Nitrogen fertilization and pruning intensity in 'Chardonnay' and 'Pinot Noir' wine-producing: effect on productivity and grape must composition

Vineyard soils do not always provide the amount of nitrogen (N) that the grapevines need. This makes it necessary to sup­plement them with nitrogen fertilizer. However, high doses of N applied can cause excess vigor in the grapevines, which can harm the composition of the grape must and, consequently, its by-products. However, excess vigor can be controlled by winter pruning. The study aimed to evaluate the productiv­ity and grape must composition in 'Chardonnay' and 'Pinot Noir' wine-producing, subjected to nitrogen fertilization and winter pruning intensity, in the southern region of Brazil. 'Chardonnay' and 'Pinot Noir' grapevines were subjected to applications of 0, 40 and 80 kg of N ha-1 year-1, since 2011. Double Guyot pruning was carried out with two pruning intensities: six buds on each branch (quality pruning) and twelve buds on each branch (production pruning). Productiv­ity, yield components (number of clusters per plant, average cluster weight, ravaz index, green pruning mass, pulp weight and skin weight), berry physical variables (Hue, Chroma, a*, b*, luminosity and berry firmness) and the must chemical composition (total soluble solids, total titratable acidity, total polyphenols, total anthocyanins, pH and TSS/TTA) were eval­uated in the 2022/23 and 2023/24 crop seasons. The high­est productivity was observed in the 'Chardonnay' and 'Pinot Noir' which were production pruned to maintain the highest number of buds per branch per plant and when the cultivars were subjected to nitrogen fertilization. Berry physical vari­ables and the must chemical composition, with the exception of total polyphenols, were not affected or were minimally af­fected by the types of pruning and the doses of N applied. Adjusting the management practice with production pruning and the application of 80 kg of N ha-1 year-1 is a strategy for in­creasing productivity in vineyards, associated with controlling the vigor of the grapevines.