Detection of plant water stress in Merlot vineyard using thermal sensors onboard UAVs

Abstract

Knowledge of the water status in commercial vineyards is of great importance when defining the production objectives and the composition of the grape must. Determining the appropriate irrigation doses allows for adjusting the balance between vigour and productive capacity of the vineyard. However, to accurately know the hydration status of the vines, it is necessary to use equipment such as pressure chambers that are hardly replicable. Much effort has been invested in finding a more straightforward simpler methodology that allows knowing the hydration of plants. In this respect, remote sensing technology is presented as an appropriate tool to obtain information from large areas quickly and efficiently. This work aimed to evaluate the accuracy of water stress detection based on thermal sensors onboard UAVs.The study was carried out in the Merlot vineyard located in Toledo-Spain; arranged on a trellis with a 2.60 x 1.10 m planting frame and established in 2002. High-resolution thermal images were obtained on different dates during the 2021 and 2022 irrigation campaign and at two intervals of the day (9:00 and 12:00 solar hours). Stem water potential (Ψm) and chlorophyll were measured at the same time.The results indicate that there are statistically significant differences between the different irrigation treatments. These differences were mainly observed in the water-steam potential measurements made in the morning.ReferencesAcevedo-Opazo, C., Tisseyre, B., Guillaume, S., & Ojeda, H. (2008). The potential of high spatial resolution information to define within-vineyard zones related to vine water status. Precision Agriculture, 9(5), 285–302. https://doi.org/10.1007/s11119-008-9073-1.Jackson, R. D. (1982). Canopy Temperature and Crop Water Stress. 1, 43–85. https://doi.org/10.1016/b978-0-12-024301-3.50009-5.Poblete-Echeverría, C., Sepulveda-Reyes, D., Ortega-Farias, S., Zuñiga, M., & Fuentes, S. (2016). Plant water stress detection based on aerial and terrestrial infrared thermography: A study case from vineyard and olive orchard. Acta Horticulturae, 1112, 141–146. https://doi.org/10.17660/ActaHortic.2016.1112.20. Acknowledgements:The authors want to thank Bodegas y Viñas Casa del Valle for allowing us to work in their vineyards and the company UTW for supply the drone images. Financial support provided by Comunidad de Madrid through calls for grants for the completion of Industrial Doctorates IND2020/AMB-17341 is greatly appreciated.