The influence of Effective Microorganisms and number of buds per cane in viticulture on chemical composition in fruits

As a result of climate warming, wine-growing zones have moved to the north, where conditions exist may result in poor fruit quality. Fruits may develop significant amounts of tannin compounds, which are not acceptable to all consumers. The aim of this study was to demonstrate the influence of selected factors on the quality and content of polyphenols in grapevine fruits. The differentiating factors were as follows: two grapevine cultivars, varied number of buds per cane, and treatment with Effective Microorganisms (EM). To determine the total content of polyphenols and individual polyphenolic compounds in the tested fruits, the UPLC-PDA-MS method was used. The results indicated that the studied factors had no effect on total soluble solids and titratable acidity in grapes. The experiment revealed that polyphenol content was most dependent on the cultivar, followed by the number of buds per cane; EM treatment had the least effect. The fruit of the ‘Regent’ cultivar was characterised by higher polyphenol content. ‘Cabernet Cortis’ berries had higher levels of phenolic acids and flavan-3-ols, while ‘Regent’ berries were higher in anthocyanins and flavonols. EM treatment had a large impact on the reduction of tannic acid compounds. Fruits from untreated plants with four buds per cane had a significantly increased content of polyphenols, including flavan-3-ols.