Browsing by Author "Owuor, B.O"

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    Assessment of Four Commercial Watermelon Cultivars and one Local Landrace for Their Response to Naturally Occurring Diseases Pests and Non-Pathogenic Disorders in Sub-Humid Tropical Conditions
    (Asian Research Publishing Network (ARPN), 2008-09) Gichimu, Bernard M.; Owuor, B.O; Dida, M. M.
    Four commercial watermelon cultivars available in Kenya and one local landrace were evaluated for their susceptibility/resistance to naturally occurring diseases, pests and non-pathogenic disorders. The accessions included three most common commercial watermelon cultivars in Kenya namely ‘Sugarbaby’, ‘Crimson Sweet’ and ‘Charleston Gray’; one newly introduced cultivar from United States namely ‘Yellow Crimson’; and one local landrace (GBK-043014) from Kakamega district in Western Kenya. No inoculation was done because the study targeted naturally occurring diseases, pests and non-pathogenic disorders. Disease rating was done when the most susceptible accession(s) was severely diseased. Data collected was subjected to analysis of variance (ANOVA) using SAS version 9.1 and differences declared significant at 5% level. The SAS procedure PRINCOMP was then used to perform a principle component (PC) analysis using severity scores and accessions plotted on two dimensions using the first two principle components (PC1 and PC2). Results demonstrated significant variation among accessions in susceptibility/resistance to various diseases, pests and non-pathogenic disorders that were observed.
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    Comparing the yield components of three most popular commercial watermelon cultivars in Kenya with one newly introduced cultivar and one landrace
    (Academic Journals, 2009-06) Gichimu, Bernard M.; Owuor, B.O; Dida, M. M.
    High yield is a major goal for watermelon (Citrullus lanatus) breeders. The objective of this study was to compare the yield components of some watermelon accessions available in Kenya and to identify high yielding accession(s) for recommendation to Kenyan growers and for use in breeding programs. A field trial involving five cultivated watermelon accessions in Kenya namely ‘Sugarbaby’, ‘Crimson Sweet’, ‘Charleston Gray’, ‘Yellow Crimson’; and one local landrace (GBK-043014) from Kakamega district in Western Kenya, was conducted at Maseno University Research Fields between September 2007 and May 2008. The experiment was laid out in a Randomized Complete Block Design with three replications. Data was collected on yield and yield components of the accessions and subjected to analysis of variance using SAS version 9.1. Differences were declared significant at 5% level based on Least Significant Difference. The landrace demonstrated the highest yield potential while ‘Yellow Crimson’ which is a newly introduced commercial cultivar performed much better compared to other commercial cultivars. Selection of desirable traits in these accessions has priority for the future breeding programs. ‘Yellow Crimson’ was also recommended to Kenyan growers as the commercial cultivar with highest yield potential.
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    Growth and nutrient uptake among three wetland plant species occurring in Lake Victoria basin in Kenya.
    (2010) Gichimu, Bernard M.; Musyimi, D. M.; Netondo, G. W.; Owuor, B.O
    Nutrient enrichment is one of the most serious threats to wetland ecosystems. Information is lacking, particularly concerning the response of wetland plants species in Kenya in regard to nutrient enrichment of wetlands. Understanding the mechanisms and adaptations that allow only certain species to thrive in the potentially stressful wetland environment requires the study of the biology of these plants. This study was carried out to investigate the growth and nutrient uptake among some selected wetland plant species in Lake Victoria basin, Kenya. Seedlings of Cyperas esculentus L., Aframomum angustifolium (Sonn.) and Phragmites australis (Cav.) Trin. Ex Steudel) were grown outdoors in pots. The pots were arranged in a completely randomised design under out-door conditions in the Botanic garden at Maseno University. Plants were provided with four nutrient dosage levels of 0 mg [no fertiliser added], 50 mg, 100 mg, 150 mg fertilizer [N: P: K, 10:26:10] per pot and replicated five times. The plants were irrigated daily with tap water for eight weeks. Data on growth which included shoot height, stem diameter, leaf number per plant, leaf area, leaf width, leaf length, shoot and root weights were determined. Leaf N and P was also determined. The data were analysed by analysis of variance (ANOVA) in SAS statistical package. Nutrient availability treatments significantly (P ≤ 0.05) influenced the growth and biochemical parameters investigated. Cyperas esculentus and A. angustifolium had higher rate of biomass accumulation as evidenced by increase in shoot and root weights compared to P. australis. Root-shoot ratios reduced with increasing nutrient concentration in C. esculentus and A. angustifolium, while that of P. australis increased up to 100mg treatment, then slightly reduced at 150mg treatment. Phragmites australis had significantly higher foliar P and N content than the other two species with increasing nutrient availability. There were significant interactions between nutrient treatments and species in most of the parameters measured. We recommend Phragmites australis as a better agroforestry plant species for reclaiming wetland areas.
