Monitoring influence of different fertilization decision treatments on winter wheat growth using hyperspectral spectrum and comparative analysis

In order to clarify the characteristics of canopy spectrum of winter wheat under the condition of different fertilizations, and to select the best variable fertilization algorithm, a field experiment was conducted in the year 2006 during winter wheat growth period. The indices of winter wheat including canopy spectrum and yields under six different fertilizer treatments were studied. The results show that through the analysis of the canopy spectral reflectance after the fertilization, variations of the reflectance before and after the fertilization, and the normalized difference vegetation index in different growth stages, there are some differences of canopy reflectance in winter wheat under different fertilizer treatments. The fertilization algorithm based on the spectral index and crop growth model (Z) is the best one. Compared with the uniform fertilization (W) and no fertilization (CK), the variable fertilizer treatments improve wheat yields significantly, the variation coefficients of yield are reduced, except the treatment based on soil nutrient (T), and the one of fertilization treatment based on the normalized SPAD value (S) is the smallest. The Z variable rate fertilization algorithm is the best in combined effect and the S variable fertilization algorithm is better in reducing yield variability. The effect of fertilization at the jointing stage on the wheat growth at the flowering or early filling stages is the biggest. A significantly correlation is observed between the vegetation indexes at the flowering or early filling stages and yield, especially Rededge triangular vegetation index (RTVI) (r=0.700), so we can use RTVI index to predict grain yield of winter wheat.