Heterosis and Combining Ability in Pearl Millet

Combining ability studies, using Method 2 and Model I (P's and F1’s) and Method 4, Model I (only F1’s), were carried out for grain yield and its components in a 10 × 10 diallel set excluding reciprocals in pearl-millet. The estimates of both the combining ability variances (σ2 gca and σ2 sca) were highly significant for all the six characters studied. Boh the methods gave similar estimates of general combining ability and specific combining ability effects. The magnitude of GCA: SCA ratio in the F1 and F2 generations was low in Method 2 and high in Method 4. High GCA: SCA ratio revealed preponderance of additive genetic variance for all the grain characters studied. Significant association between array means and general combining ability effects suggested that the former could be used effectively in the selection of good combiners. Inbreds H-19 and H-403 showed better combining ability for most of the six characters studied. H-80 was particularly good combiner for characters like earliness and ear diameter. The best crosses for grain yield were H-19 × H-403, H-19 × H-30, H-19 × H-126 and H-80 × H-224. Among these, the first two crosses involved good general combining parents. H-19 × H-403 also appeared to be a promising cross for characters like resistance to downy mildew, ear number, ear length, and earliness and thus, appeared to be the best among all. Its exploitation in varietal breeding programme, using bi-parental approach to accumulate more of additive genetic variance is, therefore, advocated.