Implementing Shading Systems in Viticulture
Shading systems are an innovative technique to protect vines from heat and sun. This technique involves installing structures such as shade canopies and shading nets to reduce sun exposure. They offer an innovative solution to protect vines from the harmful effects of heatwaves. Artificial shading helps preserve the quality of the grape and the health of the vine under challenging climatic conditions[1].
Shading tools
There are different tools to create shade.
- Shading nets, which are nets placed around the vines, on one or both sides of the row. Different degrees of occlusion are possible.
- Infrastructures: producing shade can also be done by building infrastructures. The typical example is photovoltaic panels covering vineyard plots.
- Vitiforestry: planting trees within vineyard plots creates shade while also promoting biodiversity, improving water infiltration into the soil, and enhancing air circulation…[2]
Reducing the effects of heatwaves
Too hot a climate causes several constraints for vines. Excessive temperatures can lead to early ripening of the grape and thus a higher sugar content and lower acidity in the wine[1]. Heatwaves can also cause sunburn on leaves and berries, leading to reduced yield and quality. Moreover, prolonged high temperatures cause drought phenomena, which pose problems for vine health and water management. Additionally, vines affected by heat stress are more susceptible to diseases and pests.
Moderated microclimate
Shading systems create a controlled environment that modifies extreme climatic conditions. By protecting vines from the sun, these devices limit heat stress by reducing the temperature around the vines.
For example, smart canopies like the Ombréa system (a system of retractable canopies installed above existing vineyard plots) automatically adjust shade according to climatic conditions thanks to sensors and artificial intelligence, allowing for lower temperatures while maintaining sufficient light for photosynthesis[3].
Furthermore, tests conducted in the Var region with shading nets showed that they reduce the daily maximum temperature by 1°C to 2°C[4].
Protection against sunscald
Shading reduces direct sun exposure, preventing burns on leaves and fruits. This helps preserve grape quality[1].
Reduction of evapotranspiration and evaporation
Shading structures limit water loss through evapotranspiration, helping vines cope with drought periods[5].
Artificial shading also helps retain soil moisture. In hot and dry climates, soil water evaporation is an increasing problem, leaving vines dehydrated and stressed. Shading structures block part of the solar radiation, thus reducing evaporation and maintaining soil moisture at an optimal level for vine growth[1].
Pest management
Shading systems can also assist in managing pests. Some pests and diseases are more active under high temperatures and strong light[1]. The moderated microclimate created by shading helps reduce pressure from these pests. For example, the eudemis is more active in warm weather. It usually produces 2 to 3 generations per year, but during hot and dry summers, a 4th generation can appear, worsening damage to the vine[6][7].
Effects on production
More balanced ripening
Shading systems limit temperatures around the vines, which can affect grape ripening.
For example, under canopies, grapes show slower and more balanced ripening, with a reduction in sugar concentration (up to 5%), slightly higher berry weight (+4%), and a decrease in alcohol content of the wines produced[3].
With shading nets, the onset of ripening is delayed and the veraison date is shifted by an average of 5 days. Sugar concentration is also lower, and acidity higher for the same harvest date[8].
Consistency and sustainability of production
Protected vines retain their leaves longer after harvest, promoting better ripening and optimal budburst the following year. This reduces vine mortality and stabilizes yields in the long term[3].
Multifunctionality
Protection against other climatic hazards
Some systems allow integration of hail nets or can be combined with solar panels to generate energy while financing their installation[3].
Improvement of the water cycle
Especially in vitiforestry, these devices promote better water management by recycling moisture via evapotranspiration and condensation, and by allowing better water infiltration into the soil thanks to the root system of trees[2].
Limits and challenges
Impact on photosynthesis
Excessive shade can reduce light available for photosynthesis, potentially affecting vine vigor if the system is poorly adjusted[1][2]. Once shading is installed, it is necessary to regularly monitor its effectiveness and make adjustments. This may involve moving the shading at different times of day or modifying the amount of shade according to weather conditions so that the vine always receives sufficient light.
Regulatory acceptance
These devices are not yet authorized in certain appellations (AOP), limiting their adoption despite proven benefits[3]. Indeed, shading systems can alter the balance of wines (sugar levels, etc.) and thus the expression of the terroir. The specifications of AOPs impose precise cultural practices to guarantee uniformity and typicity of wines from an appellation and do not currently allow this innovative practice. Wines must therefore be produced under IGP which can be a constraint for growers.
Installation cost and planning
Although some systems are financed by solar energy production, their initial setup remains expensive for many growers[3]. Costs vary depending on the equipment used but can reach several tens of thousands of euros per hectare.
- For shading nets, the cost is about €15,000 per hectare[9], which can be lower or higher depending on the equipment used. The lifespan of nets is about 10 years.
- For infrastructures with solar panels, the cost is about €80,000 per hectare, noting that they also require regular cleaning (twice a year)[10]. Their lifespan is 25 to 30 years with a slight performance decrease (0.5% reduction each year)[11].
- For vitiforestry, the average cost is €18 per tree and between 30 and 50 trees per hectare, thus €540 to €900 per hectare[12].
Moreover, installation and monitoring of these devices take time. For installation, it is important to assess the vineyard’s sun exposure, vine orientation, and daily sunlight hours to choose suitable equipment. Installation may require a professional, especially for large vineyards, and afterwards, close attention must be paid to ensure vines receive enough light[1].
Sources and references
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 https://www.aveniragricole.fr/benefices-ombrage-artificiel-proteger-vignes-climat-chaud.html
- ↑ 2.0 2.1 2.2 https://www.agroforesterie.fr/vitiforesterie-etat-de-lart-des-connaissances-scientifiques/
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 https://www.vitisphere.com/actualite-95401-anti-coup-de-soleil-et-antigrele-pour-cette-vigne-sous-ombriere-photovoltaique.html
- ↑ https://www.vignevin.com/wp-content/uploads/2023/04/Article-Ombrage_vigne_Provence.pdf
- ↑ https://www.vineas.net/fr/7_114/5df249b336961d543875e50d/Favoriser%20l%27ombrage%20au-dessus%20des%20vignes.html
- ↑ https://theses.hal.science/tel-02479851v1/file/86223_ILTIS_2019_archivage.pdf
- ↑ https://www.syngenta.fr/cultures/vigne/article-insecticide/eudemis-premiere-ligne-vignobles#:~:text=Eud%C3%A9mis%20raccourcit%20son%20cycle%20avec,forte%20humidit%C3%A9%20associ%C3%A9%20%C3%A0%20des
- ↑ https://www.vignevin-occitanie.com/wp-content/uploads/2024/07/Effets-de-lutilisation-de-filets-dombrage.pdf
- ↑ https://www.vignevin.com/wp-content/uploads/2022/12/1-Filets_ombrage.pdf
- ↑ https://chateauberne-vin.com/blogs/news/panneau-solaire-vigne-alliance-gagnante-pour-la-vigne
- ↑ https://www.facilasol.fr/panneaux-solaires-vignes-optimiser-votre-exploitation-viticole-grace-a-lenergie-renouvelable/
- ↑ https://www.vignevin-occitanie.com/fiches-pratiques/agroforesterie/
