Analyzing combining abilities and heterotic groups among Ghanaian maize landraces for yield and resistance/ tolerance to Maize Streak Virus Disease

Maize is an important cereal crop in Ghana. Yields in farmer fields have always been low because of over reliance on unimproved local landraces for cultivation. This study was conducted to determine if the productivity of these landraces can be improved by developing hybrid varieties that combine high yield and resistance to the Maize Streak Virus Disease (MSVD). Seventeen local landrace populations were assembled and then crossed with 5 exotic inbred lines (CML202, CML442, CML444, TZEI 23 and TZEI17). A crossing block using the North Carolina Design II was used to generate F1 top-cross hybrids which were evaluated in multi-locational trials for two years. GCA, SCA and heterosis were estimated and heterotic groups assigned to the landraces. This study was able to identify high heterosis among some of the top-cross hybrids and assigned some of the landraces into heterotic groups. Highly significant GCA and SCA effects were identified which implies MSVD incidence/resistance as well as yield related traits can be improved. CML442, CML444 and TZEI17 contributed positively to yield increases as well as improved tolerance/resistance to MSVD. Landraces LA3, LA80, LA76, and LA457 displayed highly significant SCA effects for yield, which suggests dominance and epistatic gene action. The high yielding hybrids identified show that some inbred lines and landraces combinations can contribute to significantly raise farmers’ yields and improve resistance/tolerance to MSVD in Ghanaian environments.