以杜梨砧‘爱宕’和‘喜水’梨1年生幼苗为试材, 采用砂基培养法, 运用CI-340便携式光合测定仪与H-7650透射电子显微镜研究了0、16、80和200 mg·L-1 钙（依次为钙缺乏、钙低量、对照和钙过量）处理下两品种梨叶片净光合速率（Pn）、超微结构的变化及Pn与生理生态因子的相关性。结果表明: 1）钙胁迫处理的‘爱宕’和‘喜水’梨叶片的Pn均显著低于对照; 各钙处理的两品种梨Pn均与PAR呈显著正相关, 但Pn与其他因子的相关性因处理而异。2）与对照相比, 钙过量处理的‘爱宕’叶绿体呈肿胀状, 出现空泡化,‘喜水’叶绿体发生变形、有的离壁向内弯曲; 钙低量处理的‘爱宕’叶绿体扁长, 有的离壁向内弯曲, 质体小球明显增多,‘喜水’叶绿体、线粒体出现明显的空泡化; 钙缺乏处理的两品种梨细胞叶绿体、线粒体空泡化严重, 淀粉粒少或无, 质体小球明显增多, 其中‘喜水’细胞器受损程度较重。可见, 钙胁迫对两品种梨叶片光合特性和超微结构造成了明显的影响, 其影响程度与钙浓度、品种特性有关。

The 1-year-old seedlings of ‘atago’ (Pyrus prifolia Nakai) and ‘kisui’ (Pyrus prifolia Nakai) grafted on birch-leaf pear (Pyrus betulaefolia Bge) were taken as experimental material, with sand culture, changes of leaf net photosynthetic rates(Pn) and ultrastructure, correlations between Pn and physiological and ecological factors of the two cultivars were investigated under calcium of 0 mg·L-1 (Ca deficiency), 16 mg·L-1 (low Ca) , 80 mg·L-1 (control) and 200 mg·L-1 (Ca excess) treatments using the CI-340 portable photosynthesis system and H-7650 transmission electron microscope. The results showed that Pn of ‘atago’ and ‘kisui’ pears under Ca stress were significantly lower than that of the control, and Pn of both cultivars under different Ca treatments were all positively correlated to PAR, whereas correlations to other factors were different for different treatments. Compared to the control, under Ca excess treatment, leaf chloroplast of ‘atago’ was swelled and vacuolated, and in leaf chloroplast of ‘kisui’, distortion or plasmolysis was observed. Under low Ca treatment, chloroplast of ‘atago’ became prolate, plasmolysis appeared, and platoglobuli obviously increased, as to ‘kisui’, obvious vacuolization was found in chloroplast and mitochondria. Under Ca deficiency treatment, leaf chloroplasts and mitochondrias of both cultivars were significantly vacuolated, few or no starch grains were detected, platoglobuli obviously increased, specially, organelles of ‘kisui’ were injured relatively seriously. Thus, the obvious effects of Ca stress on photosynthetic characteristic and ultrastructure of both cultivars of pears were observed, the influences degrees were correlated to Ca concentrations and the cultivar characters.