GENETIC VARIABILITY ANALYSIS FOR QUANTITATIVE TRAITS IN SOYBEAN (Glycine max (L.) Merrill)

Abstract

An investigation was undertaken to assess the extent of genetic variability, heritability, and
genetic advance for ten quantitative traits in twenty-three soybean (Glycine max (L.) Merrill)
genotypes evaluated in a Randomized Block Design (RBD) with three replications. Analysis of
variance revealed highly significant differences among genotypes for all the traits studied (p <
0.01), indicating the presence of substantial genetic variability in the experimental material. The
genotypic coefficient of variation (GCV) ranged from 7.64% (days to maturity) to 114.42% (seed
yield per plant), while the phenotypic coefficient of variation (PCV) ranged from 9.66% to
115.24% for the same traits. Phenotypic coefficient of variation was higher than the genotypic
coefficient of variation for all traits, though the difference was narrow for most characters,
suggesting relatively low environmental influence on trait expression. Broad-sense heritability
was high (>60%) for all ten traits, ranging from 62.52% (days to maturity) to 99.42% (number
of pods per plant). High heritability coupled with high genetic advance as percent of mean
(ranging up to 234.02% for seed yield per plant) was recorded for number of pods per plant, seed
yield per plant, biological yield per plant, and harvest index, indicating that these traits are
governed predominantly by additive gene action and would respond favourably to direct
phenotypic selection. Days to maturity recorded the lowest estimates of GCV (7.64%), PCV
(9.66%), and genetic advance as percent of mean (12.44%), indicating that this trait is less
amenable to improvement through simple selection. These findings suggest that emphasis on
pods per plant, seed yield per plant, biological yield, and harvest index would be rewarding in
soybean improvement programmes aimed at enhancing seed yield.