Field Crops Research, 25 (1990) 247-252 247 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Morphological and physiological characters behind high-yielding ability of oats

( Avena sativa ), and their implications for breeding

Pirjo Peltonen-Sainio University of Helsinki, Department of Crop ttusbandry, Viikki, SF-O0710 Helsinki, Finland

(Accepted 15 February 1990)

ABSTRACT

Peltonen-Sainio, Pirjo, 1990. Morphological and physiological characters behind high-yielding ability of oats (Avena sativa), and their implications for breeding. Field Crops Res., 25: 247-252.

Correlations between yielding ability and morphological and physiological characters of Arena sa- tiva L. were studied on the basis of data obtained during field trials in 1986-87 at Hankkija Plant Breeding Institute and in 1988 at the University of Helsinki, Department of Crop Husbandry. Two- way analysis of variance and Duncan's multiple range test were used to study the amount of variation in the 17 characters observed. Linear regression analysis and stepwise regression analysis were used to define the main characters connected to high-yielding ability of oats.

Most of the variation in grain yield was caused by variation in weight per panicle, days to heading, plant height, and phytomass of oats. All these characters correlated positively with yielding ability. The usefulness of indirect selection methods in breeding for yield of oats is discussed.

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

The extent of the area in Europe where oats are cultivated has become smaller during recent decades, a phenomenon which has also taken place in Finland, albeit at a slower pace. The main reason for this reduction has been the intense mechanization of farms, followed by the decreased importance of workhorses; another important reason is the increased demand for barley for feeding and malting. However, oats have some agronomic and qualitative ad- vantages, particularly in northern growing conditions, where the oat is com- petitive because it thrives in a cool climate and in acidic soils (Coffman and Frey, 1961). Recently, many researchers have also drawn attention to the superior quality of oats and to the breeding of even higher-quality oat vari- eties (Saastamoinen, 1987; Kaplan, 1988, Souza and Sorrells, 1988). High

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248 P. PELTONEN-SAINIO

yielding ability, however, is always one of the main characters necessary when new varieties are adopted for cultivation.

A plant breeder wishing to breed high-yielding varieties can apply methods of direct or indirect selection. The problem is that direct selection always re- quires many years until the breeding progeny is large enough and the grain from replicated plots can be harvested and weighed. Indirect methods, how- ever, make it possible to select, from young generations, individuals that are likely to be high-yielding (Gallais, 1984). Thus, at an early stage, indirect selection enables the breeder to eliminate material that will probably give poor yields. Characters known to be associated with high-yielding ability must be observable easily and rapidly. It is also important that the genetic variation in such characters be sufficient. In this work attention was paid to the follow- ing issues: (a) the amount of variation in chosen morphological and physio- logical characters; (b) the relationship between these characters and yielding ability; and (c) the usefulness of characters associated with high grain yields in breeding programmes.

MATERIALS AND METHODS

Field experiments were carried out in 1986-87 at Anttila Experimental Farm of the Hankkija Plant Breeding Institute, and in 1988 at Viikki Experi- mental Farm of the University of Helsinki. Seven Finnish and foreign oat varieties and twelve breeding lines from Hankkija were sown in a randomized block design with nine replications. Plot size was 8 m 2 in 1986-87 and 10 m 2 in 1988. Standard fertilizer treatments were applied.

Plot-based observations were made for 17 characters: grain yield (g m-2), transformed to a moisture content of 15%; days to heading, from sowing to when 50% of the panicles emerged; days to yellow ripeness, from sowing to when 50% of the plants had turned yellow; grain-filling period, from heading to yellow ripeness; plant height (cm) to the panicle tips when all lines were yellow-ripened; lodging (%), the percentage of each plot area at the end of the growing-season; phytomass (g), measured on 40 plants per plot as the weight of an individual oat plant cut from the soil surface when full-ripened and then air-dried; panicles per m2; weight per panicle (g), the weight of the grains of the panicle, performed on 40 plants per plot; mean panicle filling rate (mg day- 1 ), calculated by dividing the panicle weight by the length of the grain-filling period; number of grains per panicle, measured from 40 pan- icles per plot, filled grains only; single grain size (mg), calculated from 40 panicles per plot; harvest index (%), calculated by dividing the panicle weight by phytomass; size offlag leaf (cm2), from 20 leaves per plot, using a plani- meter; dry-weight oftheflag leaf (mg) from 20 leaves after drying at 100 °C for 24 h; days to flag-leaf emergence, when 50% of the flag leaves had emerged

