South Africa Wine Research Projects

2. VITICULTURE RESEARCH NEW PROJECT

2.3 SOIL AND WATER

WATER USE AND PERFORMANCE OF GRAPEVINE CULTIVARS IN RESPONSE TO CROP LOAD AND WATER REPLENISHMENT FROM THE SUBSOIL

SU-SS-J-MV 24-01 Mr John-Murray Visser, Department of Soil Science, Stellenbosch University Start date: 2024

AIM AND INDUSTRY RELEVANCE: Water scarcity challenges continue to be increasingly prominent, especially in wine-growing re gions. One way of addressing this challenge is by growing more drought-tolerant grape cultivars. As a result, a research project has been conducted since 2018 to evaluate the drought tolerance of a series of eight white and nine red cultivars. In this follow-up study, additional matters will be addressed, which include: • A comparison of the evapotranspiration of individual cultivars • How different crop loads affect cultivar performance • How the grapevines can ripen their crops while only using a fraction of one millimetre of water per day from January onwards. In this regard, two possible water sources will be investigated, namely: – Roots that explore the subsoil for available water – Water movement from the subsoil to the root zone through diffusivity Consequently, the main goal of the proposed project will be to assess the water usage and per formance of specific drought-tolerant cultivars as affected by crop load, root distribution, and water movement from the subsoil. The results will advise producers regarding differences in cultivar water use and crop load’s wa ter-saving, quality-enhancing and financial benefits. They will also clarify the role of the subsoil as a store for winter rain.

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SOUTH AFRICA WINE RESEARCH 2024