Effects of suboptimal temperature and low temperature under low light intensity on stomatal characteristics and chloroplast ultrastructure of cucumber seedlings

探讨弱光下较长时间亚适温和较短时间低温对黄瓜叶片光合机构的影响机理的差异。采用光照培养箱模拟两种逆境条件处理黄瓜幼苗，研究其对黄瓜气孔特性及叶绿体超微结构的影响。7 d弱光亚适温处理（Ⅰ）后，黄瓜叶片的Gs和Ci降低；3 d弱光低温处理（Ⅱ）的Gs明显降低，而Ci升高。条件改善后，前者的Gs和Ci均上升；而后者的Gs增加，Ci降低。处理后当天测定，7 d弱光亚适温处理叶片的气孔多数处于关闭状态，而3 d弱光低温处理的气孔开张比和开张度显著大于CK。较长时间弱光亚适温处理条件下Pn的降低与气孔开度减小有关；而较短时间的弱光低温处理时Pn降低的主要原因是叶肉因素。7 d弱光亚适温处理后淀粉粒数明显减少，而3 d弱光低温处理黄瓜幼苗的生长过程基本停止，物质运输严重受阻。 The study researched influencing mechanism differences between suboptimal and low temperatures for different times under low light intensity on the cucumber leave photosynthetic apparatus. The seedlings were treated separately under adverse conditions in growth chambers, and the effect of suboptimal temperature for 7 d (Ⅰ)and low temperature for 3 d (Ⅱ) under low light intensity on stomatal characteristics and chloroplast ultrastructure of cucumber leaves were studied. The stomatal conductance (Gs) and Intercellular CO2 concentration (Ci) of treatmentⅠdecreased. The Gs of treatment Ⅱ reduced remarkably, while the Ci raised. When the condition improved, the Gs and Ci of treatment