.5 t grain and 9.7 t straw) at Amba- samudram; potential grain yield was 10.1 t/ha under ART.

It is resistant to Bl and moderately resistant to sheath rot and tungro (Table 1). It is resistant to brown planthopper and stem borer and moderately resistant to gall midge and leaffolder (Table 2).

Variety Blast Sheath rot Sheath ASD-N blight

RTV

ADT-A DBE-A ASD-N ASD-A ADT-A CBE-A

ASDl8 1 3 3 IR50 3

7 4 5

TKM9 3 9 5 3

7 7 7 9 8 9

a By the Standard evaluation system for rice (SES) scale. N = natural condition, A = artificial condition, ADT = Aduthurai, ASD = Ambasamudram, CBE = Coimbatore.

5 9 7 9

Table 2. Reaction of ASDl8 to major pests in Tamil Nadu, India.

Reaction a

Variety BPH SB GM LF

ADT-A ASD-A ASD-N MDU-A MDU-A CBE-N ASD-A

ASD18 3 5 3 0 5 IR50 9 5 TKM9 9 9

7 5 3 3 9 7 3 0 9 7

a BY SES. BPH = brown planthopper, SB = stem borer, GM = gall midge, LF = leaffolder. ADT = Aduthurai, ASD = Ambasamudram. MDU = Madurai, CBE = Coimbatore. N = natural condition, A = artificial condition, (-) = not tested.

Integrated germplasm improvement— rainfed lowland

Three new varieties of short- Short-duration rices (120 d or less) cover duration rice released in Cambodia

almost 25% of Cambodia’s rice area. In the dry season, they are grown in about 10% of the area, either irrigated or with

R. C. Chaudhary and H. J. Nesbitt, IRRI- receding water. In the wet season, they Cambodia; G. S. Khush, IRRI, Philip- are grown in about 15% of the area as a pines; and Men Sarom, Agronomy rainfed lowland crop. Department, Phnom Penh, Cambodia A number of traditional early varieties

IRRN 16:4 (August 1991) 15

Table 1. Some Chemical Characteristics of acid sulfate soils at Unit Tatas Substation, Central Kalimantan, Indonesia.

Depth Characteristic

0-15 cm >15 cm

pH H 2 O Organic C (%) Total N (%) P Bray (ppm) K (meq/100 g) Ca (meq/100 g) Mg (meq/100g) Na (meq/100 g) CEC (meq/100 g) A1 (meq/100 g) H (meq/100 g) Texture (%)

- Clay - Silt - Sand

4.0 2.8 0.4 1.7 0.2 0.4 1.2 0.2

22.0 14.0 1.0

37 62

1

4.0 1.7 0.2 1.3 0.1 0.3 0.9 0.3

37.0 16.0

0.8

45 54

1

was 90-60-50 kg NPK/ha. All the P and K, and half the N were applied basally at transplanting; the remaining N was applied 30 d after transplanting. Pest infestation was measured at peak incidence.

BW267-3 had the highest grain yield, followed by CR61-7039-236, IR6023-10- 1-1, and IR19661-13-3-2 (Table 2). BW267-3 and IR6023-10-1-1 are intermediate tall, IR19661-13-3-2, and CR261-7039-236 are semidwarf. These four short-duration lines have the highest number of panicles/m 2 and can be developed for the tidal swamps. Grain of IR19661-13-3-2, IR6023-10-1-1, and BW267-3 are long, slender; those of

Performance of short- duration rice varieties in tidal swamps of Indonesia

H. Rosmini, Banjarbaru Research Institute for Food Crops, P.O. Box 31, Banjarbaru, South Kalimantan, Indone- sia

We screened 23 promising lines to identify short-duration rice varieties that yielded well in sulfate acid soils at Unit Tatas substation, Central Kalimantan, 1987-88 (Table 1). Seedlings (21 d old) were transplanted at 25- x 25-cm spacing in 7.5-m 2 plots in a randomized block design with four replications. Fertilizer

adapted varieties, IRRI-Cambodia Project trials were conducted in 13 provinces over four seasons 1989-90.

Of 20 entries tested in 1989 and 10 in 1990, IR66, IR72, and IR13429-150-3- 2-1-2 (named Kru) were best (Table 1). They yielded 4 t/ha across 13 locations during dry season 1990, against 3.2 t/ha of the highest yielding check. (IR36 and IR64 were the check varieties.) In 38 trials over four seasons and 2 yr, IR66, IR72, and Kru yielded 4.2, 4.1, and 4.4 t/ha, respectively, compared to 3.7 t/ha from the check. Other agronomic characters are given in Table 2.

These three varieties were tested in farmers’ fields in 13 provinces, with a traditional early variety added as local check. At some of 75 locations, IR66, IR72, and Kru yielded more than 6 t/ha (average 2.5-2.8 t/ha). A few hundred tons of seed were multiplied by the farmers themselves during 1990.

are planted; varieties such as IR36, IR42, varieties introduced via Vietnam (such as IR50, and IR66, and some IR-based NN3) are also popular. To identify more

Table 1. Yield of 3 new varieties during 1989 and 1990 wet seasons in Cambodia.

