Early detection of nutrient and biotic stress in Phaseolus vulgaris

Prerequisites for optimal, high crop yield are disease-free growth and an equilibrated supply of nutrients. Early signatures of stress-altered physiology, before appearance of symptoms in the visible spectrum, allow timely treatment. Early detection of stress development was carried out on phaseolus vulgaris bean infected with the agriculturally important grey mould pathogen and under conditions of magnesium deficiency, limiting photosynthesis. During stress development, bean plants were monitored by time-lapse imaging with thermal, video and chlorophyll fluorescence cameras, mounted on a gantry robot system. For early detection of grey mould infection, chlorophyll fluorescence imaging proved to be the most sensitive. This technique detected magnesium deficiency at least three days before visual symptoms appeared. Further development of noncontact technology for plant health monitoring will help to achieve optimal productivity in greenhouse and field cultures. Associated establishment of a stress catalogue based on early symptoms will allow swift diagnosis.