Effects of Winter Pruning on Physical and Mechanical Properties of Grapes

The trials evaluated possible changes in the physical and mechanical properties of ‘Chardonnay’ grapes trained to GDC, depending on the winter pruning system. The following pruning techniques were carried out: manual pruning (m); mechanical pruning (M); mechanical pre-pruning and hand finishing (M+m), this method had a wagon facility with two operators equipped with pneumatic scissors. During the trials were measured: working time, quality of pruning and vegetative-productive response of vines. For the 2010 harvesting, a consolidated analytical method of texture analysis was applied to evaluate the physical parameters of the grapes: pedicel detachment, skin perforation, skin thickness, and other features such as hardness, cohesiveness, springiness. Analysis of working times showed that manual pruning (m) required a greater commitment of time, while mechanical pruning (M) presented a time reduction of 93%. Mechanical pruning associated with manual finishing (M+m) lowered the time by 65%. The cost reduction is less evident but still significant. Mechanical pruning, compared with the manual pruning, gave an increase of spurs and buds density. A higher percentage of damaged spurs and in the wrong position was also detected. Generally, the increasing of mechanization levels of pruning gave origin to more bunches, sparser with smaller berries. The study of mechanical properties of berries showed significant differences in the mechanical behaviors of the pruning tests. The mechanical pruning (M) presented higher values for pedicel detachment, skin perforation, cohesiveness and springiness. The results showed that mechanical pruning can modify berry properties which can influence other mechanical interventions in the vineyard.