节水灌溉稻田水碳通量日变化特征

为了揭示不同天气条件对节水灌溉稻田水碳通量日变化的影响,采用涡度相关系统对节水灌溉稻田水碳通量进行了连续监测,分析了不同天气条件下节水灌溉稻田水汽与CO_2日变化特征。结果表明:节水灌溉稻田各月阴天与晴天典型日内水碳通量变化趋势相似,阴天变化呈现多峰变化,晴天下变化较稳定。夜间和凌晨变化较小,差异也较小,白天差异较大。水稻全生育期各月阴天下典型日稻田水汽通量的峰值是晴天下水汽通量峰值的0.5倍左右。各月之间阴天和晴天的水汽通量在生育中期的八九月峰值均较大。节水灌溉稻田夜间以呼吸排放CO_2为主,白天以光合固定CO_2为主。7、10月阴天典型日稻田CO_2通量峰值是晴天峰值的0.5倍左右,而在水稻生长旺盛的八九月,两种天气条件稻田CO_2通量日变化多数时段偏差较小。

Effect of Weather Conditions on Diurnal Variation of Water and Carbon Fluxes of Paddy Fields Under Water-saving Irrigation

In order to reveal the effect of weather conditions on water and carbon fluxes of paddy fields under water-saving irrigation , diurnal variation of water and carbon fluxes was analyzed based on experimental data measured by eddy covariance method .The re‐sults showed that diurnal variations of water and carbon fluxes under water-saving irrigation in sunny and cloudy days had the similar variation trend ;water and carbon fluxes under water-saving irrigation presented multi-peak variation in cloudy days and steady varia‐tion in sunny days ;the differences of water and carbon fluxes under water-saving irrigation between sunny and cloudy days were higher in daytime than those in nighttime ;the water flux peaks in typical cloudy days were 0 .5 times of those in typical sunny days in different months of the whole rice growth stages ;the water fluxes of paddy fields under water-saving irrigation were higher during August and September than those in other months ;paddy fields under water-saving irrigation showed net CO2 absorption during the daytime and the net CO2 release at nighttime ;the CO2 flux peaks in typical cloudy days were 0 .5 times of those in typical sunny days during July and October ;the differences of CO2 flux peaks between typical cloudy and sunny days were small during August and September .