Browsing by Author "Turyagyenda, Laban F."
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Item Cassava Brown Streak Disease Prevalence in Smallholder Cassava Cropping Systems in Northern Uganda: The Case of Acholi Sub-region(East African Nature and Science Organization, 2024-04-16) Kumakech, Alfred; Tekkara, Allan; Turyagyenda, Laban F.Cassava brown streak disease (CBSD) is a devastating disease of cassava in Uganda. Limited information exists on the incidence and severity of CBSD in Northern Uganda. The prevalence of CBSD in the eight (8) districts in the Acholi sub-region is also unknown. Therefore, the current study intended to: a) determine the prevalence and severity of CBSD in the Acholi sub-region, and b) identify the drivers of CBSD epidemics in smallholder cassava cropping systems in Acholi. An assessment of 120 cassava fields was conducted in the 2018b season. CBSD field incidence was highest in Nwoya District (51.3%) and lowest in Kitgum (6.4%), with severity ranging from 2.1 to 3.4 in the sub-region. CBSD prevalence was also highest in Nwoya (76.2%) and lowest in Kitgum and Pader Districts (30.8%). The use of CBSD-susceptible varieties (TME 14, TME 204, and NASE 12) was identified as the main driver of the epidemic. The result of the current study highlights the need for a wide-scale CBSD awareness creation and community-based cassava seed multiplication and distribution system in the Acholi sub-region to promote the up-take of CBSD-tolerant cassava varietiesItem Effects of Improved Cassava Varieties on Farmers’ Income in Northern Agro-ecological Zone, Uganda(Sustainable Agriculture Research, 2021) Akongo, Graceline O.; Otim, Godfrey A.; Turyagyenda, Laban F.; Bua, Anton; Komakech, Alfred; Obong, S.This paper examines the extent to which improved cassava varieties contribute to improvement in income of smallholder farmers in the Northern agro-ecological zone of Uganda. In order to achieve the objective, data was collected from PRELNOR supported farmers’ fields, other farmers’ fields and baseline cassava fields. Consequently, descriptive statistics, gross margin and stochastic frontier analysis were adopted during analysis. Results from the analysis revealed that higher yields per hectare were registered within PRELNOR supported farmers’ fields and yield from NAROCAS1 surpassed all the varieties (37.3 tons per hectare). Location specific results revealed that Gulu had better yields (34.5 tons per hectare) while Kitgum registered the lowest average yield (24.1 tons per hectare). Gross margin indicated that every Shilling invested in improved variety earned profit 1.3 to 1.8 times above the local variety and each shillings invested in PRELNOR supported fields generated 5.6 times above the baseline fields. The parameter estimate for profit function revealed that planting material, other production related costs, NAROCAS1, NASE14 and NASE19 were positively correlated with profit but labour and baseline field had negative correlations. Conversely, profit efficiency grew by 40% under improved varieties against local varieties. This study suggests that the difference in yields and profit between locations was caused by biophysical characteristic; disease tolerant varieties can tremendously improve profitability and income; meanwhile the profit gaps were partly attributed to inefficiency. This study recommends fast tracking adoption of pest and disease tolerant varieties and integrated research and development approach throughout the cassava value chain.Item Physiological and molecular characterization of drought responses and identification of candidate tolerance genes in cassava(AoB plants, 2013) Turyagyenda, Laban F.; Kizito, Elizabeth B.; Ferguson, Morag; Baguma, Yona; Agaba, Morris; Harvey, Jagger J. W.; Osiru, David S. O.Cassava is an important root crop to resource-poor farmers in marginal areas, where its production faces drought stress constraints. Given the difficulties associated with cassava breeding, a molecular understanding of drought tolerance in cassava will help in the identification of markers for use in marker-assisted selection and genes for transgenic improvement of drought tolerance. This study was carried out to identify candidate drought-tolerance genes and expression-based markers of drought stress in cassava. One drought-tolerant (improved variety) and one drought-susceptible (farmer-preferred) cassava landrace were grown in the glasshouse under well-watered and water-stressed conditions. Their morphological, physiological and molecular responses to drought were characterized. Morphological and physiological measurements indicate that the tolerance of the improved variety is based