Shoot topping of 'Niagara Rosada' grapevine grafted onto different rootstocks

Abstract

Vineyard cultural practices may influence amount of sugars, acids, phenolic compounds and antioxidant activity of grapes. Thus, the purpose of this study was to evaluate the effect of different shoot topping levels on the chemical characteristics of the grapes during its maturation, yield and the physicochemical characteristics and phenolic compounds of 'Niagara Rosada' grapevine grafted onto different rootstocks. The experiment was conducted in a 2-year-old vineyard of Niagara Rosada cultivar in Southeast of Brazil. The vines were trained on a unilateral cordon system in a vertical shoot positioning. The manual shoot topping was carried by leaving 6, 7, 8 or 9 leaves above the last cluster. Vines were topped 60 days after pruning, when the vines were in the beginning of bunch closure. All vines were grafted onto 'IAC 766' and 'IAC 572' rootstocks. Fruit maturation curve, yield and physicochemical grapes characteristics were analyzed to determine the effects of shoot topping levels and rootstocks. The rootstocks and the different shoot topping levels did not influence the yield, productivity and cycle duration of 'Niagara Rosada' grapevines. Larger and heavier clusters and berries were harvested from vines grafted on 'IAC 766' rootstock. However, grapes harvested from grapevines grafted on 'IAC 572' rootstock presented higher total anthocyanins content. The shoot topping carried out with 7 or 8 leaves above the latest cluster provided higher sugars, total polyphenols content and antioxidant activity.