A method for crop water status evaluation by thermal imagery for precision viticulture: preliminary results

In the light of climate change, an improvement of vineyard water status management is required. Reliable methods and sensors to properly and timely assess crop water status are needed. Survey methods based on the evaluation of leaf temperature by thermal imagery proved to be reliable sensing tools for assessing crop water status, and computing crop water stress index (CWSI). This study aimed to estimate the stem water potential (SWP) as a function of new CWSIs using thermal imagery. The in-field measurements were conducted in 2016 and 2017 on four cultivars. The new CWSIs were compared to other thermal based methods reported in the literature and correlated to the SWP contextually measured in the field using a pressure chamber. The SWP was better correlated with the new CWSIs (R²>0.65) than with other methods (R²<0.45). Thus, the SWP estimation by means of thermal imagery requires the use of a proper thermal index to take into account the influence of cultivars and weather parameters on leaf temperature.