以生长于重庆缙云山国家级自然保护区内的粉叶新木姜子(Neolitsea aurata var. glauca Yang)和四川大头茶[Polyspora speciosa (Kochs) B. M. Barthol. et T. L. Ming]2 年生幼苗为实验材料,研究了不同pH 值的模拟酸雨对叶片气体交换参数、光响应曲线和光响应参数的影响,并比较了2 树种对模拟酸雨的抗性。结果表明:四川大头茶叶片的各项气体交换参数和光响应参数总体上高于粉叶新木姜子。随模拟酸雨pH 值降低,粉叶新木姜子叶片的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)逐渐降低且总体上显著低于对照(pH 5. 6 模拟酸雨);四川大头茶叶片的Pn、Gs 和Tr 值在pH 2. 0 模拟酸雨作用下显著低于对照、在pH 3. 5 模拟酸雨作用下显著高于对照;但不同pH 值模拟酸雨对2 树种叶片的水分利用效率总体上无显著影响。经不同pH 值模拟酸雨处理后2 树种叶片的光响应曲线与对照明显不同。与对照相比,经pH 2. 0、pH 2. 5 和pH 3. 5 模拟酸雨处理后粉叶新木姜子叶片的最大净光合速率(Pmax)、光饱和点(LSP)和表观量子产量(AQY)总体上显著降低,光补偿点(LCP)显著升高;其暗呼吸速率(Rd)在pH 2. 0 和pH 3. 5 模拟酸雨作用下显著高于对照、在pH 2. 5 模拟酸雨作用下显著低于对照。四川大头茶叶片的Pmax和LSP 值在pH 2. 0 和pH 2. 5 模拟酸雨作用下显著低于对照,但在pH 3. 5 模拟酸雨作用下显著高于对照;其LCP 和Rd 值在pH 2. 5 和pH 3. 5 模拟酸雨作用下显著低于对照,但在pH 2. 0 模拟酸雨作用下均高于对照;其AQY 值在pH 2. 0、pH 2. 5 和pH 3. 5 模拟酸雨作用下均低于对照。研究结果显示:酸性较强(pH 2. 0 和pH 2. 5)的模拟酸雨均可抑制2 树种的光合作用,而酸性较弱(pH 3. 5)的模拟酸雨对四川大头茶的光合作用有一定的促进作用,表明四川大头茶对酸雨的抗性相对强于粉叶新木姜子。

Taking 2-year-old seedlings of Neolitsea aurata var. glauca Yang and Polyspora speciosa (Kochs) B. M. Barthol. et T. L. Ming grown in Jinyun Mountain National Nature Reserve of Chongqing as experimental materials, effects of simulated acid rain with different pH values on gas exchange parameters, light response curve and light response parameters of leaf were researched, and resistance of two tree species to simulated acid rain was compared. The results show that all gas exchange parameters and light response parameters of leaf of P. speciosa are generally higher than those of N. aurata var. glauca. With reducing of pH value of simulated acid rain, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of leaf of N. aurata var. glauca decrease gradually and are generally significantly lower than those of the control (simulated acid rain with pH 5. 6). Pn, Gs and Tr values of leaf of P. speciosa under simulated acid rain with pH 2. 0 are significantly lower than those of the control, while those under simulated acid rain with pH 3. 5 are significantly higher than those of the control. Effect of simulated acid rain with different pH values on water use efficiency of leaf of two tree species is generally not significant. Light response curve of leaf of two tree species after treated by simulated acid rain with different pH values is obviously different from that of the control. Compared with the control, the maximum net photosynthetic rate (Pmax ), light saturation point (LSP) and apparent quantum yield ( AQY) of leaf of N. aurata var. glauca generally decrease significantly and light compensation point (LCP) increases significantly after treated by simulated acid rain with pH 2. 0, pH 2. 5 and pH 3. 5, and its dark respiration rate (Rd) under simulated acid rain with pH 2. 0 and pH 3. 5 is significantly higher and that under simulated acid rain with pH 2. 5 is significantly lower than that of the control. Pmax and LSP values of leaf of P. speciosa under simulated acid rain with pH 2. 0 and pH 2. 5 are significantly lower and those under simulated acid rain with pH 3. 5 are significantly higher than those of the control, its LCP and Rd values under simulated acid rain with pH 2. 5 and pH 3. 5 are significantly lower and those under simulated acid rain with pH 2. 0 are higher than those of the control, and its AQY value under simulated acid rain with pH 2. 0, pH 2. 5 and pH 3. 5 is lower than those of the control. It is suggested that simulated acid rain with stronger acidity (pH 2. 0 and pH 2. 5) can inhibit photosynthesis of two tree species, while simulated acid rain with weaker acidity (pH 3. 5) has a certain promotion effect on photosynthesis of P. speciosa, which indicating that resistance of P. speciosa to acid rain is  comparatively stronger than that of N. aurata var. glauca.