中文摘要：

【目的】探讨外源EBR（24-表油菜素内酯）对低氧胁迫下黄瓜（Cucumis Sativus L．）根系的生长和抗氧化系统的影响。【方法】采用营养液水培法，以抗低氧能力较强的黄瓜品种绿霸春4号和抗低氧能力较弱的品种中农8号为材料，研究根际低氧胁迫下外源施用EBR对黄瓜根系生长、ROS及抗氧化酶活性的影响。【结果】在低氧胁迫下，EBR处理显著促进了低氧胁迫下两品种黄瓜幼苗根系生长，提高了SOD、APX、GR活性及AsA、GSH含量，降低了O^7、H2O2及MDA含量。【结论】外源EBR处理通过促进低氧胁迫下黄瓜幼苗根系中抗氧化酶活性和抗氧化剂含量的提高，降低ROS含量，增强植株抗低氧胁迫的能力。

英文摘要：

[Objective] The aim of this experiment was to study the effects of exogenous 24-epibrassinolide （EBR） on the changes in ROS, activities of antioxidant enzymes and antioxidants in cucumber （Cucumis sativus L.） seedling roots under hypoxia stress. [Method] Seedlings of a hypoxia-resistant cultivar, Lubachun No.4, and a hypoxia-sensitive cultivar, Zhongnong No.8, were subjected to nutrient solution hypoxia stress treatments. The effects of EBR on the growth, and the changes in ROS, antioxidant enzymes and antioxidants in seedlings roots were investigated. [Result] Under hypoxia stress, O2^7 level and lipid peroxidation were significantly increased in the roots upon exposure to hypoxia stress, which were inhibited by EBR application. EBR treatment significantly promoted seedlings growth and SOD, APX, GR activities, and contents of AsA, GSH under hypoxia stress. [ Conclusion ] The results obtained from this experiment showed that oxidative damage on seedling roots by hypoxia stress can be considerably alleviated and the tolerance of plants can be elevated.