Agricultural and Veterinary Sciences
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Item Yield Stability of Tropical Soybean Genotypes in Selected Agro-ecologies in Uganda(South African Journal of Plant and Soil, 2020-08-06) Obua, T.; Nabasirye, M.; Namara, M.; Tusiime, G.; Tukamuhabwa, P.Differential yield response of a genotype is the result of its interaction with the prevailing environment. This makes the task of selecting widely adapted and best soybean genotypes challenging under varied target production environments. The objectives of this study were to; (i) determine the mean performance and stability of 30 elite soybean genotypes in eight different locations, (ii) determine soybean mega-environments in Uganda and (iii) assess the discriminating and representative power of the test environments for soybean seed yield. A field study was conducted for six seasons across eight locations in Uganda. Among the tested 30 soybean genotypes, BSPS 48A-9-2 had the highest mean grain yield of 1 277 kg ha−1; followed by BSPS 48A-28 (1 256 kg ha−1). The genotype and genotype-by-environment (GGE) biplot analyses indicated that the eight test locations can be classified into three mega-environments, while Bulindi was the most discriminating and representative test environment for soybean production in Uganda. Genotypes BSPS 48A-9-2, BSPS 48A-31 and Nam II × GC 44.2 are recommend for further evaluation under farmers’ production conditions for selection and release as new soybean varieties in Uganda.Item Using GIS-Based Tools and Distribution Modeling to Determine Sweetpotato Germplasm Exploration and Documentation Priorities in Sub-Saharan Africa(HortScience, 2006-07-22) Villordon, Arthur; Gichuki, Simon; Yada, Bernard; Tukamuhabwa, Phinehas; Mwanga, Robert O. M.Detailed information on the geographic distribution of a crop is important in planning efficient germplasm conservation strategies but is often not available, particularly for minor crops. Using germplasm collection data from Kenya, Tanzania, and Uganda, we used distribution modeling to predict the distribution of sweetpotato [Ipomoea batatas L. (Lam.)] in sub-Saharan Africa. We used a consensus modeling approach using the following algorithms: genetic algorithm for rule set prediction (GARP), maximum entropy, BIOCLIM, and DOMAIN. The predicted distribution encompasses known sweetpotato production areas as well as additional areas suited for this crop species. New geographic areas where at least three models predicted presence were in Angola, Cameroon, Central African Republic, The Congo, Democratic Republic of Congo, Gabon, Ghana, Angola, Ethiopia, Mozambique, Rwanda, and the Central African Republic. This information can be used to fill gaps in current sweetpotato germplasm collections as well as to further enhance the current presence-only based distribution model. Our approach demonstrates the usefulness of considering several models in developing distribution maps.Item Bovine Trypanosomiasis in South–Western Uganda: Packed-cell Volumes and Prevalences of Infection in the Cattle(Annals of Tropical Medicine & Parasitology, 2004-10-05) Waiswa, C.; Katunguka-Rwakishaya, E.Following confirmed cases of trypanosomiasis ('nagana') and reports of trypanosome-attributable deaths among local cattle, a cross-sectional study was undertaken to determine the prevalence of bovine infection with trypanosomes in south-western Uganda. Cattle from 10 different localities were checked by the microscopical examination of wet bloodsmears and thin, stained bloodsmears, and by blood centrifugation followed by the examination of the resultant buffy coats. Of the 1309 cattle investigated, 6.42% (5.56% and 7.26% of those from the Mbarara and Mubende districts, respectively) were found to be infected. Of the positive animals, 71 (84.5%), 11 (13.1%) and two (2.4%) appeared to be infected with Trypanosoma vivax only, T. congolense only and both T. vivax and T. congolense, respectively. The prevalence of infection with T. vivax was significantly higher than that with T. congolense (P <0.001). The mean packed-cell volumes (PCV) for the trypanosome-positive animals were lower than those for the trypanosome-negative, whether the cattle considered were all those investigated (22.3% v. 29.0%; P <0.001) or just those from the Mbarara (22.8% v. 28.2%) or Mubende (21.5% v. 29.7%) districts. South-western Uganda has been relatively free of both human and bovine trypanosomiasis for the past three decades. The factors leading to the current resurgence of bovine trypanosomiasis need further investigation.Item Step by step to higher yields? Adoption and impacts of a sequenced training approach for climate-smart coffee production in Uganda(Taylor & Francis group, 2025-12) Günther, Manuela Kristin;; Bosch, Christine;; Ewell, Hanna ;; Nawrotzki, Raphael;; Kato, EdwardClimate change further exacerbates sustainability challenges in coffee