Corn hyperspectra and their red edge characteristics

Abstract

The hyperspectral reflectance of the canopy in field, the first and the third unfold leaves from the top of corn are measured indoor in different stages by a ASD FieldSpec Pro FR. The concentrations of chlorophyll and carotenoid of leaves corresponding to the spectra are determined by biochemical method. The correlation between the pigment concentrations, leaf area indices, above ground biomass and fresh leaf mass and the edge parameters of corn are analyzed. The hyperspectral reflectance are gradually getting smaller in the visible region and bigger in the near infrared region along with growth. The difference of reflectance between in the near infrared region and in the visible region is the biggest in flowering stage. There are “two peak” phenomena for the edge of canopy spectra of corn. These phenomena are first the clearer with growth, then the clearest in flowering stage and after that are gradually weaken. The position of edge (λ ) of canopy spectra are between 710nm and 740nm. There are red shift’ phenomena for λ before flowering stage, the slope of edge (Dλ ) and the area of edge (S ) before the elongation stage, but are gradually smaller and blue shift’ after flowering stage for the slope of edge (Dλ ) and the area of edge (S ) of the canopy spectra. The leaf area indices (LAI), above ground fresh biomass, above ground dry biomass and fresh leaf mass are very significantly correlative to the edge parameters λred , Dλ and S of the canopy spectra, and the concentrations of chlorophyll-a, chlorophyll-b, total chlorophyll and carotenoid of leaves also significantly correlative to their edge parameters λ and Dλ . These prove that the edge parameters (λ , Dλ and S ) can be used to estimate LAI, above ground biomass and fresh leaf mass. The parameters λ and Dλ can be used to estimate the concentrations chlorophyll and carotenoid of leaves for corn.