中文摘要：

采用营养液水培，研究了根际低氧胁迫下外源亚精胺对2个抗低氧能力不同的黄瓜品种（‘中农八号’和‘绿霸春四号’）根系中多胺含啦和呼吸代谢相关酶活性的影响。结果表明，单纯低氧处理下。黄瓜幼苗根系中腐胺、亚精胺和精胺含量显著提高，异柠檬酸脱氢酶（IDH）和琥珀酸脱氢酶（SDH）活性显著降低，乳酸脱氢酶（LDH）、乙醇脱氧酶（ADH）和丙酮酸脱羧酶（PDC）活性显著提高。同时，与抗低氧能力弱的‘中农八号’相比，抗低氧能力强的‘绿霸春四号’根系LDH活性增加幅度较低，ADH活性增加幅度较高，IDH和SDH活性降幅也较小；外源亚精胺能显著提高低氧胁迫下黄瓜幼苗根系中亚精胺和精胺含量，降低腐胺含量；根系中LDH、ADH和PDC活性降低，IDH和SDH活性升高，说明黄瓜幼苗根系中较高的亚精胺、精胺含量可能有利于提高根系有氧呼吸能力，缓解低氧胁迫对植株的伤害。

英文摘要：

Hydroponics was adopted to study the effects of exogenous spermidine on polymine contents and the activities of the enzymes relating to respiratory metabolism in the roots of two cucumber varieties （Zhongnong 8 and Liibachun 4） with different hypoxia-tolerating capacities. The results showed that hypoxia treatment could make putrescine,spermidine and spermine contents significantly increase,IDH and SDH activities significantly decline,and LDH,ADH and PDC activities significantly increase in the roots of cucumber seedlings; in the meantime, compared with Zhongnong 8 having a weak hypoxia tolerance, Lubachun 4 having a strong hypoxia tolerance showed a smaller increment in LDH activity and a larger increment in ADH activity but a smaller decrement in IDH and SDH activities in its roots. Exogenous spermidine could significantly increase spermine and spermidine contents but reduce putrescine content in the roots of cucumber seedlings under hypoxia stress ;at the same time,it could lowered LDH,ADH and PDC activities and raise IDH and SDH activities in the roots ;and this indicated that higher spermidine and spermine contents in the roots of cucumber seedlings were probably conducive to raising the aerobic respiration capacity of the roots and lessening hypoxia damage to the plants.