CHARACTERS OF HIGH-YIELDING A VENA: IMPLICATIONS FOR BREEDING 249

(only in 1987-88);flag-leaf area duration (Ad; days) from flag-leaf emerg- ence to yellow-ripeness (only in 1987-88).

R E S U LTS

The distribution of variation in the observed morphological characters of oat lines was tested with two-way analysis of variance. The differences be-

TABLE I

Total variation between grain-yield and morphological and physiological characters o f different oat breeding lines

Character Range ( m i n - m a x ) Mean cv % Probability ~ LSD0.05 for F

Grain-yield 169 -621 380 34 ** 45 ( g m -2 )

Heading 49 -67 56 10 *** 1 ( days )

Yellow ripeness 65 - 116 88 18 *** 2 ( days )

Grain-filling 16 -50 32 33 *** 1 period (days)

Plant height 51 -129 79 23 *** 5 (cm)

Lodging 0 -43 15 104 *** 4 (%)

Phytomass 1.14-3.31 2.01 29 *** 0.28 (g)

Harvest index 39 -58 51 7 *** 3 (%)

Panicles 306 -815 536 17 * 75 (no. m -2)

Panicle weight 0.56-1.69 1.01 27 ** 0.15 (g)

Panicle-filling 12.4 -60.3 33.3 22 *** 4.9 rate ( mg d a y - t )

Grain number 18-54 34 23 *** 5 per panicle

Single grain 23.1 -35.8 29.1 10 *** 1.4 size (mg)

Flag leaf Area (cm 2) 4.6 -22.9 11.9 34 *** 1.8 Dry-weight (mg) 34-110 60 27 *** 7 Emergence (days) 40 -52 45 9 *** 0.8 Duration (days) 25 -64 43 32 *** 2

~***P< 0.001, **P< 0.01, * P < 0.05; n.s., non-significant.

2 5 0 P. PELTONEN-SAINIO

TABLE 2

Phenotypic correlations between grain yield and morphophysiological characters ( 171 observations )

m • .

° I o l i o o c~ o o o o o o o o o o o

° I ° I i o o o o o o c) o o o o o o

, ** ** , , : , : : , , ,, : : :

ol ° ~ I o o o o o o o o o o o o

• * * * * * * * * * • * * * * * * * * * * * * *

ol ° I i o o o o o o o o o o o

o~ ° I I o o o o o o o o o o

o o o o o o o o o o o

~ ~ o ~ o ~ ~

o I o I o ' o I o ~ o I I o I o o o

b ~ & L ~ o k ~ L b

b ~ k b L & L b ~ b

o o o o o o o o '

~ ~ o

o l o l * i i i

o o o o o c~ ,

: : : : : :

o o o o c~ •

o o o o -~

o o o - '

? ? •

N ~ ° o ° :

o ,

~ o o ~

Days t o head ing

Days t o ye l l ow r i peness

G r a i n - f i l l i n g p e r i o d

P l a n t he igh t

L o d g i n g

P h y t o m a s s

Harvest index

Panicle density

Panicle weight

Panicle filling efficiency

Humber of grains per panicle

I ODD grain weight

Size of flag leaf

Dry weight of the flag leaf

Days t o f l a g l e a f e m e r g e n c e

L e a f a r e a d u r a t i o n

G r a i n y i e l d

CHARACTERS OF HIGH-YIELDING A VENA: IMPLICATIONS FOR BREEDING 2 51

tween lines were significant for all characters, and thus there was sufficient variation (Table 1 ). The differences were very significant (P< 0.01 ) for yield and panicle weight, and significant (P_< 0.05 ) for panicle density. All the other characters varied highly significantly (P< 0.001 ). Both genotype line and en- vironment caused much variation.

