effect of drought stress and spraying of salysilic acid and chitosan on photosynthetic pigments and antioxidant enzymes in safflower

in order to evaluate the effects of drought stress and spraying of salysilic acid and chitosan on photosynthetic pigments and antioxidant enzymes of safflower an experiement was conducted as split plot randomized complete block design at the zabol university research farm in zabol, south iran during 2012. treatments were drought stress at three levels; irrigation when the soil moisture level dropped to 25, 50 and 75 percent of available water as the main treatments, and four combinations of sprayings including non-spraying, salicylic acid (0.424 g.l-1), chitosan (5 g.l-1) and combination of salicylic acid and chitosan as sub-treatments that were applied with three replications. the results indicated that drought stress significantly decreased chlrophyl a, b, total and chlrophyl flueorecense. also drought stress increased anti-oxidant enzymes, but this increasing effect was significant in case of peroxidase enzyme. in addition, drought stress did not influence carotenoid, protein yield, and ascorbate, guaiacol peroxidase and catalase. spraying treatments increased all traits compared to the control. combination of salicylic acid and chitosan was more effective than sole application. interaction of drought stress by spraying was significant on chlorophyll a and protein yield, therefore spraying of salyclic acid and chitosan could be recommend for increase the stability of cell membranes in plants and reduce the damage caused by h2o2 of limited irrigation in safflower.