Spectral Characteristics and the Study of Pollution Degree of Maize Leaves Under Copper and Lead Stress

Abstract

A new index Absorbance Differential Vegetation Index (ADVI), which realized the monitoring of heavy metals copper and lead stress in two varieties of maize with different cultivation periods and the pollution of heavy copper and lead, was distinguished. Experiments of copper and lead pollution with different concentrations were designed and measured spectral reflectance and contents of copper ion (Cu2+) and lead ion (Pb2+) of maize under concentrations of copper and lead stress. The spectral reflectance was processed by the absorbance conversion (A) and the first-order differential (D), and the Absorbance Differential (AD) spectral curve was obtained. The Pearson correlation coefficient (r) was used to analyze the AD data and the biochemical data and select characteristic bands that sensitive to heavy metal Cu (Copper). We selected the AD value of wavelengths 501 nm, 550 nm, 673 nm and 678 nm to establish ADVI and compared it with conventional vegetation indices by calculating Pearson correlation coefficient between them and Cu contents in soil and leaves. The results suggested that ADVI showed a significant correlation with Cu2+ and Pb2+ stress concentration, the correlation of ADVI was much stronger than that of other vegetation indices and effectively distinguished copper and lead stress. It can provide theoretical basis for monitoring heavy metal stress on canopy scale.