Browsing by Author "Thagana, W.M."

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    Burrowing Nematode (Radopholus Similis) Abundance, Distribution and Agronomic Impact on Bananas in Kirinyaga County, Kenya
    (International Journal of Horticultural Science, 2026-02) Gatheru, P. K.; Thagana, W.M.; Nchore, S. B.
    Burrowing nematodes (Radopholus spp.) are the most significant parasites of bananas (Musa spp.) world over. They feed on the root tissue of bananas resulting to toppling disease at the fruit bearing stage. This study assessed the impact of farmers selected agronomic practices that influenced distribution of burrowing nematodes. We also assessed the abundance of Radopholus spp. across four AEZs namely; UM 2, UM 3, LM 3 and LM 4 of Kirinyaga County, Kenya. Purposive sampling was done on April, 2024 targeting farmers that grew ‘dwarf Cavendish’ variety of bananas, those that grew an average of 25 banana stems and those whose farms that were 1km apart. A structured questionnaire was issued to ninety farmers to collect demographic information and to determine their awareness of burrowing nematodes and toppling disease. Soil and banana root samples were also collected to determine abundance and distribution of burrowing nematodes. Data from the questionnaire and samples was subjected to R -statistical software and analysed at p≤ 0.02. The study revealed that majority of banana farmers practised mixed cropping and were not aware of toppling disease associated with Radopholus spp. It also revealed that majority of banana farmers were male and of ˃ 50 years of age. The findings also showed Radopholus spp was rarely distributed in lower AEZs of LM 3 and LM 4 compared to Pratylenchus spp. which was predominantly distributed in upper AEZs of UM 2 and UM 3 in both soil and root samples.
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    Optimisation of a Somatic Embryogenesis and Transformation Protocol for Farmer-Preferred Cassava Cultivars in Kenya
    (African Crop Science Society, 2016) Marigi, E.N.; Masanga, J.O.; Munga, T.L.; Karanja, L.S.; Ngugi, M.P.; Thagana, W.M.; Kirubi, D.; Mwangi, M.; Muiru, W.M.; Miano, D.W.; Alakonya, A.E.; Oduor, R.O.
    Cassava (Manihot esculenta Crantz) is a major food crop in developing countries, and holds potential for industrial use. It is, however, affected by various biotic and abiotic stresses that greatly affect its production. The existing regeneration and transformation protocols are not compatible with all cassava cultivars, thus efficient and robust transformation and regeneration protocols for farmer-preferred cultivars need to be optimised for ease of transfer of novel genes. The objective of this study was to develop an efficient transformation and regeneration protocol for a farmer-preferred Kenyan cassava cultivar. We cultured immature leaf lobe and stem explants on Murashige and Skoog (MS) medium, supplemented with varying concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), Picloram and á-naphthalene acetic acid (NAA). Plants were recovered on media with 6- Benzylaminopurine (BAP) and GA3 under a 16 hour light/8 hour darkness photoperiod regime. Results showed high regeneration and transformation frequencies for both cultivars. High frequencies of callus induction (>98%) for both cultivars, were obtained when 2,4-D and Picloram were used. Similarly, both auxins initiated somatic embryogenesis, with Picloram producing the highest frequency of somatic embryos (>92%) in TMS 60444, using stem explants. Gus assays revealed high frequencies of transformation of >77% (TMS 60444) and 60% (Kibanda meno mkubwa). This protocol offers promising perspectives for rapid improvement of these cultivars and, therefore, provides a platform for cleaning planting materials, as well as cassava genetic improvement programmes such as control of viral diseases
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    Studies on Seed Size and Storage on Germinability and Performance of young Jojoba (Simmondsia Chinensis L.) Seedlings in Semi-arid Areas of Kenya
    (IISTE, 2015) Inoti, S.K.; Chamshama, S.A.O.; Dodson, R.; Thagana, W.M.; Lulandala, L.L.L.
    Jojoba (Simmondsia chinesis L.) is a highly valued desert shrub for its oil which is equivalent to that of Sperm Whale, a threatened species by extinction. Cultivation of Jojoba in arid areas means provision of a cash-crop, environmental conservation and preservation of the Whale. Its seeds vary in size depending on genotype, season and seed lot. An experiment was setup in September 2012 with an objective of characterizing seed and determining the effect of size and storage on germination. The experiment was laid down in a Completely Randomized Design (CRD) with three treatments replicated thrice for the first two experiments. However, the third experiment was a factorial one with eight treatments. The seeds were grouped into three categories which were large (1,047 mg), medium (697 mg) and small (333 mg/seed). The results revealed that large seeds had significantly (P< 0.05) higher germination percentage (76%) compared with medium (33%) and small (37%) seeds. Large seeds were found to contain large cotyledon size. Large cotyledons provide a large food reserve which is essential for germination and early vigorous growth. Seed length and 100 seed weight were significantly (P≤0.05) higher for large seed as compared to medium and small seeds. Similarly, large seeds recorded a germination of 93% for a short storage of six months which was superior to that of small seeds which was 17% for the same period. Hence seed length and 100 seed weight were found to be reliable variables for characterizing Jojoba seeds which may be used in predicting germinability. We recommended that for enhanced germination and vigorous growth of seedlings, it is necessary to select and plant large Jojoba seeds which have been stored for period less than one year.