South Africa Wine Research Projects 2025

2. VITICULTURE RESEARCH COMPLETED PROJECT

DEMONSTRATION OF PLANT-BASED IRRIGATION ON WINE-GRAPE PERFORMANCE AND QUALITY IN THREE CLIMATICALLY DIFFERENT REGIONS FShip Water 2 Mr John-Murray Visser, Department of Soil Science, Stellenbosch University Project completed: 2023 Flagship Project AIM AND INDUSTRY RELEVANCE: Water scarcity is an escalating challenge for the agricultural sector, particularly in South Africa’s wine industry, where sustainable water use is critical for long-term viability. The project aimed to demonstrate the use of plant-based irrigation scheduling, specifically using stem water potential, as a practical and effective method to improve water use efficiency, grape quality, and vineyard sustainability across three climatically distinct wine-growing regions in South Africa. This approach is highly relevant in the context of increasing water scarcity and climate variability in South Africa, offering wine grape producers a science-based, adaptable strategy to manage irrigation more precisely by aligning water application with the actual needs of the vine. This study showed that plant-based irrigation scheduling, using stem water potential thresholds, can significantly reduce water use by up to 96% in some regions compared to the farmer standard practices, without compromising grape yield or quality. Water-stressed treatments often led to improved grape quality, including higher sugar content, greater flavour intensity, and more desirable wine composition. Sensory evaluations showed that wines produced under moderate stress (-1.5 MPa) were frequently rated higher in colour, taste, and aromatic complexity, especially in the Olifants River Valley. Additionally, the project evaluated remote sensing tools for irrigation planning purposes. Although helpful, these tools tended to overestimate crop water use, highlighting the need for plant-based validation to ensure accurate irrigation decisions. Overall, the results support precision irrigation as a sustainable solution for viticulture in water-limited environments and by implementing these strategies, growers can enhance water efficiency, reduce costs, and create a more sustainable future for their vineyards.

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SOUTH AFRICA WINE RESEARCH 2025