Effect of soil type on some composition parameters of Vitis vinifera L. cv. Nero d'Avola grapes at different stages of ripening

In this study, the soil effect on the chemical composition of red grapes from Vitis vinifera L. (cv Nero d'Avola) was studied. The soil effect was evaluated by considering the main soil chemical–physical parameters (e.g., texture, pH, total carbonates, cation exchange capacity, electric conductivity, organic matter, and mineral composition) of four vineyards located in the southwestern coast of Sicily (southern Italy). Grapes' quality in relation to different soils was investigated by studying some composition parameters and the (in)/homogeneity of ripeness of grapes at the harvest date. Results suggested that the soil greatly affected the quality of Nero d'Avola red grapes. The most impactful soil parameters were cation exchange capacity, electric conductivity, pH, and mineral composition (especially P and Mn content) that are directly involved into grapevine nutrition. Through multivariate statistical analysis, it was highlighted that the soil effect was remarkable within a specific vintage. However, when more vintages are considered simultaneously, the vintage effect (conceivably through the inter-annual climatic variability) is the major factor determining grapes quality.