The effect of sodium selenate on some of antioxidant enzymes activity in sunflower seedlings (Helianthus annuus L.) under salt stress

Salinity is one of the most harmful environmental factors limiting the productivity of crop plants. Selenium (Se) is a metalloid element which regarded as an antioxidant in plants, animals and human nutrition. Se have shown enhanced resistance to certain abiotic stresses including salinity, drought and etc. The present study investigates the effect of exogenous selenium mitigating the salt induced damage in sunflower plants. In this research, the plants were treated with NaCl(0, 25, 50 and 75mM) and Na2SeO4( 0, 10 and 20µM) in nutrient solutions. Plants were harvested after 23 days for biochemical assay. The results showed that in plants only treated with sodium chloride, with increasing of sodium chloride concentration, photosynthetic pigments and protein contents decreased as compared with those of control plants. In plants exposed to sodium chloride and Na2SeO4, photosynthetic pigments and protein contents were higher than of plants only exposed to sodium chloride. Antioxidant enzymes activities including catalase, guaiacol peoxidase, ascorbate peroxidase and superoxide dismutase increased in plant exposed to sodium chloride. In plants exposed to sodium chloride and Na2SeO4, the enzymes activities were higher than of plants only exposed to sodium chloride With increasing NaCl concentration, lipid peroxidation increased, however, with addition of Na2SeO4 to NaCl, MDA content decreased and antioxidant enzymes activity, significantly increased. The results showed that sodium selenate can protect plants against stress and increase antioxidant capacity.