Research On The Rice Nitrogen Diagnosis Model By The Canopy Reflectance

Nitrogen was the essential element in rice growth and development process, the diagnosis of nitrogen nutrition in Rice by spectral remote sensing technology can provide a certain theoretical basis and technology for actual agricultural production. Different nitrogen conditions, the rice growth and leaf color will show inconsistent, so can form different spectral response characteristic, according to these characteristics can be inversion of nitrogen nutrition of rice, this study cropping as the research object, to rice canopy spectral reflectance under different nitrogen levels, on the basis of analysis of the rice canopy spectral reflectance under different nitrogen levels and rice leaf chlorophyll content, leaf nitrogen content and other physiological indexes, through comparative analysis to summarize the correlation between leaf chlorophyll content and leaf nitrogen content and the best spectral parameters, at the same time, preliminary build the diagnosis model of leaf chlorophyll content and leaf nitrogen content, the main research results are as follows:1. This study on agronomy parameter of rice under different nitrogen levels and the change of the canopy spectral reflectance were analyzed, and the study found that the rice leaf area index under different nitrogen levels, the ground biomass, rice leaf chlorophyll content and leaf nitrogen content of rice has obvious difference, are characterized by increasing trend with the increase of nitrogen concentration and rice canopy spectral reflectance are obvious reflection features, various agronomy parameter under different nitrogen levels and canopy spectral reflectance has certain relevance, canopy spectral reflectance of rice and rice leaf area index, aboveground biomass and chlorophyll agronomy parameter has the close relation, this principle can be used to diagnose rice nitrogen content in agricultural production.2. Used rate rice as an example. Research the relationship between canopy spectral response characteristics and total nitrogen content of rice under different nitrogen levels,Analysis and compare the correlation of the derivative and the leaf spectral reflectance and spectral absorption of nitrogen and nitrogen partial,The results showed that the correlation between the amount of nitrogen uptake and canopy spectral reflectance was better. And the highest correlation coefficient was between the original spectral reflectance of 926 nm and the first derivative of 763 nm, Analysis the quantitative relationship between the parameters of "three sides" and the amount of nitrogen uptake, the results showed that the three parameters of Dr, SDr and SDr/SDb were better correlated with the total nitrogen content of leaves. Based on the 926 nm, the Dr、SDr and SDr /SDb of the original spectral reflectance were established. By testing the accuracy of model prediction,It was concluded that the accuracy of the model for the diagnosis of nitrogen uptake based on 926 nm was the largest.(RMSE=0.851、RPD=3.53)Therefore, the model(y=19.788-134.15x+410.1x2) was used to diagnose the leaf nitrogen uptake.3. Analysis the quantitative relationship between the parameters of "three sides" and the chl(a+b) of leaves, the results showed that the correlation between Dr、SDr/ SDb、(SDr- SDb)/(SDr+ SDb) and chl(a+b)was better, Establish the diagnostic model of chl(a+b)by them, By testing the accuracy of model prediction, The results showed the accuracy of the diagnosis model of Chl(a+b) by Dr was highest, and the Model equation was y=1.278+1.943x+0.88x2.