中文摘要：

本文以3种蛋白质类型的小麦品种在不同施氮水平下的3年田间试验为基础，研究了小麦叶片氮含量与冠层反射光谱的定量关系。结果显示，不同试验中拔节后叶片氮含量均随施氮水平呈上升趋势，同时冠层光谱反射率在不同施氮水平下存在明显差异。对于低、中、高籽粒蛋白质含量的品种，叶片氮含量与冠层反射光谱的归一化植被指数NDVI（1220，710）和红边位置均有密切的定量关系，决定系数在0．80左右。对于不同品质类型小麦品种，均可利用统一的回归方程描述其叶片氮含量随反射光谱参数的变化，对于低蛋白类型品种，采用单独的回归系数即可提高叶片氮含量估测的准确性。本研究确立的小麦叶片氮含量与冠层反射光谱的定量关系可用于不同的小麦品种、生育时期和施氮水平，为小麦氮素营养的监测诊断与精确施肥等提供理论依据和技术途径。

英文摘要：

Experiment one was conducted with two cuhivars （Xuzhou 26 and Huaimai 18） and four N application levels of 0,120,210 and 300 kg ·ha^-1 in 2001. Experiment two was designed for one cultivar, Yangmai 10, with three N application levels of O, 150 and 300 kg·ha^-1 in 2002. Experiment three included four cultivars （Xuzhou 26, Huaimai 20, Ningmai 9 and Yangmai 10） with five nitrogen levels of 0,75,150,225,300 kg·ha^-1 in 2003. On the basis of characterized protein content of these five cultivars, Xuzhou 26 and Ningmai 9 were considered as high and low protein types, respectively, and the other three cultivars were thought to be medium-protein type. The results showed that the nitrogen concentration in wheat leaves was increased with increasing nitrogen fertilizer, whereas the canopy reflectance was also significantly different under varied nitrogen application. For the different cultivar types with low, medium and high grain protein contents, the relationships of leaf nitrogen concentration to NDVI （1 220, 710） and red edge position of canopy reflectance spectra were all highly significant with R^2 of 0.80（Fig. 1 and Fig. 2）. An integrated regression equation could be used to describe the dynamic change pattern of leaf nitrogen concentration with reflectance spectra parameters in different cultivar types, although separate regression coefficients enhanced the prediction accuracy in low protein type. The above dynamic relationships of leaf nitrogen concentration to canopy reflectance spectra were feasible for different cultivars, growing stages and nitrogen levels in wheat. These results provide a theoretical basis and technical approach for monitoring of plant nitrogen status and precision management of nitrogen fertilization in wheat production.