Plant water use efficiency (WUE) links physiological processes to ecosystem-scale carbon and water cycles, making it a crucial parameter for climate change adaptation modelling. Climate and stratospheric ozone dynamics expose plants to varying intensity of ultraviolet-B radiation (UV-B), which affects stomatal function and transpiration. This meta-analysis evaluates UV-B effects on WUE using gas exchange and isotopic proxies. While UV-B radiation reduces stomatal conductance and transpiration, it also suppresses photosynthesis, particularly under non-saturating light. As a result, WUE remains unchanged or declines in UV-B exposed plants, depending on the measurement method. Instantaneous gas exchange-based WUE proxies indicate a decrease, whereas isotope-based proxies, integrating long-term fluxes, show no significant UV-B effect. The suppression of photosynthesis due to UV-B occurs only when UV-B lamps are used to increase the UV-B dose; when UV-B is excluded under field conditions there is no significant effect on WUE. Only some field studies report improved WUE under ambient UV-B, suggesting potential adaptive benefits. Overall, the findings challenge the assumption that UV-B-induced decreases in transpiration enhance WUE. Instead, they highlight a complex interplay between UV radiation, photosynthesis, and stomatal regulation, emphasizing the need to reconsider UV-B's role in plant water relations under future climate conditions.

Global Change Research Institute of the Czech Academy of Sciences Brno Czech Republic

School of Biological Earth and Environmental Sciences Environmental Research Institute University College Cork Cork Ireland

School of GeoSciences University of Edinburgh Edinburgh UK

See more in PubMed

Ač, A. , Jansen M. A. K., Grace J., and Urban O.. 2024. “Unravelling the Neglected Role of Ultraviolet Radiation on Stomata: A Meta‐Analysis With Implications for Modelling Ecosystem–Climate Interactions.” Plant, Cell & Environment 47, no. 5: 1769–1781. PubMed

Ač, A. , Malenovský Z., Olejníčková J., Gallé A., Rascher U., and Mohammed G.. 2015. “Meta‐Analysis Assessing Potential of Steady State Chlorophyll Fluorescence for Remote Sensing Detection of Plant Water, Temperature and Nitrogen Stress.” Remote Sensing of Environment 168: 420–436.

Agarwal, S. 2007. “Increased Antioxidant Activity in Cassia Seedlings Under UV‐B Radiation.” Biologia Plantarum 51: 157–160.

Allen, D. J. , Nogues S., and Baker N. R.. 1998. “Ozone Depletion and Increased UV‐B Radiation: Is There a Real Threat to Photosynthesis?” Journal of Experimental Botany 49, no. 328: 1775–1788.

Aphalo, P. J. , Albert, A. , Björn, L. O. , et al., ed. 2012. Beyond the Visible: A Handbook of Best Practice in Plant UV Photobiology. COST Action FA0906 UV4growth. Helsinki: University of Helsinki, Division of Plant Biology.

Aphalo, P. J. , and Sadras V. O.. 2022. “Explaining Pre‐Emptive Acclimation by Linking Information to Plant Phenotype.” Journal of Experimental Botany 73, no. 15: 5213–5234. PubMed PMC

Banaś, A. K. , Zgłobicki P., Kowalska E., Bażant A., Dziga D., and Strzałka W.. 2020. “All you Need Is Light. Photorepair of UV‐Induced Pyrimidine Dimers.” Genes 11, no. 11: 1304. PubMed PMC

Bandurska, H. , Niedziela J., and Chadzinikolau T.. 2013. “Separate and Combined Responses to Water Deficit and UV‐B Radiation.” Plant Science 213: 98–105. PubMed

Barnes, P. W. , Ballaré C. L., and Caldwell M. M.. 1996. “Photomorphogenic Effects of UV‐B Radiation on Plants: Consequences for Light Competition.” Journal of Plant Physiology 148, no. 1–2: 15–20.