Field a (t/ha)

Location IR66 IR72 Kru Check

1989 1990 1989 1990 1989 1990 1989 1990

Tonle Bati 5.1 ab - 5.2 ab - 5.7 a - 4.8 bc Por Lors 3.6 a - 2.6 b - 2.9 ab - 2.9 ab Ballang 4.8 3.8 ab 4.9 3.6 ac 5.2 2.5 be 4.1 Day Eth 2.7 be 5.1 bc 2.9 bd 4.7 bc 3.9 a 5.8 a 3.1 ab 4.8 c Prey Kabas 3.6 3.6 1.8 3.2 2.9 3.2 1.8 2.9

4.0 a

Kbal Po 3.2 a 3.0 ab - 3.2 ab - 2.8 b Chhbar Mom 5.4 ab 3.3 5.4 ac 3.2 5.3 ac 3.7 4.6 ae 2.5 Kompong Siem 2.5 bc - 2.6 bc - 3.0 a - 2.7 b Prey Khmer 5.4 ae 5.1 ab 5.0 be 4.9 ab 6.6 a 5.4 a 5.9 ac 4.9 ab Toul Bakha 4.0 ab 3.5 a 4.2 a 3.3 a 4.1 ab 3.1 ab 3.2 bd 2.8 ac Kirivong 4.2 b - 3.6 bc - 4.0 bc - 4.2 b Chumcar Daung 5.7 ad 5.2 ab 6.6 ab 5.4 ab 6.5 ab 5.2 a 5.7 ad 4.8 b

Kap Srau 4.7 ab - 4.6 ad - 4.0 cd - 4.8 a Prey Phdau Ta Saang

5.9 ab 4.5 ab 5.1 a 3.9 c 4.8 ac 5.1 a 4.1 be 4.6 ab 2.1 ad 2.5 ab 2.7 ad 2.0 bd 2.3 be 2.7 a 2.7 ad 2.4 ac

Bek Chan 5.9 5.6 a 5.9 5.0 ac 6.8 5.2 ah 6.6 3.9 d Tuk Will 2.3 2.0 ab 2.0 1.8 cd 2.3 2.1 a 1.7 1.6 d

Slakou 2.0 ad - 1.7 d - 2.2 ab - 1.9 bd

Toul Lapao 1.5 1.3 1.3 1.3 Toul Chrem Chrom - 1.9 ac - 2.7 ab - 1.5 bc - 2.1 ac a Any two means having a common letter at a location in a year are not significantly different by DMRT.

Table 2. Grain yield and ancillary characters of 3 early varieties in dry season (13 locations) and wet season (20 locations) trials in Cambodia, 1990.

Duration (d) Plant height (cm) Panicle length (cm) Grains/panicle Panicles/m 2 Yield (t/ha) PAcp a

Variety Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet

IR66 106±1.3 110±0.8 75±2.5 85.8±1.5 21.3±0.10 22.8±0.4 89±8.4 101±6.0 329±15.0 286±15.7 4.0 3.9 3.2±0.6 2.07±0.42 IR72 115±1.2 114±0.8 72±2.5 81.8±1.9 21.9±0.46 21.7±0.4 85±9.5 86±4.1 306±18.6 292±15.8 4.0 3.6 2.0±0.8 2.21±0.40 KRU 112±1.0 113±0.8 75±2.6 83.0±1.9 22.9±0.46 21.4±0.3 88±11.0 90±5.34 373±23.0 317±17.5 4.1 3.9 2.7±0.7 2.14±0.34 Check I11±1.2 111±1.0 77±3.0 87.8±2.0 21.7±0.51 22.4±0.5 75±14.0 80±3.8 308±19.6 291±15.5 3.2 3.6 4.0±0.5 2.86±0.43

a PAcp = phenotypic acceptability.

Integrated germplasm improvement—tidal wetland

16 IRRN 16:4 (August 1991)

- - - -

- -

-

-

-

- -

-

Table 2. Yield of 23 promising rice cultures at Unit Tatas Substation, Central Kalimantan, Indonesia, 1988.

Plant Days Panicles Grain Culture ht to /m 2 yield a

(cm) maturity (t/ha)

IR19661-13-3-2 104.7 130 214 5.1 b BW267-3 118.2 120 232 6.7 a IR6023-10-1-1 118.8 125 216 6.3a CR261-7039-236 96.7 125 239 6.4 a ROHYBl5-WAr- 125.8 145 201 2.9e

3-3 BWl00 119.3 140 155 2.8 e BR51-120-2 115.1 140 200 2.7 efg CR1009 104.2 150 190 2.7 efg IR9217-58-2-2 98.4 135 228 3.6 d IR9217-6-2-2-2-3 108.5 135 205 3.6 d Pankaj 106.9 145 196 4.4 c IR13146-45-2 108.0 135 212 3.8 d IR8192-31-2-1-2 101.1 140 147 2.4 fg IR21586-R-31-1 110.4 145 198 2.4 fg ITA230 102.7 140 217 4.4 c IR14753-120-3 102.3 125 212 2.3 g IR29723-88-2-3-3 100.4 140 179 2.3 g IR33353-64-1-2-1 100.8 125 255 2.2 gh IR19657-87-3-3 104.7 135 190 2.1 gh IR4422-480-2-3-3 101.1 135 166 1.8 h IR31917-31-3-2 95.6 140 171 2.4 fg IR52 95.2 115 247 1.3 i IR21836-90-3 107.7 140 208 1.1 i a Values followed by a common letter are not significantly different at the 5% level by DMRT.

CR261-7039-236 are medium. Amylose content is 26-28%.

These four lines are resistant to leaf blast and stem borer.

