Evaluation of Early Generation Testing in Peanuts1

Abstract

Six lines representing three botanical varieties, and crosses made in diallel among the six lines were grown at two locations to determine the value of early generation testing in peanuts (Arachis hypogaea L.).Fruit length, percentage sound mature kernels, and percentage fancy size pods of the crosses bulked and measured in FII generation were correlated with similar measures in Fa generation. Fa generation cross means for yield were not correlated with F II cross means. Estimates of general combining ability were significant and of greater magnitude than specific combining ability estimates for both Fa and F II generations for all traits except yield.The average performance of a parental line in crosses in the Fa generation was correlated with its average performance in crosses in the FII generation for yield, fruit length, sound mature kernels, and fancy size pods.The highest yielding line from nine of the 15 crosses selected using a modified pedigree method equalled or exceeded the yield of the high parent for that cross. Yields of the highest yielding selections, however, were not correlated with the yield of either the Fa or FII generations of the crosses grown in bulk.Early generation testing in peanuts of crosses be-tween lines representing different botanical varieties appears to be a useful breeding procedure for traits such as fruit length, sound mature kernels, or fancy size pods but has limited value in selecting for yield.Evaluation of crosses in early generations of self-pollinated crops assumes that performance of such hybrid progenies reflects the true potential of the crosses in late generation. Identification of superior crosses in early generations results in more efficient breeding programs.

Inheritance of Late Leafspot Resistance and Agronomic Traits in Peanut1

“…Similar results were reported by Hamid et al (6) and Wynne (17). The GCA effects for agronomic traits ( p l a n t ) 10 pods) p l a n t ) seed) Parent y i e l d ( g / l e n g t h ( (8) and Anderson (2) also reported that GP-NC 343 was the best cultivar for incorporation of resistance to early and late leafspots into a single genotype.…”

“…Although selection of individual plants for disease resistance with these peanuts would not be effective in the F, generation of these breeding populations because of low heritability, selection was possible for highly heritable traits such as increased pod length and seed size. Wynne (17) found high correlations of early and advanced generation selection for pod length and seed size. In this study of these breeding populations, we observed a high correlation between pod length and seed size with disease resistance, i. e. , plants having longer fruit and larger seeds were more resistant to leafspot.…”

Effect of Selection for Emergence and Maturity on Yield of Ontario Peanuts

“…Parental family means, which are indicative of general combining ability effects, illustrate the GCA by trial interaction through changes in rank across trials (Table 3). Even though the parental families were selected and therefore were presumably more homogeneous than a random sample, these results suggest that there were still differences in breeding directed toward the highest performing bulks, but selection of superior cultivars from crosses with lower mean yield in early generations might also occur (12).…”

Estimates of Epistasis for Diverse Peanut Cultivars1,2

“…Hammons (1973) suggested that many characters in peanuts may be based on epistatic interactions. In an evaluation ofearly generation testing, Wynne (1976) found that the yields of the F 2' S from a six-parent diallel cross were ineffective in predicting the performance ofthe bulk F5 generations and selected F slines derived by a modified pedigree program from the~~'s. He suggested that epistatic genetic variance mignt be important for yield and that, if so, selection for yield would be best practiced in late generations to allow advantageous gene combinations to come together.…”

“…Hanson et al (1967) made estimates of additive x additive epistatic variance that comprised more than one-half the total genetic variance for yield among homozygous soybean lines. Wynne andcoworkers (1970, 1975) found significant estimates of specific combining ability (SeA) for a number ofcharacters in the F 1 and F 2 generations of a six-parent diallel cross ofdiverse peanut lines. This was attributed to either dominance or geometric gene action.…”