A field experiment was conducted in three low moisture areas in Ethiopia to study general and specific combining ability (GCA and SCA) for developmental, panicle and grain traits. Twenty-four parents (6 male sterile lines and 18 fertility restorers or testers) were used along with their 108 crosses. Combining ability analysis through a line × tester set for 14 agronomic traits in three environments and on a pooled basis revealed the importance of both additive and non-additive genetic effects. However, the predominance of additive components was observed in the inheritance of most traits studied. Environments also influenced the GCA and SCA effects. The female genotypes ICSA-10, ICSA-15 and ICSA-30, the testers ICSR-14 and KLCTENT # 17DTN and the crosses ICSA-30 × KCTENT # 17DTN, ICSA-30 × ICSR-16, ICSA-15 × KCTENT #17DTN and ICSA-10 × ICSR-14 exhibited the highest and significant SCA effects for yield and some of its components, indicating their importance in hybrid development for lowland areas of Ethiopia.