Mean cumulative N loss by ammonia volatilization source of N, and application method.

CROP AND RESOURCE MANAGEMENT Fertilizer management

Influence of organic and inorganic amendments, modified urea, and application methods on ammonia volatilization in soil or mixed in the soil surface (see table saturated calcareous soil for treatments).

Three-kg air-dried soil, equilibrated with soil amendments (20 t/ha) for 4 wk under saturated conditions, was placed in 5-liter wide-mouth glass bottles. N was applied at 150 kg/ha on the surface of the

The bottles were connected with an air M. Singh, Indian Institute of Soil Science, compressor to flush out evolved NH 3 Z-6, Zone-I, Muharana Pratap Nagar, from the soil (4-5 liter/h). The NH 3 was Bhopal 462011; and T. A. Singh, G.B. trapped in 2% boric acid mixed with an Punt University of Agriculture and indicator. Boric acid was titrated against Technology, Pantnagar, Nainital 0.05 NH 2 SO 4 at regular intervals for 30 263145, India d.

Ammonia volatilization from urea significantly reduced cumulative NH 3 depends on such factors as rate of volatilization. The reduction in NH 3 loss hydrolysis of urea, concentration of appears to be due to a lowering of soil pH NH + 4 -N in the soil, and pH. Coating urea on equilibration with soil amendments with some material can reduce NH 3 (see figure). volatilization. The formation of stable ammonium

We measured NH 3 -N volatilization sulfate in soils amended with gypsum and from urea, neem cake-blended urea pyrite may have contributed to reduction (NCBU), and neem oil-coated urea of NH 3 loss. Reduction of NH 3 volatiliza- (NOCU) from a saturated calcareous soil tion from soil amended with rice husks (pH 8.25, 1.25% organic C, 23.7% and straw may be due to sorption of NH + 4 CaCO 3 , and CEC 19 meq/100 g soil) by organic matter. amended with gypsum, pyrite, rice straw, NH 3 volatilization loss from soils and rice husks. A forced draft chamber amended with NOCU was lower because technique was used to trap ammonia. a thin layer of neem oil around the prilled

urea acted as a physical barrier, reducing in saturated soil, as influenced by soil amendment, the rate of N release and thus the concen-

Application of soil amendments

Cumulative N loss (%) Soil

amendment N source Application method

Urea NCBU NOCU Surface Surface applied mixed

Gypsum 11 11 4 11 6 Pyrite 10 7 4 8 6 Rice straw 12 12 5 13 6 Rice husk 13 13 5 13 7 Control 32 34 10 32 18

LSD (0.05) Amendment x Source of N

2

Application method

3 . .

Soil pH on equilibration with amendments under saturated conditions.

IRRN 16:4 (August 1991) 17

tration of NH 4 + in the soil. NH 3 volatiliza- N was surface mixed rather than surface

tion from NCBU and with uncoated urea applied. This may be because more of the Fertilizer was the same. surface area of soil organic matter and

source, NH 3 volatilization was less when ions. inorganic sources management— Irrespective of soil amendment and N clay was available for sorption of NH 4 + -N

Fertilizer management—organic sources

Effect of gypsum-enriched biogas sludge and farmyard manure (FYM) on rice yield

G. Kuppuswamy, AR. Lakshmanan, and A. Jeyahal, DNES Research Project, Agronomy Department, Annamalai University, Annumalainagar 608002, Tamil Nadu, India

We evaluated the effect of biogas sludge and FYM on rice yields in two successive field trials, Jul-Oct 1989 and Nov-Feb 1990. Rice cultivars were IR20 and ADT37.

Soil of the experimental field the first season was clay loam with pH 7.4; EC 0.6 dS/m; 0.44% organic C; and available N, P 2 O 5 , K 2 O were 225, 14, 312 kg/ha, respectively. Soil of the experimental field the second season was clay loam with pH 7.2; EC 0.5 dS/m; 0.43% organic C; and 238, 23, 314 kg available N, P 2 O 5 , K 2 O/ha, respectively.

The biogas sludge contained 1.5% N, 0.82% P 2 O 5 , and 0.75% K 2 O. FYM

contained 0.85% N, 0.35% P 2 O 5 , 0.688 K 2 O, and 58% water in season 1, and 0.75% N, 0.61% P 2 O 5 , 0.63% K 2 O, and 57% water in season 2. In both seasons, N, P 2 O 5 , and K 2 O at 100, 50, and 50 kg/ ha were applied as urea, single super- phosphate, and muriate of potash. The experiments were laid out in a random- ized block design with three replications (see table for treatments).

Growth and yield attributes and grain and straw yields were favorably influ- enced by biogas sludge and FYM both seasons. Added gypsum acted as an absorbent, reducing the moisture content of biogas wet sludge and FYM by 30 and 10%, respectively.

enriched biogas sludge both seasons. The next best was enriched FYM. Enrichment of wet biogas sludge with gypsum increased yields 0.95 and 0.71 t/ha in the first and second seasons, respectively. Enriched FYM increased yields 0.67 and 0.56 t/ha.

Grain yields were highest with

Effect of gypsum-enriched biogas sludge and farmyard manure on rice yield.

Effect of irrigation and nitrogen on transplanted summer rice yield and water use efficiency

A. K. Choudhury, M. Saikia, and K. Dutta, Agronomy Department, Assam Agricultural University, Jorhat, Assam, India

We studied the effect of three irrigation schedules and four N levels on grain yield and water use efficiency of trans- planted summer rice (Apr-Jul) 1987-89.

