Pier Giorgio Bonicelli, Ginevra Canavera, Riccardo Collivasone, Silvia Pagani, Mario Gabrielli, Tommaso Frioni
Università cattolica del Sacro Cuore, Piacenza – Italy
One of the pressing challenges for Italian viticulture is to find new solutions to cope with climate change. Rising temperatures and lack of rainfall are in fact having serious repercussions on the productivity and quality of harvested grapes. Not least, extreme phenomena such as hailstorms, late frosts and other destructive events are becoming very frequent and affecting ever larger sectors of territory. It is clear that beyond generally valid techniques and principles, solutions must now be developed to counter climate change issues that are tuned to the specific needs of territories and local viticulture. Climate change adaptation tools are divided between long-term ones (land policies, disciplinary changes, or, on a smaller scale, planting choices) and short-term ones that can be employed annually (Palliotti et al. 2014). The former include varietal choice. Indigenous, minor or local grape varieties are now posing as innovation tools for identifying new product types, taking advantage of the different resilience of available genotypes to changing environmental conditions.
The SalViBio project (www.salvibio.eu), coordinated by the Università Cattolica del Sacro Cuore of Piacenza, has the primary objective of enhancing the viticultural biodiversity of the Colli Piacentini area to improve the competitiveness of the area’s wine production, which is strongly affected by climate change.
Evaluation of the minor grape varieties of the Piacenza area
On the approximately 5,000 hectares planted with vines in the Colli Piacentini, the most widely used grape varieties are Ortrugo and aromatic Malvasia di Candia with white berries, and Barbera and Croatina with black berries. Beyond these, a few hectares are planted with international grape varieties (Sauvignon blanc and Pinot noir), or other minor indigenous varieties (Fregoni et al. 2002). Ortrugo and Malvasia di Candia aromatica have the problem of low acidity at harvest (4.5-5 g/L), due to malic acid degradation in the presence of high temperatures post veraison, associated with slow sugar accumulation. Early harvest is therefore not a decisive choice to avoid loss of titratable acidity. In Croatina, on the other hand, the main problem is poor basal bud fertility, which in turn causes inconstant productivity and low adaptability to mechanization. Barbera, on the other hand, under certain pedoclimatic conditions is very sensitive to radiative stresses on bunch, manifesting important sunburn that causes productive losses and the impairment of the biochemical balance of musts.
Under Action 1 of the project, 29 grape varieties (18 white berry, 10 black berry, one pink berry) were evaluated for three consecutive seasons against Ortrugo, which was present in the collection as a reference (Table 1).
Among the white grape varieties, Barbesino and Lisöra were of particular interest. Barbesino and Lisöra are two white grape varieties native to Val Trebbia and Val d’Aveto, respectively (Fregoni et al. 2002). Both have been shown to maintain good titratable acidity in the grapes and moderate sugar content, imparting freshness to the wines. In particular, Barbesino showed a sugar accumulation during ripening quite comparable to that of Ortrugo, while titratable acidity was consistently 2-4 g/L higher from veraison to full ripeness (Figure 1).
In 2020, Ortrugo and Barbesino grapes were vinified in the experimental winery, and Barbesino-based wines showed higher titratable acidity levels than Ortrugo (+4.63 g/L) with the same soluble solids (Table 2).
Malvasia Rosa is a genotype isolated by Prof. Mario Fregoni by natural gem mutation of Malvasia di Candia aromatica (Fregoni et al. 2002). Although the ampelographic characteristics and aromatic complex of the two varieties are similar, Malvasia Rosa has a different berry coloration with an anthocyanin profile characterized by the exclusive presence of peonidin and cyanidin.
Among the black berry varieties, Fruttano was found to be of interest because of its late ripening and potential for producing sparkling red wines with low alcohol and fair final acidity. The grape variety has also proved particularly efficient at accumulating anthocyanins in the skins, which have high concentrations of malvidin.
Molinelli, Bucalò, Verdea, and Duraguzza have also, for different reasons, aroused interest in relation to the modern needs of Piacenza viticulture. The work demonstrated the importance of the conservation of local viticultural germoplasm in order to safeguard traits of interest for the adaptation of viticulture to the demands imposed by climate change.
