In Ethiopia, there are several maize production constraints, among which shortage of improved varieties is the
major one. The objective of this study was to observe the mean performance of crosses and estimate combining
abilities for grain yield and other agronomic traits in thirty six maize inbred lines using Line x Tester mating design.
Seventy-two lines x test crosses (L1xT1, L1xT2, L2xT1, L2xT2… L36xT1 and L36xT2) and three standard checks
were evaluated for 11 traits in alpha lattice design at Melkassa, Ethiopia. Analyses of variances showed significant
mean squares due to crosses for all traits. Among the crosses, L34xT2, L36xT2, L30xT1, L19xT1 and L33xT2
crosses were the top five highest grain yield mean performance. While L35xT1, L23xT1, L13xT1, L24xT2 and L15xT1
crosses were lowest mean grain yield performance. GCA Mean squares were significant, but SCA mean squares
were non-significant for all traits. The ratio of GCA/SCA mean square was high which exhibited the preponderance
of additive gene effects in the inheritance of all traits. Furthermore, the GCA sum of square component was greater
than the SCA sum of square for all traits, supported that variation among crosses was mainly due to additive rather
than non-additive gene effect. Inbred lines L15, L25, L27, L33, L34 and L35 were the best general combiners for
grain yield, and hence were promising parents for hybrids as well as for inclusion in breeding programmes for yield
improvements. Inbred lines L2, L3, L4, L6, L10, L27, L30, L31 and L32 had negative and significant GCA effects for
the days to anthesis, indicating that the lines had gene combinations that can enhance early maturity.