Effect of NaCl stress on the antioxidative system and osmotic regulation substance of six varieties of safflower seedlings.

Changes in the amount of chlorophyll(Chl),malondialdehyde(MDA),and soluble sugar(SS),and the activity of three antioxidant enzymes(SOD,POD,and CAT)were investigated after treatment with different NaCl concentrations.Salt tolerance was evaluated by fuzzy subordination methods.The results showed that with increasing salt concentration:(1)The total chlorophyll content of the Fengqiu safflower decreased gradually,while for the other safflowers,the content increased initially and then decreased.(2)The content of malondialdehyde(MDA)and soluble sugar(SS)enhanced significantly,and the soluble protein content initially increased,and then decreased.(3)The superoxide dismutase(SOD)activity of Heze safflower and Chuan safflower were significantly higher at 50 mmol/L salt concentration than that of the control,after which they declined.The others showed a constant decrease.With salt concentration increasing,the peroxidase(POD)and catalase(CAT)activity of all species initially increased and then decreased.(4)Using the fuzzy subordination method,the salt resis-tances of the six species decreased in the order of Fengqiu safflowerHeze safflowerChuan safflowerBozhou safflowerYunhong No.3Xinjiang safflower.