A Model On Monitoring Nitrogen Content And Growth Status Of Wheat Based On Hyperspectral Remote Sensing In Temporal And Spatial Changes

Research object:Nitrogen nutrition on crop yield and quality play an important role,but unreasonable application of nitrogen will result in waste of resources and ecological environment destruction. High quality wheat production is an urgent need for agricultural development in China, which N is the impact of wheat yield and quality. Run-time and accurate monitoring nitrogen nutrition of wheat in time and space changes lay better foundation for precision nitrogen management. Hyperspectral remote sensing technology in the field of water, fertilizer, nutrition and growth of monitoring crop showed strong predominance, and is the main mean to time quantitative monitoring of crop growth. At present, the use of high-spectral monitoring crop nitrogen status and growth have also carried out to determine sensitive spectrum band of nitrogen and construction of spectral model parameters.However, canopy spectra of various organs of wheat is "mixed spectrum", leaf nitrogen content in different growth stages also shows a certain distribution in spatial structure. In order to study the relativity of canopy reflectance and N content and the growth parameters, selection of appropriate characteristic parameters and vegetation indices, the establishment of nitrogen Nutrition Diagnosis and growth monitoring model at different temporal and spatial variations, this article based on canopy nitrogen distribution characteristics in time and space. Finally we are raising the remote sensing estimation level to provide the basis for crop monitoring for better use of satellite imaging spectrometer data.Research method:On the level of different nitrogen treatment analying the relativity different varieties and canopy spectrometry by using statistical analysis method and differential spectral, we establish the appropriate regression model and carry out model and accuracy verification.Results:The results show that, under different nitrogen levels,in the early-middle period the relativity between canopy reflectance and nitrogen nutrition index(NAI) built by the relationship between nitrogen and dry matter, the NAI is better, and spectral index of red edge inflection point (REP) is the best. Nitrogen abundance (NR) is a comprehensive index for the growth conditions and population N status and in the middle and late period correlation coefficient between canopy reflectance and NR has a highly significant (a=0.01), which RVI and VD672 have best performance. Therefore, through the NR and NAI we established nitrogen nutrition diagnosis and growth monitoring model based on plant canopy reflectance at different time.For monitoring growth parameters, chlorophyll, leaf dry weight and leaf area is a comprehensive reflection in field growing conditions. The better correlation of spectral parameters is concentrated in the vicinity of the red edge, and it is bad for the characteristic bands between canopy spectral reflectance and chlorophyll content from seedling to tillering and good for jointing to the filling stage.The two spectral parameters VOG2 and RVI near the red edge can monitor winter wheat growth condition.For monitoring leaf nitrogen content in Spatial change, the correlation between RVI of multi-angle (00)spectra and LNC is best in the tilling stage and RVI (00) can be well predicted canopy LNC.