Barnes, P. W. , Robson T. M., Zepp R. G., et al. 2023. “Interactive Effects of Changes in UV Radiation and Climate on Terrestrial Ecosystems, Biogeochemical Cycles, and Feedbacks to the Climate System.” Photochemical & Photobiological Sciences: Official Journal of the European Photochemistry Association and the European Society for Photobiology 22, no. 5: 1049–1091. PubMed PMC

Boesgaard, K. S. , Albert K. R., Ro‐Poulsen H., Michelsen A., Mikkelsen T. N., and Schmidt N. M.. 2012. “Long‐Term Structural Canopy Changes Sustain net Photosynthesis per Ground Area in High Arctic PubMed

Bonan, G. B. , and Levis S.. 2006. “Evaluating Aspects of the Community Land and Atmosphere Models (CLM3 and CAM3) Using a Dynamic Global Vegetation Model.” Journal of Climate 19, no. 11: 2290–2301.

Borenstein, M. , Hedges L. V., Higgins J. P. T., and Rothstein H. R.. 2009. Introduction to meta‐analysis. New York: Wiley.

Bornman, J. F. , Barnes P. W., Robson T. M., et al. 2019. “Linkages Between Stratospheric Ozone, UV Radiation and Climate Change and Their Implications for Terrestrial Ecosystems.” Photochemical & photobiological sciences: Official journal of the European Photochemistry Association and the European Society for Photobiology 18, no. 3: 681–716. PubMed

Britt, A. B. 1995. “Repair of DNA Damage Induced by Ultraviolet Radiation.” Plant Physiology 108, no. 3: 891–896. PubMed PMC

Chatzopoulou, A. , Tourpali K., Bais A. F., and Braesicke P.. 2025. “Twenty‐First Century Surface UV Radiation Changes Deduced From CMIP6 Models. Part II: Effects on UV Index and Plant Growth Weighted Irradiance.” Photochemical & Photobiological Sciences: Official Journal of the European Photochemistry Association and the European Society for Photobiology 24: 113–130. PubMed

Chen, M. , Huang Y., Liu G., Qin F., Yang S., and Xu X.. 2016. “Effects of Enhanced UV‐B Radiation on Morphology, Physiology, Biomass, Leaf Anatomy and Ultrastructure in Male and Female Mulberry (

Chen, T. , Qiang W., An L., and Wang X.. 2003. “Effects of cadmium combined with ultraviolet‐B radiation on growth, gas exchange, and stable carbon isotope value (δ

Cowan, I. R. 1978. “Stomatal behaviour and environment.” In Advances in botanical research, edited by Preston R. D. and Woolhouse H. W., 4, 117–228. London and New York: Academic Press.

Crestani, G. , Cunningham N., Csepregi K., Badmus U. O., and Jansen M. A. K.. 2023. “From Stressor to Protector, UV‐Induced Abiotic Stress Resistance.” Photochemical & Photobiological Sciences: Official Journal of the European Photochemistry Association and the European Society for Photobiology 22, no. 9: 2189–2204. PubMed PMC

Crous, K. Y. , Middleby K. B., Cheesman A. W., et al. 2025. “Leaf Warming in the Canopy of Mature Tropical Trees Reduced Photosynthesis due to Downregulation of Photosynthetic Capacity and Reduced Stomatal Conductance.” New Phytologist 245, no. 4: 1421–1436. PubMed

Deckmyn, G. , and Impens I.. 1997. “The Ratio UV‐B/Photosynthetically Active Radiation (PAR) Determines the Sensitivity of rye to Increased UV‐B Radiation.” Environmental and Experimental Botany 37, no. 1: 3–12.

Doughty, C. E. , Keany J. M., Wiebe B. C., et al. 2023. “Tropical Forests are Approaching Critical Temperature Thresholds.” Nature 621, no. 7977: 105–111. PubMed

Duan, B. , Ran F., Zhang X., Zhang Y., Korpelainen H., and Li C.. 2011. “Long‐Term Acclimation of Mesophyll Conductance, Carbon Isotope Discrimination and Growth in Two Contrasting

Eckes‐Shephard, A. H. , Tiavlovsky E., Chen Y., Fonti P., and Friend A. D.. 2021. “Direct Response of Tree Growth to Soil Water and its Implications for Terrestrial Carbon Cycle Modelling.” Global Change Biology 27, no. 1: 121–135. PubMed

Ehleringer, J. R. , Hall A. E., and Farquhar G. D.. 1993. “Introduction: water use in relation to productivity.” In Stable Isotopes and Plant Carbon‐Water Relations, edited by Ehleringer J. R., Hall A. E., and Farquhar G. D., 3–8. New York: Academic Press.

