Knowledge of combining ability and heterotic relation of exotic inbred lines with the
locally available ones would be helpful for efficient breeding program. The objectives of the current study were to estimate: (i) combining ability effects between Ethiopian and
CIMMYT (International Centre for Maize and Wheat Improvement) maize inbred lines
and (ii) possible heterotic relationships between the two sources of inbred lines. Forty-two crosses were produced using North Carolina Design II mating scheme by crossing six Ethiopian with seven CIMMYT inbred lines. Combined analyses over three locations
showed significant differences among the hybrids for all the studied traits. Both general
(GCA) and specific (SCA) effects were significant for most traits, indicating the
importance of both additive and non-additive effects for these traits. Female parents E2 and E4 showed significant and positive GCA effects for grain yield. Other female lines that showed desirable GCA effects were E1 for ear height, E2 for days to anthesis, ear and plant heights and E5 for days to anthesis and silkng. Among male parents, C1 was the best general combiner for all agronomic traits, but not for grain yield. Inbred lines C2 and C6 were good general combiners for plant height and days to silking, respectively. Hybrids E4 x C2 and E5 x C3 showed superior SCA effects for grain yield while few other combinations showed desirable SCA effects for days to anthesis, ear and plant heights. The results of this study indicated potential heterotic relationships between CIMMYT and Ethiopian inbred lines for use in hybrid and synthetic development and introgression of germplasm.
