The role of ascorbic acid as a key molecule antioxidant involved in biotic and abiotic stress has been well described. Thus, in order to study the effects of ascorbic acid on drought tolerance and some morphological and physiological characteristics of safflower (Carthamus tinctorius L.) under drought stress condition an experiment was conducted. The experimental design was factorial with two factors arranged in a completely randomized design (CRD), with three replications. The first factor was drought stress on 5 levels (control, -4, -6 , -8 and -12 bar) that was carried out by PEG 6000 and the second factor was ascorbic acid solution on 4 density (control, 55, 110 and 165 μm). The results showed that with increase in drought stress, germination percentage, shoot length, root length, seedling fresh weight, seedling dry weight and vigor index significantly decreased whereas catalase and peroxidase activity increased as compared to control with enhancement of drought stress. In general, priming with ascorbic acid significantly relived the harsh effects of drought stress on seedling growth, catalase and peroxidase activity of safflower and it seems that ascorbic acid was able to enhance the tolerant ability of the plant to drought stress.
