[Impacts of enhanced UV-B radiation on respiration rate, CH4 and N2O emission fluxes from rice paddy].

To investigate the impacts of enhanced UV-B radiation on respiration rate, CH4 and N2O emission fluxes from soil-rice system, outdoor pot experiment was carried out during the rice growing season in 2004. The enhanced UV-B radiation treatments were simulated by a 20% increase in its intensity. The gas emission fluxes were measured by static chamber-gas chromatograph method. Results showed that enhanced UV-B radiation (T) did not change the seasonal patterns of respiration rate, CH4 and N2O emission. Compared to the control, mean respiration rate of T was decreased by 3.11%, from (1 306.83 +/- 100.21) mg x (m2 x h)(-1) to (1 266.23 +/- 147.60) mg x (m2 x h)(-1); Mean CH4 fluxes was decreased by 15.84%, from (2.40 +/- 0.48) mg x (m2 x h)(-1) to (2.02 +/- 0.52) mg x (m2 x h)(-1); Mean N2O emission fluxes of T was increased by 5.41%, from (217.45 +/- 1.72) microg x (m2 x h)(-1) to (229.22 +/- 26.02) microg x (m2 x h)(-1), while there no significant differences (P > 0.05). Our findings suggested that enhanced UV-B radiation had no significant effects on respiration rate, CH4 and N2O emission fluxes of soil-rice system.