Shading of the fruit zone to reduce grape yield and quality losses caused by sunburn

Abstract

<p style="text-align: justify;"><strong>Aim</strong>: To test the hypothesis that shading of the fruiting zone of the plants might reduce yield losses caused by excessive exposure to sun while avoiding the most damaging effects associated with reduced radiation.</p><p style="text-align: justify;"><strong>Methods and results</strong>: A number of grapevine rows were shaded with a double layered white plastic netting on their south-facing side, from the ground to about 20 cm above the cluster zone. Data on meteorological conditions, plant growth, plant water availability, yield components and must characteristics were recorded during three growing seasons. Shading significantly increased yield but did not alter significantly the must characteristics.</p><p style="text-align: justify;"><strong>Conclusion</strong>: Partial shading of the grapevine canopy reduced yield losses attributable to excessive radiation. The must obtained from shaded berries had a lower concentration of anthocyanins, and the wines made from these musts had a lighter colour which may be detrimental to their quality.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: The study highlights the effects of solar radiation on the composition of grape musts and suggests a potentially cost-effective method to control excessive radiation in vineyards.</p>

Grapevine abiotic stress assessment and search for sustainable adaptation strategies in Mediterranean-like climates. A review

“…Besides its effects on vegetative growth, several authors have studied the management of cultural practices towards the improvement of berry growth and ripening, which may also have impacts on sugar accumulation and berry quality potential (Matsui et al 1986;Greer and Weedon 2014;Oliveira et al 2014;Hochberg et al 2015). For instance, the application of shading panels on "Semillon" grapevine variety has been suggested to delay ripening and decrease canopy temperatures, besides sugar concentration in grapes (Greer and Weedon 2013).…”

Strategies in vineyard establishment to face global warming in viticulture: a mini review

“…The VSP trellis system is widely used in viticulture; however, its behavior with respect to high temperatures is of concern, particularly if a leaf removal technique is performed in the vineyard 109 . The VSP trellis system establishes a clear spatial separation between the leaf surface and the fruit zone, which facilitates grape overexposure to solar radiation 110–112 . Cluster optimal microclimate is given under diffuse radiation, complemented by occasional patches of direct radiation that penetrate through the vegetation in different directions.…”

Effects of grapevine bunch exposure to sunlight on berry surface temperature and Lobesia botrana (Lepidoptera: Tortricidae) egg laying, hatching and larval settlement

“…In shaded positions, berry and leaf temperatures were higher and lower than air temperature, respectively. Similar results for thermal differences between leaves and berries, in both direct‐sun and shaded positions, and with respect to air temperature, have been reported in other studies (leaves: Millar, ; Smart, ; berries: Kliewer & Lider, ; Millar, ; Smart & Sinclair, ; Zoecklein et al ., ; Bergqvist et al ., ; Jogaiah et al ., ; Oliveira et al ., ). The higher temperature of berries relative to leaves can be explained by the lower efficiency of transpirational cooling in bunches, which is particularly reduced after veraison, when our measurements occurred (Millar, ; Smart & Sinclair, ; Rebucci et al ., ; Spayd et al ., ; Tarara et al ., ; Greer & Weedon, ).…”