Physiological and Enological Implications of Postveraison Trimming in an Organically-Managed Vineyard (cv. Sangiovese)

For the first time, grapevines subjected to a single-post-veraison trimming, were compared with never trimmed controls, to assess its effects on vine physiology, as well as grape and wine quality. In 2013 and 2014, post-veraison late trimming (LT), performed at 15 Brix, was compared with an untrimmed control (CK) and early (pea-size) trimming (ET). Late trimming increased the total berry skin anthocyanin and phenolic concentration without modifying the berry soluble solids, pH and titratable acidity; it also reduced malic acid levels at harvest, reduced yield, loosened bunches and limited the severity of botrytis bunch rot. Improved berry color and decreased malic acid levels were observed in ET vines only in 2013. Bunches from ET vines showed higher compactness and discoloration compared with those of LT vines. Trimming did not modify the main chemical characteristics of the wine, such as alcohol strength, dry matter, pH, and total and volatile acidity. However, in both years, a notable increase in the color components and tannins was found in LT wines, with the formation of more stable components able to enhance wine quality, whereas ET had less impact on wine color characteristics. The enological benefits induced by late trimming appeared more markedly following wine storage. Late trimming was an efficacious practice for improving the phytosanitary status of bunches and berry color, without modifying technological parameters, and for enhancing wine quality in different climatic conditions.