等渗Ca和NaCl胁迫对黄瓜叶片叶绿体超微结构及光合特性的影响

采用营养液栽培，以盐敏感型的黄瓜品种津春2号为试材，研究了等渗Ca和NaCl胁迫对黄瓜幼苗叶绿体超微结构、叶片叶绿素含量、光合特性和叶绿素荧光参数的影响。结果表明：两种盐胁迫均降低了黄瓜叶片叶绿素含量，且NaCl胁迫后下降的幅度大于Ca胁迫。Ca胁迫后，叶绿体大部分与细胞壁脱离，基粒片层数减少|等渗的NaCl胁迫后，叶绿体结构变形，基粒片层膨胀、松散，片层之间界限模糊，嗜饿颗粒明显增多。Ca胁迫后净光合速率（Pn）、气孔导度（Gs）、PSⅡ最大潜在光化学效率（Fv/Fm）、PSⅡ实际光化学效率（ΦPSⅡ）和光化学淬灭系数（qP）下降的幅度均小于NaCl胁迫。Ca胁迫下植株的胞间CO2浓度（Ci）呈下降趋势，而NaCl胁迫下Ci呈上升趋势。综上所述，Ca胁迫主要通过气孔限制引起Pn下降|而NaCl胁迫严重破坏了叶绿体超微结构，主要通过非气孔因素限制引起Pn下降。

Effects of Iso-osmotic Ca（NO3）2 and NaCl Stress on Chloroplast Ultra-structure and Photosynthesis in Cucumber leaves

Taking nutrient solution as culture method，and salt sensitive cucumber（Cucumis sativus L.）cultivar‘Jinchun No.?2’as material，this experiment studies the effects of iso-osmotic Ca and NaCl stress on cucumber seedlings’chloroplast ultra-structure，chlorophyll content，photosynthetic characteristics and chlorophyll fluorescence parameters．The results indicated that the chlorophyll content was decreased by both salt stress，and the decreasing degree of NaCl stress was bigger than that of Ca stress．The ultra-structural analysis showed that under Ca stress，most of the chloroplasts were out of the cell wall and the numbers of grana thylakoid were decreased|whereas under NaCl stress the structure of chloroplast displayed deformation，and the grana lamellae became inflation，the hungry particles increased significantly．The net photosynthesis rate（Pn），stomatal conductance（Gs），PSⅡ photochemical quantum yield（Fv/Fm），PSⅡ actual photochemical efficiency（ΦPSⅡ）and photochemical quenching（qP）were all decreased by salt stress．However，the decreasing degree of Ca stress was less than that of NaCl stress．Intercellular CO2 concentration（Ci）was decreased by Ca stress，while was increased by NaCl stress．Thus，we concluded that the stomatal limitation was a dominate factor causing Pn decrease under Ca stress and non-stomatal factor was a dominate factor causing Pn reduction under NaCl stress．