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 (Ψstem) 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 (Ig) from a 4-day dataset were computed and correlated with Ψstem, delivering significant (p < 0.0001) determination coefficients R2 up to 0.71. The prediction capability of this dataset was also validated in another commercial vineyard, achieving a prediction R2 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.