Counteracting climate change effects on Greco grapevine in the Grease project: soil and canopy management to balance resource use efficiency and wine quality

Climate change, causing increasing warming and drought in Mediterranean area, is year by year determining grapevine yield and berry quality reductions, with particular extent in some of the autochthonous grape varieties, as Greco grapevine, cultivated in the Campania Region (southern Italy) and used alone or blend in many quality label wines. Since pedo-climatic conditions affect vineyard productivity and grape quality, the adoption of adequate cultivation techniques, such as soil and canopy management, can support vineyard in counteracting climate change effects, improving grape yield and berry quality, thus allowing to obtain highly valuable wines. The evaluation of the Greco grapes quality by the analysis of primary metabolites of the grape and the secondary ones, with an oenological impact responsible for the organoleptic quality and the longevity of the white wines, is pivotal for understanding whether the adopted cultivation practices might mitigate the negative effects deriving from long-lasting exposure of grapes to drought and/or rainy periods which may determine the onset of organoleptic defects in the wines.

In the framework of the Rural Development Programme 2014-2020, Campania Region funded the Grease project to contribute to the main topic of improving grapevine productivity, resource use efficiency and resilience for the sustainable management of vineyards.

Within the general objective of the Grease project, the aim of this study was to evaluate how different combinations of main cultivation practices, as vine canopy and soil management, can allow to exert a balanced  vegetative and reproductive growth that enhances grape and wine quality, improving farm profitability.

The three-year trial was carried out in a Greco experimental vineyard of Feudi di San Gregorio winery in southern Italy (Avellino, Campania region), aiming to analyze the effects of three soil management practices (cover crops, natural coverage, and soil tillage) and two vine training systems (double guyot and double guyot flipped) on yield, berry and must quality in three vintages.  The meteorological data and soil water content were collected through weather stations and time-domain reflectometry (TDR) technique.

At harvest yield components were determined and berry quality was evaluated by measuring soluble solids, pH, titratable acidity, malic acid, phenolics, assimilable nitrogen etc. Apart usual chemical analytical methodologies, spectrophotometric and chromatographic techniques were used to determine phenolic composition of grapes and wines. Microvinifications were also performed to evaluate the variability of oenological traits under different combination of soil and canopy management.

A great effect of year on primary and secondary metabolites were detected. Soluble solids and total phenolic compounds increased passing from 2020, 2021 and 2023 while a clear trend for titratable acidity and pH was not observed due to a wide variation in malic acid content.  Among soil management practices natural coverage and cover crops resulted in grapes with lower content of soluble solids while the soil tillage determined a lower content of phenolic compounds and hydroxycinnamic acids in grapes. In two years, soil tillage determined higher content of assimilable nitrogen in grapes probably because a lower competition for nitrogen occurred. Trends observed in grapes were confirmed in wines.