The soil was acidic sandy loam (pH 5.4), low in total N (0.065%), medium in available P 2 O 5 (18 kg/ha; Bray and Kurtz No.1), and low in available K 2 O (86 kg/ ha; neutral ammonium acetate method). The rice variety used was IR50. Phos- phate and potash were applied at 20 kg each/ha. Average rainfall during the 3 yr was 688 mm.

The experiment was laid out in a randomized block design with three replications. Treatments are given in Table 1.

Irrigation schedule had no effect on grain yield. During the summer season, rainfall increased from the early vegeta-

Panicles/m 2 Filled grains/panicle Grain yield (t/ha) Straw yield (t/ha) Treatment

Season Season Season Season Season Season Season Season 1 2 1 2 1 2 1 2

Biogas wet sludge (10t/ha)

Biogas dried sludge (10 t/ha)

Biogas wet sludge ( 10 t/ha) enriched with 250 kg gypsum/ha

FYM (10 t/ha) FYM ( 10 t/ha)

enriched with 250 kg gypsum/ha

Gypsum (250 kg/ha) Control

LSD (0.05)

384

385

413

341 385

330 324

1

354 98

365 99

412 109

343 99 407 107

324 107 313 97

11 2

71 7.5 3.7 13.0 4.9

71 7.8 3.8 13.7 5.1

74 8.4 4.4 15.3 6.2

72 7.3 3.7 12.6 4.8 74 8.0 4.3 14.7 5.8

70 6.8 3.5 11.5 4.7 70 6.6 3.2 11.0 4.6

2 0.2 0.1 0.5 0.2

Table 1. Effect of irrigation schedule and N level on grain yield of summer rice in Assam, India.

Grain yield (t/ha)

1987 1988 1989 Pooled Treatment a

Irrigation Continuous sub-

mergence 7 cm water

1 DADPW 7 cm water

3 DADPW

N level (kg/ha) 0

40 80

120

LSD (0.05)

LSD (0.05)

2.2 1.4 2.7 2.1

2.0 1.6 2.7 2.1

2.1 1.6 2.8 2.2

ns 0.05 ns ns

2.0 1.7 2.2 1.9 2.2 1.4 2.7 2.1 2.0 1.5 3.0 2.2 2.2 1.5 3.1 2.3

ns ns 0.12 0.14

a DADPW = days after disappearance of ponded water.

18 IRRN 16:4 (August 1991)

tive stage to maturity. This means that grain yield for continuous shallow submergence can be achieved with 7-cm irrigation water applied 3 d after disap- pearance of ponded water, for a net savings of 24% of the water requirement (Table 2).

significantly affect yield, and 40 kg Nha appeared sufficient. The interaction of irrigation and N was not significant.

Applied N higher than 80 kg/ha did not

Table 2. Effect of irrigation schedule and N level on water requirement and water-use efficiency of summer rice in Assam, India.

Rainfall (mm) Water requirement (mm) Water-use efficiency (kg/ha/mm)

1987 1988 1989 1987 1988 1989 1987 1988 1989 Mean Treatment

Continuous sub- 504 1040 519 1304 1640 1149 1.71 0.83 2.30 1.61

7 cm water 504 1040 519 1204 1390 1009 1.66 1.14 2.71 1.84 mergence

1 DADPW 7 cm water 504 1040 519 924 1320 869 2.23 1.23 3.26 2.24

3 DADPW

Improving applied phosphorus utilization by rice in Madagascar

J. R. Hoopper and J. Rabelolala, Ma- dugascar-IRRI Rice Research Project and FOFIFA Madagascar

On the Fe-toxic, low-P soils of the Central Highlands of Madagascar, broadcast P fertilizers are fixed by the Fe and poorly utilized by the rice plant. Resource-poor farmers often cannot afford to apply the recommended 26 kg P/ha.

We compared applying 13 kg P/ha (1/2 the recommended rate) by broadcast and incorporation and by seedling root dipping, in a farmer’s field in Manjakan- driana (1,420 m) for 4 yr. Soil was 49% clay, 21% silt, 30% sand, pH 4.9, and had 3.31% organic C, CEC 10.2 meq, 5.3 ppm available P.

Effect of P rate and method of application on yield of Chianan 8, transplanted on an Fe-toxic soil, Sambaina, Manjakandriana, Madagascar.

Yield b (t/ha) Treatment a

1985/86 1986/87 1987/88 1988189 Mean

No fertilizer 2.5 d 0.8 c 0.9 c 1.1 d 1.4 NK only 3.7 c 0.8 c 1.1 c NK + 13 kg/ha B/I 3.9 bc

1.6 c 1.8 1.3 b 2.3 b 2.2 b 2.4

NK + 13 kg P/ha root dipping 4.2 ab 2.0 a 3.0 a 2.6 a 3.0 NK + 26 kg P/ha B/I 4.4 a 1.4 b 2.4 b 2.2 b 2.6

a B/I = broadcast and incorporated. N = 60 and K = 50 kg/ha. b In a column, means followed by a common letter are not significantly different at the 5% level by DMRT.

