Test cross performance and combining ability of newly introduced quality protein maize (Zea mays) inbred lines for grain yield and agronomic traits evaluated in mid-altitude agro-ecological zones of Ethiopia

Development of quality protein maize (QPM) helps to reduce human malnutrition in areas where maize is the major protein source in the diet. The objective of this study was to estimate combining ability effects of QPM inbred lines for grain yield and yield-related traits. Twenty-one newly introduced QPM inbred lines were crossed with four single cross testers in a line × tester mating design and resulted in 84 F1 progenies. These F1 hybrids, including four checks, were evaluated in an 8 × 11 alpha lattice design with two replications at four locations during 2016. Mean squares due to location, crosses, general combining ability (GCA) and specific combining ability (SCA) were significant for most traits. However, the contributions of GCA sum of squares to the variation among the hybrids were larger than SCA sum of squares, suggesting that the traits were controlled predominantly by additive gene effects. Among the inbred lines, L3, L5 and L10 showed positive and significant GCA effects for grain yield and other agronomic traits. The lines can be used in synthetic variety development. Among crosses, only L3 × T3, L9 × T1 and L15 × T2 revealed positive and significant SCA effects for grain yield, implying the presence of heterosis in these particular crosses.