Estimation of Genetic Control Model for Agronomic Traits in the Progeny of Marvdasht and MV-17 Wheat Cross under Normal and Terminal Drought Stress Conditions

The study of the genetic structure controlling agronomic traits is one of the preconditions for selecting the appropriate breeding method. In order to analyze genetic of some agronomic traits of bread wheat using generation mean analysis, parents and different generations resulting from the cross of Marvdasht × MV-17 wheat cultivars were assessed in a randomized complete block design with three replicates under normal and terminal drought stress conditions in Research Farm of Razi University (Iran) during 2015-2016 cropping season. Based on the results of weighted ANOVA, a significant difference was observed between different generations for most of the studied traits under both conditions. Generations mean analysis revealed that in addition to the additive and dominance gene effects, a variety of epistatic effects also played a role in the inheritance of most traits, and therefore cannot hope for the success of selection in first generations. The role of additive gene effect was greater than the dominance one for plant height, peduncle length and awn length, indicating usefulness of using recurrent selection to aggregate these genes followed by selecting lines with favorable agronomic characteristics. The model of genetic control for most of the traits was similar under both conditions in terms of the presence or absence of non-allelic interactions and it has not been widely affected by drought stress. The broad-sense heritability for plant height, peduncle length and awn length was estimated to be high under both conditions. The broad-sense heritability for kernel yield was moderate estimated under both conditions, but the narrow-sense heritability was very low. In general, considering the greater role of the non-additive gene effect for most of the traits, the selection is suggested in advanced generations and after access to a high level of gene fixation.