Genetic analysis of agronomic and morphological traits of durum wheat [Triticum turgidum L. spp. durum (Desf.)] using generations mean analysis under non-stress and terminal drought stress conditions

Breeders often use generation means analysis to obtain information about inheritance, gene action, and to determine effective breeding methods to improve important agronomic traits, especially under drought stress conditions. To investigate the genetic parameters of agronomic and morphological traits in durum wheat, a field experiment was carried out using F1, F2, BC1 and BC2 generations obtained from crossing of Shotordandan variety and Dena cultivar under non-stress and terminal drought stress conditions. The experiment was carried out using randomized complete block design with three replications in research field of Islamic Azad University, Ahvaz Branch, Iran in 2016-17 cropping season. To apply terminal drought stress, from anthesis stage, the irrigation of the plots was ceased until physiological maturity. The results of weighted analysis of variance of generations revealed that there was significant differences between the generations for all measured traits except number of grain.spike-1 under non-stress conditions and number of tillers and grain weight.plant-1 in drought stress conditions. The results of generations mean analysis for spike length under non-stress conditions and plant height and spike length under stress conditions showed that the three-parameters model had the best fit. However, for other measured traits, significant chi square test (χ2) indicated the presence of non-allelic interactions in the inheritance. Additive and dominance effect played roles in controlling most of the studied traits, but the effect of dominance component was greater than the additive component. Broad and narrow sense heritability of traits under non-stress conditions varied from 11-84% and from 1-75%, respectively, and under stress conditions from 24-70% and from 1-40%, respectively. Considering the greater role of genes with non-additive effect in controlling most of traits, except plant height, spike length and 1000-grain weight, selection in durum wheat advanced breeding generations, when breeding lines are fixed and relative purity achived, is suggested.