COMBINING ABILITY FOR GRAIN YIELD AND ITS CONTRIBUTING TRAITS OVER ENVIRONMENTS IN MAIZE (ZEA MAYS L.)

An investigation was carried out in maize to estimate General Combining ability (GCA), Specific Combining Ability (SCA) and their interaction with three environments. Nine maize inbred lines were crossed in all possible combinations including reciprocals in 9 x 9 diallel fashion. The resultant single cross hybrids along with parents were evaluated for their combining ability over environments. The combining ability analysis of diallel crosses across three environments showed high significance of GCA and SCA variances for all the traits viz., days to physiological maturity, plant height, cob length, cob girth, cob weight, 100 grain weight and grain yield per plant indicating the importance of both additive and non-additive gene action for the expression of these traits. The ratio of additive to non-additive variance was greater than one for all the traits except for cob length, cob girth, cob weight and grain yield across the environments, indicating the additive type of gene effects were more important in the expression days to physiological maturity, plant height and 100 grain weight and thus simple selection would confer rapid improvement of these characters. The hybrid combination UMI79 x UMI176 was the best for grain yield, cob weight, cob girth and early maturity. For reduced plant height UMI176 x UMI467 was the best across environments. The hybrid UMI176 x UMI13 was identified as the best for cob weight and cob girth. The crosses UMI79 x UMI57, UMI79 x UMI285 and UMI432 x UMI936(W) were the best for cob length.