Responses of rice growth to copper stress under free-air CO2 enrichment （FACE）

The responses of rice to the second degree contamination of copper were studied by pot experiments under free-air CO2 enrichment （FACE） with 570 μmol ·mol^-1 of CO2. The results showed that the content of copper in rice leaves was reduced with the CO2 concentration reaching 570 μmol· mol^-1 and this happened more significantly under the second degree contamination of copper. Under FACE, activities of superoxide dismutase （SOD） enzyme in rice leaves treated by copper contamination were induced, whereas the contents of glutathione （GSH） and glutathione disulfide （GSSG） had no significant difference from the control. In the presence of ambient CO2, activities of SOD enzyme treated by copper pollution were suppressed during the whole rice growth, however, the contents of GSH and GSSG were induced at tillering and jointing stages, and then restored to the control levels in later growth under the second degree contamination of copper. With the rice growing, the content of malondialdehyde （MDA） rises continuously, but there had been no significant difference between the treatments at the same growth stage. Further studies are needed on the response mechanism of rice to Cu stress under elevated CO2.

Responses of rice growth to copper stress under free-air CO2 enrichment (FACE)

The responses of rice to the second degree contamination of copper were studied by pot experiments under free-air CO₂ enrichment (FACE) with 570 μmol·mol⁻¹ of CO₂. The results showed that the content of copper in rice leaves was reduced with the CO₂ concentration reaching 570 μmol·mol⁻¹ and this happened more significantly under the second degree contamination of copper. Under FACE, activities of superoxide dismutase (SOD) enzyme in rice leaves treated by copper contamination were induced, whereas the contents of glutathione (GSH) and glutathione disulfide (GSSG) had no significant difference from the control. In the presence of ambient CO₂, activities of SOD enzyme treated by copper pollution were suppressed during the whole rice growth, however, the contents of GSH and GSSG were induced at tillering and jointing stages, and then restored to the control levels in later growth under the second degree contamination of copper. With the rice growing, the content of malondialdehyde (MDA) rises continuously, but there had been no significant difference between the treatments at the same growth stage. Further studies are needed on the response mechanism of rice to Cu stress under elevated CO₂. Supported by the Key Project of the National Natural Science Foundation of China (Grant No. 40110817), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX3-SW-440), China Postdoctoral Science Foundation, and Jiangsu Planned Projects for Postdoctoral Research Funds