Maize (Zea mays L.) is an important food crop in Ethiopia, but its productivity in farmers’ field through out the country is generally low due to limitation of high yielding improved maize hybrid varieties. Knowledge of combining ability and gene action is essential to identify good combiner inbred lines and high yielding potential hybrids to replace the local open-pollinated varieties. The objectives were to evaluate combining ability of the elite maize inbred lines with respect to yield and yield related traits and used t-test for significance level. Fourteen inbred lines were factorially mated as female (8 inbred lines) and as male parents (six inbred lines) to develop 48 single cross hybrids in the year 2013. The hybrids along with standard checks were evaluated at Bako National Maize Research Center during the year of 2014, 5 x 10 alpha lattice design with two replications. Data were recorded for grain yield and other related traits and subjected for analysis of variance using SAS soft ware. Line × tester analysis was used to estimate the general and specific combining ability effects for yield and yield related traits. Analysis of variance revealed significant variation at (p<0.05) for most of studied traits except number of ears per plant and number of kernels per row. Regarding Combining ability analysis, mean squares due to lines, testers and line x testers were significant for most of the traits. More over, variances due to GCA were higher in magnitude than SCA for the yield and yield related traits, indicating the importance of additive gene action in controlling the expression of traits. Among lines and testers L2, L4, L6, T2 and T3 showed good general GCA for most of the characters studied. Among the crosses L6 x T2 (13.2 t ha-1), L4 x T2 (12.5 tha-1) and L3 x T3 (10.9 t ha- 1) performed better for grain yield as compared to BH-546 (9.94 t ha-1 and BH-547 (10.4 t ha-1) for most traits studied. It can be concluded that the parental lines which manifested good general combining ability can be desirable parents for hybrids, since they may contribute favorable alleles in the synthesis of new varieties. Besides the hybrids that gave good yield can be potential varieties for commercial production. However, further evaluation of these breeding materials at more locations and year, is advisable to confirm the promising results observed in the present study.

Keywords: Combining Ability, Lines, Maize, Tester