Components of Variation, Combining Ability and Heterosis Studies for Yield and its Related Traits in Maize (Zea mays L.)

Components of variation and combining ability for yield and its related traits were studied in maize in a 9 x 9 half diallel set with two commercial hybrids viz., AH 421 and KH 2001 as checks. The ratio of H₂/4H₁, indicated asymmetrical distribution of dominance and recessive genes among the parents for all the traits. High heritability was observed for ear height and plant height, whereas it was medium for yield/plot and days to 50 per cent silking. Dominance component (H₁,) was observed to be significant for all the traits thereby indicating the predominance of dominance effects. The K_D/K_R ratio was greater than unity for all the traits except days to 75 per cent maturity thereby indicating the preponderance of dominant genes. Both the general and specific combining ability effects were significant for all the traits. Preponderance of additive gene effects was important in the expression of all the traits studied. Parents P₁, P₄, P₅ and P₉ were good general combiners for yield per plot and related traits and can be used as the potential parents for improving/developing heterotic pool/population. Hybrids P₁ x P₇, P₇ x P₉, P₁ x P₈, P₄ x P₈ and P₆ x P₇ need further extensive testing for their suitability and sustainable high yields.