AMELIORATIVE EFFECTS OF EXOGENOUS ASCORBIC ACID AND POTASSIUM NITRATE ON ANTIOXIDANT DEFENSE SYSTEM AND MINERAL NUTRIENT UPTAKE IN TOMATOES UNDER SALT STRESS

The aim of this study was to analyze the effects of ascorbic acid (AsA) and potassium nitrate (KNO3) on the salt-based oxidative stress in Lycopersicon esculentum Mill. leaves. The obtained results showed that the saline stress had negative effect on plant vegetative growth and other biochemical parameters. The KNO3 (10 and 20 mM) and AsA (1 and 2 mM) treatments increased the relative water content (RWC) in fresh leaves and dry matter (DM) under salinity (125 mM). The addition of AsA and KNO3 significantly increased both antioxidative enzyme activities (i.e. superoxide dismutase, peroxidase and catalase) and the photosynthetic pigments contents of the plant leaves, while the Lipid peroxidation and proline levels decreased. It was considerable that the negative effects of salt-stress were reduced for vegetative growth and other biochemical parameters of tomato plants. The results of this study showed that the usage of AsA and KNO3 could increase salt stress tolerance and ensure protection for tomato plants against oxidative stress.