2018 ASHS Annual Conference

Plant water potential is increasingly recognized as key for regulating both growth but also product quality. Directly measuring plant water potentials (preferably stem potential and continuously) is a key goal to replace the pressure chamber. To do this we have developed, using nanofabrication, a small size (in a probe about 6mm diameter and 1 cm length), inexpensive, electronic, large-range, continuous-reading water potential sensor for monitoring soil water potential and embedding directly in the stems to monitor stem potentials, especially in woody plants. The sensor is a microfluidic device with the same principle as the common soil tensiometer, but with a much smaller volume and about 100X greater range. The microtensiometer has been successfully tested embedded in the stems of field apples, grapes and almonds over months. The high spatial and temporal resolution of plant and soil Y_w provided by the microtensiometer should be a valuable tool for precision irrigation programs, research, and modeling.