1,2,1,3- 1Research Center for the Management of Environmental and Agricultural Risk (CEIGRAM), E.T.S.de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Spain(lkatenciapayares@gmail.com)
- 2Dpto. de Producción Agraria, ETSIAAB, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria s.n, 28040 Madrid, Spain
- 3Grupo de Sistemas Complejos, ETSIAAB, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria s.n,28040 Madrid, Spain.
- 4Estación Experimental de Zonas Áridas (EEZA), Consejo Superior de Investigaciones Científicas (CSIC), Ctra. de Sacramento s/n La Cañada de San Urbano, E-04120 Almería, Spain
Stem water potential (SWP) is a widely used, integrative indicator of vine water status because it reflects the combined effects of soil water availability, atmospheric demand and canopy conditions, and it provides a direct basis for irrigation decision making. However, SWP measurements with a pressure chamber are time-consuming and labor-intensive, which motivates the use of UAV-based thermal approaches as scalable alternatives for vineyard scale monitoring. This study aims to validate previously developed UAV thermal models for estimating SWP (Atencia et al., 2024), originally calibrated using data from a 2021–2022 irrigation trial, using an independent dataset collected in 2023 across three contrasting field trials (irrigation, pruning and soil type). UAV thermal acquisitions and concurrent SWP measurements were performed at two times of day (11:00 and 14:00) on multiple dates during the growing season to capture temporal variability in plant water status. Model performance and transferability across seasons and trials was evaluated by comparing CWSI-based estimates with simpler canopy–air temperature difference metrics, and by assessing how environmental and canopy conditions (e.g., atmospheric demand and seasonal progression) influence the robustness of SWP–thermal relationships. The SWP–CWSI relationship remained in 2023, but transferability of the 2021–2022 calibration decreased due to shifts in slope and intercept, likely linked to differences in atmospheric demand (including relatively low VPD during 2023 acquisitions) and the predominance of mild-to-moderate stress levels during most sampling dates. Overall, the results support the practical utility of UAV thermal indices for monitoring vine water status, while highlighting that robust conversion of CWSI to absolute SWP may require campaign-specific recalibration or models that account for key environmental and canopy covariates.
References
Atencia-Payares, L.K., Gomez, M., Tarquis, A.M., García, M., 2024. Thermal imaging from UAS for estimating crop water status in a Merlot vineyard in semi ‑ arid conditions. Irrig. Sci. https://doi.org/10.1007/s00271-024-00955-1
Jackson, R.D., Idso, S.B., Reginato, R.J., Pinter, P.J., 1981. Canopy temperature as a crop water stress indicator. 17, 1133–1138
How to cite: Atencia Payares, L. K., Garcia, M., Junquera, P., Gomez del Campo, M., and Tarquis, A.: Model Validation for Estimating Stem Water Potential in Merlot Grapevines Using Thermal UAV-Based Imagery, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3042, https://doi.org/10.5194/egusphere-egu26-3042, 2026.
