EFFECT OF EXOGENOUS APPLICATION OF SALICYLIC ACID AND SODIUM NITROPRUSSIDE ON MAIZE UNDER SELENIUM STRESS

Selenium (Se) is a naturally occurring substance that is toxic at high concentration for all life forms. It enters into environment through natural and anthropogenic sources. Therefore, this experiment was conducted to study the effect of foliar application of salicylic acid (SA) and sodium nitroprusside (SNP) on maize growing in selenium contaminated soil. Salicylic acid and sodium nitroprusside are important growth controller molecules which regulate physiological functions in plants and protect plants from environmental stresses. Two maize varieties (Pioneer 33H15 and Cargill 6142) were used in this experiment. Two concentrations of SA and SNP (50 mu M and 100 mu M) were used as a foliar spray and selenium was applied @ 20 mg kg(-1). Results showed that selenium stress caused a reduction in plant growth, chlorophyll content, gas exchange parameters and activities of enzymes such as SOD, POD and CAT. Though, foliar application of SA and SNP considerably reduces the negative impacts of selenium by enhancing the activities of antioxidant enzymes as they play an important role in modulating the cell redox balance, thereby protecting plants against oxidative damage. There was significant improvement in membrane stability index (68.33%), relative water contents (78.47%) along with increase in activities of SOD (23%), POD (16.37%) and CAT (70%) in Pioneer 33H15 where SA was applied @ 100 mu M. These results suggested that foliar application of SA might be more useful for improving maize growth by alleviating harmful effects of Se.