Browsing by Author "Dlamini, Welile Mlando"

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    The impact of weevil predation on seed viability and agronomic performance of cowpeas, Vigna unguiculata L. (Walp)
    (Stellenbosch : Stellenbosch University, 2023-03) Dlamini, Welile Mlando; Wilson, Ida; Pieterse, P. J. ; Swanepoel, Pieter Andreas ; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Cowpea, Vigna unguiculata, is a nutritious and high value legume that is often susceptible to weevil damage in storage. It is largely grown in Sub-Saharan Africa and a primary source of income for resource-poor farmers. Callosobruchus maculatus is an invasive pest of cowpea seeds in storage, better known as the cowpea weevil. In the larval stage, cowpea weevils consume food reserves from the seed endosperm. Unsuitable storage structures, where no methods of weevil control are applied, may increase weevil infestation of cowpea seeds in storage which hampers successful cowpea production. While attention is dedicated to understanding the role of generic cowpea seed damage to the legume’s production, there is a dearth of evidence on the impacts of the damage to different sites of the seeds. This study therefore aimed to quantify the germination rate of cowpea seeds damaged on different sites and assess the effect of the damage on cowpea seedling growth and yield. Undamaged cowpea seeds, also known as “black-eye beans”, were infested with cowpea weevils, then kept in storage for three months. The stored seeds were damaged on the top, bottom, side, back or hilum. Seeds with a single hole were selected from the infested seed and sorted according to the site of damage on the seeds. The positions of holes on seeds were used as treatments for the experiments and undamaged seeds served as the control group. Major findings were seed germination at day two showed a significantly poorer germination of top damaged seeds, relative to both undamaged seeds and the alternative damage sites. This result remained consistent for germination at day seven as well as for seedling height at two weeks. Seeds with a single site of damage at the top of the seed performed significantly worse than seeds where the damage was on other sites. At physiological maturity, plants grown from undamaged seed had the highest 100-seed weight. The seed weight obtained from seeds damaged at the top was significantly less than those obtained from plants grown from undamaged seed. These results suggest that farmers, to ensure seedling emergence, should refrain from planting cowpea damaged at the top, but they can still grow seeds with alternate holes. The results of the study will help farmers manage seed losses after storage, as some damaged seed can still be sown and will produce a yield. This is the first study of its kind, and it gives insight into the site of damage on seed and cowpea production. The findings could encourage further investigation into other legume crops that also suffer from weevil damage. In addition, conclusions from the study may be of practical value for smallholder farmers to support nutrition and food security in Africa.