Combining ability of quality protein maize inbred lines under low and optimum soil nitrogen environments in Ethiopia

Maize (Zea mays L.) is the most important cereal crop on which many smallholder farmers in sub-Sahara Africa (SSA) depend as a sole source of calories, proteins, and vitamins. However, conventional maize deficient two essential amino acids, lysine, tryptophan. Thereafter, Quality Protein (QPM) developed to combat protein malnutrition. In SSA low soil nitrogen also limiting factor production productivity. To determine combining ability QPM inbred lines for grain yield other agronomic traits under optimum N environments, 121 genotypes generated using 11 complete diallel mating design with 5 checks were evaluated both environments at 3 locations 2018 cropping season. Significant differences observed among major characters environments. Under non-additive gene actions more than additive action yield, number ears per plant, plant ear height, length diameter. contributions reciprocal effects GCA aspect, Parental TL156579, TL156583, TL148288 considered good general combiner line TL156612 showed higher positive when used female while parental negative male parent   Key words: Complete diallel, ability, nitrogen, quality maize, effect,