大气CO2摩尔分数升高对高、低应答水稻稻田N2O排放的影响

依托稻田大气CO₂摩尔分数（x［CO₂］）升高平台FACE （free-air CO₂ enrichment）,采用静态透明箱-气相色谱法研究x［CO₂］升高（正常x［CO₂］+200 μmol·mol^-1）对高、低应答水稻（产量对x［CO₂］升高的响应分别为>30%和10%~15%）稻田N₂O排放的影响.本试验设置4个处理：A-W （正常x［CO₂］+低应答水稻）、F-W （x［CO₂］升高+低应答水稻）、A-S （正常x［CO₂］+高应答水稻）和F-S （x［CO₂］升高+高应答水稻）.结果表明,对比正常x［CO₂］处理（A-S和A-W）,x［CO₂］升高条件下高、低应答水稻（F-S和F-W）稻田N₂O排放分别降低52.54%（P<0.05）和38.40%（P<0.05）,水稻产量分别增加22.96%（P<0.05）和12.11%（P>0.05）,稻田N₂O排放强度分别降低61.68%（P<0.05）和45.13%（P<0.05）.另外,高、低应答水稻稻田N₂O排放与稻田土壤NH₄⁺-N含量呈显著相关关系,而与NO₂^--N含量无显著相关.x［CO₂］升高条件下,土壤温度是影响高应答水稻稻田N₂O排放的重要因素.综合考虑,未来x［CO₂］升高条件下,高应答水稻品种的"增产减排"效果最佳.

Effect of Elevated CO2 on N2O Emissions from Different Rice Cultivars in Rice Fields

Using the free air CO₂ enrichment (FACE) platform, an in-situ field experiment was conducted to explore the impacts of elevated CO₂ mole fraction (xCO₂]) on N₂O emissions from strongly and weakly responsive rice cultivars. Under elevated xCO₂], grain yield of the strongly responsive rice cultivars increased significantly, by more than 30%, whereas the weakly responsive cultivars showed a growth rate of 10%-15%. The four treatments comprised A-W (normal xCO₂]+weakly responsive cultivar), F-W (elevated xCO₂]+weakly responsive cultivar), A-S (normal xCO₂]+strongly responsive cultivar), and F-S (elevated xCO₂]+strongly responsive cultivar). Compared to the normal xCO₂] treatments (A-S and A-W), when the strongly and weakly responsive cultivars were exposed to elevated xCO₂](F-S and F-W), N₂O emissions decreased by 52.54% (P<0.05) and 38.40% (P<0.05), rice yield increased by 22.96% (P<0.05) and 12.11% (P>0.05), and N₂O emission intensity decreased by 61.68% (P<0.05) and 45.13% (P<0.05), respectively. Moreover, N₂O emissions of all treatments were significantly positively correlated with NH₄⁺-N content (P<0.05), whereas not correlated with NO₂^--N content. Soil temperature is an important factor affecting the N₂O emissions of the strongly responsive cultivar in rice fields under elevated xCO₂] conditions. Through comprehensive consideration of climate conditions, in the future, priority should be given to planting the strongly responsive cultivar, ensuring high rice yield and significant reduction in N₂O emissions.