| The diagnostic method of plant leaves chlorophyll content based on spectral technology combined with algorithms and corresponding software has been widely used in agricultural production.The traditional method of chlorophyll content diagnosis based on reflection spectroscopy technology are restricted by various factors such as external light intensity,detection angle and optical path,and there are certain deficiencies in their application in actual production.In this paper,by simulating different light environment conditions and using the cosine corrector measurement method,the influence of different light intensity on the red edge region（680nm～760nm）of the transmission spectrum of pepper leaves with different nutritional status was analyzed.The first-order derivative method was used to calculate the red edge area of the red edge region of the red edge spectrum of pepper leaf transmittance and transmittance in different light intensities,and the rd edge parameters（red edge position,red edge amplitude and red edge area）,and compare and analyze the chlorophyll content diagnostic model based on the three methods of unary linear regression,multiple linear regression and ridge regression based on red edge parameters.The main contents and conclusions in this paper were as follows:（1）The transmission spectrum curves obtained by the integrating sphere measurement and the cosine corrector measurement are compared,and the spectral data needed in this study are measured by cosine corrector method.The results show that when measuring the transmission spectrum data,the method of measuring the transmission spectrum with the cosine corrector close to tile under the light source is more advantageous when measuring the transmission spectrum,and it also verifies that the red edge concept is in the transmission spectrum.The same holds true in the date.（2）The correlation between the red edge parameters of the transmission spectrum and the chlorophyll content of pepper leaves in different light intensities was analyzed.The results show that the transmission intensity red edge parameter has a higher correlation with the chlorophyll content and is less affected by the light intensity,while the correlation between red edge parameter of transmittance and chlorophyll content was lower in weak light environment,among the six measured light intensities,the transmittance intensity red edge parameter measured in the light intensity of1200μmol·m-2·s-1 has the highest correlation with the chlorophyll content.（3）The methods of unary linear regression,multiple linear regression and ridge regression were compared and analyzed to establish a diagnostic model of chlorophyll content based on the red edge parameters of the transmission spectrum.The results show that the R2 of the unary linear regression model is low,and due to single factors and large errors,the estimation ability is lower than that of the multiple linear regression model.When the multiple linear regression model is established by using three red edge parameters,it is based on 1200μmol·m-2·s-1 illumination intensity measured through intensity red edge parameters established the best estimation results,the chlorophyll content diagnostic model based on multiple linear regression method estimates the relative error of 6.34%.based on ridge regression,and that of chlorophyll content diagnosis model based on ridge regression method was 6.25%. |
