EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCES ANTIOXIDATIVE CAPACITY IN SALT STRESSED SUNFLOWER (HELIANTHUS ANNUUS L.) PLANTS

Salicylic acid (SA) is a growth regulator that promotes growth of plants under stress and non-stress conditions. The present study was conducted to assess alteration in antioxidative capacity of salt stressed sunflower plants due to foliar applied SA. Two hybrid lines of sunflower (Hisun-33 and SF-187) were grown under non-saline (control) or saline (120 mM NaCl) conditions. Varying levels of salicylic acid (0, 100, 200, 300 mg L-1) were applied foliarly. Activities of antioxidant enzymes (superoxide dismutase, catalase and peroxidase) of both cultivars increased due to salt stress. Foliar applied SA caused a significant increase in leaf SOD and POD activity. However, leaf CAT activity remained almost unchanged due to SA application under both control and saline conditions, particularly in SF-187. Furthermore, increase in growth and photosynthetic capacity of both cultivars due to exogenously applied SA may have been due to SA-induced increase in activity of peroxidase.