You, X.Pagay, V.Withayachumnankul, W.2025-10-202025-10-202025Journal of Infrared, Millimeter, and Terahertz Waves, 2025; 46(8):53-1-53-151866-68921866-6906https://hdl.handle.net/2440/147856The water status of a plant plays a critical role in its growth and biomass accumulation. It is thus essential to accurately quantify the plant water content to improve the overall productivity. Conventional methods to assessing plant water status are either destructive, contacting, or only qualitative. In this work, we present a study to nondestructively quantify, in real-time, the water status of plant leaves in a non-contact manner using terahertz waves. The presented study correlates the leaf complex permittivity with both the relative water content and water potential in the nearly full range. Therefore, the leaf water status can be quantitatively determined based on the non-destructively extracted permittivity using terahertz waves. Furthermore, singlefrequency empirical models linking the imaginary part of the leaf complex permittivity to water status have been developed, enabling the use of high-power narrowband sources in field tests. The simplified measurement and accurate evaluation presented in this study facilitates the application of terahertz technology in supporting sustainable agriculture under climate change and drought.en© The Author(s) 2025. OpenAccess This article is licensed under a CreativeCommonsAttribution 4.0 International License,which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Leaf water status; Terahertz waves; Complex permittivity; Leaf water potentialJournal article10.1007/s10762-025-01074-4747177You, X. [0000-0003-4037-9556]Withayachumnankul, W. [0000-0003-1155-567X]