COMBINING ABILITY AND SUPERIORITY FOR YIELD AND SOME RELATED TRAITS IN HALF-DIALLEL CROSSES OF NINE NEW YELLOW MAIZE INBRED LINES UNDER TWO LOCATIONS

A half diallel cross among nine new yellow maize inbred lines, i.e. Gm. 500, Gm. 505, Gm. 507, Gm. 508, Gm. 509, Gm. 515, Gm. 518, Gm. 520 and Gm. 522 was made in 2014 summer season. Parental inbred lines and their F₁ crosses along with two yellow commercial check hybrids, SC162 and SC168 were evaluated in randomized complete block design with four replications at two locations (Gemmeiza and Sids) in 2015 summer season to study the combining ability in order to identify the most superior parental inbred lines that produce superior hybrids and develop high yielding new yellow single crosses. Results indicated that mean squares among crosses exhibited highly significant for all studied traits at both locations and their combined. Mean squares due to general combining ability (GCA) and specific combining ability (SCA) were significant or highly significant for all studied traits at both locations and their combined, except GCA for ear height at Gemmaiza and SCA for plant height and ear height at Sids. The ratio of GCA/SCA was more than unity for all studied traits at both locations and their combined, except plant height and ear height at Gemmaiza, days to 50% silking at Sids and plant height at the combined data. These results indicating that the additive genetic effects were more important and played the major role in the inheritance of these studied traits. Based on combinedP₁ (Gm.500) and P₅ (Gm.509) could be considered as the best combiners for earliness, as well as P₂ (Gm.505), P₄ (Gm.508), P₇ (Gm.518) and P₈ (Gm.520) for increasing grain yield. At combined four crosses (P₁ × P₇, P₂ × P₃, P₂ × P₄ and P₇ × P₈) exhibited desirable (s^{^}_ij) towards earliness, and seven crosses (P₁ × P₃, P₁ × P₇, P₂ × P₅, P₂ × P₆, P₃ × P₆, P₄ × P₈ and P₇ × P₈) exhibited desirable (s^{^}_ij) towards high grain yield. Two new crosses No. 34 (Gm. 518 × Gm. 520 and 25 (Gm. 508 × Gm. 520) were the best combinations, where they recorded the highest percentages of superiority in grain yield over both commercial hybrids SC 162 and SC 168.