Browsing by Author "Valombola, Johanna Shekupe"

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    Assessment of farmer preferences, constraints and angro-morphological variation among Bambara groundnut (Vigna subterranea (L.) Verdc.) accessions as a basis for seed yield selection index
    (University of Namibia, 2020) Valombola, Johanna Shekupe
    Bambara groundnut (Vigna subterranea (L) Verdc) is an orphan, underutilised and less exploited crop in Africa and beyond, Yet, it is an essential traditional crop for the majority of local farmers. The first step in preparing such local germplasm for possible pre-breeding is to undertake a needs assessment study to find out what farmers have on their farms and what they would rather have as an improvement. After that, a pre-breeding program with appropriate breeding goals and objectives can be formulated. Currently, in Namibia, a pre-breeding or breeding program is yet to be put in place. Thus, objective one of this study was to investigate, using a survey instrument, constraints encountered by Bambara groundnut farmers and the farmers’ preferred morpho-types that can be used in the breeding program. The ethnobotanical study was first done across five regions, targeting some key constituencies. Data were collected on varieties, descriptors, uses, preferences, crop improvement status, seed source, and production challenges. Chi-square test showed significant differences among farmers’ preferences (P ≤ 0.05) and crop improvement status (P ≤ 0.05). The results also showed that farmers faced challenges, including susceptibility to insects and the use of low yielding, unimproved cultivar. Results further indicated that many farmers had different Bambara groundnut preferences, such as large seed size and high yield cultivar. The second objective focused on the evaluation of local and exotic Bambara groundnut germplasm. Twenty-five Bambara groundnut germplasm accessions were characterised and evaluated for diversity, using qualitative and quantitative traits. The experimental design was square lattice design replicated three times. For qualitative descriptors, data collected included seed eye colour pattern, seed coat colour, seed pattern, pod shape, pod colour, and pod texture. The Shanon Weiner Index showed high diversity, with an average value of 0.92. Also, a dendrogram indicated five clusters of similarity. Quantitative data were analysed using multiple analysis of variance, Pearson correlation moment, Principal Component Analysis (PCA), and dendrogram. Analysis of variance (ANOVA) indicated significant differences (P ≤ 0.05) among accessions for the number of pods with two or more seeds, seed length, seed width, fresh pod weight per plant, dry pod weight per plant, 100 seed weight, shelling percentage, and harvest index. Other variables that were highly significant (P ≤ 0.01) included the number of pods per plant, pod yield, seed yield, plant height, terminal leaflet width, terminal leaflet length, number of branches, fresh biomass, and dry biomass. Dendrogram sub-criterion indicated three clusters suggesting that few accessions were dissimilar, which was confirmed with Principal Component Analysis, showing that germplasm accessions with common traits were grouped into the same quadrant. For meaningful progress, crop breeding hardly focuses on a single trait at a time. Since crop yield is a polygenic traits, some breeders nowadays use a selection index technique for yield improvement. In this study, a selection index was constructed using yield traits as seed yield, biological yield, dry pod weight per plant, and fresh pod weight per hectare. The index based on three traits, namely seed yield, dry pod weight per plant, and fresh pod weight that had a GA of 41.23% and selection efficiency of 376%. This selection method for seed yield appears to be more effective and efficient compared to the conventional method, the straight selection method.
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    Co-cultivation and matching of early- and late-maturing pearl millet varieties to sowing windows can enhance climate change adaptation in semi-arid sub-Saharan agroecosystems
    (MDPI Open access journal, 2023) Awala, Simon Kamwele; Hove, Kudakwashe; Valombola, Johanna Shekupe; Nafuka, Helena Nalitende; Simasiku, Evans Kamwi; Chataika, Barthlomew; Horn, Lydia Ndinelao; Angombe, Simon; Akundabweni, Levi S.M; Mwandemele, Osmund
    In semi-arid regions, climate change has affected crop growing season length and sowing time, potentially causing low yield of the rainfed staple crop pearl millet (Pennisetum glaucum L.) and food insecurity among smallholder farmers. In this study, we used 1994–2023 rainfall data from Namibia's semi-arid NorthCentral Region (NCR), receiving November–April summer rainfall, to analyze rainfall patterns and trends and their implications on the growing season to propose climate adaptation options for the region. The results revealed high annual and monthly rainfall variabilities, with nonsignificant negative trends for November– February rainfalls, implying a shortening growing season. Furthermore, we determined the effects of sowing date on grain yields of the early-maturing Okashana-2 and local landrace Kantana pearl millet varieties and the optimal sowing window for the region, using data from a two-year split-plot field experiment conducted at the University of Namibia-Ogongo Campus, NCR, during the rainy season. Cubic polynomial regression models were applied to grain yield data sets to predict grain production for any sowing date between January and March. Both varieties produced the highest grain yields under January sowings, with Kantana exhibiting a higher yield potential than Okashana-2. Kantana, sown by 14 January, had a yield advantage of up to 36.0% over Okashana-2, but its yield gradually reduced with delays in sowing. Okashana-2 exhibited higher yield stability across January sowings, surpassing Kantana’s yields by up to 9.4% following the 14 January sowing. We determined the pearl millet optimal sowing window for the NCR from 1–7 and 1–21 January for Kantana and Okashana-2, respectively. These results suggest that co-cultivation of early and late pearl millet varieties and growing early-maturing varieties under delayed seasons could stabilize grain production in northern Namibia and enhance farmers' climate adaptation. Semi-arid agro-region policymakers could utilize this information to adjust local seed systems and extension strategies.