Investigating the Response of Selected Reference and Alternative Wine Cultivars to Dryland Conditions in the Swartland Region of South Africa

Le résumé fourni par la source

Grapevines depend on adequate water for sustainable yield and quality. However, according to climate change forecasts, rainfall in the Western Cape Province of South Africa could become lower. In the Swartland Region, many vineyards are grown under dryland conditions or with limited volumes of irrigation water. In this regard, the drought tolerance of grapevines refers to the degree to which they are adapted to arid or drought conditions. Therefore, the risk of yield losses for dryland and irrigated vineyards could be reduced if drought‐tolerant wine cultivars are planted more extensively. Therefore, a field trial was conducted in a specially planted experimental vineyard near Malmesbury, South Africa, to assess the drought tolerance of selected wine cultivars. All wine cultivars were planted in July 2018 at a spacing of 3.00 × 1.25 m and were unirrigated. Red wine cultivars were Arinarnoa, Durif, Grenache noir, Malbec, Marselan, Pinotage (reference), Shiraz (reference), Tempranillo and Touriga Naçional. White wine cultivars were Assyrtiko, Chardonnay (reference), Chenin blanc (reference), Macabeo, Marsanne, Piquepoul blanc, Verdelho and Vermentino. Grapevines were trained onto a vertical shoot positioning (VSP) trellis system. Grapevines differed in their plant water status. The strongest vegetative growth was observed for Shiraz and Assyrtiko, and the poorest growth was for Piquepoul blanc. Under the prevailing conditions, Durif, Grenache noir, Marselan and Pinotage showed potential to be selected as suitable red wine cultivars when yield is the primary consideration. For the white wine cultivars, Macabeo, Piquepoul blanc and Vermentino showed the best production potential under the prevailing conditions. However, retarded ripening should be expected for Macabeo and Piquepoul blanc. When an optimum balance is sought between yield and overall wine quality, Arinarnoa, Durif, Grenache noir, Pinotage, Chenin blanc, Macabeo, Piquepoul blanc and Vermentino would be suitable. Under the prevailing conditions, the performance index was the lowest for Malbec, Assyrtiko, Chardonnay and Verdelho.

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