This article synthetizes observations from five experiments and reports on the effects of timing and intensity of defoliation on the white and red Vitis vinifera cultivars Pinot noir, Gamay, Merlot, Chasselas, and Doral. Intensive defoliation (removal of six basal leaves + six lateral shoots per shoot) was completed at three developmental stages of the grapevine: preflowering, flowering, and bunch closure. Preflowering defoliation had tremendous consequences on vine agronomic performance, mainly to the detriment of berry set; the yield was highly affected by preflowering defoliation (approximately -35% of that from vines with no defoliation). The intensity of defoliation allowed its impact on the yield to be modulated. The intensity of defoliation also had a positive impact against millerandage, sunburn symptoms, and Botrytis cinerea development. The berry skin thickness doubled and the polyphenol concentration increased significantly with preflowering defoliation. Due to preflowering defoliation, the red wines were often preferred for their color and mouthfeel. However, this practice had a negligible impact on white wine composition. Regardless, preflowering defoliation did not negatively impact wine parameters. In the context of this study, preflowering defoliation has potential to reduce vigor and control high production potential. Preflowering defoliation also represents a prophylactic solution to reduce both chemical applications and cluster-thinning costs.

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葡萄落叶的时间和强度：瑞士五个品种的广泛概述

本文综合了五个实验的观察结果，并报告了落叶时间和强度对白色和红色葡萄品种黑比诺、佳美、梅洛、夏塞拉斯和多拉的影响。在葡萄树的三个发育阶段完成了密集的落叶（去除六片基叶+每枝六片侧枝）：花前、开花和束束闭合。花前落叶对葡萄树的农艺性能产生了巨大的影响，主要是不利于浆果；产量受开花前落叶的影响很大（大约是没有落叶的葡萄藤的-35%）。落叶的强度可以调节其对产量的影响。落叶的强度也对碾磨病、晒伤症状和灰葡萄孢的发展产生积极影响。浆果表皮厚度加倍，多酚浓度随着花前落叶而显着增加。由于开花前落叶，红葡萄酒通常因其颜色和口感而受到青睐。然而，这种做法对白葡萄酒成分的影响微乎其微。无论如何，开花前落叶不会对葡萄酒参数产生负面影响。在本研究的背景下，开花前落叶有可能降低活力并控制高生产潜力。花前落叶也代表了一种预防性解决方案，可减少化学应用和疏丛成本。这种做法对白葡萄酒成分的影响可以忽略不计。无论如何，开花前的落叶不会对葡萄酒参数产生负面影响。在本研究的背景下，开花前落叶有可能降低活力并控制高生产潜力。花前落叶也代表了一种预防性解决方案，可减少化学应用和疏丛成本。这种做法对白葡萄酒成分的影响可以忽略不计。无论如何，开花前的落叶不会对葡萄酒参数产生负面影响。在本研究的背景下，开花前落叶有可能降低活力并控制高生产潜力。花前落叶也代表了一种预防性解决方案，可减少化学应用和疏丛成本。