模拟酸雨对濒危物种夏蜡梅幼苗生理生态特性的影响

以濒危物种夏蜡梅(Sinocalycanthus chinensis)幼苗为对象，研究了不同强度酸雨（pH2.5、pH3.5、pH4.5和pH5.6（CK））对其生理生态特性的影响。结果表明：7月，不同强度酸雨处理下，净光合速率日变化均呈单峰曲线；随着酸雨pH值的降低，日均P_n值下降，各处理组之间均差异极显著。随着酸雨pH值的降低，夏蜡梅幼苗最大净光合速率(P_nmax)、光饱和点（LSP）、叶绿素相对含量（SPAD）逐渐下降。而光补偿点（LCP）、暗呼吸速率（R_d）随着酸雨pH值的降低而升高。pH3.5、pH2.5处理夏蜡梅幼苗表观量子效率（AQE）比对照低，而pH4.5处理比对照高。F_v/F_m、F_v/F_o随着酸雨pH值的降低而减小。酸雨胁迫增强了超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性，增加了丙二醛（MDA）的含量、提高了质膜的透性。总之，酸雨胁迫降低了夏蜡梅的光合能力，对其它生理指标产生不利的影响。

Effects of Simulated Acid Rain on Physiological and Ecological Characteristics of Sinocalycanthus chinensis

The physiological and ecological characteristics of the endangered Sinocalycanthus chinensis seedlings with the treatments of simulated acid rain of pH2.5, pH3.5, pH4.5 and pH5.6 (control) were determined and analyzed. The results showed that, in all treatments, the day variation of net photosynthetic rate of S.chinensis was a curve with one peak in July. The mean daily net photosynthetic rate reduced with the increasing of the acidity with significant differences among different treatments. The maximum net photosynthetic rate, light saturation point and the relative chlorophyll content decreased gradually with the increasing of the acidity, while the dark respiration rate and the light compensation point increased gradually with the increasing of the acidity. The apparent quantum yields in the treatments of pH2.5 and pH3.5 were lower that the control, while that in the treatment of pH4.5 was higher than the control. F_v/F_m and F_v/F_o reduced with the increasing of the acidity. The activity of peroxidase and superoxide dismutase, the content of malonydialdehyde and the membrane permeability significantly increased with the increasing of the acidity. The results suggested that simulated acid rain could reduce the photosynthetic capacity and had detrimental effect on the physiological traits of S.chinensis.