Physio-biochemical and Enzymatic Responses of Sunflower to Drought Stress

Drought stress is a serious adverse factor that limits sunflower growth and productivity. The stress induces a range of physiological and biochemical responses in sunflower. So, evaluation of defense systems is important for producing resistant cultivars. In this study, physio-biochemical changes and antioxidant enzymes activitiesof six sunflower lines were evaluated under normal and irrigation at 60 and 40% of the field capacity using a randomized complete block design with three replications. Different characteristics such as relative water content (RWC), chlorophyll a and b contents, carotenoid and proline contents, lipids peroxidation and accumulation of malon dialdehyde (MDA), as well as activity of antioxidative enzymes like guaiacol peroxidase (GPX), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR) were studied. The results showed significant differences among sunflower lines for physio-biochemical and enzymes activity under drought stress. According to the results, the lines C104 and RHA266 showed the better tolerance to drought stress. The founding of this study can be useful in sunflower breeding programs for producing resistant cultivars to drought stress.