模拟酸雨对乌药幼苗生理生态特性的影响

通过盆栽模拟酸雨喷淋实验，比较了不同酸雨酸度（pH值分别为2.5、3.5、4.5和5.6（CK））下，乌药(Lindera aggregata) 幼苗光合作用、叶绿素荧光、膜脂过氧化以及抗氧化酶活性的差异，探讨酸雨胁迫对乌药幼苗生理生态特性的影响.结果表明：夏季，不同酸雨酸度处理下，净光合速率日变化均呈单峰曲线，日均净光合速率随着酸雨酸度的升高而降低.随酸雨酸度的升高，乌药幼苗的最大净光合速率、相对叶绿素含量均显著降低，且pH 2.5处理的影响更为显著.酸雨处理降低了乌药的光饱和点(LSP)，而pH 2.5、pH 3.5处理的暗呼吸速率(R_d)、光补偿点(LCP)显著高于对照.F_v/F_m随着酸雨酸度的增加而减小，过氧化物酶活性(POD)、丙二醛(MDA)含量和质膜透性随酸度的增加均显著升高.超氧化物歧化酶(SOD)活性在pH 4.5处理时显著升高，pH 2.5时显著降低，而pH 3.5时与对照差异不大.总之，酸雨降低了乌药的光合能力，对其他生理指标均产生了显著的影响.

Effects of simulated acid rain on the ecophysiological characteristics of Lindera aggregata

Acid deposition in East Asia is more serious since the accelerated rate of economic development in this are- a. Acid rain can cause damage to plants and inhibit the growth and productivity of plants. Lindera aggregata （Lauraceae） is a famous traditional Chinese medicine and widely distributed in the South-eastern Asia. In order to e- valuate the effect of simulated acid rain on the growth of L. aggregata, we conducted a pot experiment with acid rain simulated by the spraying of a mixture of concentrated HzSO4 and HNO3 （V ： V=8 ： 1）. Membrane lipid peroxida- tion and antioxidant enzyme activity of L. aggregata with the application of simulated acid rain with pH 2.5, pH 3.5, pH 4.5 and pH 5.6 （CK） were determined and analyzed. The results are shown in the following. In all of the treat- ments, the day variation of net photosynthetic rate of L. aggregata is a curve with one peak. The mean daily net photosynthetic rate reduces with the increasing of the acidity. The maximum net photosynthetic rate and the relative chlorophyll content significantly decreased with the increasing of the acidity. Simulated acid rain significantly reduces the light saturation point of L. aggregata . In the treatments with pH 2.5 and 3.5, the dark respiration rate and the light compensation point are significantly higher than the other treatments. Fv/Fm reduces with the increasing of the acidity, the activity of peroxidase, The content of malonydialdehyde and the membrane permeability were signifi- cantly increase with the increasing of the acidity. The activity of superoxide dismutase significantly increases in the treatment with pH 4.5 and significantly decreases in the treatment and pH 2. 5, with no significant change in the treatment with pH 3.5. The results suggeste that simulated acid rain could reduce the photosynthetic capacity and has significant effects on the physiological traits of of L. aggregata.