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Effects of simulated acid rain on Quercus glauca seedlings photosynthesis and chlorophyll fluorescence.

模拟酸雨胁迫对青冈幼苗光合特性和叶绿素荧光参数的影响


选择亚热带常绿阔叶林优势树种青冈幼苗为研究对象,设置3个酸雨处理:pH 2.5、pH 4.0、pH 5.6(CK),研究不同强度的模拟酸雨对青冈幼苗光合特性、叶绿素荧光参数和叶绿素含量的影响.结果表明:经过2年酸雨处理,青冈的净光合速率随着酸雨强度的增加而显著上升.pH 2.5、pH 4.0处理的酸雨增大了青冈的气孔导度和蒸腾速率,且对pH 2.5处理的影响更为显著.胞间CO2浓度的大小顺序是pH 2.5>pH 5.6>pH 4.0.pH 2.5、pH 4.0处理青冈的最大净光合速率、光补偿点、光饱和点、暗呼吸速率显著高于对照,表观量子效率对酸雨胁迫不敏感.pH 2.5、pH 4.0处理青冈的PSⅡ原初光能转化效率和PSⅡ的潜在活性显著高于对照.青冈的叶绿素相对含量大小顺序是pH 2.5>pH 5.6>pH 4.0,且pH 2.5与pH 4.0之间有显著差异.说明青冈幼苗的光合参数、叶绿素荧光参数指标在pH 2.5和pH 4.0的酸雨处理下有所增加,且在pH 2.5强度下增加更为明显.

Taking the seedlings of Quercus glauca, a dominant evergreen broadleaf tree species in subtropical area, as test materials, this paper studied their photosynthesis, chlorophyll fluorescence, and chlorophyll content under effects of simulated acid rain with pH 25, 40, and 56 (CK). After 2-year acid rain stress, the net photosynthetic rate of Q. glauca increased significantly with decreasing pH of acid rain. The acid rain with pH 25 and 4.0 increased the stomatal conductance and transpiration rate, and the effect was more significant under pH 25. The intercellular CO2 concentration decreased in the order of pH 25>pH 56>pH 40. The maximum photosynthetic rate, light compensation point, light saturation point, and dark respiration rate were significantly higher under pH 25 and 40 than under pH 56, while the apparent quantum yield was not sensitive to acid rain stress. The maximal photochemical efficiency of PSⅡ and the potential activity of PSⅡ under pH 25 and 40 were significantly higher than those under pH 56. The relative chlorophyll content was in the order of pH 25>pH 56>pH 40, and there was a significant difference between pH 25 and 40. All the results suggested that the photosynthesis and chlorophyll fluorescence of Q. glauca increased under the effects of acid rain with pH 25 and 40, and the acid rain with pH 25 had more obvious effects.