Changes in vineyard establishment and canopy management urged by earlier climate-related grape ripening: A review

Abstract

One of the main objectives of wine grape growers in several viticultural areas throughout history has been the achievement of full ripening, i.e. maximum soluble solids concentration in the absence of apparent berry shrinkage. Recently, this target is somewhat losing its appeal since an increasing number of consumers from both domestic and foreign markets prefer lighter wines characterized by moderate alcohol content. The above scenario needs to be added of another actor, i.e. the global warming and its effects on vine growth and berry composition which can be summarized as it follows: (i) onset of flowering and veraison phenological stages occurs earlier; (ii) grape ripening is generally accelerated as per increment of sugar accumulation into the berries which, in turn, leads to higher alcohol content in the wine; (iii) faster depletion of organic acids in the juice and more rapid increase of pH values which, as a consequence, triggers high microbiological instability of the must during pre-fermentation; (iv) due to excessive heat summations and poor thermal excursion the overall aroma profile can result untypical shifting towards overripe; (v) uncoupling of technological (more accelerated) and phenolic (more delayed) ripening with negative effects on grape and wine aroma and flavor, especially in red grape varieties; (vi) higher frequency of berry withering up to sun burn damage. In the medium-to-long term these factors likely will affect the geographical distribution of viticulture and will require new breeding programs for selecting more adapted roostocks and scions, whereas in the short term, new management techniques able to mitigate these negative impacts are urgently needed. In this review, several tools including varietal and clonal choice, possible diversification of wines produced, suitable training system and rootstocks, traditional and innovative management techniques able to regulate a too much accelerated and/or unbalanced grape ripening process, will be presented and discussed.