Triple superphosphate (TSP) was and incorporating TSP, and root dipping dissolved in water and soil was added with 13 kg P/ha was as effective as until a sticky paste was formed (approxi- broadcasting and incorporating mately 1:4:6 of TSP, water, and soil). 26 kg P/ha (see table). Leaf tissue Seedling roots were coated in the paste analysis showed higher P levels in plants and immediately transplanted. (The first fertilized by seedling root dipping. year, rice roots were dipped in a mixture Concentrating the P around the roots of water and TSP.) N and K were applied probably reduces the amount of P fixed at 60 and 50 kg/ha, respectively. by the soil and makes more P immedi-

Averaged over 4 yr, root dipping was ately available to the rice plant. 22% more effective than broadcasting

Integrated pest management—diseases

Association of Fusarium

seeds and subsequent Seeds treated with 0.1% mercuric infection in Pakistan chloride for 1 min and untreated seeds,

moniliforme Sheld. with rice i ncidence. samples from nine localities to assess its

400/sample, were studied. Twenty seeds M. I. Ahmed and T. Raza, Plant Pathol- per sterilized petri plate were plated on ogy Department, University of Agricul- three layers of moistened blotter paper ture, Faizalabad, Pakistan and kept at 25 °C in 12 h light, 12 h dark

for 7 d. These seeds were examined Rice bakanae disease caused by under a stereoscope; microscopic slides Fusarium moniliforme Sheld.—perfect also were studied for identification. stage Gibberella fujikuroi Sawada—is Other seeds from the same samples becoming a serious threat to rice produc- were grown separately in sterilized pots, tion in Pakistan. We collected rice seed and isolations from the vascular system

of the seedlings were made on Richard's agar medium at 27 °C. A third set of seeds was planted and typical bakanae disease symptoms on the mature plants meas- ured.

Seeds from all localities but D. G. Khan showed the presence of F. monili- forme. Maximum presence of fungus on seeds was 19.75%. Nearly 20% of the seeds treated with 0.1% mercuric chloride from Gujranwala showed presence of the fungus (see table).

When the seeds were not treated before plating, highest fungus infection was near 12% in those from Sialkot. In most cases, fungus intensity was higher

IRRN 16:4 (August 1991) 19

in treated seeds, showing that the fungus Rice seeds from different localities showing percent bakanae disease infection in Pakistan.

was internally borne, or at least present inside the seed coat.

Seedlings produced from the seed samples confirmed the presence of fungus in the vascular system. Bakanae symptoms appeared on plants grown to maturity.

Reisolation of the pathogen and back- inoculation to other rice plants confirmed its pathogenicity.

Locality

Amin Abad Daska G. G. Khan Gujranwala Hafiz Abad Kala Shah Kaku Narang Mandi Sheikhupura Sialkot

Seeds a showing F. moniliforme (%) Seedlings showing Bakanae disease F. moniliforme symptoms (%) in

Treated b Untreated in vascular system (%) plants grown from untreated seeds

9.5 6.2 10 6 6.0 1.5 6 7 0.0 0.0 0 0

19.8 9.5 17 8 11.0 7.2 12 7 12.2 5.5 10 9 8.8 1.8 9 11

11.5 7.2 13 11 12.2 11.8 10 9

Effect of grain discoloration in upland rice on some yield components

E. Zulkifli, J. Klap, and J. Castano, Sukurami Research Institute for Food Crops, SARIF, P.O. Box 34, Padang 25001, West Sumatra, Indonesia

The main causal agents of grain discol- oration (GD) in upland rice in West Sumatra are different species of fungi, with Helminthosporium oryzae being the most important. Symptoms vary from spots invisible to the naked eye to a completely rotten endosperm. In suscep- tible varieties, the disease can cause complete yield loss.

We collected 50 panicles of suscep- tible upland rice variety Tondano in the Sitiung area and separated them into five groups, with disease severities of 1, 10, 30, 60, and 100%. Seeds of each severity

a Mean of 4 counts. b With 0.1% mercuric chloride for 1 min.

group were planted in plastic trays (33 seeds/tray per replication) and grown in the greenhouse, to determine the effect of the disease on germination and plant height. Additional panicles of each severity group (3 panicles/replication) were used to study the effect of disease on grains/panicle. Weight of 100 grains was calculated for each severity group,

with three replications. The higher the disease severity, the

lower the germination and seedling height (see table). The disease reduced germination as much as 40% and reduced seedling height 3-20%. The higher the severity, the more the empty grains/ panicle, with parallel weight reduction.

Effect of rice grain discoloration on some yield components. a

~~ ~

Severity of grain Seedling Grains (no./panicle) Weight of Reduction discoloration Germination b height c 100 grains e in weight

(%) (%) (cm) Filled d % Empty % (g) (%10)

1 92 a 10.9 (91) a 140 a 94 9 b 6 3.09 a 10 81 a 10.6 (86) a 137 a 90 16 b 10 2.94 a 5 30 80 bc 10.2(79) a 135 a 91 14 b 9 2.95 a 4 60 73 c 9.7 (72) ab 101 b 74 35 a 26 2.56 b 17

100 52 d 8.7 (52) b 118 b 78 33 a 22 2.27 c 26

a In a column, means followed by the same letter are not statistically different at a probability level of 0.05. b Av from 3 replications,

panicles/replication. e Av from 3 replications, 100 seeds/replication. 33 seeds/replication. c Av from 3 replications. Values in parentheses are total number of seedlings. d Av from 3 replications, 3

