Role of Salicylic Acid in Alleviating Cobalt Toxicity in Wheat (Triticum aestivum L.) Seedlings

Heavy metals pollution of soils become the most serious environmental problem resulted in decreased soil fertility and crop yield losses. Cobalt (Co), as a beneficial element, can be a contaminant in soils due to agricultural additives or metal refineries, it causes irreversible damage to several physiological and metabolic constituents at higher concentrations. In this investigation we study the effects of different Co concentrations (0, 50,150, 250, 350 µM as CoCl2) on growth and physiological processes in wheat (Triticum aestivum) plants and discuss the role of spraying with salicylic acid (0.5 mM) for ameliorating effect of cobalt toxicity in wheat leaves. Cobalt causing a significant reduction in fresh and dry biomass, shoot height, water content and total photosynthetic pigments. This was accompanied with accumulation of H2O2 and MDA contents and induction of some antioxidant enzymes activities. There was an increase in SOD activity with increasing Co concentration then decline, a significant increase in APX and PPO activities while CAT was significantly declined. Spraying wheat seedlings with salicylic acid can be recognized to significantly increase in all tested growth parameters and that was attributed to decrease, to some extent, the accumulation of H2O2 and MDA and improve the activity of antioxidant enzymes.