Estimation of genetic parameters and variance components in biparental progenies of lablab bean (Lablab purpureus L.)

The existing variation in the lablab bean is limited primarily owing to its self-pollination. Hence, bi-parental mating was attempted in the F3 generation of a cross between Arka Swagat × S.16. A study was conducted using 32 biparental progenies (BP₁), derived from a North Carolina Design II (NCD II) mating design to evaluate genetic variability, heritability and gene action for yield and related traits in lablab bean (Lablab purpureus L.) under a randomized block design with two replications. Analysis of variance revealed significant differences among sets for key traits, including number of flowers per inflorescence, pod width, number of pods per plant, shelling percentage and pod fresh weight, indicating substantial genetic variability. The genetic analysis indicated that pod yield per plant exhibited the highest estimates for genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability (broad-sense) and genetic advance as percent of mean (GAM). Similarly, high values for these parameters were observed for the number of pods per plant and the number of flowers per inflorescence. Shelling percentage and pod width exhibited moderate to high GCV, PCV, heritability and GAM, suggesting good scope forselection. Traits such as the number of inflorescences per plant and primary branches per plant showed moderate heritability but lower GAM, indicating a limited response to selection. In contrast, the number of seeds per pod, pod fresh weight and pod dry weight were characterized by low heritability and low GAM, reflecting a greater influence of non-additive gene effects and environmental factors. Narrow-sense heritability was highest for shelling percentage, pod yield per plant, number of flowers per inflorescence, pod width and number of pods per plant, whereas moderate narrow-sense heritability was recorded for the number of primary branches per plant, seeds per pod, pod fresh weight and pod dry weight. The average degree of dominance exceeded unity for all traits, indicating the presence of partial to overdominance gene action in the inheritance of the traits studied. Overall, pod yield per plant and its major contributing traits emerged as reliable selection criteria for genetic improvement in lablab bean.