The objective of this study was to determine, among five vegetation indices, calculated based on spectral reflectance data, the one that best discriminated nitrogen rates, and presented highest correlation with chlorophyll readings and tanzania grass (Panicum maximum Jacq.) dry matter. The tested vegetation indices were NDVI (normalized difference vegetation index), VARI (visible atmospherically resistant index using red edge and green bands), WDRVI (wide dynamic range vegetation index using three weighted coefficients, 0.05, 0.1 and 0.2). Four nitrogen levels (0, 80, 160 and 320 kg/ha) were evaluated in a randomized complete block design with three replications and three subsamplings per block. The indices VARI, using red edge band, and WDRVI, using weighted coefficients 0.05 and 0.1, were the best indices to discriminate nitrogen rates. The index that presented the highest correlation with chlorophyll readings and dry matter was the VARI using red edge band.
chlorophyll readings; dry mass; Panicum maximum Jacq.; spectral reflectance