Integrated pest management—insects

Duration of diapause in white 135-d variety, with IR64 (110 d) length- stem borer (SB) Scirpophaga ened the fallow period between dry and innotata wet season crops to 3 mo. That favored

the white SB, which can aestivate as S. Hendarsih, Sukamandi Research prepupae at the base of rice stubble. The Institute for Food Crops, Sukamandi; and outbreak destroyed l5,000 ha of rice in J. Soeyitno, Bogor Research Institute for the command area of the Jatiluhur Food Crops, Bogor, Indonesia Irrigation System (JIS) in Karawang,

The white SB replaced the yellow SB The JIS is divided into five regions of S. incertulas in many parts of the northern staggered water delivery. At Sukamandi, coast of West Java in the 1989-90 wet rice is transplanted ahead of that in season. Karawang. We collected aestivating

Replacement of improved Cisadane, a prepupae from Karawang (52 d after

Subang, and Indramayu districts.

harvest) and Sukamandi (96 d after harvest) and subjected them to artificial rainfall and to flooding, to simulate land preparation for rice.

Frequency and amount of rainfall was based on the previous year’s pattern. Water was poured onto prepupae in rice stubble placed in pots. Excised prepupae were placed individually in 12-cm-long, 0.5-cm-dim plastic drinking straws with cotton plugs in both ends. The straws were placed with the bottom cotton plug in contact with standing water, to simulate flooding.

Both watering methods terminated aestivation. The prepupae in the untreated

20 IRRN 16:4 (August 1991)

-

check remained in diapause. Aestivation ended sooner under artificial flooding than with artificial rainfall. Moths emerged 18-21 d after watering in the artificial flooding regime and 29-45 d after watering in the artificial rainfall regime (see table).

Morphometric measurements of green leafhopper (GLH) Nephotettix nigropictus (Stal) head and body during development

E. u. Haq and A. u. Mohsin, Entomol- ogical Research Laboratories, National Agricultural Research Centre, Isla- mabad; M. Ahmad and M. Rafiq Khan, Entomology Department, University of Agriculture, Faisalabad, Pakistan

We made morphometric measurements of the head and body of GLH during devel- opment of seven individuals. The results are in the table.

A new blister mite pest of rice in the Philippines

A. T. Barrion and J. A. Litsinger, Entomology Division, IRRI

Aceria saccharini (Acari: Eriophyidae), a blister mite pest of rice, has been reported on sugarcane in Indonesia; Australia; Taiwan, China; and India. It damages leaf sheaths and transmits streak virus disease. In 1988, it was reported to have transferred to rice in Sulawesi, Indonesia. Now it has been found in Central and Southern Luzon, Philippines.

Injury on rice is similar to that caused by thrips, and damage symptoms can be confused with tungro. Feeding produces white, chlorotic, shallow, gall-like pustules. Blisters vary in length (0.20-18 mm) and width (0.01-10 mm). The long proboscis of the mite probes vertically into the upper or lower epidermis of the leaf, lacerating tissues and rupturing both epidermal and parenchymous tissue cells.

Mites from different localities differ in color, from cream to pale yellow or

Effect of artificial watering on diapause of white stem borer larvae, Sukamandi, 1990.

Source of prepupa a

Simulated Observation source of water Karawang Sukamandi

Flooding

Rainfall

Prepupal duration 60 DAH 104 DAH Pupae transformed 5-8 DAW 4-8 DAW Moths emerged 18-21 DAW 18-21 DAW Prepupal duration 52 DAH 96 DAH Moths emerged 29-45 DAW 29-45 DAW

a DAH = days after harvest, DAW = days after watering.

Average length and width of the head and body of GLH at different stages.

Head Body

Length (mm) Width (mm) Length (mm) Width (mm)

1st nymphal instar 0.150

2d nymphal instar 0.215

3d nymphal instar 0.273

4th nymphal instar 0.457

5th nymphal instar 0.457

Adult male 0.342

Adult female 0.373

(0.131-0.171)

(0.184-0.236)

(0.236-0.302)

(0.421-0.473)

(0.315-0.368)

(0.342-0.394)

0.210

0.236 (0.210-0.263)

0.289

0.557

0.621 (0.578-0.657)

0.731 (0.684-0.815)

0.810

(0.263-0.3 15)

(0.526-0.605)

(0.763-0.842)

0.857 (0.802-0.921)

1.088 (1.026-1.131)

1.355 (1.289-1.394)

2.849 (2.710-3.078)

3.548 (3.342-3.684)

3.981 (3.736-4.210)

4.736 (4.473-4.868)

0.336

0.381

0.535 (0.486-0.578)

1.041 (1.026- 1.065)

1.157

1.390

1.661

(0.315-0.368)

(0.368-0.407)

(1.078-1.210)

(1.263-1.710)

(1.526-1.894)

orange pink. The orange pink form is more prevalent. The adult mite is microscopic in size (0.16 + 0.04 mm long, 0.05 ± 0.002 mm wide) (see figure). Mites moving on the leaf surface can be seen with the naked eye.

With magnification, the adults appear wormlike with a shield-shaped head. The body bears two pairs of slender legs anteriorly. All legs have claws, with 6-7 protruding feathered ray hairs each. The abdomen is annulated with 78-82 rings and three pairs of ventral setae. Eggs are spherical 0.05 mm in diameter, pale yellow turning to orange pink when about to hatch.

