Abstract

In order to study effects of salinity, salicylic acid, silicium and ascorbic acid on lipid peroxidation, antioxidant enzyme activity and fatty acid content of sunflower, a pot culture experiment was conducted under controlled conditions. Sunflower seeds were sown into the pots and irrigated by Hoagland’s solution. Salinity was induced by adding sodium chloride (NaCl) into nutrient solution. In addition, different concentration of salicylic acid, silicium and ascorbic acid were made by dissolving salicylic acid, silicium and ascorbic acid into the solution to reach certain concentrations. Treatments included 0, 100, 200 and 300 mM NaCl, 1 and 2 mM salicylic acid, 2 and 4 mM silicium and 0 and 4 mM ascorbic acid. The results showed that salinity significantly have effect on all assayed traits. Salinity significantly increased malondialdehyde content and antioxidant enzyme activity, but decreased protein content and fatty acid percentage. Similarly, salicylic acid enhanced antioxidant enzyme activity and decreased protein and oleic acid percentage. Among enzymes, only superoxide dismutase was affected by silicium application and its activity increased. Furthermore, silicium application led to a decrease in protein content. Lipid peroxidation and enzyme activity significantly decreased on account of ascorbic acid application. On the other hand, the interaction between salinity and ascorbic acid was significant on malondialdehyde and antioxidant enzymes activity. Ascorbic acid application significantly decreased malondialdehyde production and enzyme activity under salinity stress. In general, we concluded that ascorbic acid application into the nutrient solution can diminish adverse effect of salinity and alleviate enzyme activity via scavenging of reactive oxygen species.

Key words: Ascorbic acid, salicylic acid, silicium, salinity, sunflower.