1997 Volume 66 Issue 4 Pages 698-705
Heterosis, general (GCA) and specific combining ability (SCA), and their effects were studied for six major characters in a diallel mating system in early maturing sorghum by sowing in spring and summer. The GCA and SCA effects were highly significant for all traits studied. Some parents were identified having high positive GCA for grain yield, and low or negative GCA for culm length and days to heading which were considered as good combiners. High positive heterosis in grain yield was found for more than half of the hybrids studied. Several cross combinations had high grain yield heterosis, negative days to heading heterosis, low culm length heterosis and good performance. Genotype×seeding time interaction effect was significant for grain yield, culm length and days to heading. Genotype×planting density interaction effect was significant for grain yield in spring seeding but not in summer seeding. It is suggested that the selection of good genotypes adapted for summer sowing could be applied to either 10 or 20 cm planting densities but must be carried out in summer seeding. Some hybrids were proposed as promising cultivars if sorghum is grown after an early-season rice crop.