DETERMINANTS OF ADAPTATION OF GRAPEVINE TO AN EVOLVING CLIMATE: HYDROLOGICAL CONDITIONS AND CULTIVARS BIODIVERSITY

Soil water availability is one of the main determinants of crop yield and of adaptation to a changing climate. The aim of this study was to analyse the soil water regime, as determined by climatic conditions, in combination with the intra-specific biodiversity of yield responses of grapevine to water availability. The adaptability of wine-producing cultivars to future climate was thus assessed. In a region of southern Italy the effects of climate evolution on soil water availability were determined. Through a mechanistic model, simulations of the soil water regime were performed over the study area accounting for spatial variability of soil hydrological properties. Two climate cases were considered: reference (1961-1990) and future (2021-2050). Hydrological indicators were calculated from model outputs. For several wine-producing cultivars, hydrological requirements were determined by means of yield response functions to water availability. Cultivar-specific hydrological requirements were then evaluated against hydrological indicators of soil water availability to assess adaptability, i.e. the probability that a given cultivar attains the target yield under a specific combination of climate and soil conditions. The potential spatial distribution of wine-producing cultivars was thus determined. The future climate was characterized by higher mean temperatures and by a decrease in precipitation. The variability of soil types affected cultivars adaptability. For instance, in the alluvial terraces and alluvial plain environments the soil water availability was higher and the hydrological indicators had quite similar values in both climate cases; therefore, the adaptability of the cultivars did not vary from the reference to the future climate in a large part of these environments.