The pale yellow larva has a droplet- like shape with a large globular anterior, tapered posterior, and a pair of moder- ately long anterior legs. The protonymph, twice the size of larva, is whitish to light yellow with a thin layer of golden yellow hairs laterally. Both are orange pink when mature.

We monitored mite densities in 14 fields during the wet season. Three leaves each were sampled from the bottom,

A. saccharini adult (middle, 18×) transparent egg (right midlateral, 12×), and larva (bottom one-fifth, 18×).

middle, and top plant areas at seedling, maximum tillering, panicle initiation, and ripening stages. Ten samples per growth stage were bagged separately or placed in vials with 80% alcohol.

IRRN 16:4 (August 1991) 21

The mite population reached its peak (x = 2485 + 306/3 leaves) during the May-Jun premonsoon period and was lowest (x = 128 ± 42/3 leaves) during the late Nov-Dec postmonsoon period. A. saccharini preferred relatively young, greenish foliage, with this order of preference—maximum tillering > panicle initiation > seedling > ripening stage (see table). It was most abundant in the middle to apical one-third stratum of the dorsal leaf surface.

A quadrat insect sampler for direct seeded rice

J. P. Bandong and J. A. Litsinger, Entomology Division, IRRI

Direct seeding pregerminated rice is gaining popularity in many rice-growing areas. Entomologists need a sampling device equivalent to the rice hill used for sampling in transplanted rice cultures. In direct seeded rice, single plants are hard to distinguish and have few tillers.

In the Philippines, a rice hill normally occupies 400-500 cm 2 at 20- × 20- or 20- × 25-cm hill spacing. We developed a sampler based on crop area.

A simple quadrat, constructed from flat metal bars, is fastened to an anchor- ing bar with a wing nut screw (see figure). The anchoring bar allows the quadrat to be raised as the crop grows.

The quadrat is rectangular rather than square to allow plants to be more easily grasped by hand and facilitates counting tillers, leaves, and insect pests. The quadrat will cover 0.05-m2 sampling area, so that 20 samples equal 1 m2.

soil at randomly chosen points in the field. The quadrat is attached with its leading side open. Once the quadrat is firmly anchored, the notched front bar is fitted into place to enclose the sample plants.

We have used this approach to sample stem borer egg masses, dead- hearts and whiteheads, and leaves damaged by leaf feeders. Direct counts of less mobile insects can also be made.

The anchoring bar is jabbed into the

22 IRRN 16:4 (August 1991)

Effect of plant age on relative abundance and vertical distribution of A. saccharini on rice in the Philippines. IRRI, May-December 1990. a

Adults and immatures (no.) on leaf blade

Plant stage (age) b Dorsal surface Ventral surface

Apical third Mid-third Lower third Apical third Mid-third Lower third

Seedling ( 18 DT) Maximum tillering

(45 DT) Panicle initiation

(60 DT) Ripening (1 10 DT)

27 ± 1024 ±

456 ±

0

11 c 137 a

37 b

C

81 ± 52 c 1485 ± 186 a

812 ± 72 b

0 c

16 ± 8 c 434 ± 25 a

168 ± 30 b

0 c

42 ± 18 c 211 ± 22 a

85 ± 36 b

0 c

723 ± 68 a 15 ± 10 c

644 ± 96 b

8 5 c

6 ± 4 c 301 ± 48 b

594 ± 176 a

18 ± 6 c

a Av of 10 replications. In a column, values followed by the same letter are not significantly different at 5% level by LSD. b DT = days after transplanting.

The quadrat sampler.

Farming systems—deepwater rice Cropping patterns for deepwater rice environments

R. B. Thakur, Rajendra Agricultural Uni- versity, Pusa, Bihar 848125, India

In North Bihar, 60% of the rice area is classified as deep water, where crops are

never assured. Under such situations, farmers can grow only one rice crop, in the rainy season.

Farmers have adopted various cropping sequences to minimize risks. We evalu- ated the suitability and economics of some rice-based cropping patterns for the deep water ecosystem of North Bihar.

_

_

The multiple cropping experiment from 1985-86 to 1986-87 consisted of seven cropping patterns (see table). Two- year rotations were maintained so that a rice - sugarcane sequence could be completed for comparison. The experi- ment was laid out in a randomized block design with four replications.

Soil of the experimental area was silty-clay with pH 8.2, 0.6% organic C, and 272.0, 32.4, and 131.5 kg/ha avail- able N, P 2 O 5 , and K 2 O, respectively. Maximum water depth was 67 cm in 1985-86, 81 cm in 1986-87.

Varieties used were deepwater rice (DWR) variety Janki, sweet potato RS5 and Cross-4, jute JRC321, black gram T9, and green gram G65.

Depending upon the land situation, DWR may be sown from Feb to Jun. In all the intercropping sequences, the rice crop was sown in the last week of Feb and fertilized after harvest of the inter- crops with 20 kg N/ha applied as

topdressing. In rotational treatments, such as rice - sweet potato and rice - sugarcane - green gram, rice was sown in mid-Jun. Sweet potato and sugarcane were planted after the harvest of rice in Feb.

Among the crop sequences, rice - cross-4. statistically superior to rice - sweet potato cost:benefit ratio, rice - green gram was rice yield per year (see table). In terms of produced significantly more equivalent sesame and rice - sweet potato cross-4

Rice - sugarcane - green gram 2.2 33.5 - 0.5 3.3 Rice + black gram Rice + black gram 0.3 2.2 0.3 2.3 0.68

Production potential, production efficiency, cost: return ratio of cropping sequences in North Bihar, India.

