Short-term canopy strategies to enhance grapevine adaptation to climate change

Abstract

Context and purpose of the study – Viticulture faces significant challenges due to climate change, with increased frequency of extreme weather events impacting grapevine growth, grape quality, and wine production. These issues, once confined to warmer regions of southern Europe, now affect cooler areas like Northern Italy, where there is an increasing frequency of storms, heavy rainfall, and heatwaves which can lead to ripening arrest and quanti-qualitative losses. This issue affects both red and white grape varieties, with the latter particularly vulnerable due to reduced acidity levels, crucial for aromatic and sparkling wine production. To address the impact of high day and nighttime temperatures in the summer (from July until harvest), the present study was aimed at testing different short-term adaptation solutions including the use of shading nets and the spraying of particle films such as kaolin and zeolite, the first reducing overall incoming solar radiation and the latter increasing albedo while reducing the temperature of leaves and fruits.

Materials and Methods – The experiment was conducted in an organic vineyard of Vitis vinifera cv. Glera, cultivated for Prosecco wine production in Norther-East Italy. From pre-véraison (early July) until harvest, a complete randomized block design was applied with the following three treatments plus an untreated control: shading net (black 40%), kaolin and zeolite applied on both canopy sides of three adjacent vine rows per block. Throughout the experimental period, continuous monitoring of berry temperature and canopy microclimate, as well as physiological and morphological measurements, were carried out at regular intervals. At grape maturity, various cluster/berry morphometric parameters, yield variables and berry composition qualitative analyses were assessed to determine whether the treatments had significantly affected the chemical properties of grapes, must, and base wine.

Results – Treated vines exhibited sustained stomatal conductance compared to the control. This improved physiological activity in treated plants aligns with the average temperature data recorded by sensors on canopies and berries. Berry and canopy temperatures in the control plants were consistently higher than those of the treated plants. The treatments also had a significant effect on berry characteristics evaluated at harvest. Notable changes in acidity, calcium, copper content, and berry weight were obtained, suggesting the potential applicability of these short-term adaptation techniques not only for fostering vine adaptation to heatwaves in the field but also for preserving and in some cases improving berry chemical characteristics and wine quality.