| 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=0.3999x0.3989. The coefficient of determination R2 was 0.6870, and the RE, RMSE and R2 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. |