Mean Performance and Heterosis in Single Crosses of Selected Quality Protein Maize (QPM) Inbred Lines

Knowledge of the extent of heterosis and per se performance of parental lines plays a crucial role for the breeding programs to develop competitive hybrids. Hence, this research was planned to evaluate the performances of QPM inbred lines and their single crosses; and estimate the magnitudes of mid-parent, better parent and standard heterosis for grain yield and its components. Ten inbred lines were crossed following diallel method II to produce 45 single crosses. A total of 57 genotypes (10 inbred lines, 45 single crosses and two standard checks) were evaluated in alpha lattice design at Ambo and Bako in 2014, with two replications. Combined analysis of variance showed highly significant (P ≤ 0.01) variations among genotypes for grain yield and yield components studied. Interaction effects of all traits with the environments except for ears plant-1 were highly significant (P ≤ 0.01). Five hybrids, viz., P3 x P10, P7 xP10, P4 x P10, P6 x P10 and P9 x P10 were significantly superior to AMH760Q (the best check) with yield advantages ranging of 45.9 to 29.7%. These hybrids also had significantly higher percentage of mid-parent (MPH) and better -parent heterosis (BPH) for grain yield ranging from 292.7 to 163% and 248.4 % to 128.6%, respectively. Indeed these hybrids shared P10 as common male parent which had no pedigree relationship with the parental lines used to form the crosses. The result is, therefore, in line with the established fact of positive association between heterosis and genetic distance of parental lines. P10 is not only a distant relative to these other parents but had also desirable traits for high grain yield, which could be exploited in the breeding program. Moreover, the five highest yielding hybrids identified in this study need to be further evaluated across locations for possible release as single cross hybrids.