| To clarify the physiological effects of melatonin at optimal concentrations on enhancing salt tolerance in wheat seedlings, the wheat cultivars ‘Shangmai 5226’ and ‘Shangmai 1619’ were used as experimental materials. Treatments included a control (CK), 250 mmol/L NaCl solution (S), S + 25 μmol/L melatonin (25MT), S + 50 μmol/L melatonin (50MT), S + 100 μmol/L melatonin (100MT), S + 200 μmol/L melatonin (200MT), and S + 400 μmol/L melatonin (400MT). The effects of melatonin on growth and physiological characteristics were evaluated under salt stress. The results showed that all melatonin treatments (25~400 μmol/L) improved the growth and physiological characteristics of wheat seedlings under salt stress to varying degrees. The 200MT treatment significantly increased plant height, root length, dry weight, fresh weight, and root-to-shoot ratio, as well as chlorophyll content, soluble sugar content, peroxidase (POD) activity, and superoxide dismutase (SOD) activity, while significantly reducing malondialdehyde (MDA) and proline content in both cultivars. These findings indicate that 200 μmol/L melatonin effectively alleviates the adverse effects of salt stress and represents an optimal concentration for promoting wheat seedling growth under such conditions. |
