Alleviation of allelopathic stress of benzoic acid by indole acetic acid in Solanum lycopersicum

• Autotoxicity reported in the natural and agricultural ecosystems. It is prevalent in monocropping system. It caused soil sickness and decreases crop production.
• The various physiological processes of crop plants are adversely affected under allelopathic stress.
• Phytohormones increase plant tolerance against environmental stresses and help in adaptation to plant in adverse condition.
• The purpose of the present study was to evaluate the interactive effects of IAA and BA in tomato seedlings under allelopathic stress in hydroponic culture.

The present study investigates the alleviation of allelochemical stress induced by benzoic acid (BA), an autotoxic compound, by exogenous indole acetic acid (IAA) in tomato seedlings. The experiment was conducted in hydroponic culture in glass house conditions. BA was applied 0.5 and 1.0 mM concentrations with and without IAA (1.0 mM). Root and shoot length, fresh and dry weight, pigment, protein, sugar content and nitrate reductase activity decreased in the seedlings treated with BA, while they increased in BA combined with IAA. Lipid peroxidation, electrolyte leakage and proline level enhanced in the seedlings under BA stress, but these parameters decreased in combined BA + IAA treatment. IAA protected the seedlings against oxidative stress caused by reactive oxygen species (ROS). IAA buttressed defense system of tomato plant against BA toxicity which was evident from increased activities of antioxidant enzymes. IAA has potential to enhance tolerance to stress in the tomato seedlings under allelochemical toxicity.