水杨酸增强黄瓜幼苗耐盐性的生理机制

【目的】明确外源水杨酸（Salicylic acid，SA）对黄瓜（Cucumis sativus L.）幼苗耐盐性的作用。【方法】采用SA根际注射和叶面喷施相结合的方法，研究了NaCl胁迫下黄瓜幼苗对外源SA的生理响应。【结果】外源SA促进了NaCl胁迫下黄瓜叶片可溶性糖和Pro的积累，最高分别使两者含量提高了110.4%和82.2%。SA处理提高了NaCl胁迫下黄瓜叶片SOD、POD、CAT活性，降低了非胁迫条件下黄瓜叶片SOD活性。SA使NaCl胁迫下黄瓜幼苗保持较高的含水量，并与单一NaCl胁迫对照达到极显著差异水平（n=10，P＜0.01）。施用外源SA后，与单一NaCl胁迫相比黄瓜叶片MDA含量和原生质膜电解质渗透率分别降低了30.9%和79.9%。SA处理能够显著改善NaCl胁迫下黄瓜植株的株高、茎粗和干物质积累（n=10，P＜0.05），有效地缓解NaCl对黄瓜幼苗生长的抑制作用。【结论】外源SA可以通过提高植株渗透调节能力和抗氧化能力，维持植株水分平衡，保护膜结构和功能，减轻NaCl对黄瓜幼苗的胁迫伤害。

Physiological Mechanisms of Salicylic Acid Enhancing the Salt Tolerance of Cucumber Seedling

By a way root injection and foliar spray with 50 mg·L-1 of salicylic acid (SA), the physiological responses of Cucumis sativus L. (cv. Xinjinyan No.4 ) on exogenous SA were studied under NaCl stress. The results showed that exogenous SA enhanced the accumulation of soluble sugar and proline (Fig.1), improved the activities of superoxide dismutase, peroxidase and catalase (Fig.2), and decreased the malondialdehyde content and electrolyte leakage (Fig.3) in leaves, increased the water content of dry weight in whole plant under NaCl stress, thus effectively alleviated the inhibition of NaCl to seedling growth. These results suggested which exogenous SA has a important role on NaCl tolerance of cucumber seedlings via the osmotic regulation and antioxidation, water balance and membrane stability.