COMBINING ABILITY AND STANDARD HETEROSIS OF YIELD AND YIELD RELATED TRAITS OF HIGHLAND MAIZE (Zea mays L.) INBRED LINES

Abstract

Combining ability of inbred lines is important information in maize hybrid breeding programs to incorporate genotypes from various germplasm sources. Genetic progress and variety development depends on germplasm quality and breeding methods. This study was conducted with germplasm developed using double haploid technology (DH) lines. Sixty-six F1 crosses resulted from diallel crosses of 12 maize inbred lines with four standard checks Argane (AMH800), Kolba (AMH853), JIbat (AMH851) and Wenchi (AMH850) were evaluated to estimate general combining ability (GCA) and specific combining ability (SCA) for yield and yield related traits using alpha-lattice design with three replications during the 2017 cropping season at Ambo, Holeta and Kulumsa. Analysis of variance showed that mean squares due to entries were significant for most of the traits studied, such as grain yield, thousand kennels weight, days to silking, ear per plant, plant height, ear height, husk cover, ear rot, ear aspect, plant aspect, kernel rows per row, ear length and ear diameter that indicate existence of variability among the materials evaluated. Genotypes x environment showed highly significant difference at (P<0.01) for most traits but significant (P<0.05) for grain yield. Mean squares due to crosses were significant (p<0.05) at two location (Holeta and Kulumsa). GCA and SCA mean squares revealed significant (p<0.05) differences for grain yield and most yield related traits in all location and across location. . Both additive and non - additive genetic effects were significant for grain yield. Mean squares due to environment were significant (P<0.05) for some traits. Inbred lines P2, P9 and P12 were good general combiners as these lines showed significant and positive GCA effects for grain yield. Among the crosses, L1xL11, L2 x L12, L4xL9 and L5xL9 manifested positive and significant SCA effects for grain yield, indicating high yielding potential of the cross combinations across location. For pooled analysis across location genotypes attained lowest standard heterosis over the hybrid check Kolba (AMH853) so that selection of high specific combining ability crosses was unacceptable for variety development. In general, this study identified inbred lines and hybrid combinations that had desirable expression of important traits but all the newly developed crosses were low yielder than Kolba (AMH853) and which will be useful for the development of high yielding varieties as possible option.