| Millet is an important food crop in China,but in recent years,excessive use of chemical fertilizer has caused great harm,which was not conducive to the sustainable development of agriculture.The application of organic fertilizer can largely alleviate these problems.Hyperspectral can quickly and accurately obtain the real-time information of the nutrition and growth status of large-area crops,which is helpful to achieve the goal of high yield,high efficiency and high quality of crop production.This study analyzed the change rule and their relations of different types of organic fertilizer and chlorophyll and leaf area of millet under different application and different application amount of organic fertilizer.To explore the effect of different types and amount of organic fertilizer of millet,studied the varieties and their relationship between chlorophyll,leaf area index and canopy spectrum of different millet.Partial least square(PLS)was used to select the original canopy spectrum and the pretreatment methods,screened the characteristic bands of chlorophyll and leaf area index,and constructing the model,chose the best pretreatment method by compared the effects of these model.The main conclusions were as follows:(1)The effect of organic fertilizer treatment on the chlorophyll content of Jingu 21 and Jingu 28 was the largest at booting stage and heading stage,the best application was cow and the optimal dosage was N3.The effect of organic fertilizer treatment on leaf area index was the largest at the booting stage.The best application of sheep manure and chicken manure was applied to Jingu 21 and Jingu 28 respectively,and the best application amount was N3.(2)The application of chicken manure had the greatest effect on the spectral reflectance of millet.The reflectance of the spectrum showed N3>N2>N1>CK>N4 of Jingu21,and the reflectance showed N3>N2>N4>N1>CK of Jingu21 spectra under different application amounts of organic fertilizers.The application of N3 level organic fertilizer greatly improved the canopy spectral reflectance of two millet varieties.The change of canopy spectrum was basically the same as that of agronomic parameters.The canopy structure and physicochemical indexes of millet were changed with different application of organic fertilizer.(3)Compared with the original spectral reflectance,the correlation between the pretreated spectra and chlorophyll and leaf area index of millet was changed correspondingly.Compared with the estimation models based on the chlorophyll and LAI original spectra of millet and the three pretreatment methods,the second-order differential derivative pretreatment method has the best estimation effect on the model.In the estimation models of canopy spectrum with chlorophyll and leaf area index,R2 reached 0.756 and 0.729 respectively,and RMSE was relatively small.Under the SNV pretreatment method,the estimated value and the measured value did not fit well,and the agronomic parameters of millet could not be well predicted. |
