模拟酸雨对青冈光合及叶绿素荧光参数的影响

Effects of simulating acid rain on photosynthesis and chlorophyll fluorescence parameters of Quercus glauca

在重度酸雨(pH 2.5)、中度酸雨(pH 4.0)和弱酸性酸雨(pH 5.6)3个酸雨梯度下,研究地上酸雨、全淋酸雨、土壤酸雨3种处理方式对青冈幼苗叶绿素荧光和光合参数的影响,并以空白为对照.结果表明:在重度酸雨条件下,地上酸雨处理显著阻碍青冈幼苗叶绿素合成,降低PSⅡ原初光能转化效率(Fv/Fm)、潜在活性(Fv/Fo)和实际光化学量子产量(Y),以及净光合速率(Pn)、蒸腾速率(Tr)等光合参数,提高光补偿点和暗呼吸速率,全淋酸雨处理下青冈幼苗受到抑制作用其次,而土壤酸雨处理对其有一定的促进作用;中度酸雨和弱酸性酸雨条件下,不同处理方式除暗呼吸速率(Rd)低于对照外,其余均高于对照,并且全淋酸雨>土壤酸雨>地上酸雨处理.可见,在重度酸雨条件下,地上酸雨处理对幼苗的抑制作用最强;中度和弱酸性酸雨条件下,全淋酸雨处理对于幼苗的促进作用最强.不同酸雨强度对青冈幼苗叶绿素相对含量(SPAD)、PSⅡ原初光能转化效率(Fv/Fm)、PSⅡ潜在活性(Fv/Fo)、实际光化学量子产量(Y)、净光合速率(Pn)、蒸腾速率(Tr)和最大净光合速率(Amax)影响显著,不同酸雨处理方式对幼苗SPAD、Fv/Fm、Y、Pn、Tr、Amax和光饱和点(LSP)影响显著,二者交互作用对SPAD、Fv/Fm、Y、Pn和Amax影响显著.

At three levels of simulated acid rainfall intensities with pH values of 2.5 （ severe）, 4.0 （medium） and 5.6 （light） respectively, the responses of chlorophyll fluorescence and photosyn- thetic parameters of Quercus glauca seedlings were studied in three acid rainfall treatments, i.e. on- ly the aboveground of seedlings exposed to acid rain （ T1 ） , both of the seedlings and soil exposed to acid rain （T2）, only the soil exposed to acid rain （T3 ） compared with blank control （CK）. Under the severe acid rainfall, T1 significantly inhibited chlorophyll synthesis, and thus reduced the pri- mary photochemical efficiency of PS Ⅱ （ Fv/Fm ） , potential activity of PS Ⅱ （ Fv/Fo ） , apparent quantum （ Y）, net photosynthetic rate （ Pn ）, and transpiration rate （ Tr） , but increased the light compensation point （LCP） and clark respiration rate （Rd ） of Q. glauca seedlings. T2 inhibited, but T3 played a little enhancement on the aforementioned parameters of Q. glauca seedlings. Under the conditions of medium and light acid rainfall intensities, the above parameters in the three treat- ments were higher than that of CK, except with lower Rd. The chlorophyll fluorescence and photo- synthetic parameters showed a similar tendency in the three treatments, i.e. T2 〉T3 〉T1. It indica- ted that T1 had the strongest inhibition on seedlings in condition of the severe acid rainfall, while T2 had the most dramatic facilitating effect on seedlings under the medium and light acid rainfall. In- tensity of acid rainfall had significant influences on SPAD, Fv/Fm, Fv/Fo, Y, Pn, Tr and maxi- mum photosynthetic rate （Amax ） , whereas treatments of acid rainfall affected SPAD, Fv/Fm, Y,Pn, Tr, Amax and light saturation point （LSP）. The interaction of acid rainfall intensities and treat- ments played significant effects on SPAD, Fv/Fm, Y, Pn and Amax.