Thermal and multispectral sensors model for determining the water status in a commercial vineyard in semiarid conditions.

Spain counts roughly 941.000 hectares of vineyards, of which 41% are grown under irrigation systems. Water status is a relevant parameter in grapevines as it affects yield, fruit composition, and wine quality. Water stress reduces photosynthetic activity and vegetative growth and limits berry ripening. Mapping the crop's water status is essential for adjusting irrigation doses based on the specific water demands of different agroclimatic zones [2]. Thus, maps can be generated based on water status level ranges. Remote sensing through thermal and multispectral sensors onboard Unmanned Aerial Systems (UASs) can provide such maps with sufficient detail and rapidity. This tool allows obtaining high-resolution images that aid in assessing crop heterogeneity [3]. In a commercial vineyard located in the central region of Spain, we developed models to obtain values of stem water potential (SWP) based on canopy temperature estimated from high-resolution aerial images of a thermal sensor (Tc) [1] and multivariable linear regression models based on combinations of multispectral bands [4]. These models were developed using measurements and data from two previous irrigation seasons (2021 and 2022) on experimental vines in different plots with different management practices, irrigation, and climatic conditions. The modelled values of SWP were validated with measurements in the same vines for the 2023 season. The application of the two developed models allows for spatial and temporal analysis of the water status of vines, aiding in the on-field characterization of water stress. This dynamic spatial mapping improves irrigation management through climatological information and high-resolution sensors. ACKNOWLEDGEMENTS The authors thank Bodegas y Viñas Casa del Valle for allowing us to work in their vineyards and the company UTW for supplying the drone images. Comunidad de Madrid provided financial support through calls for grants to complete Doctorado Industrial IND2020/AMB-17341, which was greatly appreciated. M.G. was supported by a "María Zambrano" contract for the Universidad Politécnica de Madrid, financed by the Spanish Ministerio de Universidades and by "European Union NextGenerationEU/PRTR".   REFERENCES [1] Atencia, L. K., del Campo, M. V., Nowack Yruretagoyena, J. C., Tarquis Alfonso, A. M., and Hermoso Peralo, R.: Detection of plant water stress in Merlot vineyard using thermal sensors onboard UAVs , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16111, https://doi.org/10.5194/egusphere-egu23-16111, 2023. [2] Atencia Payares LK, Tarquis AM, Hermoso Peralo R, Cano J, Cámara J, Nowack J, Gómez del Campo M. Multispectral and Thermal Sensors Onboard UAVs for Heterogeneity in Merlot Vineyard Detection: Contribution to Zoning Maps. Remote Sensing. 2023; 15(16):4024. https://doi.org/10.3390/rs15164024. [3] Atencia Payares LK, Tarquis AM, Hermoso Peralo R, Cano J, Cámara J, Nowack J, Gómez del Campo M. Soil vineyard variability evaluated with multispectral sensors on board of UAVs. X International Symposium on Irrigation of Horticultural Crops, Stellenbosch, South Africa, 29th January to 2nd February 2023. [4] Nowack, J. C., Atencia, L. K., Gómez del Campo, M., and Tarquis, A. M.: Assessing plant water status in Merlot vineyards using Worldview-3 multispectral images in central Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16082, https://doi.org/10.5194/egusphere-egu23-16082, 2023.