Effects of late-season source limitation induced by trimming and antitranspirants canopy sprays on grape composition during ripening in Vitis vinifera cv. Sangiovese.

The global warming and the general improvement of vineyard management techniques over the last fifty years appear to have upgraded the quality of wine worldwide. Besides, in some wine regions where heat summations largely exceed technological requirements for the grown varieties, grapes showed at harvest a too high level of sugar and subsequent wine alcohol excess, low acidity, alteration of aroma composition and, in black varieties, unbalanced phenolic ripening with insufficient berry skin colour. The final aim of the research is to test the effects of post veraison trimming or anti-transpirant spray on sugar accumulation rate and berry phenolic compounds evolution during ripening. This trial was conducted in 2009 and 2010 on Sangiovese (V. vinifera L.) vines trained to Free Cordon trellis system. Three treatments were compared: non-trimmed control (C); shoot trimming, 1 week after full veraison (TRIMM ); anti-transpirant Pinolene sprayed at 2% concentration, 1 week after full veraison (PIN). Measurements on leaf gas exchange showed that Pinolene spray reduced photosynthetic activity on laterals leaves compared to control ones since the day of spray and up to three-four weeks later. After shoot trimming, the total leaf area of TRIMM vines was reduced at about 40 % of the control. Yield per vine was unaffected by both treatments while both treatments showed in 2009 an higher effect in reducing sugars accumulation rate during ripening compared to 2010. In particular PIN treatments was less effective in 2010, while TRIMM effect, although little, was maintained also in the second year. Despite the differences in sugar accumulation, acidity, pH and anthocyanins concentration during ripening were not significantly affected by treatments. The results showed a quite interesting perspective about canopy management techniques, since trimming or Pinolene spray, slowed down sugars accumulation, giving rise to an improved synchrony between technological and phenolic ripening. The results demonstrate the potential of the news canopy management techniques to upgrade the enological grape quality in face to the global climate warming.