on drought avoidance, through reduction of water loss via partial stomatal closure. Ten genes that have previously been biologically validated as conferring or being associated with drought tolerance in other plant species were confirmed as being drought responsive in cassava. Four genes (MeALDH, MeZFP, MeMSD and MeRD28) were identified as candidate cassava drought-tolerance genes, as they were exclusively up-regulated in the drought-tolerant genotype to comparable levels known to confer drought tolerance in other species. Based on these genes, we hypothesize that the basis of the tolerance at the cellular level is probably through mitigation of the oxidative burst and osmotic adjustment. This study provides an initial characterization of the molecular response of cassava to drought stress resembling field conditions. The drought-responsive genes can now be used as expression-based markers of drought stress tolerance in cassava, and the candidate tolerance genes tested in the context of breeding (as possible quantitative trait loci) and engineering drought tolerance in transgenics.Item Re-Fining Citrus Leaf and Fruit Spot Disease Control Options in Northern Uganda(East African Nature and Science Organization, 2024-03-05) Kumakech, Alfred; Turyagyenda, Laban F.Citrus leaf and fruit spot disease, caused by Pseudocercospora angolensis has, since 2010, come about as the most dreadful disease of citrus in Northern Uganda. Over the last few years, feedback from citrus farmers has helped in re-fining management strategies. In the first years of citrus leaf and fruit spot disease outbreak in Northern Uganda, chemical treatment was promoted as part of a control package, in addition to the destruction of heavily diseased plants and buckthorn to remove inoculum. Buck horning and destruction of diseased plants is labour-intensive and time-consuming, especially when many infected citrus trees have to be taken out, or buck horned. Research findings indicate citrus leaf and fruit spot disease fungus can be weakened with fungicide sprays to the extent that even when disease symptoms are present on leaves, it does not automatically lead to infection of fruits. This gave rise to a new control strategy where only infected plants in an orchard are pruned, and all the citrus trees in the orchard are treated with fungicides. The pruning of visibly infected plants in an orchard will lessen the inoculum load, and the fungicide sprays will stop pathogen replication. This method is not labour intensive and takes less time when equated to severe buck horning of all the trees in the orchard. However, pruning and fungicide treatment need to move together with the control of new infections that can happen via unrestricted entry during harvestingItem Yield and Disease Responses of Improved Groundnut Genotypes Under Natural Disease Infection in Northern Uganda: Implication for Groundnut Disease Management(Journal of Agricultural Science, 2022) Kumakech, Alfred; Otim, Godfrey A.; Opio, Tonny; Komakech, Alfred; Turyagyenda, Laban F.Groundnut production in Uganda is constrained by groundnut rosette disease (GRD), the main cause of yield loss experienced by farmers. We conducted the current study to assess the responses of improved groundnuts to diseases (rosette and late leaf spot) and yield under local conditions. Four released groundnut genotypes (Serenut 5R, Serenut 8R, Serenut 9T and Serenut 14R) were evaluated in four locations in northern Uganda for two seasons in 2019. We established the experiment following randomised complete block design with three replications. GRD severity (harvest) and late leaf spot (LLS) severity (harvest) on the four genotypes were not significantly (P > 0.05) different but positively correlated with the Area Under Disease Progress Curve (AUDPC). Genotype-by-location interaction for LLS AUDPC, GRD AUDPC and dry pod yield were significant (P < .001). Season-by-genotype interaction was not significant (P = 0.367). Days to 50% flowering were also not significant (P > 0.05). Highest and lowest yields were recorded for Serenut 9T in the Omoro district (1,291 kg/acre) and the Amuru district (609 kg/acre), respectively. Dry pod yield was significantly (P < 0.001) negatively correlated with GRD severity and GRD AUDPC. Yield performance of the four genotypes was not significantly (P < 0.05) different in the districts, except for Kitgum, where yields of Serenut 9T and Serenut 8R were significantly (P < 0.05) higher. These genotypes could be used to manage GRD by smallholder farmers in Northern Uganda. Special consideration should therefore be given to these four groundnut genotypes for GRD management in the Acholi sub-region.