Terroir, climat et sol

Grapevine faces multiple biotic and/or abiotic stresses, which are interrelated. Depending on their incidence, they can have a negative impact on the development and production of the plant, but also on its longevity, leading to vine dieback. One of the consequences of vine dieback on production is the increased replacement rate of dead or missing vines within a parcel.

Pinking describes the appearance of a salmon-red blush in white bottled wines produced exclusively from white grape varieties. It is understood as an undesirable chromatic phenomenon by both wine consumers and the industry. Nowadays, there are no treatments to fully reverse pinking once it occurs. Partial reversion has been shown after exposure of pinked wine to ultraviolet (UV) light.

The relationship between grape production and leaf surface is a highly debated aspect in terms of the impact it may have on the composition and quality of grapes, especially in areas that focus their cultivation on high-quality wine. In many occasions, the limitation of the unitary production level in these areas is claimed to be the main factor for achieving high quality levels in the wine, forgetting the importance of the source-sink relationship and other environmental factors and management of the canopy. Taking this consideration into account, this work seeks to know the response of the vine as a whole, and the individual shoot as well, to the application of various alternatives of leaves and clusters removal, carried out in the phase immediately before veraison, in cv. Verdejo, in Spain.

As the quality and typicity of wine are influenced by the climate, it is essential to have a good knowledge of climate variability, especially with regard to temperature, which has a great impact on vine behavior and grape ripening.

With climate change, it is progressively more often to obtain grapes with an acceptable content in sugars or acids but with immature tannins described as green, aggressive or hard (noted as GAH onwards). During winemaking, the oenologist has to make decisions related to the elaboration of such grapes based mainly on empirical experience, given the lack of objective criteria to this concern. An increase in the chemical and sensory knowledge of immature tannins would allow managing this GAH character of grapes with the maximum possible efficiency during winemaking processes. The present work aims at isolating and identifying the group of compounds responsible for the GAH character present in wines.