Using Physiological Traits to Evaluating Resistance of Different Barley Promising Lines to Water Deficit Stress

To study water-stress-tolerant barley varieties, 20 barley lines were cultivated under full irrigation and limited irrigation conditions where irrigation was stopped at anthesis stage in two separate field experiments during the 2007-2009 growing seasons at the Saatloo Research Farm, Azerbaijan, Iran. The experiments were laid out using RCBD with three replications. The results from combined analysis of variance in both normal and stress conditions indicated that there were significant differences among genotypes with regard to all studied traits which were due to high variation among the genotypes. It was found that the activity of enzymes including SOD, GPX and CAT were increased under drought stress conditions, so that tolerant genotypes had more changes in enzyme activity. On the other hand, MDA, Dityrosine and 8-oHdg were increased under stress conditions where sensitive genotypes had stronger enzyme activity. Calculations of the correlation coefficients among the studied traits under both stress and normal conditions also indicated that there were negative and significant differences between antioxidant activity, lipid, protein, and DNA decadence. Finally, with regard to all traits, it was revealed that in normal conditions genotypes 18 and 19 were the best performing lines, whereas the genotype 14 was least adapted line. Therefore, genotypes 18 and 19 showed higher levels of resistance to water stress and the genotype 15 was more sensitive to the drought conditions. The results also indicated that selecting more tolerant genotypes under stress conditions was the way to overcome water deficit stress under terminal drought conditions.