中文摘要：

采用营养液水培法，研究了低氧胁迫下亚精胺（Spd）对黄瓜幼苗净光合速率（Pa）、细胞间隙CO2浓度（Ci）、气孔导度（Gs）、蒸腾速率（Tr）以及量子效率（Фc）和羧化效率（CE）的影响．结果表明，低氧胁迫下，黄瓜植株Pn呈下降趋势，处理10d后达最低值，为同期对照的63．33％，而低氧胁迫的外源Spd处理10d时Pn升高了1．25倍；Ci与Pn呈一定负相关性（R^2=0．4730～0．7118），Ga与Tr的变化幅度较大，低氧胁迫下有明显下降趋势，Spd处理后其值有所上升，两者呈显著相关（R^2=0．7821～0．9458），但与Pn的相关性不显著；低氧下中，和CE比对照分别下降了63．01％和72．33％，而Spd处理后，Фc和CE值分别提高了23％和14％．表明在低氧胁迫下黄瓜幼苗的光合抑制主要是由非气孔限制所引起的，而外源Spd可通过对光系统的修饰减轻黄瓜幼苗的低氧胁迫伤害．

英文摘要：

With water culture, this paper studied the effects of exogenous spermidine （Spd） on the net photosynthetic rate （Pn） , intercellular CO2 concentrations （ Ci ） , stomatal conductance （ Gs ）, transpiration rate （ Tr ）, apparent quantum yield （ Фc ）, and carboxylation efficiency （CE） of cucumber seedlings under hypoxia stress. The results showed that the P decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63.33% of the control. Compared with that of hypoxia-stressed plants, the P, after 10 days application of exogenous Spd increased 1.25 times. A negative correlation （R^2 = 0. 4730 ~ 0. 7118） was found between Po and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr （R^2 = 0. 7821 -0. 9458）, but these two parameters had no significant correlation with P ; Hypoxia stress induced a decrease of Фc and CE by 63.01% and 72. 33%, respectively, while hypoxia stress plus exogenous Spd application made Фc and CE increase by 23% and 14% , respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.