Effects of pre-bloom leaf removal on growth of berry tissues and must composition in two redVitis viniferaL. cultivars

Abstract

Background and Aims: Little work has been conducted on the effects that summer pruning operations have on the relative growth of grapevine berry parts. Our paper studies whether pre‐bloom leaf removal is able to modify the proportions of seed, skin and flesh in ripe grapevines berries and the related effects on must composition. Methods and Results: Pre‐bloom defoliation (D) of the first six basal leaves on main shoots was applied to the field‐grown cvs Barbera and Lambrusco salamino (Vitis vinifera L.) in Italy's Po Valley and compared with non‐defoliated controls. D showed reduced fruitset, hence yield per shoot, and concurrently improved must soluble solids and total anthocyanins in both cultivars as a likely result of increased leaf‐to‐fruit ratio (+3.4 cm2/g and +5.2 cm2/g for Barbera and Lambrusco, respectively) and improved relative skin mass (from 6.0 to 9.0% in Barbera and from 8.1 to 10.4% in Lambrusco). In both cultivars, skin and seed mass were highly correlated with total berry mass and changes in relative skin mass were generally not related to berry size. Conclusions: These results indicate that berry size per se is not the primary factor in determining final grape composition, which instead seems to depend upon factors differentially affecting the growth of the various berry components. Significance of the Study: Pre‐bloom D induced a consistent, site and cultivar‐independent increase in relative skin mass suggesting this effect being strongly physiologically regulated.

Berry Size and Qualitative Characteristics of Vitis vinifera L. cv. Syrah

“…However, this theoretical model is, obviously, based on the assumption that the skin weight per unit area remains constant independently from berry size. From our data it is evident that, similarly to what can be found in literature Walker et al, 2005, Poni et al, 2009, changes in skin:berry weight ratio in relation to berry size are low (<1%). This lack of change in skin:berry weight ratio might be ascribed to the increase in skin weight per unit area (Fig.…”

Canopy management effects on ‘Syrah’ grapevines under tropical semi-arid conditions

“…This is a consequence of the differential effect in carbohydrate metabolism in the grapevine. In addition to the intensity of leaf removal, the time period and frequency with which it is carried out, the cultivar, rootstock used, production period in tropical climates, vine training system, spacing between plants and rows, and the reserves available in the roots also determine the responses (Intrieri et al, 2008;Poni et al, 2008;Poni et al, 2009;Lee and Skinkis, 2013).…”

“…It has been observed that different leaf removal methods, including both manual and mechanized, changed the canopy structure, leaf density, and the percentage of leaves and clusters, but did not affect bud fertility, shoot density, nor plant vigor (Percival et al, 1994). Early 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 time of leaf removal and shoot topping may affect fruit composition (Lee and Skinkis, 2013).…”

The effects of early leaf removal and cluster thinning treatments on berry growth and grape composition in cultivars Vranac and Cabernet Sauvignon

“…Removing the leaves from cluster zone increases the evaporative potential within the fruit zone, lowering the humidity and making the cluster microclimate less conducive for the development of fungal diseases [11]. In the Sangiovese variety, characterized by highly compact clusters, early defoliation significantly reduced the fruit set, yield per shoot, cluster weight, number of berries per cluster, and cluster compactness [6,7,12]. Autochtonous variety, Vranac is also characterized by highly compacted clusters; we decided to apply these agro-techniques in order to reduce the yield parameters hoping that it would have the same beneficial effects as in the case of Sangiovese variety.…”