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    Morphological Characterization of Some Wild and Cultivated Watermelon (Citrullus Sp.) Accessions in Kenya
    (2009-03) Gichimu, Bernard M.; Owuor, B.O; Mwai, Gideon N.; Dida, Mathews M.
    Genetic diversity and relatedness were assessed among three most common commercial watermelon cultivars in Kenya; one newly introduced commercial cultivar from the U.S., one Kenyan landrace and one wild (Citrullus colocynthis) accession. The six accessions were grown in the field for two seasons under sub humid tropical conditions. Randomized Complete Block Design (RCBD) with three replications was used. Data was collected on morphological features of watermelon which include vine, leaf, flower, fruit and seed characteristics. A descriptor list with 21 morphological (qualitative and quantitative) characters was adopted from Diez et al., (2005) and Jarret and Griffin, (2007) and was refined and used in characterization. The data was used to calculate genetic similarity and to construct a dendrogram using the unweighted pair-group method with arithmetic average (UPGMA). Data on quantitative characters was subjected to Analysis of Variance (ANOVA) using SAS statistical package and effects declared significant at 5% level. The procedure PRINCOMP was then used to perform a principle component (PC) analysis using six quantitative variables and accessions plotted on two dimensions using the first two principle components (PC1 and PC2). The cluster analysis results demonstrated high morphological diversity (54-42%) between unimproved accessions (wild accession and landrace) and commercial cultivars and low morphological diversity (8-27%) among commercial cultivars. The ANOVA conducted on quantitative characters of cultivated accessions demonstrated highly significant variation between accessions. Results of the principle component analyses for the six quantitative traits indicated that the first two PCs explained 68% and 29% (a total of 97%) of the total variation. The low morphological diversity observed among commercial cultivars emphasizes the need to expand the genetic base of the cultivated watermelon in Kenya.
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    Yield of three Commercial Watermelon Cultivars in Kenya as compared to a local landrace
    (2010) Gichimu, Bernard M.; Owuor, B.O; Dida, M. M.
    High yield is a major goal for watermelon (Citrullus lanatus) breeders. The objective of this study was to measure the yield potential of some watermelon accessions available in Kenya and identify high yielding ones for growers and for use in breeding programmes. A field trial was conducted at Maseno University Research Fields for two seasons between September 2007 and May 2008. Accessions studied included three most common commercial cultivars in Kenya, namely: ‘Sugarbaby’, ‘Crimson Sweet’ and ‘Charleston Gray’, one cultivar (‘Yellow Crimson’) newly introduced from the United States, and one local landrace (GBK-043014) from Kakamega district in Western Kenya. The experiment was laid out in a Randomized Complete Block Design with three replications. Data was collected on total number of female flowers per plant, main vine length, number of branches on the main vine, number and weight of fruits. Data collected were subjected to analysis of variance using SAS version 9.1 and significantly different means were separated using the Least Significant Difference test at P = 0.05. Linear regression was done to establish relationships between variables. Results revealed significant variation among accessions in all the yield components that were measured. The landrace had the highest yield compared to commercial cultivars owing to its long vine and extensive branching. It was therefore concluded that selection of desirable traits in this accession be given priority for future breeding programmes. ‘Yellow Crimson’ performed much better than other commercial cultivars and is therefore recommended to Kenyan growers as the cultivar with highest yield potential.