Role of melatonin seed priming on antioxidant enzymes and biochemical responses of Carthamus tinctorius L. under drought stress conditions

Drought has profound effects on productivity of crops in arid and semi- arid regions causing deleterious effects on the functions of crops leading to oxidative stress. In the present study, extensive melatonin seed priming experiments were conducted to assess the antioxidant enzymes and biochemical responses of fresh and old primed seeds of safflower under drought conditions. Safflower seeds were soaked in water (hydropriming) or melatonin (0.1 and 0.5 mM) for 6 h. The lipid peroxidation was significantly decreased by melatonin-seed priming. Such effects were more prominent in a plant grown from fresh seeds compared with plants from old seeds. The antioxidant enzymes varied in activity under drought condition. Our results demonstrated that the response to melatonin seed priming was dose-dependent. In addition, the results of this study indicated that the stability of safflower improved by melatonin because the membranes remain intact or sustained a little injury and antioxidant enzymes work properly. This is the first report on the effect of melatonin-seed priming on field condition; it also provides evidence that melatonin could improve the tolerance of safflower to drought.