模拟酸雨对台湾桤木光合特性的影响

通过模拟酸雨实验，研究酸雨胁迫（pH2．5、3．0、35、4．0、4．5）对台湾桤木光合作用的影响。结果表明，随着酸雨酸度的降低，台湾桤木叶片的净光合速率、蒸腾速率和气孔导度呈上升趋势。pH2．5时，叶片的净光合速率达最低点，比对照（CK）降低28．6％；pH4．5时，叶片的净光合速率比CK高10．2％；pH2．5时，叶片的蒸腾速率达最低点，比cK降低59．5％，而pH3．0、3．5、4．0、4．5分别比CK降低57．4％、53．1％、50．1％和34．7％。随着酸雨胁迫时间的持续，台湾桤木叶片净光合速率先降低后升高，蒸腾速率先升高后降低，气孔导度先降低后升高；胞间CO2浓度前期降低，9月达最低，其后又升高；气孔限制值先升高后降低，水分利用效率先降低后升高。

Effects of simulated acid rain on photosynthesis of Alnus formosana

By simulated acid rain experiment,the effects of acid rain in different intensity stress(pH 2.5,3.0,3.5,4.0,4.5) on photosynthesis of Alnus formosana were investigated.It showed that the lower the acidity of acid rain,the net photosynthetic rate,transpiration rate and stomatal conductance in A.formosana leaves were generally observed in upward trend.When the pH value is 2.5,the net photosynthetic rate reached a minimum,decreased by 28.6% to the control CK;when the pH value is 4.5,its net photosynthetic rate increased by 10.2% compared with the control;when the pH value is 2.5,transpiration rate reached a minimum,decreased by 59.5% to the control;and when the pH being 3.0,3.5,4.0,4.5,their net photosynthetic rates were decreased by 57.4%,53.1%,50.1% and 34.7% compared with the control,respectively.With the persistence of stress time by acid rain,the net photosynthetic rate of the A.formosana leaves showed a trend which first increased and then decreased,the transpiration rate generally increased firstly and then decreased,the stomatal conductance decreased at first and then rose,the intercellular carbon dioxide concentration generally reduced to a minimum in September and then increased,the stomatal limitation generally increased firstly and then decreased,the water use efficiency decreased at first and then increased.