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University of KwaZulu-Natal (2019)

Pre- and post-harvest response of selected indigenous leafy vegetables to water stress

Maseko, Innocent

Titre : Pre- and post-harvest response of selected indigenous leafy vegetables to water stress.

Auteur : Maseko, Innocent.

Université de soutenance : University of KwaZulu-Natal


Résumé partiel
South Africa has wide diversity of African leafy vegetables (ALVs) rich in nutrients and adapted to marginal production. However, there is limited availability of ALVs in South Africa due to lack of cultivation owing to limited agronomic and postharvest management information. The increase in population growth, malnutrition and climate change necessitates production of more food using limited water resources. The aim of this study was to evaluate pre and postharvest response of Amaranthus cruentus (pigweed), Vigna unguiculata (cowpea), Corchorus olitorius (Jute mallow) and a reference crop B. vulgaris (Swiss chard) to varying irrigation regimes. The current study consisted of a literature review and five experiments (two agronomic studies and three post-harvest studies. In literature, the performance of ALVs is drawn in comparison to exotic counterparts grown under different conditions ; yet agronomic and nutritional factors are only valid when crops are grown under the same condition. Hence in the four experiments of this study, Swiss chard was used as a reference crop grown under same locality. Swiss chard was chosen because it is an alien leafy vegetable that has been indigenised in sub-Saharan Africa and is highly nutritious (contains high levels of Fe, Zn and β-carotene). Before conducting experiments there was need to identify potential gaps and research priorities for this study and even for future research. This was done by conducting a literature review study (Chapter 2) on the status of production and utilisation of ALVs in South Africa for the period 1994–2017. Results of the review indicated that there is a decline in consumption of ALVs partly as a result of limited availability and negative perception. In order to promote ALVs, further research on agronomy, post-harvest handling, storage and processing is required in South Africa. Field and rain shelter experiments were conducted at Roodeplaat, Pretoria, over two summer seasons, 2015/2016 and 2016/2017 to evaluate growth, yield and water-use of selected leafy vegetables under varying water regimes. A randomised complete block design with three replicates was used. The treatments evaluated were : three irrigation regimes (30%, 60% and 100% of crop water requirement (ETc) on three ALVs – Amaranthus cruentus, Corchorus olitorius and Vigna unguiculata and a reference crop, Beta vulgaris. Seeds of A. cruentus and C. olitorius were obtained from the seed bank of the Agricultural Research Council (ARC) - Vegetable and Ornamental Plants (VOP), Roodeplaat, Pretoria seed bank. Vigna unguiculata (Bechuana white, a runner type) and Swiss chard (B. vulgaris L.) cultivar ‘Ford Hook Giant’ seeds were obtained from Hygrotech Seed Pty. Ltd., South Africa. Soil samples were taken from the field prior to land preparation and soil fertility analyses done at the Agricultural Research Council–Institute for Soil, Climate and Water (ARC–ISCW). Nitrogen, phosphate and potassium were applied according to the results and recommendations of the soil fertility analysis for both seasons


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