Masters Degrees (Agronomy)

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Browsing Masters Degrees (Agronomy) by Author "Baloyi, Nsovo Happiness"

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    Genetic, anatomical and morphological characterization of bambara groundnut (vigna subterranea (l.) Verdc) landraces in South Africa.
    (Stellenbosch : Stellenbosch University, 2023-03) Baloyi, Nsovo Happiness; Swanepoel, Pieter Andreas ; Voster, Alvera; Phiri, Ethel Emerentia; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Bambara groundnut (Vigna subterranea (L.) Verdc), an underutilized grain legume that is typically grown by female subsistence farmers in the rural parts of Africa. However, it is grown at a low rate especially in South Africa with sowing rate ranging from 25-160kg per hectare. Although it has the potential to yield high amounts of seed and can grow under adverse weather conditions, among other benefits, it remains underutilized and under researched. To date there are no improved varieties and farmers therefore rely on indigenous knowledge systems to select varieties based on their preferences thereby unconsciously contributing to genetic erosion of the crop. The aim of this study was to characterize and determine whether bambara groundnut landraces classified based on seed coat colour are both morphologically and genetically similar, to eventually aid the selection of genotypes with favourable attributes for breeding programs and development of genetically enhanced varieties. An assessment of 48 landraces from the Limpopo province, South Africa, was undertaken using morphological descriptors like number of pods per plant and type of growth habit. Landraces were analysed for anatomical differences on the leaf epidermis such as trichome type and trichome density. The extent of the genetic diversity and population structure of the landraces were assessed through genotyping using Restriction-Site Associated DNA (RAD) Sequencing. Considerable differences in the yield parameters number of pods per plant, and growth habit were observed which means that some genotypes yield more than others. According to literature the type of growth that is preferred by farmers for efficiency during harvesting is the bunch and semi- bunch type because the pods attach to the crown of the stem while the spreading type is preferred for fields with weeds. Anatomical assessment of the leaf revealed that there are genotypes with high trichome density and two types of trichomes on the same plant which makes them more resilient to disease pressure than others. However, correlation and hierarchical cluster analysis indicate that these findings are not related to the seed coat colour which therefore means that use of one morphological character to classify genotypes into landraces should not be undertaken. This was further supported by the genotyping and population structure analysis results which indicated the presence of two sub-populations that are not related to seed coat colour. This the first report to highlight the importance of trichome type and density as a morphological descriptor to aid the selection of landraces for introduction into effective breeding programs.