Combining Ability, Gene Action and Heterosis in Some Inbred Lines of Maize at Two Sowing Dates Using Factorial Mating Design

Combining ability, gene action and heterosis was studied for no. of days to 50% tasseling, no. of days to 50% silking, flag leaf area, plant height, no. of rows/ear, no. of grains/row, 300-grain weight and grain yield/plant in a Factorial Mating in Randomized Completely Randomized Design conducted separately in spring and autumn sowing dates, 2013 through hybridization between three parents of maize as female named [K-122 (1), Dkc (6418) (2), Dh(13×14) (3) and four parents as male named [HA-cross (4), Tietar (5) and Hvp-9433 (6) and H-1040 (7)]. The comparison of values revealed that the variability among hybrids was more than that among parents and the grand mean of all characters at autumn sowing date is better than the spring sowing date. Parents 1, 2, 3, 5 and 7 were the best general combiner for most characters at both sowing dates. The results of SCA effects revealed that the hybrids [3×7], [2×6] and [1×6] had a best specific combiner in desirable direction for most characters at both sowing dates. The values of dominance genetic variance were greater than additive genetic variance for all studied characters at both sowing dates, which depicts the importance of dominant gene effect for controlling these characters. Average degree of dominance, was greater than unity for all of the characters at both sowing dates. These results indicated that these characters were affected by over-dominance effects of some genes controlling the characters under study which is reflected in the low narrowsense heritability. The high heterosis were exhibited by the following hybrid combinations [1×6, 2×6, 3×4, 3×5 and 3×7] for most studied characters at both sowing dates might be utilized for developing high yielding hybrid varieties.