Abstract
The aim of this study was to evaluate the effects of shoot topping and leaf removal practices on vegetative vigor, yield and physicochemical characteristics of the 'Syrah' grape in the semi-arid tropical climate conditions of the Sao Francisco River Valley in the northeast of Brazil. The experiment was conducted over five growing cycles from 2010 to 2012 in a 'Syrah' commercial vineyard in the municipality of Casa Nova, Bahia, Brazil. Treatments consisted of leaf removal once or twice during fruit set or at the beginning of bunch closure, and one or two shoot toppings of the berry when pea-sized or 10 days after berry growth had commenced. Leaf removal and shoot topping did not affect yield, plant vigor components nor the main attributes of fruit quality. In contrast, there was a seasonal effect with higher yield and better balance between production and vigor in grapes produced in the first half of 2012. The Syrah grape quality was favored in cycles in the first half of the year when its ripening phase coincided with the period of mild temperatures.
Highlights
Leaf removal and shoot topping are common practices in grapevine canopy management worldwide
Leaf removal carried out near flowering reduces the supply of carbohydrates to the fruit set/berry development and increases the leaf/fruit and skin/pulp ratios, resulting in less compact clusters which are less susceptible to disease, resulting in improved fruit composition and fewer thinned clusters (Poni et al, 2006; Poni et al, 2008; Poni et al, 2009; Intrieri et al, 2008; Austin et al, 2011)
The results indicate that titratable acidity of the grapes was more stable in the crop seasons in the first half of the year, except in those that were harvested from plants that had received a single shoot topping at the stage when the berry was pea size – K (T5 and T8)
Summary
Leaf removal and shoot topping are common practices in grapevine canopy management worldwide. The time of leaf removal and shoot topping may affect fruit composition (Lee and Skinkis, 2013). These practices may affect the cluster microclimate, leading to modification of, or accumulation of certain phenolic compounds (Lemut et al, 2011). Intensive and very late leaf removal may lead to sunburn in the grape clusters, pigmentation of the berry, and deficient maturation as a consequence of reduction in the leaf area/production ratio (Bergqvist et al, 2001)
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