Field radiometry for vineyard status monitoring under Mediterranean conditions

Abstract

Field radiometry based on high spectral capacity of spectroradiometers is an alternative to the high-cost direct or destructive measurements for monitoring agricultural vegetation. Parameters related with phenology, status and physiognomy either at leaf, plant or canopy level can potentially be estimated and monitored using measurements of the reflected energy in the visible and near infrared spectrum range. In this work, hyperspectral indices derived from combination of reflectance measurements were proposed for estimating biophysical parameters of vines plants and monitoring their water status. A vineyard of 100 has of Vitis vinifera was studied in the Castilla y León region of Spain. The biophysical parameters that have been controlled for the plants were Leaf Area Index (LAI), chlorophyll relative content, and vegetation water content (VWC). Soil moisture observations were also included in the dataset. Correlation between these parameters and hyperspectral indices was established and evaluated. Good results were found using the Soil-Adjusted Vegetation Index (SAVI), the Photochemical Reflectance Index (PRI), the Transformed Chlorophyll Absorption in Reflectance Index (TCARI) and the Chlorophyll Normalized Difference Index, (CNDI) for LAI, VWC and chlorophyll characterization, with a high number of significant correlations (R>0.60), specially for SAVI.