THE EFFECT OF SALT STRESS ON ANTIOXIDANT ENZYMES' ACTIVITY AND LIPID PEROXIDATION ON THE WHEAT SEEDLING

Salt stress as a major adverse factor can lower leaf water potential, leading to reduced turgor and some other responses, and ultimately lower crop productivity in arid and semi arid zones. Wheat is one of the main crops occupying a large area in Iran, where salt stress is the most limiting factor. Clearly, plant salt stress tolerance requires the activation of complex metabolic activities including antioxidative pathways, especially reactive oxygen species (ROS) and scavenging systems within the cells which can contribute to continued growth under water stress. In the work reported in this paper, the seeds of two local wheat cultivars (Alvand and Sardari) were grown hydroponically. Seedlings were subjected to Hoagland's solution as control, and 50, 100, 150 and 200 mM NaCl for 10 days. As a result, SOD (superoxide dismutase) increased in Sardari with the increase of salt stress, while in the case of Alvand, SOD showed constant activity at all salt stress levels. Meanwhile, CAT and GR exhibited the same trends in the two cultivars of wheat in salt stress conditions. Results indicated that in the case of Sardari, the scavenging of ROS by the scavenging system especially by SOD, CAT and GR was done well and damage to membranes or MDA was controlled. But in the case of Alvand, damage to membranes increased with the rise of stress levels. It can be concluded that all three antioxidant enzymes were limiting factors for this cultivar. Also these reasons led to the sensitivity of Alvand to salt stress