摘要:
以无柄小叶榕幼苗为研究材料，研究了不同NaCl浓度处理对无柄小叶榕气体交换、叶绿素荧光和抗氧化酶活性的影响。结果表明：在低浓度NaCl胁迫（50 mmol/L）处理7 d后，无柄小叶榕净光合速率（Pn）、气孔导度(Gs)和胞间 CO2 浓度（Ci）分别下降24%、31%和30%。低浓度NaCl处理并没有引起光化学猝灭（qP）和开放PSII反应中心激发能捕获效率（F′v/F′m）的下降；低浓度NaCl胁迫下无柄小叶榕Pn的下降主要是气孔因素引起的；高浓度NaCl胁迫（200 mmol/L）处理7 d后，Pn、Gs、Ci、qP和F′v/F′m分别下降了81%、54%、51%、72.7%和87.6%。表明高浓度NaCl胁迫下无柄小叶榕Pn的下降是由气孔因素和非气孔因素共同作用的结果，即除了降低气孔因子外，还通过降低F′v/F′m和qP，从而降低电子传递速率和Pn；高浓度NaCl胁迫还使非光化学猝灭（NPQ）、MDA含量、SOD和POD活性显著上升。表明尽管高浓度NaCl胁迫诱导一定程度的光能耗散，但仍不能及时地耗散过剩的激发能，导致了膜脂过氧化的发生。
Abstract:
In this study, chlorophyll fluorescence, gas exchange and antioxidant activity in Ficus concinna var. subsessilis were investigated under NaCl stress. Under a low NaCl concentration (50 mmol/L) treatment for 7 d, net photosynthetic rate (Pn), stomatal conductance (Gs) and intercellular CO2 concentration (Ci) in the F. concinna var. subsessilis seedlings decreased by 24%, 31% and 30%, respectively, in comparison to the control. However, low NaCl concentrations did not decrease the efficiency of energy conversion of open PSⅡ(F′v/F′m) and the proportion of open PSII reaction centers (qP). These results indicated that the decline of Pn under low NaCl concentrations was due to the stomatal factors. Under a high NaCl concentration (200 mmol/L) treatment for 7 d, Pn, Gs, Ci, qP and F′v/F′m in the seedlings dropped by 81%, 54%, 51%, 72.7% and 87.6%, respectively, compared to the control. Additionally, high NaCl concentrations also decreased the F′v/F′m and qP, thereby resulting in an reduction in electron transport flow and Pn. The non-photochemical quenching (NPQ), MDA content, SOD and POD activities of the seedlings were significantly increased after high NaCl concentration stresses. These results showed that, though the light energy dissipation was increased, excessive excitation energy was still accumulated under high NaCl concentrations, which induces the increase of activities of antioxidant enzymes and the aggravation of membrane lipid peroxidation, while the decrease of Pn under high NaCl concentrations was due to both stomatal and non-stomatal factors.
百度学术
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