Defoliation is a viticultural practice carried out to improve the microclimate of the grapevine canopy, which has a positive impact on the quality of grapes and wine. In our own vineyard with the 'Sauvignon Blanc’, we performed a block experiment in 2014 with three treatments: control without defoliation (K), defoliation 1 – defoliation in the grape zone when the berries are pea-sized (D1), and defoliation 2 – defoliation in the zone above the grapes before ripening (D2). With the study, we would like to find out whether different timing: (T1) 25. 8., (T2) 4. 9., (T3) 12. 9., (T4) 20. 9. 2014 and zones of defoliation affect the quantity and quality of grapes and wines sauvignon. The analysis of the grapes showed no significant differences in berries weight at harvest. D1 and D2 had different impact on the soluble dry matter content (SDMC) in the berries; differences among treatments have been shown in the last two sampling periods. In the third sampling, both defoliations have brought the expected results, an increase in SDMC. But due to precipitation before harvest, there was a berry decrease in SDMC. D2 did not give the expected results, as the SDMC remained the same as in the control. No significant differences in titratable and total acid content were recognized among treatments in the experiment. A significant increase in total analysed phenolic contents is shown in the second and third sampling period at D1. At third sampling, D1 has a significant impact on the synthesis of phenolic substances in the skin of the variety 'Sauvignon'. To better understand the impact of vine defoliation on the quality of grapes and wine, the experiment would need to be repeated for another year.
|
