[Study on mechanism of enhanced UV-B radiation influencing on N2O emission from soil-winter wheat system].

To study the influencing mechanisms of enhanced UV-B radiation on the emission of N20 from soil-wheat system, outdoor pot experiments with simulating 20% supplemental level of UV-B were conducted. Results indicate that the enhanced UV-B had no significant impact on the emission of N20 from soil-wheat system in turning- green stage, but declined the N2O flux and the rate of the system's respiration in elongation stage. The impact mechanisms of enhanced UV-B radiation on the N2O flux were to directly change the nitrogen metabolism process of wheat plant, such as significantly increasing soluble protein, total nitrogen and total phosphorus in wheat leaves. But the effects of UV-B radiation on soil N2O emission may be indirect, namely, UV-B treatment by working on wheat plant significantly increased the soil available nitrogen, soil microbial biomass C and N, and also changed the ratio of soil microbial C: N(from 5.0 to 6.8) in winter-wheat rhizosphere.