Drought Stress Effects on Gene Action and Combining Ability of Maize Inbred Lines

This study was carried out to investigate the genetic structure of the 36 maize hybrids established from eighteen female lines and two male testers according to line × tester method under normal irrigation and drought stress conditions. Two separate experiments، normal irrigation and drought stress at grain filling stage were performed in Moghan for two years، using a RBCD with three replications. The results showed that the effect of gene action could be both non-additive and additive in the expression of grain yield under both conditions. However، GCA/SCA variance ratio revealed that non-additive genetic variance was more important for grain yield than additive variance. Analysis of general combining ability indicated that the variation of combining ability of lines in non-water stress condition was higher than that in water stress condition. The reactions of general combining ability of lines in both conditions were not similar. Lines L8، L11 and L17 in normal irrigation and lines L15، L16 and L17 in stress condition showed better general combining abilities for grain yield. The K3653/2 tester showed better general combining abilities for grain yield in both conditions. The crosses such as L1×T1، L4×T1 and L8×T1 in normal irrigation condition and L9×T2 in drought stress condition showed better specific combining abilities for grain yield.