植株氮素浓度是反应作物氮素营养状况的关键指标, 对作物的产量与品质具有重要的影响。 作物大面积氮素营养的实时监测不仅对区域上氮肥投入提供决策, 而且还对区域上氮素循环的估算提供依据。 传统的地面传感器虽然有较高的精度, 但很难在区域尺度上大面积获取数据, 且目前存在的高光谱卫星影像如MODIS, Hyperion的空间分辨率普遍不高。 随着卫星遥感的发展, 近些年来高空间分辨率的多通道卫星逐渐发射升空, 这些高分辨率的卫星遥感数据将对大尺度上植被生理生化指标反演提供可能。 该研究从2014年—2016年在内蒙古阴山北麓武川县进行了三年不同氮水平的马铃薯田间试验, 借助地面马铃薯冠层高光谱实测数据, 模拟近几年发射的具有红边波段的多通道卫星WorldView-2和VENμS不同宽度波段, 并构建多种光谱指数, 建立光谱指数与马铃薯地上部植株氮素浓度的估测模型, 进行马铃薯关键生育期冠层氮素营养的实时监测。 结果表明, 波段宽度和波段位置的选择决定着光谱指数对氮素浓度的响应程度, 基于红边波段的光谱指数具有更高的灵敏性。 生育时期显著影响光谱指数对马铃薯地上部氮素浓度的估测能力, 苗期土壤背景对光谱反射率具有显著干扰, 马铃薯块茎形成期后植株氮素浓度的预测效果最佳。 基于WorldView-2和VENμS卫星红光、 红边和近红外特定波段构成的融合光谱指数NDRE/NDVI相对其他指数来说在马铃薯植株氮素浓度估测上更具优势, 与不同生育时期马铃薯植株氮素浓度都具有较高的相关性, 相关系数r在063～081之间。 其中, 生殖生长期基于VENμS卫星红光、 红边和近红外通道构成的融合光谱指数VENμS-NDRE/NDVI与马铃薯植株氮素浓度相关性最高（r=081）, 模型验证结果的决定系数为056, 且验证误差较小, RMSE和RE%分别为038%, 1045%, 模型估测值与实测值的验证斜率最接近1, 为082; WorldView-2-NDRE/NDVI与马铃薯植株氮素浓度也具有较高的相关性（r=074）, 模型验证结果的决定系数为049, 验证误差RMSE和RE%分别为041%和1112%, 模型估测值与实测值的验证斜率为078。 多通道卫星模拟的结果证明, 基于红边宽波段的融合光谱指数能用来进行马铃薯植株氮浓度的监测。

Plant nitrogen concentration (PNC) is one of the most important nutrient elements that directly affectscrop growth and yield. High-throughput ground-based remote sensing, passive or active re?ectance sensors, has the potential to provide more information for making better-informed management decisions for nitrogen fertilizer inputs at the canopy scale in real time but it is difficult to obtain data at the regional scale. For that multi-channel satellites with high spatial resolution (WorldView-2 and VENμS satellites with red edge bands) were tested in this study to estimating PNC on large scale at different growth stages of potato varieties. Experiments were conducted in 2014, 2015 and 2016 to remotely estimate the PNC of diverse potato varieties under different nitrogen levels in Wuchuan County of Northern Yin mountain, Inner Mongolia. The results showed that the combined spectral index NDRE/NDVI based on the red, red edge and near-infrared channels of the VENμS and WorldView-2 satellite is superior to other indices in estimating the PNC of potato varieties. The spectral index (NDRE/NDVI) of VENμS and WorldView-2 satellites had a high correlation with PNC at different growth stages, and the correlation coefficient ranged between 063 and 081. The spectral index (NDRE/NDVI) of VENμS had the highest correlation coefficient with PNC (r=081) at reproduction growth stage. The growth stages significantly affected the spectral index to estimate the PNC. The calibration models of spectral index (NDRE/NDVI) of two satellites based on the data of three years was validated to predict the PNC at reproduction growth stage. The predictive model of VENμS-NDRE/NDVI had the highest coefficient of determination (056), the lowest RMSE (038%) and RE (1045%) with a slope of 082, as well as the predictive model of WorldView-2-NDRE/NDV had higher coefficient of determination (049), lower RMSE (041%) and RE (1112%) with a slope of 078. In conclusion, the results of multi-channel satellite simulations showed that the combined spectral index based on the red edge width band can be used to monitor the PNC of potato varieties.