Inheritance of seed protein and seed oil content in early maturing soybean

Abstract

The inheritance of seed protein, seed oil, and the sum of protein and oil was investigated in two early maturing soybean crosses, 'Maple Presto' × 'Sioux' and 'Maple Presto' × X446-2-1, in 2 years (1981 and 1982) at one location (Winnipeg). Analyses of variance of the parental performance over years indicated that the parents differed significantly for all three traits studied and that genotype by year interactions were effectively zero. Generation means analysis indicated that gene action for seed protein was primarily additive, with partial dominance for low protein. Seed oil was also conditioned primarily by additive gene action. Partial dominance was not consistently detected over years and therefore was of minor importance. Additive × additive epistatic effects for seed oil were also detected but were not consistent over years. The sum of seed protein and oil was conditioned solely by additive gene action. Variance analyses indicated a predominance of additive genetic variance for all three traits. Dominance variance was also detected for both seed protein and the sum of protein and oil. Broad sense heritability for the F2 generation ranged from 76 to 83% for seed protein and from 68 to 86% for the sum of protein and oil, while narrow sense heritability ranged from 34 to 72% for seed protein and from 39 to 65% for the sum of protein and oil. Narrow sense heritability values equalled broad sense values for seed oil and ranged from 58 to 68%. Heritability was also estimated from standard unit parent – progeny regression analyses and values for all three traits were found to approach the variance analyses estimated broad sense heritabilities. Comparisons with the results of late maturing soybean crosses are made and implications of the results obtained in this study on early maturing soybean breeding programs are discussed.Key words: Glycine max, heritability, 00 and 000 maturity groups, breeding strategies.