中文摘要：

通过田间小区试验,选择3个小麦品种,在不同氮素水平下,在测定小麦冠层反射光谱和叶片氮素含量基础上,提出小麦冠层光谱角算法,分析小麦冠层光谱角与氮素营养水平的定量关系。结果发现：对选择的3个小麦品种,光谱角均随氮素施用量增加而增大,光谱角预测叶片氮素的最佳模型为y=0.3999x^0.3989,其决定系数R^2为0.6870,其预测的RE、RMSE和R^2分别为1.63%、0.1609、0.7515。利用光谱角算法可以监测小麦冠层氮素营养的差异。

英文摘要：

Nitrogen is an important factor for crop growth and environment. A search for real-time,rapid and accurate monitoring methods on nitrogen nutrition is a necessary approach for precise fertilization and efficiency enhancement. In this paper,three wheat varieties（ Xinchun 6,Xinchun 17 and Xinchun 22） were selected to investigate the correlations between the canopy hyperspectral characteristics at four nitrogen levels and the leaves nitrogen content（ LNC）,and thereby an improved spectral angle（ SA） could be utilized for prediction of LNC. The spectral angles of wheat canopy by different nitrogen treatments were higher with the nitrogen increased and the best spectral angle model for prediction of leaf nitrogen was y = 0. 3999x^0. 3989. The coefficient of determination R^2 was 0.6870,and the RE,RMSE and R^2 were 1. 63%,0. 1609,and 0. 7515,respectively. Spectral angle was feasible for monitoring differences in leaves nitrogen content,providing a theoretical basis for precise fertilization in agriculture.