S15 - Session P3 - Measuring plant stress to design and steer agroecological systems: the grape vine example

Authors: Philippe Cousin *, Olivier Husson, Stephan Reinig, Maelys Richardoz

Benefits of the measurement of Eh and pH of leaves: Work and a recent bibliographic study have made it possible to correlate the development of pests and diseases with specific oxidation-reduction conditions (measured through the redox potential, Eh) and acid-base (pH) of plants, in relation to the conditions of soil, cultural practices, genotype and climatic conditions. It would thus become possible to diagnose or even quantify the effect of certain stresses undergone by cultivation via these measures. This opens up new perspectives on the management of practices for agro-ecological crop protection by regulation of Eh-pH conditions. Such a prophylactic approach would maintain the plant in good health, under conditions unfavourable to pests, rather than having to fight against these pests once they have developed, often by overoxidation. Conventional electrochemical measurements are very delicate and time-consuming, which makes them impractical for farmers. Due to these measurement difficulties, the number of references on the conditions of plant balance and the impact of practices remains very limited. Portable near infrared spectrometry (NIRS) would make it possible to overcome these difficulties. This has been shown for wheat and rapeseed first with measurement campaigns combining classic electrochemistry (Eh, pH, CE) and spectrometry with the spectrometer developed by the company SENSEEN, during 2020 and confirm now for rice and grape vine in 2021. The paper will present in detail the status of plan stress for grape vine with a large measurement campaign in 2021 and the ability to predict Eh and pH by low-cost portable spectrometer using innovative AI-based chemometrics. In conclusion, the simple, reliable, fast and inexpensive measurement by portable near infrared spectrometry of these plant health indicators should make it possible to develop a unique expertise on the effects of agricultural practices and thus to have practical tools for redox control of the plant health.