Heterosis and Combining Ability for Grain Yield and its Components in Induced Sorghum Mutants

Heterosis, general combining ability (GCA) and specific combining ability (SCA), and their effects were studied for five major traits in a design II mating system in pure sorghum lines obtained by induced mutation. Significant genotype effect was detected for all traits. GCA effects were highly significant for all traits studied. Effects due to SCA were of less magnitude except on plant height. Some parents were identified having high GCA for grain yield and low or negative GCA for days to anthesis, which were considered as good combiners. The ratio of general combining ability to specific combining ability indicated that additive gene effect was the predominant type of gene action for most yield contributing traits. High positive heterosis for grain yield and its components, including days to anthesis and plant height, as found for more than half of the hybrids studied. Some pure lines evaluated may be used directly as male parents of hybrids and as breeding lines for incorporation into selection programs. The results demonstrate for this set of genotypes the considerable potential that exists for improving the yield performance of sorghum in Western Africa. Importance of genotype x environment interaction underlines the necessity of evaluating breeding materials under a broad range of dry land conditions. This research would assist decisions on parental selection for more extensive study of heterozygosity involving large numbers of genotypes.

Keywords
Combining ability, heterosis, hybrid breeding, Sorghum bicolor, West Africa