蒸腾作用和光合作用是两个密切联系、相互耦合的过程,主导作物的生理活动及产量形成,研究不同尺度水碳耦合关系对提高水分利用效率(WUE)意义重大.以光合仪、涡度相关仪等实测数据为依据,分析了我国华北地区夏玉米叶片和冠层尺度的光合与蒸腾(蒸散)的变化规律,率定和验证了SMPT-SB模型在这两个尺度的应用效果.结果表明,在夏玉米生育期典型日内,叶片尺度的光合与蒸腾速率,以及冠层尺度的光合与蒸散速率日变化趋势基本一致,但冠层尺度蒸散受表层土壤含水量的影响较大.SMPT-SB耦合模型估算的叶片光合、蒸腾和WUE与实测值之间的回归系数接近1,确定系数大于0.74,二者之间的相对误差小于11%,能够较好反映叶片光合与蒸腾之间的耦合关系.SMPT-SB耦合模型估算的冠层尺度光合与实测值一致性也较好,但该模型低估了表层土壤含水量较高时的冠层蒸散量,并在一定程度上导致了冠层WUE的高估.该研究为理解不同尺度水碳耦合关系及提高水分利用效率提供科学依据. Transpiration and photosynthesis are two closely related and mutually coupled processes that lead the physiological activities and yield formation of crops. It is of great significance to study the water-carbon coupling relationship at different scales to improve the water use efficiency (WUE) The law of photosynthesis and transpiration (evapotranspiration) of summer maize leaves and canopy in North China was analyzed, and the application effect of SMPT-SB model on these two scales was calibrated and verified.The results show that , The diurnal variation of photosynthesis and transpiration rate of leaf-scale photosynthesis and transpiration rate were basically the same in the typical days of summer maize growth period, but the canopy-level evapotranspiration was greatly affected by the surface soil moisture content.SMPT-SB The regression coefficient between leaf photosynthesis, transpiration and WUE measured by the coupled model is close to 1, and the coefficient of determination is greater than 0.74. The relative error between the two is less than 11%, which can better reflect the coupling relationship between leaf photosynthesis and transpiration The agreement between the photosynthesis and the measured values ​​estimated by the SMPT-SB coupling model is also good, but the model underestimates the canopy evapotranspiration when the surface soil moisture is high Led to overestimation canopy WUE to some extent. The study is to understand the different dimensions of water and carbon coupling relationship to improve water use efficiency to provide a scientific basis.