The use of vineyard spectral signatures to identify table grape cultivars

Abstract

Vineyards have characteristic responses to sunlight. The reflectance values at the different wavelengths are typical of vegetation and define its spectral signature. The aim of this work was to determine the spectral signatures of table grape vineyards located in the production area of Robinvale (Victoria, Australia) in order to identify cultivars in the vineyard. Spectral signatures were detected from images in eight bands from the Worldview 3 platform. Spectral signatures for a representative number of plots were extracted using satellite reflectance images for each cultivar. Spectral signatures were also collected in the field, from the same cultivars, with a FieldSpec® HandHeld 2 portable spectroradiometer. Signatures were analyzed to determine the average spectral response for each plot and the variability in terms of coefficient of variation. Results showed that some cultivars exhibited different spectral signatures and trends while other cultivars had similar behavior. All the cultivars covered different regions of the Cartesian surface and were therefore distinguishable, except for ‘IFG 68-175’. Therefore, spectral signatures represent a powerful tool for a preliminary characterization of cultivars and vineyards. Spectral signatures were successfully used to classify vineyards down to the cultivar level and, within the same cultivar, to identify different management practices.