ESTIMATION OF STATISTICAL GENETIC . PARAMETERS AND COMBINING ABILITY IN MAIZE CROSSES UNDER DIFFERENT ENVIRONMENTS

Abstract

This investigation aimed to study the effect of heterosis, combining ability estimates and correlations among yield and its attributes under six different environments in maize. Eight inbred lines and their 28 F 1 's produced using diallcl fushion were evaluated for twelve characters, viz. , tasseling and silking dates, plant and -ear heights, number of leaves/plant, stem dian1eter, ear length, ear circumference, number of rows/ear, number of kernels/row, I 00-kernel weight, grain yield/plant in 1995 season. The results showed that environments, crosses and crosses by environments mean squares were significant for all traits under study. Percentage of heterotic effect of the F 1 hybrids relative to grand mean and check variety ranged from -48.81 to 38.18% and from -58.85 to 11.08%, respectively for grain yield/plant. Ten and one hybrids significantly exceeded the grand mean and check variety respectively. The hybrid (P5 x P7) had the highest heterosis values of 38.18 and 11.08% over grand mean and check variety, respectively. Both additive and non-additive genetic effects were involved in the inheritance of most traits, with difference of their relative importance in the expression of each trait. High GCA/SCA ratios which exceeded the unity were obtained for most characters in combined data. Significant mean squares obtained for interactions of both GCA and SCA with environments for all traits with exception of (SCA x Env.) for ear circumference, indicated the