GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 Effects of severe shoot trimming at different phenological stages on the composition of Merlot grapes

Effects of severe shoot trimming at different phenological stages on the composition of Merlot grapes

Abstract

Context and purpose of the study – High concentration of sugars in grapes and alcohols in wines is one of the consequences of climate change on viticulture production in several wine regions. One of the options to alleviate this potential problem is to perform severe shoot trimming of the vines to limit the production of carbohydrates. Two different studies were performed in order to investigate the effects of severe shoot trimming on the composition of Merlot grapes; in a first study severe shoot trimming was performed at three different phenological stages (at berry set, at the beginning of veraison and at the end of veraison), while in a second study two trimming treatments (standard shoot trimming and severe shoot trimming performed at the end of veraison) were combined with two shoot densities in order to evaluate the relative impact of these treatments on Merlot grape composition.

Material and methods – In a study conducted during years 2013 and 2014 severe shoot trimming (65 cm shoot height) was performed at berry set (berries 2-4 mm in diameter), at the beginning of veraison (when <5% of berries had changed color), and at the end of veraison (when >80% of berries had changed color). These treatments were compared with a standard canopy treatment (125 cm shoot height). Another study was conducted during years 2015 and 2016, where standard canopy treatment (125 cm shoot height) and severe shoot trimming at the end of veraison (65 cm shoot height) were combined with two shoot densities per vine (obtained with 35% shoot thinning vs. untreated).

Results – Severe shoot trimming at all the three investigated stages reduced sugars in grapes, although this effect was the greatest in the two veraison treatments. Severe shoot trimming at berry set and at the beginning of veraison reduced also the concentration of total anthocyanins in grapes, while severe shoot trimming at the end of veraison obtained similar values of total anthocyanins to the standard canopy treatment. Photosynthetic active radiation in the cluster zone was greater in all treatments with severe shoot trimming because of greater light penetration from the upper part of the canopy. We hypothesize that greater light penetration around clusters in combination to the intensive accumulation of anthocyanins during the first weeks of berry ripening, enabled the treatment of severe shoot trimming at the end of veraison to obtain similar values of total anthocyanins to the standard canopy treatment. No effects on yield components, titratable acidity, pH and total phenolics in berries were observed in any of these treatments. In a study where standard and severe shoot trimming were combined with two shoot densities, a consistent effect on the reduction of grape sugar concentration was achieved only with late severe shoot trimming. Higher shoot density reduced sugars in grapes only in one season, while at the same time reduced the concentration of total anthocyanins in berries.

DOI:

Publication date: September 29, 2023

Issue: GiESCO 2019

Type: Poster

Authors

Marijan BUBOLA1*, Sanja RADEKA1, Sara ROSSI1, Tomislav PLAVŠA1, Milan OPLANIĆ1, Ádám István HEGYI2, László LAKATOS2, Kálmán Zoltán VACZY2

1 Institute of Agriculture and Tourism, Karla Huguesa 8, HR-52440 Poreč, Croatia
2 Eszterházy Károly University, Food and Wine Research Institute, Leányka utca 6, H-3300 Eger, Hungary

Contact the author

Keywords

severe shoot trimming, shoot thinning, Brix, anthocyanins, phenolics

Tags

GiESCO | GiESCO 2019 | IVES Conference Series

Citation

Related articles…

Water deficit impacts grape development without dramatically changing thiol precursor levels

The use of new fungus disease-tolerant grapevine varieties is a long-term and promising solution to reduce chemical input in viticulture. However, little is known about the effects of water deficit (WD) on the thiol aromatic potential of new varieties coming up from breeding programs. Varietal thiols such as 3-sulfanylhexan-ol (3SH), 4-methyl-4-sulfanylpentan-2-one (4MSP) and their derivatives are powerful aromatic compounds present in wines coming from odorless precursors in grapes, and could contribute to the wine typicity of such varieties.

Classification of the wine-growing environment of Central Mancha (Spain). First works

This paper describes a zoning study performed on a vast territory of around 86,500 hectares, situated in the countryside area of La Mancha Central (Castilla-La Mancha). The aim of the study was to classify the environment according to a small number of ecological criteria, establish the relevant territorial units and generate thematic maps with the different levels of criteria employed and synthetic maps by crossing these criteria.

PRODUCTION OF A FUNCTIONAL BEVERAGE FROM WINEMAKING BY-PRODUCTS: A NEW WAY OF VALORISATION

In the challenge of transforming waste into useful products that can be re-used in a circular economy perspective, winery by-products can be considered as a source of potentially bioactive molecules such as polyphenols. The wine industry generates each year 20 million tons of by-products. Kombucha fermentation is an ancestral process which allow to increase the biological properties of tea by the action of a microbial consortium formed by yeasts and bacteria called SCOBY. It belongs to the field of healthy food for which the interest of consumers is growing. The objective of this work was to propose a new functional beverage made from winemaking by-products fermented by a Kombucha SCOBY.

Impact of chitosan treatment on the physico-chemical features of a sangiovese red wine

Chitosan is gaining interest in red winemaking thanks to its ability to inhibit the development of Brettanomyces spp. yeast, or other undesired wine microbial threats. However, little is known about potential side-effects of its addition on the physico-chemical parameters of red wines.

Better understand the soil wet bulb formation with subsurface or aerial drip irrigation in viticulture

The gradual change in rainfall patterns experienced in the south of France vineyards, especially around the Mediterranean sea, means that the vines are increasingly subject to summer drought. The winegrowers developped the use of irrigation techniques to ensure the maintenance of competitive yields in the production of wines under Protected Geographical Indication label. In practice, drip irrigation pipes can be installed above the ground or buried into the soil as well as at different distances from the vine row. The objective of this study was to examine the profiles of the wet bulbs of the soil obtained from two drip irrigation systems : aerial drip located under the vine row and subsurface drip placed in the middle of the inter-row. This experiment took place over two consecutive seasons (2020-2021) on a 3.4 ha Viognier plot in the Mediterranean region (PGI Oc, France) on sandy clay soil. The annual rainfalls were less than 400 mm. Soil water content probes were installed at different depths (20 – 40 – 60 – 80 cm) and at different lateralities from the vine row (30 – 60 – 90 – 120 cm) to control the formation of the soil wet bulb during irrigation. The mapping and the analysis of the data allowed a better understanding and differentiation of the water percolation when irrigating with subsurface or aerial drip. For the same amount of water and without differences of vine water status, it is shown that in a subsurface drip irrigation situation, the size of the wet bulb formed is larger than in aerial drip irrigation system.