外源硝酸钙对盐胁迫黄瓜幼苗生长和光合作用的影响

以较耐盐黄瓜品种新泰密刺为试材,采用营养液栽培,研究了叶面喷施Ca(NO3)2对盐胁迫(65 mmol/L NaCl)下黄瓜幼苗生长、叶片叶绿素含量、光合及叶绿素荧光参数的影响。结果表明,外源Ca(NO3)2显著提高了盐胁迫下黄瓜幼苗的干鲜重和叶片叶绿素含量;Ca(NO3)2也提高了盐胁迫下黄瓜叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ实际光化学效率(ФPSⅡ)、光条件下最大光化学效率(F'v/F'm)和光化学淬灭系数(qP),而对胞间CO2浓度(Ci)、暗条件下最大化学效率(Fv/Fm)和非光化学淬灭系数(qN)没有显著影响。这些结果说明外源Ca(NO3)2可能通过提高叶绿素含量和调节气孔限制,以缓解盐胁迫对黄瓜幼苗光化学效率的抑制,进而提高植株耐盐胁迫能力,促进其生长。

Effects of Exogenous Ca( NO3 )2 on Growth and Photosynthesis of Cucumber Seedlings under Salt Stress

Taking salt-tolerant cucumber(Cucumis sativus L.) variety Xintaimici as the tested material,a water culture experiment was conducted to study the effects of foliar spraying exogenous Ca(NO3)2 on the growth,leaf chlorophyll content,photosynthesis and chlorophyll fluorescence parameters of cucumber seedlings under salt stress(65 mmol/L NaCl).The results showed that spraying Ca(NO3)2 upon the leaf surface could significantly increase the dry weight and fresh weight of salt-stressed cucumber seedlings,as well as the chlorophyll content in the leaves.The application of Ca(NO3)2 also enhanced the net photosynthetic rate(Pn),stomata1 conductance(Gs),transpiration rate(Tr),the actual photochemical efficiency of PSⅡ(ФPSⅡ),the maximum photochemical efficiency under light condition(F′v/F′m) and photochemical quenching coefficient(qP) of cucumber seedling leaves under salt stress,but it had no significant influence on intercellular CO2 concentration(Ci),maximal photochemical efficiency under dark condition(Fv/Fm) and non-photochemical quenching coefficient(qN).It was suggested that exogenous Ca(NO3)2 might alleviate the inhibition of salt stress to the photochemical efficiency of cucumber seedlings,thus enhance their tolerance to salt stress,and promote their growth,through increasing the leaf chlorophyll content and regulating the limit of stoma.