Adaptation of the regional agronomic diagnosis for grapevine yield analysis

Yield issues are crucial for winegrowers. In France, yield is often lower than winegrowers' objectives, and there is a need to understand the causes and magnitude of yield variability in vineyard systems. The yield formation process for grapevine (Vitis vinifera) takes place over two consecutive years. Grapevine is also characterised by a limited control of phenology, a winter dormancy period and the existence of storage organs. We adapted the regional agronomic diagnosis approach as defined by Dore et al. (1997) to quantify grapevine yield variability in two complementary case studies. The regional agronomic diagnosis proved useful in acquiring knowledge on grapevine functioning, reflecting on the data collection strategy, and leveraging interventions to better control yield by integrating multiple factors, particularly in the context of transitioning viticulture systems. Furthermore, the successful application of a regional agronomic diagnosis to grapevine crops can be considered as a major contribution to increasing the understanding of yield formation. It helps winegrowers manage yield variability when addressing planned or unplanned changing conditions, such as an agroecological transition or climate change.