Genetic Variability, Combining Ability, Gene Action and Superiority for New White Maize Inbred Lines (Zea mays L.)

A half diallel (9 x 9) analysis using nine new white maize inbred lines derived from different sources were evaluated to estimate genetic variability, combining ability, gene action and superiority% of the F₁,s over commercial check hybrids. All possible combinations were done among these lines at Sids Agricultural Research Station in season 2019 to obtain 36 crosses. These crosses along with two commercial hybrids; (SC. 10 and SC. 2031) were evaluated in field trails at three locations; (Sids, Sakha and Nubaria Agricultural Research Stations) using RCBD with three replications in the growing season 2020. Results showed significant differences among the three locations for all the studied traits, indicating that the locations differed in the environmental conditions. The GCA and SCA variances were significant or highly significant for most of the studied traits, indicating that the importance of additive as well as non-additive types of gene effects in the inheritance of these traits. The inbred line-Sd-14 was the best general combiner for earliness, shorter plant and lower ear placement. While the inbred lines Sk-9 and Sk-12 were the best general combiners for longer ear length and high grain yield. Thirteen crosses among all had positive and significant SCA effects for grain yield ard fed^-1 toward high yielding, indicating that these crosses combinations could effectively be exploited in hybrid breeding programs in the National Maize Research Programs. Positive and significant correlation between grain yield ard fed^-1 with plant height, ear height, late wilt resistant% and ear length, indicating that the indirect selection for linked traits with yield would be useful and effective for improving grain yield. The cross Sd-1 x Sd-42 showed the best superiority % of yield by value (7.91%) compared to the best check hybrid SC-2031 along with other six single crosses that were significantly positive in compared to the best check hybrid in the yield. The results revealed that the majority of the gene action controlling the grain yield trait is the additive gene, and therefore direct selection is considered useful and would be effective in improve such trait in this study. While, the majority of the gene action controlling days to 50% silking trait is non-additive gene action, and therefore the cross-breeding programs are effective and beneficial in turn of improving such traits in maize crop.