Alleviation of salinity stress by hydrogen peroxide and nitric oxide in tomato plants

Salinity is one of the major abiotic stress factors limiting plant growth and productivity, particularly in arid and semi-arid climates. Hydrogen Peroxide (H₂O₂) and Nitric Oxide (NO) are important signaling molecules in plant response to abiotic stress. In this research the effects of foliar sprays with H₂O₂ (10 mM) and NO (0.1 mM sodium nitroprusside, as a NO donor) on alleviation of Salinity stress (0, 25, 50 and 100 mM NaCl) were investigated in Tomato (Solanum lycopersicum L. cv. Falat). Photosynthetic attributes, plant-water relations, membrane stability index and growth parameters were decreased by NaCl treatments. Exogenous H₂O₂ and NO application enhanced salt stress tolerance in tomato plants by improving the photosynthetic efficiency and plant water status as measured by relative water content and membrane stability index. These results were positively reflected by the increase in plant growth under salinity stress conditions. The results of this study described that under the adverse conditions of salinity stress, H₂O₂ and NO could activate the photosynthetic system and improve the physiological attributes in plant growth.