Abstract
<p style="text-align: justify;"><strong>Aim:</strong> The objective of this work is to investigate the effects of defoliation on cv. Pinot noir under the mild-climate conditions of Switzerland, with particular attention to berry anatomical traits and wine sensory parameters.<strong></strong></p><p style="text-align: justify;"><strong>Methods and results:</strong> Defoliation (removal of 6 basal leaves + 6 lateral shoots per shoot) was completed at three developmental stages of grapevine, i.e., pre-flowering, late flowering and bunch closure. These experimentations were performed repeatedly over six years. In addition to the vintage effect, pre-flowering defoliation had a consistent impact on vine agronomic behaviour. The yield was highly affected by the technique (-30 %). The berry skin thickness doubled, and the polyphenol concentration increased significantly. The free glutathione concentration in the must decreased.</p><p style="text-align: justify;"><strong>Conclusion:</strong> Leaf removal at early pre-flowering stage had tremendous consequences on the vine agronomic performance, mainly to the detriment of berry set, thus having a great impact on yield, berry skin thickness, must composition, and wine composition.<strong></strong></p><p style="text-align: justify;"><strong>Significance and impact of the study:</strong> Hypothesis about the competition for assimilates between the growing canopy and the inflorescences during the early season was developed. Furthermore, the role of glutathione and anthocyanins – as antioxidants against UV stress – was interpreted, demonstrating that grapevine is able to adapt to abiotic stresses and ensure a sustainable development.</p>
Highlights
The role of glutathione and anthocyanins – as antioxidants against UV stress – was interpreted, demonstrating that grapevine is able to adapt to abiotic stresses and ensure a sustainable development
Grapevine defoliation in the cluster zone is a common practice in most vineyards to improve the microclimate and prevent the development of Botrytis cinerea
The preflowering treatment (B) consistently showed earliness: at flowering stage, 72 ± 8 % of flowering was completed against an average of 57 ± 13 % in the three other treatments (A, C, D). This tendency was confirmed at veraison stage; the two latest leaf defoliation treatments (C) and (D) showed a delay (-9 % on average) in comparison to the pre-flowering and control treatments (B) and (A)
Summary
Grapevine defoliation in the cluster zone is a common practice in most vineyards to improve the microclimate and prevent the development of Botrytis cinerea. It is usually realized between the phenological stages berry set and veraison. Pre-flowering defoliation strongly affects berry set, berry number per bunch and yield (Kotseridis et al, 2012; Poni and Bernizzoni, 2010; Sabbatini and Howell, 2010). The defoliation impact on berry set mainly depends on vintages (Hed et al, 2015) and grape variety (Kotseridis et al, 2012). Fruit set and yield are not affected when defoliation is completed after berry set (Feng et al, 2015; Nicolosi et al, 2012; Tardaguila et al, 2008)
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