Influence of summer management practices and date of harvesting on organic acids concentration and sugar concentration in grapes of Vitis vinifera L., cv. Riesling

摘要

The impact of summer canopy management was investigated in Vitis vinifera L., cv. Riesling. Sugar and organic acid concentrations were measured for the six defoliation treatments. Titratable acidity (TA) was measured twice before harvest and once at the date of harvest. The same measurements were done twice during wine ageing. The young wine was measured for concentrations of malic, tartaric and volatile acids. Treatments with appropriate defoliation, where shortened lateral shoots (up to two leaves) were retained, supported the process of wine grape ripening to the greatest extend in the cool climate of the Czech Republic, while treatments with almost no defoliation yielded the worst results. The TA decreased during fruit ripening after veraison and continued to decrease during wine maturation. The tendency of decreasing with time was shown for the malic to tartaric acid ratio as well. Concentrations of volatile acids were sufficiently low in each of the treatments.