Abstract: To clarify the regulation effect of exogenous arginine (Arg) on the growth of mung bean seedlings under salt-alkali stress, we analyzed the effects of foliar spraying of different concentrations of Arg on morphological and physiological indices of seedlings of two mung bean cultivars, “Lyufeng 2” and “Lyufeng 5”, which were treated with 150 mmol·L^-1 salt-alkali. The results showed that appropriate Arg concentration (1.0-1.5 mmol·L^-1) significantly improved the resistance of mung bean seedlings under salt-alkali stress, and alleviated the damage to aboveground tissue and roots. The content of photosynthetic pigments, the activities of antioxidant enzyme (SOD, POD, CAT), and osmoregulatory substances (soluble sugars, soluble proteins, proline) significantly increased, while the production rate of ROS metabolite superoxide anion (O₂^-_·) and the content of membrane lipid peroxidation product malondialdehyde (MDA) significantly decreased. In conclusion, Arg can protect the integrity of cell structure and promote seedling growth by increasing the activities of antioxidant enzymes and osmoregulatory substances and decreasing the production of membrane lipid peroxides, thus enhancing salt tolerance of mung bean seedlings.

Key words: saline-alkali stress, arginine, mung bean, osmoregulation, protective enzyme, membrane lipid peroxide