Effect of early shoot trimming on canopy architecture and vine performance of Carricante grapevines

Morpho-physiological changes, excessive sugar accumulation, low acidity and color, and atypical flavors have been well documented worldwide as a consequence of global warming. These upheavals suggest a re-think of viticulture models and/or management strategies. This study focused on early shoot trimming to evaluate how changes in canopy architecture can influence its functionality and grape qualitative-quantitative traits. The experiment was carried out in 2023 in a 12-year-old vineyard on Etna Mount (Sicily island) on the white grape variety Carricante. At the BBCH73 stage (berries groat-sized), all shoots on 180 vines were trimmed at the height of the node above the last bunch (TR), whereas the other 180 vines were subjected to late shoot trimming during the last week of August (CT). The early trimming removed 61% of the total leaf area and did not cause any berry drop. The vine performances were influenced by high temperatures in summer, with peaks of over 46 °C, which were responsible for the premature senescence of basal leaves from primary shoots and the lack of development of laterals in CT vines. The TR determined a change in vine architecture, characterized by a reduced vigour and canopy height and an increase in the leaf area (+34%), thanks to lateral shoot development, resulting in the most dense canopy. In the TR vines, the yield and their components were unchanged compared to CT vines, whereas a reduction in sugar (21.6 vs. 23.1 °Brix) and an increase in polyphenols (+20%) were found.