Browsing by Author "Motsei, Nonofo"

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    A validation of fruitlook data using eddy covariance in a fully mature and high-density japanese plum orchard in the western cape, south africa
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Mashabatu, Munashe; Motsei, Nonofo; Jovanovic, Nebojsa
    The cultivation of Japanese plums (Prunus salicina Lindl.) in South Africa has increased over the years, yet their water use is unknown. Their cultivation in the Western Cape Province of South Africa is highly dependent on supplementary irrigation, indicating their high water use demand. This study used remote sensing techniques to estimate the actual evapotranspiration (ETc act) of the Japanese plums to assess their water use on a large scale. The accuracy of the procedure had to be validated before getting to tangible conclusions. The eddy covariance was used to measure ETc act in an African Delight plum orchard to validate the FruitLook remote sensing data for the 2023–2024 hydrological year and irrigation season. The seasonal and annual plum crop water requirements measured using the eddy covariance system were 751 and 996 mm, while those estimated by FruitLook were 744 and 948 mm, respectively. Although FruitLook slightly underestimated plum ETc act by a Pbias of −6.15%, it performed well with a Nash–Sutcliffe efficiency (NSE) of 0.91. FruitLook underestimated evapotranspiration mainly during the peak summer season with full vegetation cover when the model may inaccurately represent irrigation impacts, soil moisture availability, and localized advection effects, better captured by the eddy covariance system. Based on the results, FruitLook proved to be sufficiently accurate for large-scale applications to estimate evapotranspiration in Japanese plum orchards in the Western Cape.
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    Assessing the seasonal water requirement of fully mature Japanese plum orchards: A systematic review
    (Multidisciplinary Digital Publishing Institute (MDPI), 2024) Mashabatu, Munashe; Motsei, Nonofo; Jovanović, Nebojša; Dube, Timothy; Mathews, Ubaidullah; Nqumkana, Yolanda
    Japanese plums have relatively high water requirements, which depend on supplementing rainfall volumes with accurately quantified irrigation water. There is a lack of knowledge on the seasonal water requirements of plum orchards. This gap in the literature poses an imminent threat to the long-term sustainability of the South African plum industry, which is particularly plagued by climate change and diminishing water resources. The systematic literature review conducted in this study aimed to provide a foundation for supporting water management in irrigated Japanese plum [Prunus salicina Lindl.] orchards. Seventeen peer-reviewed articles obtained from the literature were analyzed. Approximately 66% of the cultivars were cultivated under different regulated deficit irrigation regimes for water-saving purposes and to increase fruit quality. This review of our knowledge provided benchmark figures on the annual water requirements of Japanese plums. The full-year plum crop water requirements obtained from the literature ranged between 921 and 1211 mm a−1. Canopy growth, pruning and growing season length were the most common causes of differences in the water requirement estimates. Further research is required to measure the water requirement of plums from planting to full-bearing age and the response of plum trees to water stress, especially in the South African context.
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    Modelling soil water redistribution in irrigated Japanese plum (prunus salicina) orchards in the Western Cape (South Africa)
    (MDPI, 2023) Jovanovic, Nebojša; Motsei, Nonofo; Mashabatu, Munashe
    Japanese plum (Prunus salicina) farming in the Western Cape (South Africa) is an important industry for the export market and job creation and is a large water user; however, adequate information on water requirements of this crop is not available in this semi-arid area. The objective of this study was to determine seasonal plum water requirements for the purpose of water use planning and allocation. The study made use of experimental data from four fully bearing, high-yielding plum orchards (cv African Delight and Fortune) in two major plum production regions (Robertson and Wellington). Crop water requirements and the soil water balance were modelled with the physically based HYDRUS-2D model. Seasonal crop water requirements were estimated to be between 524 mm (cv Fortune inWellington) and 864 mm (cv African Delight in Robertson).
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    Quantifying the consumptive water use of Japanese plum orchards in the Western Cape province using the SEBS and SEBAL models
    (Universty of the Western Cape, 2024) Motsei, Nonofo; Jovanović, Nebojša
    Japanese plums form part of a multi-billion-rand deciduous fruit industry in South Africa. As with other dry countries, South Africa faces several water-related challenges, namely increasing water scarcity driven by a high population growth rate, rising intersectoral competition for water resources and climate change. Due to the low and erratic rainfall in the country, plums are grown under irrigation. As such the availability of water is crucial for the sustainability and growth of the South African fruit industry. Previous studies have successfully determined the water requirements of various fruit crops (e.g., apples, oranges), however, the water use requirements of plum orchards have not been sufficiently investigated. This paucity of knowledge forms the baseline of this study which aims to quantify the seasonal water use of high performing full-bearing Japanese plum orchards. To address this aim, the study was divided into two sections. In the first section, the water use of optimally irrigated, full bearing and high performing Japanese plum orchards planted to mid and late maturing Fortune and African Delight cultivars was estimated using the SEBS model and Fruit Look (SEBAL).