中文摘要：

为研究不同核心波长时波段宽度对小麦冠层叶片氮素营养监测精度的影响,以作物氮素营养无损监测仪的最佳光谱指数NDSI（R860,R720）和RSI（R990,R720）为例,分析核心波长的反射率、光谱指数及基于光谱指数的冠层叶片氮积累量监测模型随波段宽度的变化规律。结果显示,随波段宽度的增加,核心波长为720 nm时反射率快速上升,核心波长为860 nm时反射率非常缓慢下降,核心波长为990 nm时反射率缓慢上升;光谱指数NDSI（R860,R720）和RSI（R990,R720）逐渐减小;监测模型的建模精度和预测精度均逐渐减小,误差逐渐增大。860 nm和720 nm两个核心波长的适宜宽度分别小于96 nm和28 nm时,基于NDSI（R860,R720）的监测模型的表现保持稳定;990 nm和720 nm两个核心波长的适宜宽度分别小于3 nm和13 nm时,基于RSI（R990,R720）的监测模型的表现持续保持稳定。

英文摘要：

The responses of canopy spectral reflectance,optimum spectral indices and monitoring models for leaf nitrogen accumulation（LNA） in wheat to the changes in bandwidths were analyzed on the basis of the sensitive bands of 720 nm,860 nm and 990 nm.The results showed that with increasing bandwidth,the reflectance increased sharply at 720 nm and slowly at 990 nm,but decreased at 860 nm.The values of NDSI（R860,R720） and RSI（R990,R720） decreased gradually,along with reduced accuracy of calibration and validation for monitoring models.The monitoring models based on NDSI（R860,R720） displayed stable performance with the bandwidths of the key bands less than 96 nm and 28 nm,respectively,while those of RSI（R990,R720） less than 3 nm and 13 nm,respectively.These results helped to provide theoretical basis and technical approach for manufacturing economical portable nitrogen monitoring instrument.