Exploiting Heterotic Groups of Cotton Gossypium hirsutum L by Utilizing Broad Based Populations for Both Hybrid and Varietal Development

Abstract

Cotton is one of the major crops where commercial exploitation of heterosis has newlineincreased in substantial production levels. The genetic basis of heterosis is given by the newlineformula HF1 = and#931;dy2 and this implies the role of enhancing the genetic diversity of newlineheterotic populations to improve the performance of hybrids. In this study, four parent newlinebased populations of opposite heterotic groups (Stay Green and High RGR) were newlineevaluated in segregating generations with respect to variability for combing ability and newlinesubjected to reciprocal selection for combining ability. The first component of the newlinedevelopmental phase was started by evaluating DC F2 populations for the ability to newlinecombine with reciprocal testers and based on their ability to combine with opposite newlinetesters ten elite combiners were selected from each group to initiate the culminating newlinephase of reciprocal selection for combining ability, where there is 10 x 10 set of crosses newlineinvolving DC F4 lines of opposite groups. A comparison of derived F1s at the newlinedevelopmental phase and at culminating phase was made to understand the extent of newlineimprovement of derived F1s in these groups of crosses. Parental diversity or newlinecomplementation is required even for the varietal development where, different newlineheterotic groups were explored to develop multiple parent-based lines to derive new newlinelines with improved per se performance. The improvement in hybrid performance was newlinebroadly compared with the potential of lines derived through multiple parent based newlinepopulations involving different heterotic groups. As a group, derived F1s of culminating newlinephase were more potential than derived F1s of the developmental phase. Some varietal newlinelines especially some compact lines were also among the group of most potential newlinegenotypes.