cultivation. Addressing these requires effective delivery mechanisms for sustainable farming practices, particularly in smallholder contexts. We assess a novel public-private extension approach in Uganda, called Stepwise, comprising a sequence of climate-smart and good agricultural practices in four incremental steps. Using a mixed-method approach, an index that captures adoption intensity rather than binary uptake, and survey data from 915 Robusta and Arabica coffee farmers, we find adoption levels around 46% and relatively uniform amongst treated, spillover and comparison farmers. Regional variations suggest differing benefits across coffee varieties. Qualitative findings identify barriers to adoption, including financial and labour constraints, suboptimal training delivery, and input and output market imperfections. Despite relatively low uptake, adoption of more than half of the Stepwise practices is associated with substantial gains: inverse probability weighted regression adjustment reveals a 23% increase in yield and a 32% increase in revenue. Our findings add to the adoption literature, which often highlights limited uptake, and have important policy implications. Strengthening producer organizations, delivering targeted training but also innovative solutions for access to inputs and fair pricing, hold considerable potential to increase the adoption of climate-smart practices, particularly among resource-constrained farmers.Item Implementing the Uganda lower secondary competence-based curriculum: the equity question(Emerald Publishing, 2025-12) Barasa, Mercy Chemutai;; Ssentamu, Proscovia Namubiru;; Chang’ach, John Koskey ;; Kurgat, Susan JepkoechPurpose – This paper aims to explore the extent to which the Uganda lower secondary curriculum (LSC) reform, instituted in January 2020, has ensured equitable educational opportunities for secondary school learners considering school and learner socio-economic status. Design/methodology/approach – A qualitative approach was adopted in which the experiences and perceptions of both facilitators and implementers of the reform were gathered using interviews and lesson observations. Findings – Data revealed disparities among high and low socio-economic-status schools in their preparedness and capacity to implement the reform, with the consequence of divergent educational opportunities for learners in these contexts. Research limitations/implications – The sample was limited to government-aided secondary schools and thus excluded private schools; the majority in Uganda. This means that the findings may be limited in generalizability. However, the majority of private schools serve the lower socio-economic demographic, so the study findings and implications may extend to them as well. Practical implications – The findings suggest that unless the government intervenes with measures to boost the capacity of schools in low socio-economic contexts to implement the reform, the outcome of the curriculum may be a society further stratified along socio-economic lines. Social implications – The findings indicate that the new LSC may contribute greatly to social stratification through disparate educational opportunities for different sections of the Ugandan populace. This could work against national socio-economic ambitions and also lead to non-achievement of the UN SDG4 of quality, equitable, inclusive education for all. Originality/value – This paper demonstrates how Uganda, a developing nation, is faring in the achievement of the global educational policy goal of equity in the implementation of its competence-based LSC reform. It highlights key policy and research gaps that should be addressed to promote equitable learning opportunities for all learners.Item Ureide Essay to Assess N2-fixation Abilities of Soybean (Glycine Max) Genotypes under Different Bradyrhizobium Strains(Journal of Crop Science and Biotechnology, 2017) Agoyi, Eric E.; Afutu, Emmanuel; Tumuhairwe, John B.; Chigeza, Godfree; Tukamuhabwa, PhinehasThe high protein content of soybean (Glycine max) seeds results in high nitrogen demand, causing a huge nitrogen uptake during plant growth. As a legume crop, soybean can fix atmospheric N through symbiotic associations with Bradyrhizobia and perform well in African nitrogen poor soils. This study aimed at establishing the ability of promiscuous soybean genotypes to fix nitrogen and devise the relationship between nodule scores and amount of nitrogen fixed. Twelve soybean genotypes were inoculated with Bradyrhizobium japonicum Strain USDA 110 (specific) and Bradyrhizobium sp. Strain USDA 3456 (native) and raised in pots in a greenhouse. At the R3.5 growth stage, nodules were scored and xylem sap was extracted, which xylem sap was used to carry out ureide, amino-N, and nitrates assays. The relative abundance of ureide was used to devise the proportion of nitrogen fixed by each genotype. The proportion of nitrogen derived from