Evaluation of combining ability and gene effect in maize S7 inbred lines based on second Griffing methods under normal and water scarcity conditions

To evaluate the general and specific combining ability of maize lines, five S7 maize lines and their offsprings were evaluated in randomized complete block design with two replications under normal and water deficit conditions at the research field of Graduate University of Advanced Technology, Kerman, Iran, in 2017 and grain yield and its components were measured. The results of analysis of variance indicated that there was a significant difference between lines as well as general and specific combining ability of parents and hybrids. Based on the results of the diallel analysis by second Griffing’s method, number of grain per row, number of grain rows, number of grain per ear, ear length and 100 grain weight were more influenced by the additive effects than the non-additive gene effects, while the number of ear was more controlled by the non-additive gene effects and grain yield per plant was approximately controlled by equal portion of the additive and non-additive gene effects. The line KSC704-S7-1 showed significant and positive general combining ability for grain yield and more related traits under both water deficit stress and non-stress conditions, so this line can be used to improve grain yield in breeding programs. In addition, P1×P3 and P2×P5 hybrids showed significant and positive specific combining ability for grain yield and most related traits under water deficit stress and normal conditions, respectively, which are introduced as the best hybrids for improving maize grain yield under water deficit stress and normal conditions, respectively.