Abstract: Relying on China's Rice FACE Platform （Free air CO₂ enrichment）, under two fertilization methods, namely, fertilizer and 50% organic fertilizer instead of chemical fertilizer, the effects of increasing atmospheric CO₂ concentration （ambient atmosphere +200 μmol/mol） on photosynthesis, antioxidant enzyme activity and copper and zinc absorption in rice were studied. The results showed that increasing CO₂ concentration significantly increased the net photosynthetic rate, and malondialdehyde content in rice leaves at the heading stage and zinc content in rice grains at the maturity stage, but significantly decreased the stomatal conductance and antioxidant enzyme activities of rice leaves at the heading stage. Under the treatment of chemical fertilizer replaced by 50% organic fertilizer （COF）, compared with the normal atmospheric CO₂ concentration, the increase of atmospheric CO₂ concentration significantly increased the peroxidase activity, but decreased the stomatal conductance and transpiration rate of rice leaves, the content of malondialdehyde and the contents of copper and zinc in rice grains. Therefore, the substitution of chemical fertilizer with 50% organic fertilizer at equal nitrogen application could help to improve the adaptability of rice to the increase of CO₂ concentration.

Key words: increasing CO₂ concentration, rice, substituting the chemical fertilizer with organic fertilizer, photosynthesis, heavy metal content, antioxidant enzyme activity