Abstract:
Maize (Zea mays L.) is one of the cereals that provide calorie requirements in the Ethiopian
diet. The national average maize yield in Ethiopia is low and thus, knowledge of combining
ability and heterosis is a prerequisite to develop high yielding maize varieties. The objective
of the present study was to estimate combining ability of elite maize inbred lines for grain
yield and related agronomic traits, to identify crosses with higher yield than the standard
check and to determine the relationship existing between grain yield andyield related traits. A
total of 36 diallel crosses generated by crossing 9 elite maize inbred lines using half diallel
mating scheme and four standard checks were studied for different agronomic and yield traits
during the 2017 cropping season at Ambo and Kulumsa Agricultural Research Centers. The
genotypes were evaluated in alpha lattice design replicated twice in both locations. Analyses
of variances showed significant mean squares due to crosses were observed for most traits
studied.The highest grain yield was obtained from crosses L1 x L3, L3 x L8, L4 x L8 and L8 x
L9.GCA mean squares were significant for all studied traits whereas, SCA mean squares
were significant for grain yield, days to anthesis, ear per plant and ear diameter. Relatively
larger GCA over SCA variances were observed in the current study for most studied traits
revealed the predominance of additive gene action in controlling these traits. Inbred lines L3
and L8 were the best general combiners for grain yield, and hence are promising parents for
hybrid development program. Inbred lines L2, L4, L6, L7 and L8 had negative and
significant GCA effects for days to anthesis and silking. Whereas, L1, L2 and L6 showed
negative and significant GCA effects for plant and ear height. Based on mean grain yield,
standard heterosis and specific combining ability effects, L1 x L3, L1 x L5, L2 x L4, L2 x L7,
L3 x L8, L7 x L9 and L8 x L9 are promising crosses that could be promoted for further use in
maize breeding program. Grain yield revealed positive and highly significant (P<0.01)
phenotypic and genotypic correlation with number of ears per plant, ear length, number of
kernels per row and thousand kernel weight. The information generated from this study shall
have important implications in the development of maize varieties with desirable traits’
composition for highland sub-humid agro-ecology of Ethiopia.
