Flowers and berries abscission (coulure) can lead, during some vintages and for sensitive cultivars, to dramatic yield losses with detrimental impacts on the wine industry. Many exogenous and endogenous factors are known to favor defaults in reproductive development and coulure, among which extreme temperatures and carbon imbalances play a major role.
Several previous open-field experiments have shown that foliar applications with guaiacol solutions can modify wine volatile composition. After such treatment, guaiacol glycoconjugates were detected in fruits, leaves and shoots of Monastrell variety, suggesting that aglycone compounds could be released during wine processing with some changes on the wine aroma.
At the beginning of ripening, grape berries switch their water import pathway from the xylem to the phloem. However, the cause of the decline in xylem inflow remains a matter of debate. Applying xylem-mobile dye in conjunction with root or shoot pressurization demonstrated that the direction of xylem flow was reversible and responded to pressure manipulation.
It has been known for a long time that altering microclimate affects fruit composition and wine quality. The research project Heat Berry focuses on future scenarios of the climate change regarding higher temperatures and the risk of increasing sun radiation to the fruit. Field experiments were conducted in 2015 and 2016 at an experimental site at Geisenheim (Germany) using Riesling (clone 198-25 grafted to rootstock SO4).
Physiological measurements are the most accurate way of assessing plant water status. However, they are time-consuming, costly and invasive for the plant. Visible to shortwave infrared imaging spectrometers can be used to detect and monitor several biochemical variations in the leaf offering a faster, cheaper and non-destructive alternative to the traditional methods. In this study, hyperspectral images were used to obtain the spectral signatures of grapevine leaves (Vitis Vinifera L. cv. Shiraz) under different water conditions.
The effect of grapevine age on growth and berry development was studied from 2014 to 2016 on an experimental vineyard managed by the Hochschule Geisenheim University in Geisenheim, Germany. The vineyard was initially planted in 1971 with Vitis vinifera (L.) cv. Riesling grafted on 5C Teleki.
Grapevines of the variety Vitis vinifera L. cv. Pinot Noir (clone 9-18, grafted onto 5BB) were subjected to different water regimes (irrigation treatments) over the growing season. Physiological indicators were used to monitor the plant water status (leaf and stem water potentials and relative carbon isotope composition (13C) in must sugars).
Due to the important contribution of agriculture to the global carbon dioxide (CO2) balance, new techniques are currently being developed to accurately estimate the carbon balance of different crops. Field studies to date in grapevines have been based on carbon allocation and biomass accumulation dynamics.
Climate change projections show major changes regarding temperature: a global warming with an increase average temperature and in frequency and severity of punctual heat events. Such changes in temperature will significantly affect the grapevine growing cycle and the bunch microclimate, known to be a major regulator of grape metabolism.
Plant acclimation to the light environment involves changes in plant morphology, carbon- and water-physiology, yield and quality of harvestable organs.
Rotundone is the aroma compound responsible for peppery aroma in red wines which was discovered in 2008 in a Syrah wine from Australia. More recently, it has been found in several cultivars grown in the South West of France such as Duras, Gamay and Malbec.
In this study, the response of Tannat, an emblematic variety of the Uruguay, to the modification of the source relationship (S/S) was evaluated, through the leaf removal on fruit set and thinning of clusters at veraison, measuring the composition of the grape.
Climate change has become a threat to wine industry due to increases in temperature and reductions of water in Mediterranean climates. Therefore, it is necessary to improve our knowledge about mechanisms conferring resistance to water shortages in grapevines varieties, especially at the leaf level which includes the evaporative sites in plants and experience the highest water tension through their hydraulic systems.
Climate change scenarios predict increases in the frequency and severity of droughts in arid zones. Under these conditions some plants can rapidly acclimate to stress and further fortify their defenses by retaining memories of stress which enable stronger or more rapid responses if an environmental perturbation recurs.
In the context of climate change, clones could be a way of adaptation and need to be investigated. Repositories of clones are primarily dedicated to diversity maintenance while specific experimental plots with replicates are designed for clone characterization. However, all these field experiments are time consuming and expensive to maintain.