UV-A辐射对土壤-冬小麦系统呼吸速率和N2O排放的影响

Influence of UV-A Radiation on Respiration Rate and N_2O Emission in Soil-Winter Wheat System

为研究UV-A辐射增强对土壤-冬小麦系统微量气体释放的影响规律,通过室外盆栽试验,人工模拟UV-A辐射增强,UV-A辐射强度处理分别比自然光(CK)增加10%(T1)和20%(T2)。采用静态箱-气相色谱法测定了不同UV-A辐射强度下裸土、土壤-冬小麦系统的呼吸速率和N2O排放通量。结果表明:T1和T2处理下裸土呼吸速率分别比CK高83%(P=0.022)和263%(P=0.038),T2处理比T1高99%(P=0.073);T1和T2处理使裸土N2O排放通量比CK分别增加了64%(P=0.019)和186%(P=0.059),但T2与T1处理间的N2O排放通量差异不显著(P=0.123)。UV-A辐射增强没有显著影响土壤-冬小麦系统的呼吸速率大小;T2处理下土壤-冬小麦系统的N2O排放通量显著高于CK(P=0.012)和T1(P=0.010),分别比CK和T1高33%和40%,但T1和CK的N2O排放通量无显著差异(P=0.352)。UV-A辐射增强没有影响冬小麦生物量(P>0.05),但T2处理下土壤-冬小麦系统的土壤微生物碳和亚硝酸氧化菌的数量明显高于对照。

Extensive work has been done to understand the effect of enhanced UV-B （280-320 nm） radiation because of the depletion of the stratospheric ozone layer on plants, however, the available information related to the effect of UV-A （320-400 nm） on plants or ecosystem is limited. It merits further studies due to the facts that UV-A constitutes a major portion of the solar radiation and passes through the stratospheric ozone layer almost unattenuated. To investigate the impact of enhanced UV-A radiation on trace gases emission from bare soil and soil-winter wheat system, outdoor pot experiments with simulating 0%（CK）, 10% （T1） and 20% （T2） supplement of UV-A were conducted, and static dark chamber-gas chromatograph method were used to measure respiration rate and N2O emission fluxes. Results indicated that enhanced UV-A radiation increased respiration rate and N2O emission fluxes in bare soil, soil respiration rates of T1 and T2 were 1.83 and 3.63 times larger than those of CK （P=0.022, 0.038, respectively）, and soil respiration rates of T2 were 1.99 times larger than those of T1 （P= 0.073）. N2O emission fluxes in bare soil of T1 and T2 were 1.64 and 2.86 times larger than that of CK （P=0.019, 0.059, respectively）, while there no significant difference between T2 fluxes and T1 fluxes （P=0.123）. Enhanced UV-A radiation had no significant impact on respiration rate of soil-winter Wheat system, but 20% supplemental UV-A radiation increased significantly N2O emission fluxes from soil-winter wheat system,N2O emission fluxes of T2 were 1.33 and 1.40 times larger than those of CK （P=0.012） and T1 （P=0.010）, while T1 and CK had no significant difference in N2O emission fluxes （P=0.352）. In addition, enhanced UV-A radiation had no significant impact on biomass of winterwheat （P〉0.05）, but soil microbial biomass C and nitrite-oxidation bacteria quantity of T2 were obviously higher than those of CK.