干旱胁迫下香蕉幼苗对外源ALA的生理响应

【目的】探讨外源5一氨基乙酰丙酸（ALA）对干旱胁迫下香蕉幼苗生长和生理特性的影响，为合理利用ALA提高香蕉抗旱性提供理论依据。【方法】以巴西蕉幼苗为试材，考察10％PEG-6000模拟干旱胁迫条件下，经不同浓度ALA处理后巴西蕉幼苗生长指标及功能叶片中相对含水量、丙二醛（MDA）含量、可溶性蛋白含量、相对电导率、SOD和POD活性等生理指标的变化。【结果】在10％PEG-6000胁迫下，香蕉幼苗生长受到显著抑制，而经过不同质量浓度的ALA处理后，各项生长指标均有所升高，其中以10mg／LALA处理后效果最为显著，各项指标均达最大值，其叶面积、地上部分鲜重、地下部分鲜重及根冠比比干旱胁迫对照分别显著提高了11．60％、19．50％、6．73％和13．64％。各浓度ALA处理均提高了干旱胁迫下幼苗叶片中可溶性蛋白和脯氨酸含量，减缓了相对含水量下降的趋势，降低了MDA含量和质膜透性，同时显著提高了SOD和POD的活性，且以10rag／t,ALA处理后的酶活性最高。【结论】适宜浓度（10mg／L）的ALA能显著促进干旱胁迫下巴西蕉幼苗的生长，通过调节渗透调节物质含量和保护酶活性可有效减缓干旱胁迫对香蕉幼苗的伤害，提高香蕉的抗旱能力。

Physiological response of banana seedling to exogenous ALA under drought stress

Objective]The objective of this study was to investigate the effects of exogenous 5-aminolevulinic acid （ALA） on banana seedling growth and physiological characteristics under drought stress so that theoretical references could be provid- ed for appropriately using ALA to improve drought resistance of banana seedlings. Method]Several growth indicators of brazil banana seedlings treated by ALA under drought stress （10% PEG-6000） were measured. Some physiological indicators of the functional leaves like relative water content,MDA and soluble protein content,relative conductivity,and the activities of SOD and POD were also determined. Result]The growth of banana seedlings under 10% PEG-6000 stress was inhibited, but af- ter the treatment of different concentrations of ALA,all the growth indicators increased. Especially every index of the seedlings treated by 10 mg/L ALA had the maximum value,in which the leaf area,overground-FW,underground-FW and root/shoot as- cended by 11.59%, 19.53%, 6.73% and 13.63%,respectively,compared with the control Each treatment of ALA could improve the contents of soluble protein and proline of the seedlings, slow down the falling trend of RWC, reduce the content of MDA and membrane permeability in leaves, and markedly enhance the activities of SOD and POD. Additionally, 10 mg/L ALA treatment led to the strongest enzyme activity. Conclusion]These results showed that ALA treatment with the appropriate concentration （10 mg/L） could significantly promote the growth of the seedlings under drought stress, and effectively alleviate the danaage of drought stress on banana seedlings by means of adjusting the content of osmotic adjustment substances and preserving enzyme activity.