Combining ability and heterotic grouping of early maturing provitamin A maize inbreds across Striga infested and optimal environments

Abstract

The development, deployment and production of stress tolerant provitamin A maize is crucial to the fight against vitamin A deficiency in sub-Saharan Africa (SSA) where maize is a major staple food crop. Fifteen early maturing provitamin A and two early normal yellow endosperm maize inbreds were crossed using the diallel mating design to generate 136 single-cross hybrids. The hybrids were evaluated during 2015 growing season at three locations under two Striga infested and three optimal growing environments in Nigeria. The objectives were to (i) determine the combining ability and heterotic groups of early maturing provitamin A inbreds; (ii) examine the performance of the inbreds in hybrid combinations across environments and (iii) identify early maturing provitamin A inbred testers for use in tropical maize breeding programs. The general combining ability (GCA) and specific combining ability (SCA) effects were significant for grain yield and most other traits indicating that additive and non-additive genetic effects were important in the inheritance of these characters. Inbreds TZEI 10, TZEIOR 108, and TZEI 17 had significant positive GCA for grain yield. TZEIOR 108, TZEIOR 42, and TZEI 10 had significant negative GCA for Striga damage while TZEIOR 122, TZEIOR 127, TZEIOR 108, and TZEI 10 had significant negative GCA for number of emerged Striga plants. The inbreds were classified based on heterotic groups’ SCA and GCA of grain yield (HSGCA), SCA and GCA of multiple traits (HGCAMT) methods into four, three and five heterotic groups, respectively. The inbreds TZEIOR 108, TZEI 10 and TZEI 17 were identified as testers. Hybrids 8, 3, 5, 10 and 1 were identified as high yielding and most stable across environments.