COMBINING ABILITY AND HETEROSIS FOR GRAIN YIELD AND YIELD RELATED TRAITS OF MAIZE (Zea mays L.) INBREED LINES AT HARAMAYA, EASTERN ETHIOPIA

Information on combining ability and heterosis of maize (Zea mays L.) inbred lines is essential to maximize their use for variety development. This study was conducted to estimate general and specific combining ability effects of maize inbred lines and estimate the amount of standard heterosis of the hybrids for yield and yield-related traits. Eight maize inbred lines were mated through a half diallel mating design (Griffing’s Method IV, Model I). The resulting twenty-eight F1 hybrids along with two standard checks were evaluated using Alpha-Lattice Design with three replications during 2018 main cropping season at Haramaya University Research Site (Raare). Analysis of variance indicated that significant mean square due to genotype for all trait studied, that revealed the existence of genetic variability. Among the cross L3×L6 (11.19 ton ha-1), L3×L8 (9.99 ton ha-1), L2×L5 (9.33 ton ha-1), and L6×L8 (9.31 ton ha-1) showed higher yield, which could be utilized for future evaluation in maize breeding activity. The highest standard heterosis for grain yield was retained from the crosses L3×L6 (20.58%), L3×L8 (7.65%), over BHQPY 545 and L3×L6 (49.20%), L3×L8 (33.20%), over MH138, indicating these hybrids superior for commercial cultivation. Genetic analysis of variance due to mean squares for general combining ability (GCA) and specific combining ability (SCA) effects were significant for almost all traits studied that indicate the importance of both additive and non-additive gene action. The ratio of GCA:SCA were more than unity in most of the traits implying the predominance of additive gene action in controlling the inheritance of the traits. Parental line L3 and L8 had significant and positive gca effects for grain yield, which indicate that these parents can be used for developing open-pollinated varieties, while L3×L6, L3×L8, L2×L5, and L6× L8 were good specific combiners for grain yield. From this study four potential hybrids were identified over the best standard checks (BHQPY545), as a result these high yielding hybrids can be promoted for direct use or further improvement after confirming the result across locations and years.