Effect of canopy management and harvest date on soundness of grapes, essential grape contents and the style of Sauvignon blanc wines. In the year 2009 three different variants of canopy management in the grape zone were investigated in a vineyard of the Landwirtschaftliche Versuchszentrum Steiermark in Southern Styria: untreated control (variant 1), single defoliation immediately after end of flowering (variant 2 - "half shade"), permanent defoliation from end of flowering onwards (variant 3). Furthermore, all different variants were harvested at three different dates each (early: 17 degrees KMW medium: 19 degrees KMW late: 20 degrees KMW). The parameters examined were the quality of grapes, yield data, and quality determining contents and aroma substances of the berries and the berry juice, respectively. All experimental variants were microvinified identically and the wines subjected to a descriptive assessment. In the untreated control an increased proportion of rot could be observed with the late harvest date. Yield per vine always was higher by trend with the untreated variant. The berries from variant 2 and 3 showed higher yellow colour values in the skin, but the concentration of 2-isobutyl-3-methoxypyrazine (IBMP) was lower. With increasing maturity the IBMP content also decreased. The amount of free assimilable nitrogen generally increased with increasing berry ripening, but in particular the content in variant 3 was lower by up to 13 %. The total of free and bound monoterpenes increased with the degree of ripeness, better exposed variants showing significantly higher (up to 50 %) concentrations. The sensory evaluation resulted in a preference for variant 3 with the early harvest date, the late harvest date wines of the untreated control variant were described as more intense, richer in fragrances and more fill-bodied and they were preferred to the others. From the medium harvest date wines those from grapes of variant 2 ("half shade") were preferred. Harvest date and canopy management in the grape zone have a significant impact on the quality and contents of the berries and consequently on the wine style. From the results available to date from the year 2009 it can be concluded that with regard to aromatic development the intervention in the grape zone (defoliation) may be more severe, the sooner the harvest will take place. In further analytical and olfactory studies, the aging potential of these wines will be observed.
