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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(NO3)2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(NO3)2胁迫。Ca(NO3)2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(NO3)2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(NO3)2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(NO3)2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。
Using nutrient solution cultivation, salt-sensitive cucumber variety Jinchun 2 was used to study the effects of isotonic Ca (NO3) 2 and NaCl stress on the chloroplast ultrastructure, leaf chlorophyll content, photosynthetic characteristics and chlorophyll fluorescence parameters Impact. The results showed that both of the two kinds of salt stress decreased the chlorophyll content of cucumber leaves, and the decrease extent of NaCl content was greater than that of Ca (NO3) 2 stress. After Ca (NO3) 2 stress, most of the chloroplast was detached from the cell wall, and the number of the mitochondria decreased. Under NaCl stress, the chloroplast structure was deformed, the basal lamina was swollen and loose, the boundaries between the layers were vague, Granules increased significantly. The photosynthetic rate (Pn), stomatal conductance (Gs), maximum potential photochemical efficiency of PS Ⅱ (Fv / Fm), PSⅡ actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient (qP) decreased after Ca (NO3) Less than NaCl stress. Under the stress of Ca (NO3) 2, the intercellular CO2 concentration (Ci) decreased, while Ci increased under NaCl stress. In summary, Ca (NO3) 2 stress caused Pn decline mainly through stomatal limitation. However, NaCl stress severely damaged the chloroplast ultrastructure, which mainly caused the decrease of Pn by non-stomatal limitation.