Effects of ascorbic acid and gibberellin A3 on alleviation of salt stress in common bean (Phaseolus vulgaris L.) seedlings

Salinity, a severe environmental factor, has limited the growth and productivity of crops. Many compounds have been applied to minimize the harmful effects of salt stress on plant growth. An experiment was conducted to investigate the interactive effects of exogenous ascorbic acid (AsA) and gibberellic acid (GA(3)) on common bean (Phaseolus vulgaris L. cv. Naz) seedlings under salt stress. The changes of growth parameters, photosynthetic and non-photosynthetic pigments and potassium content showed that the addition of 1 mM AsA and/or 0.05 mM GA(3) considerably decreased the oxidative damage in common bean plants treated with 200 mM NaCl. The NaCl-stressed seedlings exposed to AsA or GA(3), specifically in their combination, exhibited an improvement in sodium accumulation in both roots and shoots, as compared to NaCl-treated plants. NaCl treatment increased hydrogen peroxide (H2O2) content and lipid peroxidation indicated by accumulation of malondialdehyde (MDA), whereas the interaction of AsA with GA(3) decreased the amounts of MDA and H2O2. In the meantime, interactive effect of these substances enhanced protein content and the activity of the antioxidant enzyme, guaiacol peroxidase, in common bean plants under salt stress. It was concluded that synergistic interaction between AsA and GA(3) could alleviate the adverse effects of salinity on P. vulgaris seedlings.