Estimation of Combining Ability of Agronomic and Physiological Traits of Inbred Lines of Maize (Zea Mays L.) using Line × Tester Crosses Under Normal Irrigation and Drought Stress Conditions

Achieving optimal results in breeding programs require to make informed choices of parents based on general and specific combining ability. Determining of the combining ability and genetic variance components is one of the most important stage in breeding program of maize inbred lines. For this purpose, the number of 25 early maturity lines with two testers (k1263/1 early and late A679) crossed in line × tester method and 50 hybrids were evaluated in a randomized complete block design with three replications in both the normal irrigation and drought stress conditions in 2013 in Mashhad Agricultural Research Station. The results of the analysis of variance showed significant differences among hybrids for all traits in both environments at the 1% probability level. Variance of line × tester and ratio of &sigma2sca / &sigma2 gca indicated greater role of non-additive variance (dominance variance) for most of the traits in both irrigation conditions. For yield and other traits in normal conditions, the lines 1, 5, 14, 15 and 18 and in stress condition, the lines 1, 10, 18, 26 and 31 have positive and significant GCA and the earliness, the lines 1, 7, 8, 10 and 28 have negative and significant GCA in both conditions. For yield, composition including L5 × T1, L9 × T1, L16 × T2 and L19 × T1 in normal conditions and combinations of L1 × T1, L13 × T1, L27 × T2 and L16 × T2 had a positive and significant SCA in drought conditions. The selected genotypes can be used in regional trails and also for estimation of genotype × environment interaction effects.