Predicting the Frequency of Transgressive RILs and Minimum Population Size Required to Recover Them in Dolichos Bean [Lablab purpureus (L.) Sweet]

Background: Allocation of resources only to a few promising segregating populations that are likely to result in high frequency of transgressive recombinant inbred lines (RILs) for use as pure-line cultivars would help enhance efficiency of breeding self-pollinated crops including dolichos bean. The use of an objective criterion to identify promising segregating populations is therefore assumes importance. The prediction of frequency of transgressive RILs that could be derived from advanced generations of segregating populations of crosses is one such criterion. Methods: We predicted the frequency of RILs that transgressed the better parent (HA 5) from two reciprocal crosses derived from two elite but genetically diverse parents (HA 4 and HA 5) for four quantitative traits based on estimates of mid parental value [m], additive genetic effects [a] and additive genetic variance [σ2A]. Result: The frequency of transgressive RILs predicted from H 5 × HA 4 was higher than those predicted from H 4 × HA 5 for primary branches plant-1, pods plant-1 and grain weight plant-1, while it was comparable between the crosses for pod weight plant-1. The required minimum population size was relatively smaller to recover the transgressive RILs from the cross which was predicted to result in higher frequency of RILs than that was predicted to result in lower frequency of RILs.
