Crossing maize ( Zea mays
L.) genotypes obtained from different sources could result in better utilisation of hybrid vigor. Such heterotic response is poorly exploited in the drought-stressed areas of Ethiopia, due to problems in adaptation of some of introduced materials. This study was conducted to determine the heterosis and combining ability of eight elite maize genotypes. The eight parents were selected based on per se
and top-cross performance. The parents were crossed in diallel fashion. The resulting crosses and their parents were evaluated in a randomised complete block design with three replicates at three locations for two years in Ethiopia. The combined analysis of variance showed that the mean square due to genotypes and general combining ability (GCA) were significant (P=0.01) for all the six traits studied. However, the mean square due to specific combining ability (SCA) was significant for days to tasselling, days to silking, plant height, and grain yield. The magnitude of GCA was higher than the SCA in all the cases indicating that additive gene action was more important than non-additive in the inheritance of these traits. Mid-parent heterosis occurred in varying degrees for the different traits. It was in the range of - 11.6 to 21.9% for grain yield. DTP-2 C4 and Melkasa 92 DTP1 had significant and positive GCA for days to tasselling, days to silking, plant height, and grain yield. Hence, these parents can be used to develop intermediate maturing varieties while AW-8047 significantly reduced (had negative GCA for) tasselling, silking, and plant height without affecting grain yield indicating that AW-8047 can be used as source population to develop early varieties.