Assessing and mapping vineyard water status using a ground mobile thermal imaging platform

Water status directly affects yield and crop quality in grapevines. Precision viticulture demands the application of new available technologies and methodologies for accurate irrigation management in vineyards. The objective of this work was the development of an on-the-go thermal imaging application for the assessment and mapping of vineyard water status, building a dataset from a commercial Tempranillo (Vitis vinifera L.) vineyard over two consecutive seasons and validating it in another commercial vineyard from a different winegrowing region. Thermal imaging was performed with a thermal camera mounted in an all-terrain vehicle, moving at 5 km/h and operating at a distance from the canopy of 1.20 m. Stem water potential (Ψ) was used for validation as the grapevine water status reference method, using a Scholander pressure chamber. Crop Water Stress Index (CWSI) and Stomatal Conductance Index (I) from a 4-day dataset were computed and correlated with Ψ, delivering significant (p < 0.0001) determination coefficients R up to 0.71. The prediction capability of this dataset was also validated in another commercial vineyard, achieving a prediction R up to 0.82 (RMSE of 0.123 MPa). The predicted values of both indices were thus employed for mapping vineyard water status in the second plot. These results evidence the potential applicability of on-the-go thermal imaging for assessing and mapping water status in commercial vineyards required for precision viticulture.The work leading to these results has received funding from the European Union under grant agreement nº 737669 (VineScout project). The authors acknowledge Daniel Sepúlveda and Marioli Carrasco for their help with the measurement of the stem water potential. Special thanks to Bodegas Vivanco and Pago de Carraovejas for providing the vineyards to conduct the study