Remote sensing to detect plant stress, with particular reference to stress caused by the greenbug: a review

Crop stress caused by adverse growing conditions, such as nutrient deficiency, pest infestation, disease, and drought, can be detected using techniques of remote sensing. Symptoms of crop stress can be detected by variation in reflectance from plant surfaces of incident solar radiation in particular wavelength bands using radiometry. For example, some radiometers can record the quantity of light reflected in red and near infrared bands, which has proven useful for detecting plant stress. Vegetation indices calculated from the quantity of reflected light in these bands have been used to quantify levels of stress. Plants subjected to certain stresses, for example water stress, have higher leaf temperature than non-stressed plants. A change in the amount of thermal energy radiated by plants can sometimes be detected using infrared thermometers. In this review, applications of radiometry for detecting plant stress, with particular emphasis on detecting stress to cereals caused by the greenbug, Schizaphis graminum Rondani, are summarized and approaches for future research are outlined.