中文摘要：

为阐释Ca^2＋对低氧胁迫下黄瓜幼苗光合效率和细胞超微结构的影响，以中农8号黄瓜品种为试材，在水培条件下，研究在低氧胁迫下Ca^2＋与黄瓜幼苗光合效率和叶绿体超微结构的关系。结果表明：低氧胁迫下，气孔限制是导致缺钙植株光合速率（Pn）下降的主要原因，非气孔限制是导致单纯低氧胁迫和低氧高钙处理Pn下降的主要原因；低氧胁迫下，光补偿点提高，光饱和点和最大光合速率降低，高钙可以降低其变化的幅度，缺钙则增大其变化的幅度；低氧胁迫下表观量子效率变化不大，羧化效率有增加的趋势；低氧胁迫下叶绿体和线粒体受到伤害，高钙可以修复或缓解低氧胁迫对叶绿体和线粒体的伤害。总之，高钙对缓解低氧胁迫对黄瓜幼苗光合效率和细胞超微结构的影响均有良好的效应，可有效缓解低氧胁迫造成的伤害。

英文摘要：

Cucumber Zhongnong No. 8 was water cultured as experimental material to explore the effect of calcium on photosynthetic efficiency and cellular ultramicroscopic structure of cucumber （ Cucumis sativus L. ） seedlings under hypoxia. It was found that stomatal inhibition accounted mainly for the decline of P. （net photosynthetic rate） in calcium deftcient seedlings under hypoxia while non-stomatal inhibition was the main reson for P, decline in seedlings only exposure to hypoxia and seedlings exposure to high-concentration calcium under hypoxia. Light compensation point of seedlings was increased while light saturation point and maximum P. declined under hypoxia. High-concentration calcium narrowed the fluctuation scope while calcium deficiency expanded. AQY（ apparent quantum yield） remained more or less stable under hypoxia while CE（ carboxylation efficiency） tended to increase. Chloroplast and mitochondria were damaged under hypoxia, and high-concentration calcium could alleviate or restore the damages. Calcium played a positive role in alleviating damage by hypoxia stress, demonstrating by increased photosynthetic efficiency and ultramicroscopic structure.