Estimating Nitrogen Content Of Cucumber Leaves Based On NIR Spectroscopy

摘要

A machine vision method CCD camera and a NIR method NDVI tester were used to measure the spectral reflectance of the cucumber leaves in different nitrogen levels. After the reflectance information of cucumber leaves were obtained, the vegetation indexes, RVI, NDVI and GNDVI were calculated and then the correlation coefficients between each vegetation index and nitrogen content or leave area were analyzed. The result showed that there was an obvious linear correlation between NDVI got from CCD camera and nitrogen content of leaves or leave area, the R2 were 0.8209 and 0.7017 respectively. The high correlations were also observed between GNDVI and nitrogen content of leaves or leave area, the R2 were 0.7625 and 0.6762 respectively. The trend of correlation between RVI and nitrogen content is disagreed with the correlation between RVI and leave area. There is an obvious linear correlation between RVI and leave area, and the R2 is 0.8577. However the correlations between RVI and nitrogen content appears nonlinear relationship, and R2 is only 0.5988. The experimental result prove machine vision method CCD camera can be used as a good method on diagnosing nitrogen content of cucumbers. Both Machine vision method and NIR method of NDVI tester on cucumber leaves are proved to be significant and convenient.