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.

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

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 effeet 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 PS Ⅱ and the potential activity0f PS Ⅱ 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.