1Department of Plant Breeding and Genetics, Indira Gandhi Krishi Vishwa Vidyalaya, Raipur, M.P.
Genetics of harvest index and its components was studied following line × tester approach. Thirty cross combinations (3 × 10) along with parental strains were studied for 16 characters. Analysis of variance indicated the existence of significant variation among F1 and parents for all 16 characters. Combining ability analysis showed both additive and nonadditive types of gene action playing significant role in controlling the expression of all characters under study. The exception was economical yield for which only nonadditive gene action was found to be significant. The comparative roles were worked out on the basis of their expected mean squares. For days to flowering, plant height, second leaf length, number of ear bearing tillers/plant, grain length and width, additive type of gene action was important, whereas for the remaining characters, viz. harvest index, economical yield, and biological yield, nonadditive type of gene action seems to be playing significant role. For economic yield, PI. 16 and cross B2 among tails and IR54and IR 36 among semidwarfs were good general combiners. The crosses exhibiting higher sca effect for economic yield were IR 36 × Safri 17 and IR 54 × Pragati.
Gene action, combining ability, additive and nonadditive variance
