Type of gene action and heritability of morphologic traits of wheat under drought stress conditions

Drought limits the agricultural production by preventing the crop plants from expressing their full genetic potential. Generation mean analysis was used to study the type of gene action، heritability and the best genetic model of agronomic traits under drought stress and non-drought stress conditions. The experiment was conducted using two randomized complete block design with two replications for each condition in Karaj research station on 2002. Generation mean analysis was performed with Mather and Jinks model and joint scaling test. The thirteen traits included tiller number، spike length، spike number، peduncle length، awn length، plant height، stem length، spike seed weight، spikelet per spike، plant spikes weight، grains per spikes، 100 grain weight and grain yield، were evaluated. The analysis showed disagreement of additive-dominance model for all traits، resulted that there is epistatic interactions between the genes of each trait. The epistatic interactions between the genes of each trait showed the polygeny inheritance of traits. For the majority of the traits، the degree of dominance was ranged partial-dominant to over-dominant effect. The heterosis of grain yield in non-stress and stress status was 13. 9 and 37. 9 percent، respectively، resulted the importance and magnitude of heterosis of yield under stress condition to non-stress condition. Also the heterosis and heterobeltiosis of 100 grain weight and grains per spikes as main yield components in stress condition were higher than non-stress condition.