Spectroscopic detection and monitoring of plant diseases and stress: principles, case studies on fruit and vegetable crops, and perspectives

The present paper aims to highlight the potential of vegetation spectroscopy for detecting and monitoring plant responses to environmental constraints, in order to increase crop yield and quality, as well as optimize management and input efforts. First, it briefly reports basic concepts of vegetation optical properties. It then reports some case studies from the Plant Pathology group of the Department of Agriculture, Food and Environment of the University of Pisa concerning the spectroscopic detection and monitoring of diseases and abiotic stress conditions in fruit and vegetable crops. These studies highlight the capability of spectral data to accurately monitor specific plant responses to stress conditions, even prior to the onset of visual symptoms. Furthermore, they show that vegetation spectroscopy can be a rapid, non-destructive, and relatively inexpensive tool to accurately estimate an array of leaf physiological, biochemical and morphological parameters commonly investigated to monitor plant/stress interactions. The presented results could be used in many frameworks such as precision agriculture, high-throughput plant phenotyping, and smart nursery management. Knowledge gaps and perspectives of the proposed approach are finally reported such as the need to explore other major crop diseases/stress, to develop spectral sensors, and to advance algorithms for exploitation of spectral data.