中文摘要：

精确控制营养液溶氧浓度和外源乙烯浓度，研究了黄瓜幼苗根系在低氧水培时的生长情况以及PAs含量的变化。结果表明．外源乙烯对根际低氧逆境下黄瓜幼苗根系的生长有抑制作用，虽然根径增粗，含水量增加。但根系的总根数、总表面积、总体积、干重和鲜重都有所减少，随着乙烯浓度的增加，抑制作用增强；外源乙烯对根际低氧逆境下黄瓜幼苗根系PAs含量有着明显的拮抗作用，外源乙烯使根际低氧逆境下黄瓜幼苗根系的伤害症状加重。

英文摘要：

The effects of exogenous ethylene with different concentrations on growth of root system and endogenous polyamines in cucumber （Cucumis sativus L.） seedlings under root-zone hypoxia stress were investigated. The results showed that exogenous ethylene inhibited root growth of cucumber seedlings under root-zone hypoxia stress. Applied with exogenous ethylene, both root diameter and water content of cucumber seedlings under hypoxia stress increased. However, exogenous ethylene reduced the total amount, area and volume of root system, and reduced biomass of cucumber seedlings under hypoxia stress. The inhibiting effects of ethylene on growth increased with increasing concentrations of ethylene. Exogenous ethylene counteracted obviously with contents of endogenous polyamines in root system of cucumber seedlings. In conclusion, exogenous ethylene aggravated harm of hypoxia stress on root system of cucumber seedlings.