Crop yield (t/ha)

Cropping sequence 1985-86 1986-87 Equivalent rice grain Cost:return

1985-86 1986-87 Main Subsequent Main Subsequent yield (t/ha ratio crop crop crop crop per yr)

Rice + sesame Rice + sesame 2.1 0.4 1.9 0.5 4.2 1.37 Rice - sweet Rice - sweet 1.9 15.2 1.9 14.3 3.7 0.54

Rice - sweet Rice - sweet 2.1 16.6 2.0 17.1 4.2 0.73

Rice + jute for Rice + jute for 1.8 0.6 1.9 0.5 3.0 0.49

potato potato

potato potato

fiber fiber

2.1 0.5 3.4 0.92

LSD (0.05) 0.3 0.18

Farming systems—irrigated rice were 120-60-30 kg NPK/ha for rice, 100-

Transplanted rice-based cropping sequences in an irrigation canal command Experimental soil was Vertisol with pH Rice - berseem gave the highest area of Rajasthan 7.6 and 0.61% organic C. Medium-duration production and benefit:cost ratio (see

60-30 for wheat, 60-30-0 for barley, 25- drinum, and chickpea Cicer arietinum to 30-0 for berseem, and 25-40-0 for follow rice in the dry season (DS) 1981-85. chickpea.

(130-135 d) Jaya rice variety was trans- table). Its net return ($1,812.5/ha) was A. Sharma and S. S. Tomar, Rajasthan planted the first week of Jul. DS crops were 42% higher than that of the dominant Agricultural University, Agricultural sown in Nov. Recommended fertilizer rates rice - wheat cropping sequence. Research Station, Borkhera, Kota 324001 (Rajasthan), India Grain yields and returns from rice-based cropping sequences in irrigation canal command area of

Rajasthan, Kota, India, 1981-85.

The canal command area of Rajasthan has assured irrigation. Rice is a major wet season (Jun-Oct) crop. We evaluated some rice-based cropping sequences

Mean grain yield (t/ha) Gross Net Benefit: Crop sequence

Wet season return return

Dry season ($ha) ($/ha) cost ratio

Rice - berseem 7.0 20 a + 0.4 2437.5 1812.5 2.90 Rice - chickpea 7.1 1.4 1762.5 1237.5 2.36

involving improved cultivars of wheat Rice - wheat 6.8 3.2 1837.5 1275.0 2.26

Triticum aestivum, barley Hordium Rice -barley 6.7 3.8 1725.0 1187.5 2.21

vulgare, berseem Trifolium alexan- a Berseem as green fodder.

Rice-based cropping Wet season rice followed by alternate dry wet season crop; sunflower cultivar systems for Andhra Pradesh season crops occupies most of the area Mordan, safflower Manjira, groundnut

under irrigation in AP. We evaluated ICGS-11, and maize EH4012 were the B. V. Kumar and K. A. Reddy, All India rice - sunflower, rice - safflower, dry season crops. Coordinated Agronomic Research rice - groundnut, and rice - maize Soil was sandy clay loam, pH 8.1 Project, Andhra Pradesh (AP) Agricul- cropping sequences in 1988-89 and 1989- (clay 20-27%, silt 8-l0%, sand 65-70%), tural University, Hyderabad 500020, AP, 90. Rice variety WGL22245 was trans- low to medium in available N (250-300 India planted at 20- × 10-cm spacing for the kg/ha), high in available P (30 kg/ha) and

IRRN 16:4 (August 1991) 23

-

Rice + black gram Rice + black gram 2.1 2.2 0.5 - - - -

available K (400 kg/ha). The experiment was laid out in a randomized block design with four replications.

Fertilizer was applied at 120-60-60 kg NPK/ha to rice and 20-50-0 to groundnut, 120-60-40 to maize, 40-30-40 to saf- flower, and 80-50-30 to sunflower.

Total grain yield was highest with rice - maize (see table). Rice - sunflower recorded the highest net income, but had the lowest benefit:cost ratio because total cost was high in proportion to net income. Benefit:cost ratio was highest in rice - maize.

Grain yield and income from rice-based cropping sequences in Hyderabad, India, 1988-90.

Year Cropping sequence

1988-89 Rice - sunflower Rice - safflower Rice - groundnut Rice - maize

1989-90 Rice - sunflower Rice - safflower Rice - groundnut Rice - maize

Grain yield (t/ha)

Crop 1 Crop 2

2.70 1.10 2.60 0.70 2.69 0.87 2.50 1.40

3.45 1.20 3.70 1.10 3.37 0.60 3.73 2.70

Total cost

($/ha)

381 270 298 215

442 353 370 250

Gross income ($/ha)

864 624 683 510

999 810 844 582

Net income ($/ha)

417 354 385 295

557 457 474 332

Benefit: cost ratio

2.33 2.31 2.29 2.37

2.25 2.29 2.28 2.32

ANNOUNCEMENT Tropical crops symposium postponed. It is now scheduled to take postponed one year place in September 1992.

For further information, contact The International Symposium on Tropi- Dr. N. K. Nayar, Department of Agricul- cal Crop Research and Biotechnology, tural Botany, College of Agriculture, scheduled for September 199 1 in Kerala Agricultural University, Trivan- Trivandrum, Kerala, India, has been drum 695522, India.