Impact of water deficit stress on biochemical characteristics of safflower cultivars.

Water deficit stress is one of the severe limitations of crop growth especially in arid and semiarid regions of the world as it effect the plant growth at all stages of development. In the present study, four safflower genotypes Esfahan native, Esfahan-14, PI537,598 and IL111 were tested for their growth and crop yield under water-deficit stress. A detailed biochemical analysis was carried out at various levels of irrigation to find out the genotypic variation and the activity of several enzymes known to play significant role under drought stress. A split plot experiment based on randomized complete blocks design was conducted at three levels of irrigation: 100 % (normal water requirement for safflower), 75 % and 50 %. A significant increase in the activity of SOD, CAT, GPX enzymes and the levels of ABA and proline was observed with an increase in the water stress level in the leaves of all the genotypes investigated. The highest increase in the activities of antioxidant enzymes and proline and ABA content with reduced electrolyte leakage was observed in the relatively drought tolerance native Esfahan cultivar. These results suggest that the cultivars that exhibit highest levels of antioxidant enzymes activity and proline and ABA content under water deficit conditions may provide better drought tolerance in safflower.