Formation of heterotic pools and understanding relationship between molecular divergence and heterosis in pearl millet [Pennisetum glaucum (L.) R. Br.]

The present investigation was made to generate information on the heterotic pools amongst pearl millet hybrid parents. A set of 17 representative parents was selected from a diverse set of 147 hybrid parents using SSR based genetic distance (GD) and clustering pattern; 136 hybrids were developed in diallel fashion and evaluated at two locations in India. Moderate positive significant correlation (r = 0.37, p<0.01) and (r = 0.33, p<0.01) was found between GD and mid-parent heterosis (MPH) and better-parent heterosis (BPH), respectively, for grain yield for all the hybrids. Higher correlation between genetically closer individuals was observed for grain yield heterosis when the parents of B- and R- crosses had lesser genetic distance (<0.68 GD) in comparison to those parental combinations having GD higher than 0.68, indicating that the GD based predictions for grain yield are better when the parents are genetically related than when they are genetically diverse. In this study, all the pearl millet hybrid parents seems to exist in two broad-based heterotic pools; one each represented by seed and restorer parents as B × R hybrids showed highest mean heterosis for grain yield than either of B × B or R × R crosses. Further, four heterotic pools have been identified in this diverse set of hybrid parents of pearl millet, two each for seed parents (HPB1 and HPB2) and for restorer parents (HPR3 and HPR4). Among these, HPB1 × HPR3 was identified having the highest heterotic level, and could be further used to develop higher yielding pearl millet hybrids.