GENETIC ANALYSIS FOR COMBINING ABILITY AND ESTIMATION OF SOME GENETIC PARAMETERS OF YIELD AND ITS COMPONENTS IN MAIZE USING HALF DIALLEL CROSS

Abstract

A field experiment was carried out at the field crops research station of the Agricultural Research Abu-Ghraib during the season of 2014, in order to study the general and specific combining abilities and gene action heritability. As well as, the average degree of dominance for yield and its components within the method of the half diallel cross using the fixed model, among six inbred lines of maize: (Sy-2, Zm-9, AM-65, ART-A2, ART-C19, and Sy-35) to produce 15 hybrids. Seeds of genotypes (6 inbred lines + 15 hybrids). The results of the genetic analysis showed that there were highly significant differences for mean squares of general and specific combining abilities for all studied traits and the ratio of the variance component of σ2gca to the σ2sca was less than one for all studied traits. The effects of GCA were positive and negative among parents for all studied traits, where the inbred line (Sy-2) was shown a significantly superior GCA effect for ear length, number of rows per ear, number of grains per row, and 250-grain weight. The effects of SCA were positive and negative among crosses for all studied traits. The hybrid (Sy-2×ART-2) gave the highest SCA effect for ear length, number of rows per ear, number of grains per row, and grain yield per plant, while the hybrid (AM-56×ART-2) gave the highest effect for 250-grain weight. The values of non-additive genetic variance (σ2D) were more than that of additive genetic variance (σ2A) for all studied traits. The values of the average degree of dominance (ā) were more than one for all studied traits, this indicated over-dominance control for these traits.