WINETECH Technical Yearbook 2021

before harvest on aroma precursors (figure 4). CONCLUSIONS MP increased grape aromatic precursor concentrations compared to VSP-trained vines, principally due to significant berry size reduction. Overall, climatic conditions of the vintage appeared to dictate the total potential of aromatic precursors in both systems. The highest content of precursors was positively correlated with low minimum temperatures during the month prior to harvest, indicated by the Cold Night Index. These findings serve to inform producers regarding the potential of alternative training systems. SUMMARY Minimal pruning was developed to reduce vineyard labour input costs, while higher yields and lower pH and higher acidities have been frequently associated with

the system. However, its effect on the aromatic composition of grapes is not well documented. This study comparing MP to traditional VSP training confirms that the higher yielding MP training system presented a greater aroma potential of grapes than VSP. Mainly due to a positive effect on the concentration of aromatic precursors by a reduction in berry size. In fact, biosynthesis of aromatic precursors was very similar for both trellis systems and highly responsive to the climatic effects induced through different seasons. In this instance, the Cold Night Index (mean minimum temperature in the month prior to ripening) proved to be valuable in explaining differences in aromatic precursor concentration among seasons. ACKNOWLEDGEMENTS The experimental work was carried out over various seasons and would not be possible

Etchebarne, F., Terblanche, E., Iacono, M.B., Leclercq, L., Pirrone, M., Angenieux, M., Saurin, N. & Ojeda, H., 2015. Proceedings of XV International Symposium of GESCO : 65- 68. Gruissan, France, 31 May-5 June 2015. Rousseau, J., 2006. Minimal pruning. Progrès Agricole et Viticole 123(5): 97-102. Tonietto, J. & Carbonneau, A., 2004. A multicriteria climatic classification system for grape-growing regions worldwide. Agricultural and Forest Meteorology 124: 81-97. Amsterdam.

without the valuable scientific contributions of María Iacono, Lucile Leclercq, Miguel Pirrone, Magaly Angenieux and Nicolas Saurin. In addition, the authors would like to thank Veronica Chavez Parra and Jean- Noël Lacapere for their tireless technical assistance during this trial. REFERENCES Clingeleffer, P., 1992. Development of management systems for low cost, high quality wine production and vigour control in cool climate Australian vineyards. Viticulture Enological Science 48: 130-34. Ojeda, H., Saurin, V., Rousseau, J., Blateyron, L., Heywang, M. & Carbonneau, A., 2007. Minimal pruning performance in dry terroir of the south of France: Evolution of berry and wine quality from different harvest dates. Proceedings of XV International Symposium of GESCO : 852-859. Porec, Croatia, 20-23 June 2007.

For more information, contact Etienne Terblanche at etienne@vinpro.co.za.

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