大气CO_(2)摩尔分数升高对高、低应答水稻稻田N_(2)O排放的影响

Effect of Elevated CO_(2) on N_(2)O Emissions from Different Rice Cultivars in Rice Fields

依托稻田大气CO_(2)摩尔分数(x[CO_(2)])升高平台FACE(free-air CO_(2) enrichment),采用静态透明箱-气相色谱法研究x[CO_(2)]升高(正常x[CO_(2)]+200μmol·mol-1)对高、低应答水稻(产量对x[CO_(2)]升高的响应分别为>30%和10%~15%)稻田N_(2)O排放的影响.本试验设置4个处理:A-W(正常x[CO_(2)]+低应答水稻)、F-W(x[CO_(2)]升高+低应答水稻)、A-S(正常x[CO_(2)]+高应答水稻)和F-S(x[CO_(2)]升高+高应答水稻).结果表明,对比正常x[CO_(2)]处理(A-S和A-W),x[CO_(2)]升高条件下高、低应答水稻(F-S和F-W)稻田N_(2)O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N_(2)O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N_(2)O排放与稻田土壤NH^(+)_(4)-N含量呈显著相关关系,而与NO^(-)_(2)-N含量无显著相关.x[CO_(2)]升高条件下,土壤温度是影响高应答水稻稻田N_(2)O排放的重要因素.综合考虑,未来x[CO_(2)]升高条件下,高应答水稻品种的“增产减排”效果最佳.

Using the free air CO_(2) enrichment(FACE)platform,an in-situ field experiment was conducted to explore the impacts of elevated CO_(2) mole fraction(x[CO_(2)])on N_(2)O emissions from strongly and weakly responsive rice cultivars.Under elevated x[CO_(2)],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 x[CO_(2)]+weakly responsive cultivar),F-W(elevated x[CO_(2)]+weakly responsive cultivar),A-S(normal x[CO_(2)]+strongly responsive cultivar),and F-S(elevated x[CO_(2)]+strongly responsive cultivar).Compared to the normal x[CO_(2)]treatments(A-S and A-W),when the strongly and weakly responsive cultivars were exposed to elevated x[CO_(2)](F-S and F-W),N_(2)O 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 N_(2)O emission intensity decreased by 61.68%(P<0.05)and 45.13%(P<0.05),respectively.Moreover,N_(2)O emissions of all treatments were significantly positively correlated with NH^(+)_(4)-N content(P<0.05),whereas not correlated with NO^(-)_(2)-N content.Soil temperature is an important factor affecting the N_(2)O emissions of the strongly responsive cultivar in rice fields under elevated x[CO_(2)]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 N_(2)O emissions.