Selection of sampling sites and pigment parameters in estimating plant pigment status by canopy hyperspectral reflectance in corn plants

The leaf chlorophyll content, carotenoid content and chlorophyll/carotenoid ratio were investigated in relation to fifteen hyperspectral vegetation indices at different layers (upper, middle and low) of the corn plants in a field experiment. The chlorophyll/carotenoid (Chl/Car) ratio appeared to increase with the morphological height decreasing. The hyperspectral variables were significantly related to the leaf chlorophyll content(mg·g^-1FW)with the highest coefficient of 0.56(n=77) yielded, while they were better correlated to the leaf chlorophyll/carotenoid ratio with the highest coefficient of 0.75(n=77) yielded. The chlorophyll/carotenoid ratio at the low layer was better correlated with the spectral indices than that at the upper layer or at the middle layer. The results suggested that the accuracy could be improved by using the Chl/Car ratio as the pigment parameter when estimating the pigment status in the corn plants by hyperspectral reflectance.