Variability assessment of Bambara groundnut (Vigna subterranea (L) Verdc) landraces based on the qualitative trait seed coat colour

Abstract

In many parts of Sub-Saharan Africa, female subsistence farmers rely on the production of underutilized crops such as Bambara groundnut (Vigna subterranea (L.) Verdc) for both sustenance and generating income. Bambara groundnut is, however, grown at a low rate especially in South Africa. Although it has the potential to yield high amounts of seed and can grow under adverse weather conditions, amongst offering other benefits, it remains underutilized and under-researched. To date there are no improved varieties. Farmers therefore rely on indigenous knowledge systems to select varieties based on their preferences, thereby unconsciously contributing to genetic erosion of the crop. Improved varieties are important for adaptability under environmental stochasticity. This study was conducted to determine whether seed coat colour can be used as a basis for selecting Bambara groundnut landraces with favourable agronomic traits for breeding programs and development of genetically enhanced varieties. A completely randomized design with ten replications was used to assess whether landraces classified based on seed coat colour are both morphologically and genetically similar. Significant differences (P<0.05) in the yield parameters, number of pods per plant, and growth habit were observed. This suggests that some genotypes yield more seed than others. Anatomical assessment of the leaf revealed that there are genotypes with high trichome density and two types of trichomes on the same plant. These characteristics make those plants more resilient to disease pressure than others. There is, however, little evidence that these findings are related to the seed coat colour. Attributing one character i.e. seed coat colour to genetic diversity is therefore reductive and should not be undertaken.