Browsing by Author "Mobe, Nompumelelo Thelma"

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    The influence of canopy cover and cultivar on rates of water use in apple orchards in the Western Cape Province, South Africa
    (University of the Western Cape, 2020) Mobe, Nompumelelo Thelma; Mazvimavi, D.
    Water availability and climate related issues are some of the greatest crop production risks to irrigated agriculture in arid regions. In South Africa, for example, the increasing frequency and severity of droughts related to climate change and the growing competition for limited water resources among different users threaten the sustainability and growth of irrigated agriculture, especially the water-intensive fruit industry. Major fruit such as apples (Malus domestica Borkh) are produced entirely under irrigation in South Africa. As a result, there has been considerable research to accurately quantify the water requirements of fruit tree orchards in order to maximize water productivity.
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    Using sap flow data to assess variations in water use and water status of apple orchards of varying age groups in the western cape province of South Africa
    (Water Research Commission, 2020) Mazvimavi, Dominic; Mobe, Nompumelelo Thelma; Dzikiti, S.
    No accurate quantitative information currently exists on how water use of apple (Malus domestica) orchards varies from planting to full-bearing age, leading to poor irrigation and water allocation decision making. This study sought to address this knowledge gap by investigating how the water use and tree water status vary with canopy cover, cultivar, and climatic conditions in 12 orchards growing in prime apple-producing regions in South Africa. The orchards were planted to the Golden Delicious/Golden Delicious Reinders cultivars which are widely planted in South Africa and the Cripps’ Pink/Cripps’ Red/Rosy Glow which are high-value late-season cultivars. The performance of two transpiration reduction coefficients, one based on sap flow (Ksf) and the other based on soil water depletion (Ks) (FAO approach) were evaluated against the midday stem water potential (MSWP) in all the orchards. While canopy cover had a clear effect on the whole-tree sap flow rates, there were no significant differences in the transpiration per unit leaf area among the cultivars. The daily average sap flux density under unstressed conditions was highest (~284 cm3.cm-2) in the medium canopy cover orchards (30-44% fractional cover), followed by the mature orchards (~226 cm3.cm-2), and was lowest in the young orchards (~137 cm3.cm-2).