Terroir 2016 banner
IVES 9 IVES Conference Series 9 Impact of defoliation on leaf and berry compounds of Vitis vinifera L. Cv. Riesling investigated using non-destructive methods)

Impact of defoliation on leaf and berry compounds of Vitis vinifera L. Cv. Riesling investigated using non-destructive methods)

Abstract

Climate change has a strong impact on the earlier onset of important phenological stages and plant development in viticulture. Hence, the adaptation of plant management is important to reply to climate related changes on a seasonal or long-term scale. In particular, a change in precipitation and higher temperatures entails the risk negatively impacting on fruit quality. An experiment was conducted where different canopy management strategies were applied to Riesling grapevines (Vitis vinifera L. cv. Riesling) planted in Winkel (Rheingau, Germany). Leaf removal at different canopy positions using various methods (e.g. manual vs. mechanical defoliation practices) led to a reduced photosynthetic active leaf area. Through modifications of the leaf area to fruit weight ratio, the berry ripening can be altered. Leaf removal of the bunch zone impacts fruit parameter and most importantly fruit health. Four different defoliation practices within a VSP trellis system were compared to a non-defoliated control during three growing seasons in an organic treated site: mechanical defoliation above the canopy (MDC); manually defoliation prior to flowering (DpF); defoliation of the bunch zone past flowering: Bunch zone defoliation (BZD) either suction fan plucking (EB490® Binger Seilzug, Germany) and mechanical defoliation or pulsation jetting of compressed air (DmS) (Siegwald®, Germany). Non-destructive measurements using a polyphenolmeter (Multiplex®3, Force-A, Orsay, France) were performed on leaves and berries to estimate the nutrition and ripening stage.

The chlorophyll index showed the lowest values for BZD and highest for control leaves. Additionally, on-the-go measurements were established to determine leaf components achieving vineyard maps in response to nitrogen or chlorophyll index. Furthermore, the data can be used for zoning the vineyard and harvest based on such mapping. When the severity of Botrytis cinerea was compared to control all treatments showed lower disease pressure (BZD -5.3 %, DpF -3.0 % and DmS -2.3 % respectively). Yield differed between -16 % (MDC), -8% DpF, -1 % (DmS) and +1 % (BZD) compared to the control having the highest (1.4 g) and BZD the lowest (1.1 g) single berry weight with a lower bunch compactness in 2014. Defoliation treatments influence the number of cluster per vine, where the lowest were found for DpF plants, accompanied with the lowest yield per single vine. These results help understanding the canopy characteristics and offer an opportunity to adapt the vineyard management strategies to seasonal changes.

DOI:

Publication date: June 23, 2020

Issue: Terroir 2016

Type: Article

Authors

Susanne TITTMANN, Vanessa STOEBER, Manfred STOLL

Geisenheim University, Department of general and organic viticulture, Von – Lade – Str. 1 D-65366 Geisenheim

Contact the author

Keywords

defoliation, non-invasive determination of leaf components, Multiplex, Plasmopara viticola, Vitis vinifera

Tags

IVES Conference Series | Terroir 2016

Citation

Related articles…

Mechanisms involved in the heating of the environment by the aerodynamic action of a wind machine to protect a vineyard against spring frost

One of the main consequences of global warming is the rise of the mean temperature. Thus, the heat summation by the plants begins sooner in the early spring, and by cumulating growing degree-days, phenological development tends to happen earlier. However, spring frost is still a recurrent phenomenon causing serious damages to buds and therefore, threatening the harvests of the winegrowers. The wind machine is a solution to protect fruit crops against spring frost that is increasingly used. It is composed of a 10-m mast with a blowing fan at its peak. By tapping into the strength of the nocturnal thermal inversion, it sweeps the crop by propelling warm air above to the ground. Thus, stratification is momentarily suppressed. Furthermore, the continuous action of the machine, alone or in synergy, or the addition of a heater allow the bud to be bathed in a warmer environment. Also, the punctual action of the tower’s warm gust reaches the bud directly at each rotation period. All these actions allow the bud to continuously warm up, but with different intensities and over a different period. Although there is evidence of the effectiveness of the wind machines, the thermal transfers involved in those mechanisms raise questions about their true nature. Field measurements based on ultrasonic anemometers and fast responding thermocouples complemented by laboratory measurements on a reduced scale model allow to characterize both the airflow produced by the wind machine and the local temperature in its vicinity. Those experiments were realized in the vineyard of Quincy, in the framework of the SICTAG project. In the future paper, we will detail the aeraulic characterization of the wind machine and the thermal effects resulting from it and we will focus on how the wind machine warms up the local atmosphere and enables to reduce the freezing risk.

Grapevine bud fertility under elevated carbon dioxide

Aims: Microscopic bud dissection is a common tool used to assess grapevine bud fertility and therefore to predict the yield of the following season

New insights on thiol precursors catabolism by yeast during wine fermentation: identification of the N-Acetyl-L-Cysteine conjugate

Understanding the catabolism of thiol precursors is essential for understanding the revelation of varietal thiols in wine. For many years, knowledge of these precursors has been limited to the S-conjugates of glutathione, cysteine (Cys3SH) and the dipeptides g-GluCys and CysGly, without being able to explain the full origin of 3-sulfanylhexan-1-ol (3SH) in wines

Rare earth elements in grapes and soil: study of different soil extraction methods

Lanthanides, together with scandium and yttrium, make up the group of Rare Earth Elements (REEs). An official method for analysis of the bioavailable REEs accumulated by plants, depending mainly on soil characteristics, chemical speciation in soil and the specific ability of the plant, is still lacking.

Enhancing vineyard resilience: evaluating sustainable practices in the Douro demarcated region

In mediterranean agriculture, sustainability and productivity are seriously threatened by climate change and water scarcity. This situation is exacerbated by poor management practices such as excessive use of agrochemicals, overgrazing, and monoculture. The Douro demarcated region (ddr) is an emblematic region, classified world heritage site by UNESCO in 2001. Viticulture is the main agricultural activity in DDR, widely known to produce port wine.