Observation of shoot growth: a simple and operational decision-making tool for monitoring vine water status in the vineyard

In vineyard management, the monitoring of vine water status is of great importance, because this variable influences harvest quality, yield and, in the longer term, vineyard sustainability. Numerous tools and methods have been proposed to monitor vine water status, but they often involve the use of costly and complex equipment and can be logistically demanding. Methods based on the observation of vine shoot growth are interesting potential alternatives, because they are simple to carry out and therefore potentially better adapted for use in production vineyards. However, these methods have never been evaluated or compared to reference measurements made on several cultivars and during several vintages. The objective of this article was to study their characteristics (validity range, specificity and sensitivity) in order to be able to give recommendations for their rigorous implementation in an experimental or operational context. The study was carried out using the iG-Apex method to measure vine shoot growth and predawn leaf water potential as reference measurements in 55 fields located in the Tavel vineyard (Occitanie, France) during the 2008 to 2012 vintages. The results showed that iG-Apex can be used as an operational tool for monitoring vine water status at field scale and for a predawn leaf water potential ranging from -0.2 MPa to -0.8 MPa. Nevertheless, precautions must be taken when interpreting the results, as the method is not specific to water constraint and is also sensitive to other phenomena. Furthermore, it could be relevant to use this method for the collective monitoring of vine shoot growth over large spatial areas, in addition to more precise and more localised monitoring carried out with reference measurements.