Reflectance indices for the detection of water stress in greenhouse tomato (Solanum lycopersicum)

Abstract

This study determined various water stress related indices, which are based on crop-reflected radiation in different wavebands, for early plant water stress detection in greenhouse tomato through portable spectroradiometer and multispectral camera. It also provides recommendations for the most appropriate reflectance indices to be used for irrigation scheduling in greenhouses. Reflectance indices were evaluated according to recent literature, including PRI, NDVI, WI, VOGREI and SRI. It was concluded that the near-infrared region was the most suitable spectrum for early water stress detection in greenhouse tomatoes while NDVI800 and rNDVI showed high correlation with soil water content with R2 values of 0.85 and 0.83, respectively. The results suggested that different protocol, based on hourly variation, must be conducted and reflectance indices based on hyperspectral camera measurements, should be studied, in order to create a proper tool for irrigation management in greenhouse plants.