Techniques to modify cluster architecture and their effect on the viticultural performance of the Sauvignon Blanc cultivar

Abstract: The objective of this work was to evaluate the effect of different techniques to modify grape cluster architecture on the incidence and severity of botrytis bunch rot, as well as on the viticultural performance of the 'Sauvignon Blanc' grapevine (Vitis vinifera). Associated with fungicides, four treatments were tested: control, 30 ppm gibberellic acid sprayed at full bloom, 1,000 ppm prohexadione calcium sprayed at full bloom, and berry thinning at the stage of beginning of berry touch. The experiment was carried out in the 2015, 2016, and 2017 vintages. Clusters were treated with fungicides during the stages of full bloom, beginning of berry touch, veraison, and around 15 days before harvest. Berry thinning does not cause losses in the yield and quality of 'Sauvignon Blanc', and, despite having little effect on cluster architecture, is effective in reducing the incidence and severity of Botrytis cinerea. Prohexadione calcium improves grape phenolic maturation, is effective in reducing the incidence and severity of B. cinerea, and reduces cluster compactness by decreasing berry diameter. The application of gibberellic acid spray at full bloom is not recommended because it decreases yield and bud fertility and increases berry susceptibility to B. cinerea infection.摘要：本研究旨在评估不同调控葡萄果穗结构的技术对葡萄灰霉穗腐病（Botrytis bunch rot）的发病率与病情严重度的影响，以及长相思（Sauvignon Blanc）欧亚种葡萄（Vitis vinifera）的栽培性状表现。本试验结合杀菌剂施用，设置4个处理组：对照组、盛花期喷施30ppm赤霉素（gibberellic acid）、盛花期喷施1000ppm调环酸钙（prohexadione calcium），以及浆果始接期进行果穗疏果。试验于2015、2016和2017三个葡萄采收季开展。试验分别于盛花期、浆果始接期、转色期（veraison）及采收前约15天对果穗喷施杀菌剂。果穗疏果不会造成长相思葡萄的产量与品质损失，尽管其对果穗结构影响微弱，但可有效降低灰葡萄孢（Botrytis cinerea）的侵染发病率与病情严重度。调环酸钙可提升葡萄酚类物质成熟度，可有效降低灰葡萄孢的侵染发病率与病情严重度，并通过减小浆果直径降低果穗紧密度。不建议在盛花期喷施赤霉素，因其会降低产量与芽育性，并提升浆果对灰葡萄孢侵染的敏感性。