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

Abstract

Salicylic acid (SA) is a growth regulator that promotes growth of plants under stress and nonstress 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.