A microtensiometer sensor to continuously monitor stem water potentials in woody plants – design and field testing

A.N. Lakso, S. Zhu, M. Santiago, K. Shackel, V. Volkov, A.D. Stroock
Water is one of the most critical limitations to growth, productivity, fruit or nut quality and profitability in fruit and nut crops. Irrigation is a large user of water resources, thus optimizing the management of water resources is also critical. Directly measuring plant response to soil water, weather and irrigation is the key to optimal water management. To do so, we have developed and tested an electronic, large-range, continuous-reading water potential sensor for embedding in the trunks of woody plants to monitor stem water potentials. The sensor is a microelectromechanical system (MEMS)-based microtensiometer that can measure plant stem water potential continuously with a high degree of precision. The sensor chip has the same principle as the common soil tensiometer, but with a much smaller volume and 100-200 times greater range. Its advantages include unprecedented range of detection, low power consumption, small size, low potential cost due to micromanufacture and ease of integration into sensor networks. The sensor chip is integrated with associated data handling, logging and wireless transmission for online monitoring. Challenges include optimizing installation and insulation methods and materials; learning how different species and varieties react to the embedded sensor and scaling up production for consistency and lowering cost. The microtensiometer has been field tested in potted and field-grown apple, grape and almond. Current designs and methods have given very good long-term results with high correlations to stem potentials by pressure chamber in multiple crops with good installation sensor-tissue contact. The ability to monitor plant stress with the microtensiometer will be a valuable tool for precision irrigation programs, research, and modeling. Scalable microtensiometer arrays in conjunction with wireless networks and remote sensing offers the potential to provide continuous, high-resolution data to optimize irrigation and water resource management for sustainable crop production.
Lakso, A.N., Zhu, S., Santiago, M., Shackel, K., Volkov, V. and Stroock, A.D. (2022). A microtensiometer sensor to continuously monitor stem water potentials in woody plants – design and field testing. Acta Hortic. 1335, 317-324
DOI: 10.17660/ActaHortic.2022.1335.39
stem water potential, sensor, fruit crops, nut crops, irrigation, drought stress

Acta Horticulturae