Drought helps improve the quality and colour of Sangiovese grapes, the Tuscan grapevine par excellence, but only if the water stress is imposed during specific stages of ripening and according to precise intensity levels. These are the conclusions of a research study conducted by the Department of Agri-Food and Agri-Environmental Sciences at the University of Pisa published in the journal ‘Frontiers in Plant Science’, which was recently awarded the SOI-Patron Prize by the Italian Society of Horticulture.
“The results obtained showed for the first time how the combination of intensity and timing of water deficit application significantly influences the accumulation and specific profile of anthocyanins and flavonols in the berries,” explains Giacomo Palai, research fellow at the University of Pisa and first author of the study.
On the right Giacomo Palai, on the left Giovanni Caruso
In particular, moderate water deficit before veraison (when the berries are still green, from June until mid-July) increases the concentration of flavonoids in the berries, whereas severe post-veraison water deficit (from mid-July through harvest) has an effect on the colour of the berries – and therefore of the wine – making them darker and closer to blue shades.
“Water stress as a tool to manage phenolic concentration,” Palai continues, “is very important especially for Sangiovese in Tuscany, which is often a bit too pale. Wines produced in this way, on the other hand, have a more intense colour and higher phenol concentrations, which brings them closer to the standards of international vine varieties”.
Palai’s study is part of a broader research activity conducted at Precision Fruit Growing Lab, coordinated by Prof. Giovanni Caruso, and at the Viticulture and Oenology Research Laboratory, coordinated by Prof. Claudio D’Onofrio.
“In recent years, Italian viticulture has been experiencing a period of strong pressure due to climate change, with less rainfall and longer drought periods that jeopardize the quality of grapes, especially in the areas that are best suited to this variety,” says Giovanni Caruso. “In this context, the development of specific irrigation treatments and protocols to manage water deficits are essential tools to maintain and increase grape quality, exploiting and turning potentially critical conditions into positive drivers.”