MODELING THE IMPACT OF FUTURE CLIMATE SCENARIOS ON YIELD AND YIELD VARIABILITY OF GRAPEVINE

A mechanistic growth model was used to evaluate the mean yield and yie ld variability of grapevine Vitis vinifera L. under current and future climates. The model used was previously validated using field experim ent data. The effect of elevated CO2 on grapevine growth was also cons idered. Adaptation of 2 varieties (Sangiovese and Cabernet Sauvignon) to scenarios of increased CO2 and climate change, and potential change s in agricultural risk (i.e. inter-seasonal variability), were examine d. Before testing the effect of climate scenarios, we analysed the sen sitivity of modelled grapevine yield to arbitrary changes in the 3 dri ving variables (temperature, solar radiation and CO2). The results sho wed the model to be more sensitive to changes in CO2 concentration and temperature than to changes in radiation. Analyses made using transie nt GCM (general circulation model) scenarios (UKTR and GFDL) showed di fferent changes in mean fruit dry matter for the different scenarios, whereas mean total dry matter, and fruit and total dry matter variabil ity, were predicted to increase under almost all the scenarios. Predic tions based on equilibrium scenarios (UKLO and UKHI) gave similar resu lts. For Sangiovese, variety adaptation analysis suggested a better ad aptation in terms of mean production, but a worse adaptation in terms of yield variability.