Pedoclimatic comparison of three viticultural areas of Italy devoted to high-quality Aglianico and Cabernet Sauvignon production

Aim: The study aims to show how different pedo-climatic conditions (past, present, and future) in three Italian sites at different latitudes (from center to southern), affect the adaptation of two red grapevine cultivars: Aglianico and Cabernet Sauvignon.

Methods and Results: The pedoclimatic conditions of three experimental vineyards in three Italian regions (Campania, Molise and Sicily) were analyzed through a pedological survey to characterize the soils and to perform a climatic evaluation. The latter was based on local weather information and on the Regional Climate Model COSMO-CLM at high-resolution (8km x 8km) climate projections RCP 4.5 and RCP 8.5 (2010-2100) and Reference Climate (RC, 1971-2005). The degree of grapevine adaptation to future climatic scenarios in each experimental vineyard was evaluated through the use of bioclimatic indices (e.g., Amerine and Winkler). 

Results showed how climate change will affect the cultivation of Aglianico and Cabernet Sauvignon, considering both the thermal and water needs of the cultivars in the analyzed viticultural areas. The RCP 8.5 scenario was the worst one for all experimental sites in terms of A&W but also for precipitation and extreme events, while RCP 4.5 highlighted differences among sites and time periods analyzed. For instance, for Aglianico, the thermal requirement (2110 GDD) will be reached in the RCP 4.5 in all experimental sites, while in the RCP 8.5 it will occur but mainly in a shorter time (~ 7 days less for 2070-100). Moreover, the increase in the frequency of extreme events during the grapevine season (i.e. maximum temperature >35°C, April-October) is expected to occur in the last time window of RCP 4.5 (2070-2100 with an increase of ~5%) and during the whole RCP 8.5 scenario. In this last scenario, the increase ranges from 15% (2010-2040) to 50% (2070-100) at all sites.

Conclusion: 

The present study explored how future climate scenarios will impact Aglianico and Cabernet Sauvignon vineyard cultivation in central and southern Italy, considering the specific thermal requirements of these two vineyards. The results, in terms of climatic requirements (Amerine and Winkler index) showed how the two vineyards could react to future climate change in three sites located in central and southern Italy. 

Significance and Impact of the Study: The present work is the first example in southern Italy to evaluate the impact of climate change on two red grapevines varieties (indigenous cv and international one) to climate change. The degree of adaptation was evaluated by means of a thermal index widely used in viticulture, the Amerine and Winkler. This study has a direct impact at local and national scale, because it introduces a procedure that helps stakeholders to assess the adaptability of the wine-growing systems of territories.