Monitoring Plant Nitrogen Accumulation With Hyperspectral Remote Sensing In Winter Wheat

In this paper, the winter wheat (Jing9428) was planted in Shanxi Agricultural University crop station as subject to measure hyperspectral reflectance and agronomic parameters in different growth stages. The correlations between the agronomic parameters, nitrogen accumulation and canopy hyperspectral reflectance, first derivative spectral of winter wheat were analyzed. According to the technology path of spectral parameters-agronomy parameters-nitrogen accumulation, the predicting models of nitrogen accumulation based on parameters by linking the above two models with agronomic parameter as intersection were constructed in winter wheat. The results showed that:1The canopy spectral reflectance of winter wheat treated with different nitrogen statues had a similar tendency during different growth period. There was an obvious spectral peak in510-650nm, and the reflectance lifted rapidly during650-750nm, reflectance values were high in near-infrared platform, and have an obvious peak and trough. There was a "Twin Peaks" phenomenon in the red edge region of first derivative Spectral reflectance. Meanwhile, reflection gradually weakened with the growth and development of winter wheat.2At different growth stages of winter wheat, chlorophyll content, carotenoid content, LAI and aboveground biomass changed consistency that was "heading stages> jointing stages> filling stages". After the treatments of different nitrogen statues, four agronomic parameters increased with nitrogen levels.3In jointing stage of winter wheat, there was significant correlation between chlorophyll content and FDRVI (678,887) FDRVI (678,899) FDRVI (678,934), carotenoid content and FDMSAVI2(678,935) FDRVI (678,888) FDRVI (678,935), LAI and FDDVI(634,1016) FDRDVI(634,1016) FDMSAVI2(634,1016), aboveground biomass and FDDVI (670,1129) FDNDVI (670,956) FDMSAVI2(670,1129). In heading stages, there was significant correlation between the chlorophyll content of winter wheat and RVI (759,1080) RDVI (759,1095) RDVI (759,1096), carotenoid content and FDDVI (760,1096) FDRDVI (760,922) FDMSAVI2(760,1096), LAI and FDDVI (656,806) FDDVI (656,822) FDMSAVI2 (656,822), aboveground biomass and FDDVI (758,800) FDRDVI (758,800) FDMSAVI2(758,800).In Filling stage, there was a significant correlation between chlorophyll content and Dy, λr and SDy, carotenoid content and FDDVI (679,801) FDMSAVI2(679,801), λr, LAI and FDDVI (754,816) FDRDVI (754,816) λr, aboveground biomass and FDDVI (757,830) FDDVI (757,961) λr.4. The correlation between the chlorophyll content, carotenoid content, LAI, aboveground biomass and nitrogen accumulation of the jointing stages, heading stages and filling stages were analyzed. The results showed that four agronomy parameters significantly related to nitrogen accumulation.5the nitrogen accumulation monitoring model of winter wheat was constructed with the connection point of agronomic parameters. The best agronomic parameter was chlorophyll content to monitor the nitrogen accumulation in jointing, heading and filling stages. Meanwhile, the best arguments were FDRVI (678,934) FDRVI (759,1080), Xr. Then, the agronomic parameter was LAI, the best spectral parameters were FDMSAVI2(634,1016), FDMSAVI2(656,822) and λr.