【摘要】 通过1年的盆栽试验,研究3种不同pH值(3.0、4.0、5.0)的模拟酸雨溶液对樟树2年生幼苗光合特性的影响。结果表明:与对照相比,pH3.0酸雨降低了樟树的光补偿点、光饱和点,pH4.0、5.0酸雨增高了樟树的光补偿点、光饱和点;pH3.0、4.0酸雨提高了樟树最大净光合速率和表观量子效率,其中最大净光合速率分别增高54.53%、30.74%,表观量子效率分别增高27.07%、22.61%,pH5.0酸雨降低了樟树最大净光合速率和表观量子效率,分别下降23.79%和4.14%。3种酸雨均提高了樟树的暗呼吸速率,分别提高2.70%、80.45%、47.55%,降低了樟树气孔导度的最小值,分别降低了19.38%、70.93%、14.10%。pH3.0、4.0酸雨提高了樟树气孔导度的最大值和日变化幅度,其中气孔导度的最大值分别提高了40.12%、24.39%,日变化幅度分别提高了61.29%、58.31%,pH5.0酸雨降低了樟树气孔导度的最大值和日变化幅度,分别降低32.37%和38.87%。3种酸雨均提高了樟树胞间CO2浓度最小值,分别提高13.22%、9.87%、3.27%,降低了樟树气孔限制值的日变化幅度,分别降低33.15%、43.31%、52.35%。樟树的净光合速率日变化呈不对称的"双峰型"曲线,峰值出现在10:00、14:00,12:00表现"光合午休",酸雨导致"午休"下降幅度增大,降低樟树净光合速率的日变化幅度,分别降低27.68%、10.77%、28.90%;pH3.0、4.0酸雨增大了樟树的日均净光合速率,pH5.0酸雨降低了樟树的日均净光合速率。更多还原

【Abstract】 Cinnamomum camphora is one of the dominant green species in the southern districts in China,and also acid rain is widespread contaminants in the environment.In this paper,we tried to study if photosynthetic characteristics of C.camphora seedlings planted in pots would change by irrigating with three different pH values(3.0,4.0,5.0)of simulated acid rain.The results showed that the light compensation point and saturation point of C.camphora fell under pH3.0,but rose under pH4.0 and pH5.0.Apparent quantum yield(AQY)increased by 54.53%,30.74%,and the net photosynthetic rate(P_n)increased by 27.07%,22.61% under pH3.0 and pH4.0,respectively,but decreased by 23.79% and 4.14% under pH5.0.The dark respiration rates(R-d)rose under three different pH treatments.The diurnal variation of P_n in C.camphora treated with acid rain presented the asymmetry double peak curves,occurring at 10:00 and 14:00 respectively.Midday depression of P_n was found at 12:00.The range of diurnal variation of P_n decreased by 27.68%,10.77%,28.90% under pH3.0,4.0 and 5.0 treatments,respectively,but under pH3.0 and 4.0 treatments,the daily P_n all ascended.The minimum of stomatal conductance(G_s)decreased by 19.38%,70.93% and 14.10% in view of different pH values(3.0、4.0、5.0)of simulated acid rain,but the maximum increased by 40.12%,24.39% and the range of diurnal variation of G_s increased by 61.29%,58.31% under pH3.0 and 4.0,respectively.The minimum of intercellular CO_ 2 concentration(C_i)increased by 13.22%,9.87%,3.27%,but the range of diurnal variation of stomatal limit(L-s)decreased by 33.15%,43.31%,52.35% under pH3.0,4.0,5.0 treatments,respectively.更多还原