Towards adaptation to climate change in Rioja: Quality evaluation of wines obtained from Grenache x Tempranillo selections

Wine colour is the first quality characteristic to be assessed, especially regarding red wines. Anthocyanins are very well known to be the main responsible compounds for red wine colour. Red cultivars can synthesize and accumulate anthocyanins in berry skin to express their colour. However, anthocyanin accumulation is often influenced by a series of factors, such as genetic regulation, phytohormones, environmental conditions and viticultural management.

‘Mavrodafni’ (Vitis vinifera L.) is considered one of the oldest grapevine cultivars indigenous to the Greek vineyard, with western Peloponnese being its primary center of cultivation. ‘Renio’ is considered to be either a variant of ‘Mavrodafni’ or an altogether different cultivar. Both ‘Mavrodafni’ and ‘Renio’ can be found in the vineyards of the centers of cultivation, since ‘Renio’ is considered to be more productive compared to ‘Mavrodafni’, and for this reason, it has gradually replaced ‘Mavrodafni’ from cultivation over the course of time. The aim of the present study was to assay the mechanical properties, the polyphenolic content and the antioxidant capacity of skin extracts and must of berries coming from ‘Mavrodafni’ and ‘Renio’, cultivated in the same vineyard as well as in the different regions of cultivation of the PDO Mavrodafni Patras.

During bottle aging, the development of wine aroma through low and gradual oxygen exposure is often positive in red wines, but can be unfavorable in many cases, resulting in a rapid loss of fresh, fruity flavors. Prematurely aged wines are marked by intense prune and fig aromatic nuances that dominate the desirable bouquet achieved through aging (Pons et al., 2013). This aromatic defect, in part, is caused by the presence of 3-methyl-2,4-nonanedione (MND). MND content was shown to be lower in nonoxidized red wines and higher in oxidized red wines, which systematically exceeds the odor detection threshold (62 ng/L).

Climate is the major factor influencing the dynamics of the vegetative cycle and can determine the timing of phenological periods. Knowledge of the phenology of varieties, their chronological duration, and thermal requirements, allows not only for the better management of interventions in the vineyard, but also to predict the varieties’ behaviour in a scenario of climate change, giving the wine producer the possibility of selecting the grape varieties that are best adapted to the climatic conditions of a certain terroir. In 2014, Symington Family Estates, Vinhos, established two grape variety libraries in two different places with distinctive climate conditions (Douro Superior, and Cima Corgo), with the commitment of contributing to a deeper agronomic and oenological understanding of some grape varieties, in hot climate conditions. In these research vineyards are represented local varieties that are important in the regional and national viticulture, but also others that have over time been forgotten — as well as five international reference cultivars. From 2017 to 2021, phenological observations have been made three times a week, following a defined protocol, to determine the average dates of budbreak, flowering and veraison. With the climate data of each location, the thermal requirements of each variety and the chronological duration of each phase have been calculated. During maturation, berry samples have been gathered weekly to study the dynamics of sugar accumulation, between other parameters. The data was analysed applying phenological and sugar accumulation models available in literature. The results obtained show significant differences between the varieties over several parameters, from the chronological duration and thermal requirements to complete the various stages of development, to the differences between the two locations, confirming the influence of the climate on phenology and the stages of maturation, in these specific conditions.

Durante el bienio 1998-1999 se estudió el uso consuntivo de cultivos de viña var. Listán negro, en cuatro fincas situadas en la Comarca de Tacoronte-Acentejo, en la isla de Tenerife.