采用营养液水培，研究了根际低氧胁迫下外源亚精胺对两个抗低氧能力不同的黄瓜(Cucumis sativus)品种（‘中农8号’和‘绿霸春4号’）根系中多胺含量和超氧化物 歧化酶(SOD)、过氧化物 酶(POD)、过氧化氢酶(CAT)活性的影响。结果表明，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 ，同时，根系中SOD、POD、CAT活性也相应提高，使得幼苗鲜重和干重明显增加；单纯低氧 处理及外源亚精胺的加入，抗低氧能力较强的品种‘绿霸春4号’较抗低氧能力较弱的品种 ‘中农8号’根系中抗氧化酶活性高。黄瓜幼苗根系中较高的亚精胺、精胺含量和较低的腐 胺含量可能有利于提高抗氧化酶活性，增强幼苗的低氧逆境适应能力。
Polyamines (PAs) have long been recognized to be linked with growth, differentiation, plant senescence and defense reactions of plants to various environmental stresses. However, little is known about their physiological relevance in plants subjected to hypoxia stress. In the present experiment, the effects of exogenous spermidine on polyamine content and antioxidant enzyme activities in seedlings of two cucumber cultivars (Cucumis sativus cv. Zhongnong No.8 and cv. Lübachun No.4) with different resistances to hypoxia stress were investigated. The results showed that under hypoxia treatment, the contents of putrescine (Put), spermidine (Spd), and spermine (Spm) in roots of seedlings of two cucumber cultivars increased significantly in the early period of treatment and then decreased in the later period. Over the entire treatment period, concentrations of PAs were significantly higher than those in the control. Activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) over the treatment period followed the same pattern as PAs. The fresh weight and dry weight of the two cucumber cultivar seedlings were significantly lower than the controls. Exogenous Spd treatment increased the contents of Spd and Spm in roots while decreased the Put content when compared to the hypoxia treatment, enhanced the activities of the antioxidant enzymes, and the fresh and dry weight of seedlings were similar to the controls. Under the same treatment, the activities of the antioxidant enzymes in the roots of the hypoxia_resistant cultivar (cv. Lübachun No.4) were higher than in the hypoxia_sensitive cultivar (cv. Zhongnong No.8). These results indicated that exogenous Spd can change the contents of PAs in the roots of both cucumber cultivars under hypoxia stress, and higher levels of Spd and Spm in roots can enhance both the activities of antioxidant enzymes and the growth of cucumber cultivar seedlings.