淹水胁迫对不结球白菜幼苗光合特性的影响

以不结球白菜(Brassica campestris ssp.chinensis Makino)‘新矮青’为材料,研究了不同淹水处理(根淹、半淹)对其幼苗叶片光合参数、叶绿素含量、荧光参数的影响。结果显示:淹水5 d时,根淹和半淹处理使不结球白菜的净光合速率(P n)、气孔导度(G s)、蒸腾速率(T r)、最大光化学效率(F v/F m)显著下降,分别为对照的43.1%和22.1%(根淹和半淹,下同)、26.4%和14.3%、40.2%和33.2%、87.9%和77.1%;淹水处理使不结球白菜的叶绿素含量、PSⅡ有效光化学量子产量(Yield)、电子传递速率(ETR)也显著下降;根淹和半淹处理使不结球白菜的水分利用效率(WUE)、光化学猝灭系数(q P)呈下降趋势,而胞间CO2浓度(Ci)、非光化学猝灭系数(q N)显著上升,分别为对照的105.3%和115.6%、120.6%和147.4%。这表明淹水胁迫能显著影响不结球白菜的相关光合指标,且随着淹水时间的延长和淹水深度的增加,不结球白菜受到的胁迫损伤不断加重。

Effects of Waterlogging Stress on Photosynthetic Characteristics of Pak-Choi

Using Pak-Choi (Brassica campestris ssp. chinensis Makino) variety ‘Xinaiqing’ as the tested material, we investigated the effects of waterlogging with different stress depth on its photosynthetic characteristics, chlorophyll content and chlorophyll fluorescence. Results showed that: under 5 d waterlogging, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), photosystemⅡ (Fv/Fm) of the surface submergence of soil and the semi-submergence of plants were significantly lower, accounting for 43.1% and 22.1%, 26.4% and 14.3%, 40.2% and 33.2%, and 87.9% and 77.1% of the control, respectively. Chlorophyll content, effective photochemical quantum yield (Yield) and electron transport rate (ETR) were also significantly decreased. Water use efficiency (WUE) and coefficient of photochemical quenching (qP) during root submergence were slightly lower, but significantly decreased during the semi-submergence of plants. However, intercellular carbon dioxide concentration (Ci) and non-photochemical quenching coefficient (qN) of the surface submergence of soil and the semi-submergence of plants were significantly increased, accounting for 105.3% and 115.6%, and 120.6% and 147.4% of the control, respectively. The above results indicated that there were significant effects on photosynthetic characteristics under waterlogging stress, and these parameters showed greater change under submergence waterlogging stress than that under root waterlogging stress.