M. Giaccone

Influence of intensity of post‐veraison defoliation or shoot trimming on vine physiology, yield components, berry and wine composition in Aglianico grapevines

Background and Aims Post-veraison trimming and defoliation have been proposed as strategies to decrease the concentration of berry carbohydrate at harvest and of wine alcohol, but it is unclear which of these two pruning techniques is more suitable and at what intensity they should be applied. The aim of this 3-year study was to compare the suitability of two intensities of post-veraison trimming or defoliation in controlling sugar accumulation in the berries of Aglianico grapevines. Methods and Results Five treatments were compared: two intensities of defoliation, two intensities of shoot trimming and a control. All pruning treatments decreased berry TSS at harvest and wine alcohol concentration. Defoliation and trimming of moderate intensity also improved wine sensory score, whereas intense defoliation and trimming can affect negatively this parameter. Conclusions Post-veraison defoliation and trimming of moderate intensity appear to be suitable strategies for decreasing berry TSS at harvest and wine alcohol concentration. Significance of the Study The selection of the correct intensity of leaf removal appears to be one of the critical factors in correctly designing a suitable strategy of post-veraison summer pruning that aims to decrease sugar accumulation in the berries, whereas the choice of the type of pruning appears to be less crucial.

Effects of Early Shading and Defoliation on Bunch Compactness, Yield Components, and Berry Composition of Aglianico Grapevines under Warm Climate Conditions

Prebloom leaf removal is a canopy management practice used in viticulture to decrease bunch compactness at harvest. However, this practice may not be suitable in dry and warm areas because it may expose bunches to excessive direct sunlight, undesirably decreasing titratable acidity and increasing the pH of berry juice. This study was designed to test the hypothesis that shading between preanthesis and fruit set may be used for Aglianico grapevines as an alternative strategy to decrease bunch compactness without removing leaves around the bunches. This treatment was also thought to maintain berry juice acidity at harvest. The following nine treatments were compared: two defoliations (50 and 90% leaf removal), five whole-canopy shadings (10, 30, 50, 75, and 90% reduction of ambient light), one partial canopy shading (using a 30% shade net), and an unshaded and undefoliated control treatment. Fruit set, berry number per bunch, bunch weight, and yield per vine were significantly affected by several of these treatments. Bunch compactness was reduced only by shading in the range of 50 to 90%. Surprisingly, defoliation decreased fruit set but not bunch compactness because the defoliation caused shortening of the total length of the bunch axes. Berry composition was not negatively affected by 50 to 90% shading, whereas defoliations and 10 to 30% shading decreased titratable acidity and increased the pH of the berry juice at harvest. Flower number per bunch in 2010 decreased linearly with decreasing net photosynthesis per shoot measured in 2009 between prebloom and fruit set. The results of this study suggest that early shading may be an efficient alternative practice to decrease bunch compactness without any negative effect on berry juice composition at harvest.

Fruit position within the canopy affects kernel lipid composition of hazelnuts

BACKGROUND The aim of this research was to study the variability in kernel composition within the canopy of hazelnut trees. RESULTS Kernel fresh and dry weight increased linearly with fruit height above the ground. Fat content decreased, while protein and ash content increased, from the bottom to the top layers of the canopy. The level of unsaturation of fatty acids decreased from the bottom to the top of the canopy. Thus, the kernels located in the bottom layers of the canopy appear to be more interesting from a nutritional point of view, but their lipids may be more exposed to oxidation. The content of different phytosterols increased progressively from bottom to top canopy layers. CONCLUSION Most of these effects correlated with the pattern in light distribution inside the canopy. The results of this study indicate that fruit position within the canopy is an important factor in determining hazelnut kernel growth and composition.