中文摘要：

采用营养液水培，研究了根际低氧胁迫下不同浓度外源亚精胺（Spd）处理对黄瓜幼苗根系和叶片中多胺含量、抗氧化酶活性、O2^-产生速率、H2O2和MDA含量的影响。结果表明，营养液中添加0．05mmol·L^-1Spd，可促进低氧胁迫下黄瓜幼苗的生长，缓解低氧胁迫的伤害；低氧胁迫下黄瓜幼苗体内抗氧化酶活性和多胺含量之间存在着密切的关系，0．05mmol·L^-1外源Spd可明显提高植株体内Spd和Spm含量，降低Put含量，提高（Spa＋Spm）／Put比值，增强抗氧化酶活性，降低O2^-产生速率、H2O2和MDA含量，从而促进植株的生长，提高植株对低氧胁迫的耐性。

英文摘要：

Effects of different exogenous spermidine （Spd） concentrations on polyamines contents, antioxidant enzyme activities, O2： production rate, H2O2 and MDA contents in roots and leaves of cucumber （ Cucumis sativus L. ） cuhivar ‘Zhongnong 8＇ were investigated in hydroponics. The results showed that exogenous Spd at 0. 05 mmol · L^-1 significantly enhanced the growth of cucumber seedlings and alleviated the damage of hypoxia stress efficiently. Under hypoxia stress, the activities of antioxidant enzymes were associated closely with polyamines contents. The addition of 0. 05 mmol · L^-1 exogenous Spd obviously increased endogenous leaves of Spd, spermine （Spm） , and （ Spd ＋ Spm） /Put ratio, while decreased putrescine （Put） content, enhanced the activities of antioxidant enzymes, decreased the O2^- production rate, H2O2 and MDA contents. Therefore, exogenous Spd at a suitable concentration promoted the growth of cucumber seedlings under hypoxia stress, and improved the tolerance of cucumber seedlings to hypoxia stress.