Farman, J. C. , Gardiner B. G., and Shanklin J. D.. 1985. “Large Losses of Total Ozone in Antarctica Reveal Seasonal ClO x/NO x Interaction.” Nature 315, no. 6016: 207–210.

Farquhar, G. D. , Hubick K. T., Condon A. G., and Richards R. A.. 1989. “Carbon isotope fractionation and plant water‐use efficiency.” In Stable Isotopes in Ecological Research, edited by Rundel P. W., Ehleringer J. R., and Nagy K. A., 21–40. New York, NY: Springer.

Fiscus, E. L. , and Booker F. L.. 1995. “Is Increased UV‐B a Threat to Crop Photosynthesis and Productivity?” Photosynthesis Research 43: 81–92. PubMed

Ge, X. M. , Hu X., Zhang J., et al. 2020. “UV Resistance LOCUS8 Mediates Ultraviolet‐B‐Induced Stomatal Closure in an Ethylene‐Dependent Manner.” Plant Science 301: 110679. PubMed

III Gitz , D. G. , Liu‐Gitz L., Britz S., and Sullivan J.. 2005. “Ultraviolet‐B Effects on Stomatal Density, Water‐use Efficiency, and Stable Carbon Isotope Discrimination in Four Glasshouse‐Grown Soybean (

Goessling, H. F. , Rackow T., and Jung T.. 2025. “Recent Global Temperature Surge Intensified by Record‐Low Planetary Albedo.” Science 387, no. 6729: 68–73. PubMed

González‐Villagra, J. , Marjorie R. D., Alberdi M., et al. 2020. “Solar UV Irradiation Effects on Photosynthetic Performance, Biochemical Markers, and Gene Expression in Highbush Blueberry (

Graven, H. , Keeling R. F., and Rogelj J.. 2020. “Changes to Carbon Isotopes in Atmospheric CO PubMed PMC

Guerrieri, R. , Belmecheri S., Ollinger S. V., et al. 2019. “Disentangling the Role of Photosynthesis and Stomatal Conductance on Rising Forest Water‐use Efficiency.” Proceedings of the National Academy of Sciences 116, no. 34: 16909–16914. PubMed PMC

Gupta, D. , and Prasad S. M.. 2021. “Priming With 5‐Aminolevulinic Acid (ALA) Attenuates UV‐B Induced Damaging Effects in Two Varieties of

Hatfield, J. L. , and Dold C.. 2019. “Water‐use Efficiency: Advances and Challenges in a Changing Climate.” Frontiers in Plant Science 10: 103. PubMed PMC

He, Z. S. , Zhan S. F., and Wu S. L.. 2014. “Interactive Effects of Increased UV‐B and Rainfall on the Growth and Physiology of Tibetan Barley on the Tibetan Plateau.” Ekoloji Dergisi 23: 18–26.

Hideg, É. , Jansen M. A. K., and Strid Å.. 2013. “UV‐B Exposure, ROS, and Stress: Inseparable Companions or Loosely Linked Associates?” Trends in Plant Science 18, no. 2: 107–115. PubMed

Hodnebrog, Ø. , Myhre G., and Jouan C., et al. 2024. “Recent Reductions in Aerosol Emissions Have Increased Earth's Energy Imbalance.” Communications Earth & Environment 5: 166.

Jansen, M. A. K. , Ač A., Klem K., and Urban O.. 2022. “A Meta‐Analysis of the Interactive Effects of UV and Drought on Plants.” Plant, Cell & Environment 45, no. 1: 41–54. PubMed

Jansen, M. A. K. , Bilger W., Hideg É., et al. 2019. “Interactive Effects of UV‐B Radiation in a Complex Environment.” Plant Physiology and Biochemistry 134: 1–8. PubMed

Jansen, M. A. K. , and Bornman J. F.. 2012. “UV‐B Radiation: From Generic Stressor to Specific Regulator.” Physiologia Plantarum 145, no. 4: 501–504. PubMed

Jansen, M. A. K. , Gaba V., and Greenberg B. M.. 1998. “Higher Plants and UV‐B Radiation: Balancing Damage, Repair and Acclimation.” Trends in Plant Science 3, no. 4: 131–135.

