Combining Ability for Biological Yield and Harvest Index in Sorghum

Six newly developed ms lines alongwith a standard ms line were crossed with five restorers. The resulting 35 crosses were evaluated for grain yield, dry fodder yield, biological yield and harvest index (HI) on plot basis. Heterosis over ms lines varied from 109 to 147% for yield characters and 9.2% for HI. Over restorers, heterosis was 84% for grain yield, 32% for biological yield, and 44% for HI. These characters were governed by both additive and nonadditive gene action but the proportion of additive genetic variance was higher for HI. Heritability was 32% for grain yield, 50% for fodder and biological yields, and 61% for HI. Estimates of σ²gca of new ms lines were higher than testers for grain yield and HI. New ms lines will, therefore, he more useful to exploit additive genetic variance for developing future hybrids. MS 340A and SPV 683 were good general combiners for grain and biological yields, while ms 340A, 450A and SPV 467 were good combiners for HI. Hybrids with high HI can be bred by using lines already improved for this trait.