PocketSTRESS: A new mobile technology for estimating stomatal conductance in vineyards to optimize water stress management

Optimizing water stress management is crucial especially for crops, like grapevine, for which water availability influences both quantitative and qualitative aspects of productions. In this study, a new mobile technology (PocketSTRESS) is presented, which provides farmers with stomatal conductance (gs)-based, easy-to-interpret information on the presence and the extent of water stress. PocketSTRESS makes use of sensors available in common smartphones to derive 3D leaf scans, which are used to estimate the χ parameter of the Campbell’s ellipsoidal leaf angle distribution. Cultivar specific coefficients allow deriving gs as a linear function of χ. Estimated gs values are automatically compared with thresholds to classify the water status in four categories: no stress, mild, moderate and severe stress. Relationships between gs and χ, already available for cvs. Chardonnay and Malvasia, were here derived for cvs. Pinot Blanc (R2 = 0.92), Sangiovese (R2 = 0.69) and Moltepulciano (R2 = 0.71). The capability to assess water status and the accuracy (trueness and precision) quantified according to the ISO 5725 protocol demonstrated the reliability of the method and its potential for being evaluated under operational farming conditions. Indeed, the extendibility to different cultivars, the cost-effectiveness, and the high usability and interpretability of outputs represent key features to optimize water stress management in viticulture also in medium and small farms. Science4Impact Statement: Our results open to new opportunities to support water stress management in vineyards, thanks to a new mobile app that allows estimating stomatal conductance from 3D leaf scans.