Jenkins, G. I. 2014. “The UV‐B Photoreceptor UVR8: From Structure to Physiology.” The Plant Cell 26, no. 1: 21–37. PubMed PMC

Jenkins, G. I. 2017. “Photomorphogenic Responses to Ultraviolet‐B Light.” Plant, Cell & Environment 40: 2544–2557. PubMed

Kataria, S. , Jajoo A., and Guruprasad K. N.. 2014. “Impact of Increasing Ultraviolet‐B (UV‐B) Radiation on Photosynthetic Processes.” Journal of Photochemistry and Photobiology B: Biology 137: 55–66. PubMed

Keiller, D. R. , and Holmes M. G.. 2001. “Effects of Long‐Term Exposure to Elevated UV‐B Radiation on the Photosynthetic Performance of Five Broad‐Leaved Tree Species.” Photosynthesis Research 67: 229–240. PubMed

Kumari, R. , Singh S., and Agrawal S. B.. 2009. “Effects of Supplemental Ultraviolet‐B Radiation on Growth and Physiology of

Lake, J. A. , Field K. J., Davey M. P., Beerling D. J., and Lomax B. H.. 2009. “Metabolomic and Physiological Responses Reveal Multi‐Phasic Acclimation of PubMed

Lawson, T. , and Vialet‐Chabrand S.. 2019. “Speedy Stomata, Photosynthesis and Plant Water use Efficiency.” New Phytologist 221, no. 1: 93–98. PubMed

Leonardi, C. , Guichard S., and Bertin N.. 2000. “High Vapour Pressure Deficit Influences Growth, Transpiration and Quality of Tomato Fruits.” Scientia Horticulturae 84, no. 3–4: 285–296.

Lingwan, M. 2024. “Damage and Repair: How PubMed PMC

Lou, Y. , Wu L., Lixuan R., et al. 2016. “Effects of Silicon Application on Diurnal Variations of Physiological Properties of Rice Leaves of Plants at the Heading Stage Under Elevated UV‐B Radiation.” International Journal of Biometeorology 60: 311–318. PubMed

Marchin, R. M. , Broadhead A. A., Bostic L. E., Dunn R. R., and Hoffmann W. A.. 2016. “Stomatal Acclimation to Vapour Pressure Deficit Doubles Transpiration of Small Tree Seedlings With Warming.” Plant Cell & Environment 39, no. 10: 2221–2234. PubMed

Martínez‐Lüscher, J. , Morales F., Delrot S., et al. 2013. “Short‐and Long‐Term Physiological Responses of Grapevine Leaves to UV‐B Radiation.” Plant Science 213: 114–122. PubMed

Mathias, J. M. , and Hudiburg T. W.. 2022. “isocalcR: An R Package to Streamline and Standardize Stable Isotope Calculations in Ecological Research.” Global Change Biology 28, no. 24: 7428–7436. PubMed

McKenzie, R. , Bernhard G., Liley B., et al. 2019. “Success of Montreal Protocol Demonstrated by Comparing High‐Quality UV Measurements With “World Avoided” Calculations From two Chemistry‐Climate Models.” Scientific Reports 9, no. 1: 12332. PubMed PMC

Neale, P. J. , Hylander S., Banaszak A. T., et al. (2025) “Environmental consequences of interacting effects of changes in stratospheric ozone, ultraviolet radiation and climate: UNEP Environmental Effects Assessment Panel, Update 2024.” Photochemical & Photobiological Sciences (In Press). PubMed PMC

Neugart, S. , Steininger V., Fernandes C., et al. 2024. “A Synchronized, Large‐Scale Field Experiment Using PubMed

Nogués, S. , Allen D. J., Morison J. I. L., and Baker N. R.. 1999. “Characterization of Stomatal Closure Caused by Ultraviolet‐B Radiation.” Plant Physiology 121, no. 2: 489–496. PubMed PMC

Oleson, K. W. , Niu G. Y., and Yang Z. L., et al. 2008. “Improvements to the Community Land Model and Their Impact on the Hydrological Cycle.” Journal of Geophysical Research: Biogeosciences 113: G01021.

