地表UV-B辐射增强对土壤-冬小麦系统N_2O排放的影响机理研究

Study on Mechanism of Enhanced UV-B Radiation Influencing on N_2O Emission from Soil-Winter Wheat System

为了解UV-B增强条件下农田N2O响应规律,采用室外盆栽实验,研究了地表UV-B辐射增强20%对土壤-冬小麦系统N2O排放的影响及其影响机理.结果表明,在小麦返青期,UV-B辐射增强处理对该系统N2O的排放影响不显著;在小麦的拔节期,UV-B辐射增强处理显著降低了土壤-小麦系统N2O的排放,并减少了该系统的呼吸速率.UV-B辐射增强对N2O的影响机理主要表现在对小麦植株N代谢过程的影响,如显著增加了植株叶片中可溶性蛋白质、TN、TP的含量.UV-B辐射增强对土壤产N2O的影响表现为间接影响,主要是显著增加了小麦根区土壤有效氮和土壤微生物碳、氮的量,并改变了土壤微生物的C/N,使之由5.0增至6.8.

To study the influencing mechanisms of enhanced UV-B radiation on the emission of N2O 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 N2O 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 wlnter-wheat rhizosphere.