Climate change: Anti-transpirant effects on grape physiology and berry and wine composition (Vitis Vinifera L.)

Plant growth, yield and quality are highly dependent on climate. In the last few decades the trend of increasing global temperatures has affected the accumulation of sugars in berries and hence the degree of alcohol in resultant wines. Therefore numerous studies have considered different agronomic practices that limit photosynthetic activity. The aim of our study was to evaluate the effect of a natural anti-transpirant on grapevine physiology and berry and wine composition on different cultivars. In 2013 and 2014, in South Italy and Souther Australia, Aglianico and Falanghina, Shiraz and Semillon vines were treated at veraison with the anti-transpirant Vapor Gard® (T) and compared with a control (C) sprayed just with water. A bunch thinning (BT) treatment was also applied to both the Vapor Gard® treatment and the control. For each treatment was assessed vegetative response (pruning weight) and production (production and number of bunches per plant, TSS, pH, TA, polyphenols, anthocyanins) of individual varieties. Consideration was also the effectiveness of the film terpene that has come to form on the leaves, limiting gas exchange, through measurements of net photosynthesis and transpiration (LI-6400). The results demonstrate that the application of anti-transpirant has reduced assimilation rate (A), transpiration rate (E), stomatal conductance (gs), sugars berries accumulation (TSS) and wine alcohol degrees (% vol.). No significant differences between treatments were observed for other berry and wine compositional measures taken between cultivars. This method may be a useful tool to reduce berry sugar content which can result in lower alcohol content in wines.