Chlorophyll And Leaf Area Index Estimation Based On Hyperspectral Remote Sensing Of Summer Corn

This study, using summer corn as the object, clarifies corn leaf chlorophyll and leaf areaindex of spatial and temporal variation of summer, analyzes the quantified relationshipbetween the process of chlorophyll and leaf area index and spectral reflectance, buildhyperspectral estimation based on chlorophyll and leaf area index and vegetation red edgeparameters of the exponential model, to achieve hyperspectral remote sensing monitoringsummer corn chlorophyll and leaf area index with the theories and methods of remote sensing,thereby guiding summer corn farmland management. The major conclusions are as follows:(1) Through the research on spectral characteristics of summer corn, it shows thatdifferent growth stages of summer corn spectral characteristic curve trends are roughly thesame with a green healthy vegetation characteristic. As the growth period goes by, thecoverage of the physical and chemical composition of leaves and biological are changing, sothat the spectrum feature in the local band has some differences. Reflectance in jointing stagein the whole band is significantly higher than that in heading, filling and dough stage,however, in the near infrared region, reflectance over the growth period was significantlydecreased."Red edge" is one of the most significant characteristics of vegetation spectral,which is also obvious in this study. From the jointing stage, the red edge position has beenshowing "red shift" phenomenon, to achieve the maximum filling to dough stage due to thedecay of chlorophyll, leaf area index and coverage decreases, red absorption reduced summercorn edge position "blue shift" phenomenon, the amplitude of the red edge and red edge of thearea with the decreasing of fertility.(2) By studying the reflectance characteristics of canopy hyperspectrum in differentgrowth period of summer corn and the response characteristics of leaf chlorophyll content andleaf area index, it indicated that the original spectral reflectance of canopy and its firstderivative spectra and chlorophyll content in filling stage and dough stage has closely relatedto the leaf area index, which is well manifested throughout the growth period. This is due tothe removal of soil and atmospheric radiation when to seek a first derivative. It ensures thefeasibility that use the derivative spectrum to estimate chlorophyll content and leaf area index be estimated, dynamically monitor the situation and guide field management of pests anddiseases.(3) This study made a regression analysis of canopy chlorophyll content and leaf areaindex and vegetation index and red edge parameters of summer corn at different period, usingthe mean square error (RMSE) and the mean relative error (RE) to make an accuracy test onremote sensing estimation of regression model. The results indicates that in terms ofchlorophyll content the fitting effect in jointing stage and ratio vegetation index RVI is better,chlorophyll content and normalized difference vegetation index NDVI in heading and fillingstages is better, chlorophyll content in the dough stage and vegetation index DVI is better,jointing, heading, filling and dough stage and fitting results were red edge area Sredbetter.Heading and dough stage of leaf area index and normalized difference vegetation index NDVIfitting effect is better, fitting effect of leaf area index and the filling ratio index RVI better,heading, filling and dough stage were associated with red edge amplitude Dλredfitting better.