中文摘要：

试验以珙桐幼苗为材料,探讨了重金属（Hg（2＋）和Cd（2＋））对珙桐（Davidia involucrata Baill.）光合作用的影响。结果表明：Hg Cl2溶液浓度≥50 mg·L（-1）时,Pn显著下降;Hg Cl2溶液浓度〈200 mg·L（-1）时,Ci显著增加;但在1 000 mg·L（-1）和2 000 mg·L（-1）Hg Cl2溶液时,Ci显著下降;Hg Cl2溶液浓度≥200 mg·L（-1）时,Gs显著下降。当Cd Cl2溶液为10mg·L（-1）时,Pn、Gs和Ci较对照变化不显著;而在Cd Cl2溶液为20 mg·L（-1）后,Pn、Gs和Ci均显著下降;随着Cd Cl2浓度不断增大（≥50 mg·L（-1））,Pn和Gs显著下降,而Ci呈显著上升。因此利用不同浓度的Hg Cl2溶液和Cd Cl2溶液分别短时处理幼苗后,对其光合作用产生了极大的影响,其中Cd Cl2的影响相对较小。

英文摘要：

To test the effect of two heavy metal ions（ Hg（2＋）and Cd（2＋）） on photosynthesis of Davidia involucrata,we carried out with different concentrations of Hg Cl2 and Cd Cl2 solution. The results show that when the applied Hg Cl2 concentration was more than 50 mg · L（-1）,Pn decreased significantly. When the content solution of Hg Cl2 was less than 200 mg · L（-1）,Gi increased obviously. When Hg Cl2 concentration was more than 200 mg · L（-1）,Gs decreased obviously. And Ci decreased obviously by concentrations of Hg Cl2 at 1 000 mg · L（-1）and 2 000 mg ·L（-1）. Relative to control,the changes of Pn,Gs and Ci were not obvious at the treated Cd Cl2 concentration 10 mg ·L（-1）. After 20 mg · L（-1）Cd Cl2 solution was daubed,Pn,Gs and Ci decreased apparently. With the increase of treated Cd Cl2concentrations（ ≥ 50 mg · L（-1））,Pn and Gs decreased significantly,Ci increased obviously. In the short time treatment experiment,the concentration of Hg Cl2 and Cd Cl2 solution both have great influence on the photosynthesis in D. involucrata seedlings and the influence of Hg Cl2 is more significant than that of Cd Cl2.