Effect of F2 Inter se Mating on Quantitative Traits Mean, Range, Variance and Heritability in Dolichos Bean (Lablab purpureus L. Sweet var. Lignosus)

Abstract

Background: Pedigree method of breeding in predominantly self-pollinated crop like dolichos bean enable exploiting only fixable genetic effects as a result of rapid increase in homozygosis. One or a few cycles of inter-mating in F2 generation help create populations with high frequency of desired recombinants which otherwise cannot be realized in later generations. The objective of the present investigation was to assess the impact of inter se mating in F2 population on nine quantitative traits’ (QTs) mean and variability parameters.Methods: Randomly selected 20 pairs of a single cross-derived F2 plants with flowering synchrony were inter se mated. Progenies derived from 20 paired crosses (designated as BIP F3 progenies) and those (F3) derived from their 40 F2 parents were evaluated for 9 QTs. Statistics such as mean, absolute range (AR) and standardized range (SR), variance (σ2), additive genetic variance (σ2A) and narrow-sense heritability (NS-h2) were estimated. BIP F3 progenies were compared with those of F3 progenies for QTs mean, AR/SR, σ2, σ2A and NS-h2. Significance of differences between BIP F3 progenies and F3 progenies for mean and σ2 were examined using two-sample t test and Levene’s tests, respectively. Result: The random mating in F2 population was effective in increasing the means, variances, σ2A and NS-h2 of racemes plant-1, fresh pods node-1, fresh pods plant-1 and fresh pod yield plant-1 in dolichos bean. Considering that random mating followed by selfing is a method of genetic improvement for future breeding rather than for immediate use, our results suggest long-term genetic gain and better prospects of deriving superior pure-lines with desired traits/combination of traits from inter-mated population in dolichos bean.