Agricultural and Biological Research

Combining ability study of QMM inbred lines for endosperm modification score and tryptophan content under low and optimum soil nitrogen environments

Helena Moreira*, Ginette Ross

The nutritional benefit of quality protein maize is more demonstrated on children who live under nutritional insecurity and also children suffering from a severe disease (Kwashiorkor) which is due to protein deficiency. To determine the effects of soil nitrogen on combining ability of tryptophan, endosperm modification score, protein and protein Quality Index (QI), 121 genotypes with five checks were sib-mated to generate F2 grains under low and optimum N environments. Hereafter 100 grains of each F2 generation were used for endosperm modification scores and tryptophan and protein concentration analysis in maize kernel endosperm. The results of the study indicated contribution of General Combining Ability (GCA), Specific Combining Ability (SCA) and reciprocal effects were important for all measured traits under both environments indicating quality traitsinheritance were controlled by both additive and non-additive gene action. Inbred lines TL156579, TL156583, and VL05128 had good potential for endosperm modification score and inbred lines TL147078 and VL05128 had good potential for tryptophan, protein and protein quality index under low N environment. Under optimum N environment, parental lines TL156579, TL156583 and VL05128 had good potential for endosperm modification whereas parental lines TL156591 had good potential for tryptophan and protein concentration in grain and quality index. Hybrids TL155932 x VL05128 TL148288 x TL147078, TL155932 x TL156612, TL156612 x VL05128 and TL156579 x TL156591 had significant differences between F1 hybrids and their F1 reciprocals for grain yield under low N environment. Under both low and optimum N environments, the importance of reciprocal effects was also identified for endosperm modification score, tryptophan, protein, and quality index.