The Ervi, for the relaunch of Piacenza’s red wines
L’Ervi is a black grape variety obtained by crossing Barbera and Croatina. It was obtained in the 1970s by Prof. Mario Fregoni as part of his extensive genetic improvement program dedicated to local viticulture (Fregoni et al. 2002). Since 2003, Ervi has been included in the list of grape varieties suitable for cultivation in Emilia-Romagna.
Studied for two years as part of the SalViBio project, Ervi, with the same training form, has a lower yield than Barbera. In particular, average bunch weight was found to be higher than Croatina and lower than Barbera (264 g), while average shoot fertility was found to be higher than Croatina and lower than Barbera (19 bunches/vine). At ripening, Ervi had higher grape sugar concentration (25.1° Brix) than Croatina and Barbera, while titratable acidity was lower than Barbera but higher than Croatina. The aspect of greatest interest regarding Ervi is its particular predisposition to accumulate anthocyanins. In both years the accumulation of total anthocyanins in the grapes was earlier and higher than in the parent grapes.
Wines produced in 2020 and 2021 showed that the analytical data found on the grapes are also confirmed following the winemaking process. Wines made from Ervi had good alcohol content combined with sustained acidity, although lower than Barbera. Color intensity is higher in Ervi grapes than in Barbera with an anthocyanin profile characterized mainly by Malvidin.
In summary, Ervi is a grape variety that stands as a useful solution to some of the key problems of the two parents. More productive and consistent than Croatina, it is suitable for mechanical pruning and is less susceptible to sunburn than Barbera, while also retaining better acidity and phenolic load than Croatina. It is therefore a versatile grape variety, suitable for producing fine red wines, to be drunk young or suitable for aging. Because of its positive characteristics and also thanks to the knowledge made available by the operational groups for innovation financed by the Emilia-Romagna Region (ValorInVitis and SalViBio), today some wineries produce pure wines made with Ervi, and nurseries produce more than 20000 rooted cuttings/year.
Santa Maria and Melara: the grapes of the local vin santo
Santa Maria and Melara (Figure 2 a, b) are two minor native white grape varieties grown in the eastern areas of the Colli Piacentini, specifically along the valleys of the Apennine streams Arda, Ongina and Stirone (Fregoni et al. 2002). The two varieties are officially listed in the National Register of Wine Vine Varieties and are suitable for cultivation in Emilia-Romagna. To date, the area planted with vines is limited to about 5ha and 0.5ha, respectively, for Santa Maria and Melara, all in the Vigoleno area in the municipality of Vernasca (PC), although there are also mixed vineyards in the area in which the varieties are present jointly with other local ones.
The two varieties are used for the production of vin santo after a period of drying on trellises (Figure 3), specifically Vin Santo di Vigoleno, a mention within the Colli Piacentini DOC.
As part of the SalViBio project, the ripening evolution and wilting dynamics of the two varieties were studied in 2021 and 2022 in three different areas of Piacenza. The two grape varieties showed a certain propensity to change their vegetative-productive characteristics in relation to vigor. In the Vigoleno areal, Santa Maria showed superior production due to the higher berry weight.
Comparison of the ripening kinetics of Ortrugo, Santa Maria and Melara showed that, throughout the season, the ratio of sugars to acidity remained higher in the two minor varieties (Figure 4). This was confirmed in all three areals evaluated. This suggests that the two varieties may be used for even different purposes than the production of passito or vin santo wines. In particular, Santa Maria seems to be suitable for the production of pure still wines because of its excellent technological maturity. In addition, considering that in the production of vin santo a significant sorting of grapes is carried out, with a percentage of discards at the most variable on a seasonal basis of clusters unsuitable for drying because they are too compact or less ripe, the data suggest that discarded grapes can be used to increase the acidity of musts made from Ortrugo grapes.
In the drying phase, Santa Maria grapes showed higher daily dehydration rate, and therefore faster sugar concentration than Melara (Fig.5); reducing the drying time could ensure an advantage both in economic terms, limiting the related expenses, and in terms of health, as drying is a phase of possible microbial infection.
Fregoni M., Zamboni M., Colla R. (2002) – Caratterizzazione ampelografica dei vitigni autoctoni piacentini. Università Cattolica S.C. Cattedra di Viticoltura Piacenza.
Palliotti, A., Tombesi, S., Silvestroni, O., Lanari, V., Gatti, M., & Poni, S. (2014). Changes in vineyard establishment and canopy management urged by earlier climate-related grape ripening: A review. Scientia Horticulturae, 178, 43-54.
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