Variations in physiological indices of bread wheat flag leaf in response to drought stress

Drought stress as the most important abiotic stress has an important role in reducing crop production in arid and semi-arid regions of the world. The physiological traits related to drought stress are of utmost importance in this regard. In order to evaluate the effect of drought stress on physiological indices of bread wheat flag leaf، a split plot experiment was conducted based on randomized complete block design with three replications at the Faculty of Agriculture، Azad University of Khorasgan during 2008-2009 growing season. The three different irrigation conditions including normal irrigation، irrigation cease from 50% of head emergence to harvesting as well as irrigation cease from 50% of head emergence to harvesting with 30% increase in N fertilizer were assigned as the main plots and 7 genotypes of bread wheat were consisted as sub plots. The results of ANOVA showed that the physiological traits of relative water content، leaf water content، moisture retention capacity، cut leaves water retention، water loss ratio، as well as seed yield trait had significant differences under different environmental conditions. The amount of physiological traits under drought stress with extra N fertilizer was significantly greater than under drought stress without extra N fertilizer. In fact، extra N fertilizer increased plant tolerance to drought stress conditions through increasing the vegetative growth and leaf water content. Results showed that Pishtaz and Sepahan cultivars as well as line 11 which possessed the greatest grain yield، had the highest physiological traits and the lowest amount of water loss in different environments