Articles
INFLUENCE OF SPUR PRUNING ON THE YIELD OF ‘ISTRIAN MALVASIA’ GRAPE IN ISTRIA (CROATIA)
To our present knowledge mechanization has not been applied so far to Istrian Malvasia, the mostly grown cultivar, nor to others.
Due to the shortage of manual labor, grape production in Istria is decreasing.
The usage of spur-pruned training systems has shown improvements such as less working hours per unit of land, more suitable morphological characteristics for mechanized work and, in the long run, a significant increase in grapevine growing.
Due to the fact that Istrian Malvasia is the mostly grown, it had to be studied how spur pruning is linked to yield and grape quality.
The study was carried out on Istrian Malvasia near Pore≈ during 1992–1994 in a single vineyard trained to espalier with spur pruning.
The percentage of budburst was 67.9% in 1992, 77.0% in 1993, and 71.0% in 1994. The comparison of these results with previous surveys shows that in the present research there were more unopened eyes.
Bud fertility percentage was 1.33% in 1992, 1.59% in 1993, and 1.26% in 1994, yielding an average of 1.39. Yield per shoot was 617.6 g (three-year mean), which corresponds to 4.5 clusters per shoot, with a weight of 134.9 g per cluster.
The grape quality evaluated as sugar concentration, titratable acidity (TA) and pH, showed on average of 18.81% (measured by refractometer), 6.77 g/l, and 3.31, respectively.
The above results of Istrian Malvasia guarantee respecting the legislation by the Republic Croatia for obtaining quality wine.
The results obtained on Istrian Malvasia show that the espalier with spurs is adequate to fulfill the criteria of quality and quantity, though further research will try to optimize the length and number of spurs per vine.