Monitoring the water status of economic plants with continuous wave terahertz radiation

Monitoring the water status of economic plants is of vital importance for optimizing irrigation strategies and for a deeper understanding of the influence of drought stress. Most of the conventional techniques for measuring the water content of plants are destructive. Here, we use terahertz (THz) waves to non-destructively determine the water status of living plants. Terahertz waves are somewhat less heavily absorbed by water than infrared waves and can be used in transmission geometry. Furthermore, they allow for a sub-millimetre spatial resolution.Here, we investigate the applicability of a CW photomixing THz system to monitor the water status of economic plants. Our study focuses on Coffea arabica for its large economical impact. Results indicate that inexpensive and robust CW THz systems can be used to monitor the water status of plants. Since this technique is totally non-destructive and a single measurement takes just a few seconds, accurate long time studies are feasible.