WINETECH Technical Yearbook 2021

blanc grapes composition, and Volschenk and Hunter (2001) found a significant impact on grape composition mostly on aroma and flavour descriptors, even though not on the wine quality. The evaluation (chemistry or sensory) of wines made from different trellising systems has been included in very few studies and only the overall wine quality was evaluated. Van Zyl and Van Huyssteen (1980) found differences in ratings between Chenin blanc wines of different systems mainly due to colour. The literature suggests that divided canopy trellis produce better wines due to better light interception (Reynolds & Vanden Heuvel, 2009. In contrast, other authors did not find a significant effect on Chenin blanc wine quality for trellis systems which have been converted (Volschenk & Hunter, 2001). PROBLEM STATEMENT Despite the work done for grapes, not much has been investigated on trellising systems’ effects on wine composition. Usually,

studies have included many variables due to the variability of the blocks included in the work. Factors such as vineyard location can influence mesoclimate and macroclimate, even when the same cultivar is investigated. Other factors such as vine age, clone, soil composition, row orientation, etcetera can complicate the interpretation of the results. In 2017 and 2018, we had the opportunity to work in a Chenin blanc model block containing six different trellis systems, planted all at the same time. The study covered limited viticultural aspects, but focused rather on the comprehensive profiling of the resulting wines. The results will be presented in the next two parts of the series, dedicated to chemistry and sensory aspects of aroma, taste, mouthfeel, and wine quality. SUMMARY The desired wine characters start with berry composition in addition to winemaking and ageing process.

Grape composition plays a significant role in defining wine style and typicality and there are ways in which grape composition can be altered or modified. Among these ways are viticultural practices – including trellising systems. REFERENCES Volschenk, C.G. & Hunter, J.J., 2001. Effect of trellis conversion on the performance of Chenin blanc/99 Richter grapevines. South African Journal of Enology and Viticulture 22: 31-35. Shaulis, N.J., Amberg, H. & Crowe, D., 1966. Response of Concord grapes to light, exposure, and Geneva Double Curtain training. Proceedings of the American Society for Horticultural Science 89: 268-280. Gladstones, J., 1992. Viticulture and environ- ment: A study of the effects of environment on grapegrowing and wine qualities, with emphasis on present and future areas for growing winegrapes in Australia. Adelaide: Winetitles.

Van Zyl, J.L. & Van Huyssteen, L., 1980. Comparative studies on wine grapes on different trellising systems (Part 2): Micro- climatic studies, grape composition and wine quality. South African Journal of Enology and Viticulture 1: 15-25. Reynolds, A.G. & Vanden Heuvel, J.E., 2009. Influence of grapevine training systems on vine growth and fruit composition: A review. American Journal of Enology and Viticulture 60: 251-268.

For more information, contact Astrid Buica at astrid.buica@gmail.com.

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