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依托FACE技术平台,采用稳定13C同位素技术,通过将小麦(C3作物)种植于长期单作玉米(C4作物)的土壤上,研究了大气CO2浓度升高和不同氮肥水平对土壤排放CO2的δ13C值及根际呼吸的影响.结果表明:种植小麦后土壤排放CO2的δ13C值随作物生长逐渐降低,CO2浓度升高200μmol·mol-1显著降低了孕穗、抽穗期(施氮量为250kg·hm-2,HN)与拔节、孕穗期(施氮量为150kg·hm-2,LN)土壤排放CO2的δ13C值,显著提高了孕穗、抽穗期的根际呼吸比例.拔节至成熟期,根际呼吸占土壤呼吸的比例在高CO2浓度下为24%～48%(HN)和21%～48%(LN),在正常CO2浓度下为20%～36%(HN)和19%～32%(LN).不同CO2浓度下土壤排放CO2的δ13C值和根际呼吸对氮肥增加的响应不同,CO2浓度与氮肥用量在拔节期对根际呼吸的交互效应显著.
Relying on the FACE technology platform, stable 13C isotope techniques were used to study the effects of elevated atmospheric CO2 concentration and δ13C values of different nitrogen levels on soil CO2 emissions by planting wheat (C3 crop) on long-term monoculture corn (C4 crop) And rhizospheric respiration.The results showed that the δ13C value of soil CO2 emission after wheat planting decreased gradually with the growth of the crop and the CO2 concentration of 200 μmol · mol-1 significantly reduced the booting and heading stages (the nitrogen application rate was 250 kg · hm- 2, HN) and δ13C values of CO2 emission at jointing and booting stage (150 kg · hm-2, LN), significantly increased the rhizospheric respiration rate at booting and heading stages. Soil respiration rates were 24% -48% (HN) and 21% -48% (LN) at high CO2 concentrations and 20% -36% (HN) and 19% -32% at normal CO2 concentrations LN) .The δ13C values of soil CO2 emissions and rhizospheric respiration at different CO2 concentrations had different response to the increase of nitrogen fertilizer, and the interaction effects of CO2 concentration and nitrogen fertilizer on rhizosphere respiration were significant at jointing stage.