Grain yield of maize (Zea mays L.) in the tropics are generally low and information on combining ability among tropical maize inbred lines has not been reported for West Africa. This study was conducted to estimate combining abilities of maize inbred lines developed for West Africa. Crosses obtained from ten inbreds including five of tropical origin (A) and five of temperate x tropical origin (B) were evaluated in three environments of forest-first and -second seasons, and the savanna. For the forest ecology yield of A x A crosses were significantly better than those of A x B which in turn were significantly higher than those of B x B. In the savanna, A x B crosses tended to be better than A x A which in turn seems better than B x B although these differences were not significant. Average grain yields of all 45 crosses in the three environments were 3.30 t ha 1 for the forest first season, 3.6] t ha 1 for the forest-second season and 8.05 t ha -1 for the savanna, showing the greatest yield in the savanna ecology. General combining ability (GCA) effect was significant in all environments whereas specific ability (SCA) effect was significantly only in the savanna. Furthermore, all the five A type inbreds had positive GCA effects for grain yield in the two forest environment while three A and two B inbreds had positive effects in the savanna. SCA effects appear to be the major factor for the high yield potential in the savanna. Data obtained from this study show clearly the environmental advantage of maize cultivation in the savanna belt of West Africa and the efficacy of the US Corn Belt germplasm after introduction of tropical adaptation and biotic resistance for the tropics.

Maize; Plant Genetic Resources

Maize; Forest Ecology; Germplasm

Africa; West Africa

Nigeria