Experimental Study On Remote Sensing Inversion Of Vegetable Biochemical Parameters

Biochemical parameters are important indicators to measure the growth of crops.Using hyperspectral remote sensing technology to monitor the biochemical parameters of crop growth stage plays an important role in crop growth monitoring and yield estimation.The main scientific problem in this paper is how to monitor the changes of several biochemical parameters at different growth stages simultaneously through spectral reflectance,that is,to study which bands/spectral indices are more favorable for biochemical parameter inversion and what kind of quantitative correlation/model between these bands/spectral indices and biochemical parameters.In this study,because pakchoi has the advantages of large demand,short growth cycle and vigorous life,it is the representative of vegetable crops.The variation of spectral reflectance in the canopy of pakchoi under water stress was studied by means of indoor remote sensing simulation.1-The experiment was a three-gradient water stress experiment.The relationship between water content and canopy spectral reflectance of Pakchoi was investigated,and the spectral index of pakchoi was established by means of ANOVA and factor analysis;2-The experiment was a five-gradient water stress experiment.The biochemical parameters and spectral reflectance of leaves were obtained by changing the water content.Then the estimation model of biochemical parameters in different growth stages was established by correlation analysis and regression analysis.The main conclusions of this study are as follows:1.The remote sensing simulation of canopy spectral index of pakchoi shows that the growth of Pakchoi can be quantitatively described by drought index and growth index.Among them,the combination of green,red and short wave infrared bands can reflect the drought situation,and the combination of green,red and near infrared bands can reflect the health situation.The drought index was positively correlated with the degree of drought,and the growth index was positively correlated with the state of health.However,in the later stage of maturity,the growth index of the severe drought group decreased,while that of the normal water supply group remained unchanged;The index curve of the mild drought group was between the normal water supply group and the severe drought group,that shows that the index construction is reasonable.2.It is found that the biochemical parameters of Pakchoi leaves have different correlation with each other in different growth periods,and the sensitive band of each biochemical parameter is also different.There was a significant positive correlation between dry matter quality and chlorophyll content in the growing period,but the correlation was weak in the mature period;The dry matter quality and chlorophyll content had strong correlation with green,yellow and shortwave infrared in growing period,and the representative bands were 550 nm?580nm?700nm and 2110 nm;However,in the mature stage,the chlorophyll content was negatively correlated with the green and red bands,and the representative bands were 550 nm and 700 nm.The dry matter quality has a strong correlation with red and short wave infrared band,and the representative bands are 660 nm and 2110 nm.3.The biochemical parameter estimation models of each growth stage satisfy the multiple linear regression model,and the inversion accuracy of the model is good.when the inversion accuracy is X±0.2,the dry matter quality reaches more than 90% in each growth stage,and the accuracy of chlorophyll content in each growth stage is 73.3% and 97%,respectively.