Development of a new heavy metal vegetation index for improving monitoring of copper and lead concentration in corn

Abstract

This study analysed the spectral characters of corn grown in metal-spiked soil, and thus to develop a new vegetation index to characterize copper and lead concentrations in corn leaves. The significant correlation between the leaf-metal and the leaf-spectra suggested that the Cu and Pb stress caused the spectra changes in visible and near-infrared ranges. Heavy Metal Stress Vegetation Indices based on the first difference reflectance (dVIs) were established using the characteristic wavelengths. The results of regression models show that the index that combines the first difference reflectance in 497, 632 and 677 nm wavelengths is the best potential indicator of the Cu stress, and the index that combines the first difference reflectance in 456, 668 and 686 nm wavelengths most strongly indicates the Pb stress. In addition, compared with six normal vegetation indices, the proposed dVI has better robustness and effectiveness. This study may provide a theoretical basis for the monitoring of heavy metal stress at corn canopy scale.