The following characters were strongly (r> 0.80) correlated with yielding ability: days to heading; days to yellow ripeness; lodging; biomass; panicle weight; Ao; and days to emergence of the flag leaf (Table 2 ). Stepwise regres- sion analysis (backward elimination) revealed that days to heading, biomass, weight per panicle, and plant height explained 81% of the variation among lines in grain-yield. Neither Ad nor days to flag-leaf emergence were used in this analysis, because observations had been made only in 1987-88.

D I S C U S S I O N

Days to heading, weight per panicle, plant height, and biomass accounted together for 81% of the total variation in grain yield.

Days to yellow ripeness, the length of the grain-filling period, days to flag- leaf emergence, and, as well as days to heading, correlated positively and strongly with yielding ability (r ranging from 0.77 to 0.90). The mean pani- cle-filling rate was not, however, associated with grain-yield, a finding which means that low yield was not a consequence of poor grain-filling rate, but that the yield was more abundant when there was more time for the grains to fill.

Of the yield components, weight per panicle best accounted for the varia- tion in yield. Grain number per panicle was not a good indicator of high- yielding ability, a finding which is contradictory to the results ofApel ( 1984 ). Number of panicles per m 2 did not strongly affect yield.

Plant height and phytomass, which characterize the properties of the oat stand, were strongly positively correlated with yielding ability. However, har- vest index did not correlate with yield, contrary to Johnson et al. (1983). Rosielle and Frey (1975) and Wych and Stuthman (1983) proposed that oats with a high harvest index had superior yielding ability.

Both flag-leaf area and flag-leaf dry weight correlated positively, but only moderately, with grain-yield. According to Tanner et al. ( 1966 ), varieties with smaller flag leaves are better yielders, and according to Ledent (1977), the area of the lower leaves of wheat correlates better with yield than area of flag leaf. The correlation between size and dry-weight of flag leaf was very strong ( r= 0.92 ) in oats. More research work is needed to better define the associa- tion between leaf characters and yielding ability.

In any consideration of the usefulness of indirect selection methods in yield breeding of oats, it is obvious that the characters used as indicators of high grain-yield must vary enough for selection to be possible. The characters must have a high heritability, and the plant breeder's observation work should be

2 5 2 P. PELTONEN-SAINIO

easy and rapid. Saad E1 Din ( 1979 ) claimed that indirect selection methods are more efficient in yield breeding than direct methods, whereas Johnson et al. (1983) and Rasmusson (1987) thought that ideotype breeding cannot substitute for traditional yield breeding.

According to the present work, done in dense plots, the characters with the best indicative value, on the basis of their significant correlation with yielding ability, were weight per panicle (r=0.81), plant height (r=0.78), days to heading (r = 0.84), and phytomass (r = 0.81 ). The heritability of these char- acters is known to be relatively high in cereals (see, e.g., Hsu and Walton, 1970; Rosielle and Frey, 1975; Mahon, 1983, Gallais, 1984; Rekunen, 1988). In the northern conditions for cultivation, it is important to select early-ma- turing individuals with heavy panicles and vigorous growth habit, and to avoid lines with too high straw content.

REFERENCES

Apel, P., 1984. Photosynthesis and assimilate partitioning in relation to plant breeding. In: P. Vose and S.G. Blixt (Editors), Crop Breeding. A Contemporary Basis. Pergamon, Ox- ford, pp. 163-184.

Coffman, F.A. and Frey, K.J., 1961. Influence of climate and physiologic factors on growth in oats. In: F.A. Coffman (Editor), Oats and Oat Improvement, pp. 420-456.

Gallais, A., 1984. Use of indirect selection in plant breeding. In: W. Lange, A.C. Zeven and N.G. Hogenboom (Editors), Efficiency in Plant Breeding. Pudoc, Wageningen, pp. 45-60.

Hsu, P. and Walton, P.D., 1970. The inheritance of morphological and agronomic characters in spring wheat. Euphytica, 19: 54-60.

Johnson, S.K., Helsel, D.B. and Frey, K.J., 1983. Direct and indirect selection for grain yield in oats (Arena sativa L. ). Euphytica, 32:407-413.

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