Effect of forcing vine regrowth on 'Tempranillo' (Vitis vinifera L.) berry development and quality in Extremadura

Abstract

In warmer regions, fruit ripening in the wine grape tends to take place during the hottest part of the growing season. This can have negative consequences on the qualitative characteristics of the grape berries at harvest. Forcing vines to regrow can be an aggressive but effective technique to delay the harvest date, but needs to be evaluated carefully in each growing condition. In 2017, in an experimental vineyard in Extremadura, forcing was conducted 3 (F1 treatment) and 22 (F2 treatment) days after anthesis (May 18 and June 6) by hedging growing shoots to seven nodes and removing summer laterals, leaves and primary clusters. Vines grown using conventional practices were used for the Control treatment. Forcing delayed the harvest date from August 22 (Control) to September 14 (F1) and October 19 (F2). Shifting the berry growth period modified the duration of the different fruit development stages. Compared to the Control treatment, the F1 and F2 berries were smaller at harvest, but had similar skin weight percentages; however, the seed weight percentage of the F2 berries was higher. The differences in grape composition observed at harvest between the various treatments were further accentuated in the wines. At harvest, the F2 berries had significantly higher total polyphenol and anthocyanin content than the Control and F1 berries, which had similar values. In the wines, both F1 and F2 characteristics differed considerably from the Control, most notably in the high F2 tannin concentration. These preliminary results from the first year of study indicate the potential of this technique to obtain wine grapes with very different characteristics, offering new viticultural perspectives in warm climate areas.