Agronomic performance and wine phenolic composition of ‘Merlot’ grown in altitude region with different rootstocks

Several studies have reported the influence of rootstocks on grape and wine composition, however, there is considerable variability in the results. The objective of this work was to evaluate the effects of three different rootstocks on vegetative-productive balance and the wine composition of ‘Merlot’. The present work was conducted in the municipality of Painel, during the 2014/2015, 2015/2016 and 2016/2017 vintages. The vegetative, productive, and enological variables of ‘Merlot’ grafted onto ‘Paulsen 1103’, ‘3309 Couderc’ and ‘101-14 Mgt’ rootstocks were evaluated. The ANOVA results showed that‘3309C’ rootstock promoted an increase in the productive indices, and consequently in more adequate vegetative-productive balance for ‘Merlot’ variety compared to the rootstocks ‘Paulsen 1103’ and ‘101-14 Mgt’. The rootstocks ‘3309C’ and ‘101-14 Mgt’ provided more adequate maturation indices for ‘Merlot’. The ‘101-14 Mgt’ rootstock was associated with the highest contents of flavonoid compounds, while the ‘3309C’ rootstock was related to higher contents of non-flavonoid compounds, especially resveratrol.