Estimation of Combining Abilities for Grain Yield of Tropical and Exotic Maize Inbred Lines in Diverse Environments

Abstract

Studies on the combining ability of maize inbred lines have enhanced the effective
selection of parents of promising hybrids for specific or across agro-ecologies.
Exotic lines have been reported to provide novel genes for maize improvement. This
trial, therefore, estimated the combining abilities for grain yield of local and exotic
inbred lines of two types of maize. One hundred and fifty white and 66 yellow
hybrid maize were evaluated in three locations in the rainforest, derived savannah,
and savannah agro-ecologies of Nigeria for two years. The layout for the white
maize was a 19 x 8-lattice design, while a 10 x 7-lattice design was used for the
yellow maize, with three replicates each. Estimated grain yields were pooled and
analyzed for each location and across locations. Mean squares due to environments,
genotypes, genotype-environment interactions, and male x female interactions were
significant in all locations and across locations. Three inbred lines, BD74-171,
BD74-179, and BD74-170, had significant positive general combining ability
(GCA) across locations for the white maize, while TZEI12, TZEI16, BD74-161, and
BD74-222 were identified as good general combiners for the yellow maize. Hence,
the respective lines can be tracked for the improvement of white and yellow hybrids
adapted to the locations. White hybrids BD74-175 x BD74-147, BD74-170 x
TZEI106, and TZEI4 x BD74-152 and six yellow hybrids had significant positive
specific combining ability (SCA) across locations. They are recommended for
further research in the agro-ecologies. Higher SCA over GCA in grain yield
indicates the predominance of non-additive gene effects controlling the inheritance
of grain yield in the two types of maize in the locations.