Germination, reserve metabolism and antioxidant enzyme activities in safflower as affected by seed treatments after accelerated aging

The viability of safflower (Carthamus tinctorius L.) seeds decreases with aging and reduction in vigor has detrimental effects on agricultural production. Seed treatments are economical and effective techniques to the alleviate the effects of aging. The objective of the research was to study the effects of seed treatments after accelerated aging (AA) on germination variables, biochemical content and antioxidant enzyme activities in safflower seeds. Seeds of two safflower cultivars were subjected to AA treatment at 43 ± 1°C for 72 h, and after the AA treatment, aged seeds were treated with glutathione, ascorbic acid and calcium chloride (CaCl2). Accelerated aging reduced germination and normal seedling percentage, soluble sugars, protein, tocopherol and peroxidase activity. Seed treatments significantly improved germination and normal seedling percentage, and decreased reducing sugars, free fatty acids, free amino acids, malondialdehyde, hydrogen peroxide and superoxide dismutase activity, though extent of these changes was different between the treatments and cultivars. Correlation and principal coordinate analysis revealed significant correlations between germination variables, biochemical content and antioxidant enzyme activities and CaCl2 treatment differed from the other treatments. Our results show that ascorbic acid, glutathione and CaCl2 treatments after AA treatment alleviate aging damage, and CaCl2 treatment was more effective than the other treatments for reducing aging damage and improving vigor in safflower seeds.