Pre-flowering defoliation affects berry structure and enhances wine sensory parameters

Aim: 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.Methods and results: 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.Conclusion: 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.Significance and impact of the study: 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.