Ormrod, D. P. , Schmidt A., and Livingston N. J.. 1997. “Effect of UV‐B Radiation on the Shoot dry Matter Production and Stable Carbon Isotope Composition of two

Pernicová, N. , Urban O., Čáslavský J., et al. 2024. “Impacts of Elevated CO PubMed

Podolec, R. , Demarsy E., and Ulm R.. 2021. “Perception and Signaling of Ultraviolet‐B Radiation in Plants.” Annual Review of Plant Biology 72: 793–822. PubMed

Poulson, M. E. , Boeger M. R. T., and Donahue R. A.. 2006. “Response of Photosynthesis to High Light and Drought for PubMed

Rai, N. , Morales L. O., and Aphalo P. J.. 2021. “Perception of Solar UV Radiation by Plants: Photoreceptors and Mechanisms.” Plant Physiology 186: 1382–1396. PubMed PMC

Rai, N. , O'hara A., Farkas D., et al. 2020. “The Photoreceptor UVR8 Mediates the Perception of Both UV‐B and UV‐A Wavelengths up to 350 nm of Sunlight With Responsivity Moderated by Cryptochromes.” Plant, Cell & Environment 43, no. 6: 1513–1527. PubMed

Robson, T. M. , Klem K., Urban O., and Jansen M. A.. 2015. “Re‐Interpreting Plant Morphological Responses to UV‐B Radiation.” Plant, Cell & Environment 38, no. 5: 856–866. PubMed

Schumacher, D. L. , Singh J., Hauser M., Fischer E. M., Wild M., and Seneviratne S. I.. 2024. “Exacerbated Summer European Warming not Captured by Climate Models Neglecting Long‐Term Aerosol Changes.” Communications Earth & Environment 5: 182.

Seibt, U. , Rajabi A., Griffiths H., and Berry J. A.. 2008. “Carbon Isotopes and Water Use Efficiency: Sense and Sensitivity.” Oecologia 155: 441–454. PubMed

Stapleton, A. E. 1992. “Ultraviolet Radiation and Plants: Burning Questions.” The Plant Cell 4, no. 11: 1353. PubMed PMC

Strange, B. M. , Monson R. K., Szejner P., Ehleringer J., and Hu J.. 2023. “The North American Monsoon Buffers Forests Against the Ongoing Megadrought in the Southwestern United States.” Global Change Biology 29: 4354–4367. PubMed

Sullivan, J. H. , Gitz D. C., Peek M. S., and McElrone A. J.. 2003. “Response of Three Eastern Tree Species to Supplemental UV‐B Radiation: Leaf Chemistry and Gas Exchange.” Agricultural and Forest Meteorology 120: 219–228.

Teramura, A. H. , and Sullivan J. H.. 1994. “Effects of UV‐B Radiation on Photosynthesis and Growth of Terrestrial Plants.” Photosynthesis Research 39: 463–473. PubMed

Treydte, K. , Liu L., Padrón R. S., et al. 2024. “Recent Human‐Induced Atmospheric Drying Across Europe Unprecedented in the Last 400 Years.” Nature Geoscience 17: 58–65.

Tricker, P. J. , Trewin H., Kull O., et al. 2005. “Stomatal Conductance and not Stomatal Density Determines the Long‐Term Reduction in Leaf Transpiration of Poplar in Elevated CO PubMed

Urban, J. , Ingwers M., McGuire M. A., and Teskey R. O.. 2017. “Stomatal Conductance Increases With Rising Temperature.” Plant Signaling & Behavior 12, no. 8: e1356534. PubMed PMC

Vanhaelewyn, L. , Prinsen E., Van Der Straeten D., and Vandenbussche F.. 2016. “Hormone‐Controlled UV‐B Responses in Plants.” Journal of Experimental Botany 67, no. 15: 4469–4482. PubMed

von Caemmerer, S. , and Quick W. P.. 2000. “Rubisco: physiology

Wang, S. , Zhang S., Liu X., Bai L., and Qin Q.. 2024. “Effect of UV‐B Radiation on Photosynthesis Based Flavonoid Synthesis in Daylily Leaves.” Phytochemistry Letters 62: 24–33.

Wargent, J. J. , Elfadly E. M., Moore J. P., and Paul N. D.. 2011. “Increased Exposure to UV‐B Radiation During Early Development Leads to Enhanced Photoprotection and Improved Long‐Term Performance in PubMed

Wargent, J. J. , Gegas V. C., Jenkins G. I., Doonan J. H., and Paul N. D.. 2009. “UVR8 in PubMed