Verifying sensitivity of a sensor system for logging xylem’s acoustic emissions related to drought stress

Novel field-instruments are required for non-invasive, automated early detection of plant water-stress. In preparations for field trials, we evaluated sensitivity of a novel embedded sensor system designed for in-field logging of ultrasonic acoustic emissions (AE) related to formation of xylem embolism. The designed sensor system entails an analog frontend for high-impedance piezoelectric sensors, an event-driven 2.5 MS/s A/D conversion with wake-up capability, on-board real-time frequency-domain AE processing, and micro-SD card storage. The system's water-stress detection sensitivity was tested in laboratory dehydration experiments on grapevine (Vitis vinifera, L.) pot-plants. It was confirmed that its sensitivity is comparable to a reference laboratory AE measurement chain. The designed sensor system enables detection of grapevine water-stress corresponding to moderate leaf water potential below -0.9 MPa.