Abstract
In order to delay the development of ripening with the grape variety ‘Grüner Veltliner’ the methods “Three applications of an antiperspirant in the period after flowering“, “Total defoliation above the grape zone at the end of the development stage bunch closure“ and “Keeping the canopy short at a height of 70 cm“ were applied over two growing seasons. In order to evaluate the effects of these measures, selected generative and vegetative parameters were collected and analyzed, and sensory wine evaluations were performed after microvinification. Three applications of the antiperspirant after flowering resulted in a year-dependent reduction of the sugar content in the must by 1.9 and 1.2 °KMW and of the acid content in the must by 0.8 and 0.4 g/l, respectively. Total defoliation above the grape zone at development stage “Bunch closure” also led to a reduction of must weight in both years, by 1.2 and 1.0 °KMW, respectively, without affecting acidity. In 2021, keeping the canopy short at a height of 70 cm reduced cluster weight and thus also yield compared to the control variant (-17 g per cluster and -0,7 kg/vine). Thereby, must weight was only reduced by trend (-0.4 °KMW) and acidity was not affected. In 2022, however, the effects on the yield parameters were not significant, even though there were trends towards a reduction in yield (-0.65 kg/vine) and in cluster weight (-33 g). Neither in 2021 nor in 2022 the contents of nitrogen, potassium and total phenols in the musts were influenced by the methods of delaying ripening. Extrapolated pruning wood weights were generally at a low level with significant differences between the variants “Total defoliation above the grape zone at bunch closure“ (1600 kg/ha) and “Canopy height = 70 cm“ (1073 kg/ha). The values of the other two variants were 1308 kg/ha and 1313 kg/ha, respectively. In 2021, the wine of the variant “Canopy height = 70 cm“ was evaluated sensorially significantly worse. However, in the evaluation of the wines of the 2022 vintage, there were no significant sensory differences.