Heterosis and combining ability for grain yield and yield component traits of maize in Eastern Ethiopia
Combining ability analysis for grain yield and yield component traits in maize were carried out in 8×8 diallel cross. The analysis of variance showed there is highly significant variation between the genotypes for all the traits considered. Year of testing was significant only for days to maturity and grain yield per hectare. The highest percentage of heterosis for grain over the standard varieties (BH 660) was observed by the cross L1 x L4 (29.3%) followed by crosses L1 x L5 (28.3%), L3 x L5 (21.7%) and L1 x L7 (20.8%). Mid-parent heterosis for days to maturity ranged from -2.5 to -23.9%, whereas that of better parent heterosis ranged from 0 to -13% indicating that the hybrids tend to be earlier in maturity than the parents. The mean squares due to GCA for days to maturity, ear diameter, member of kernels per row, 1000 kernel weight and grain yield were significant, indicating the importance of additive genetic variance in controlling these traits. The mean squares due to SCA were also significant for days to maturity, ear length, member of kernels per row and 1000 kernel weight indicating the importance of non-additive genetic variance in controlling these traits. The inbred lines L1, L3, and L4 were good general combiners for grain yield.
Keywords: Maize, Combining ability, General combining ability, Specific combining ability, Standard heterosis