atmospheric N2 (Ndfa) ranged from 47.9 to 78.8% under USDA 3456 and from 36.7 to 78.7% under USDA 110. A strong correlation was found between nodule scores, especially nodules’ effectiveness, and Ndfa. The genotypes Wondersoya (78.8%), Maksoy 2N (78.4%), Namsoy 3 (78.3%), and Maksoy 3N (75.7%) had high nitrogen-fixing ability in response to USDA 3456. Promiscuous soybean genotypes can fix nitrogen equally under both native and specific Bradyrhizobium types. Nodules’ effectiveness can be a good predictor of biological nitrogen fixation. This study highlighted that crop improvement to boost soybean production in Africa should target promiscuous varieties for better yield with less inputs.Item Genetic variation and response to selection for storage root dry matter and associated traits in a population of yam bean (Pachyrhizus spp.) interspecies crosses(Euphytica, 2021-03-22) Agaba, Rolland; Rubaihayo, Patrick; Tukamuhabwa, Phinehas; Mwanga, Robert O. M.; Tumwegamire, Silver; Ndirigwe, Jean; Gru¨neberg, WolfgangThe goal of yam bean improvement in Africa is to develop superior high yielding and high dry matter cultivars that are preferred for adoption. In this study, the estimates of variance components, heritability and response to selection were studied in F3 yam bean families selected from interspecies crosses targeting improvement of storage root dry matter and associated traits. Breeding populations were generated using North Carolina II (NC II) mating design involving high dry matter P. tuberosus chuin cultivar, low dry matter P. ahipa and the high yielding P. erosus yam beans. The progenies were advanced through selfing from F1 to F2 population and then exposed to selection at 10% selection intensity to obtain 83 high dry matter lines. The selected lines were evaluated in an F3 trial using a randomized complete block design (RCBD) with three replications at the National Crops Resources Research Institute (NaCRRI) Namulonge, in Central Uganda. The results revealed significant (P < 0.001) genetic variation for storage root dry matter (RDM), storage root fresh yield (RFY), storage root dry yield (RDY), vine yield (VNY), fresh biomass yield (FBY), harvest index (HI), starch (STA) and protein (PRO) content. High genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were obtained for VNY, RDY, FBY, RFY, RDM and STA. Narrow sense heritability was higher than 0.5 and response to selection was 15.5 to 33.1 for RDM, RFY, RDY, VNY, FBY and STA, indicating rapid genetic progress is achievable and early generation selection would be effective to improve these traits. Significant (P < 0.01) positive genetic correlations were observed between RDM, RDY, RFY, VNY, FBY and STA ranging from 0.422 to 0.963 implying that simultaneous improvement of these traits is possible in the current yam bean populations.Item Yield Stability of Rust-resistant Soybean Lines at Four mid-altitude Tropical Locations(Euphytica, 2012-03-15) Tukamuhabwa, P.; Oloka, H. K.; Sengooba, T.; Kabayi, P.Asian soybean rust is a major threat to worldwide soybean production at present. Host plant resistance offers the most sustainable control strategy to resource poor farmers in sub-Saharan Africa and worldwide. Using 13 soybean lines bred for resistance to soybean rust, and 2 checks, yield trials were conducted at four regions of Uganda for four consecutive seasons to determine yield stability and reaction to soybean rust disease. An additive main effects and multiplicative interaction (AMMI) model was used to assess the yield stability of the soybean lines. Stable lines identified included MNG 7.13, MNG 8.10, and MNG 1.63, which showed the lowest environmental interaction. These lines also out-yielded the local checks by over 300 kg ha−1, indicating that they have potential to boost soybean yields in the tropics. Line MNG 8.10 showed adaptability to most of the locations and had the highest yield among the three most stable lines, making it the most promising line; it is therefore recommended for release to improve soybean production and productivity in the region.Item Evaluation of Soybean Entries in the Pan-African Trials for Response to Coniothyrium glycines, the Cause of Red Leaf Blotch(Plant disease, 2022-02-05) Murithi, Harun M.; Obua, Tonny; Tukamuhabwa, Phinehas; Hartman, Glen L.Red leaf blotch (RLB), caused by the fungus Coniothyrium glycines, is an important disease of soybean known to cause yield losses across soybean-growing regions in Africa. Fungicides are one option to manage this disease, but utilization of host resistance may be a better option suited for smallholder soybean farmers in Africa. Fifty-nine soybean entries were evaluated for RLB severity in nine field locations in Ethiopia, Kenya, Uganda, and Zambia. Disease incidence was 100% and disease severity differed (P < 0.01) among entries at eight of the nine locations. Mean severity ratings ranged from 1.4 to 3.2 based on a 0-to-5 scale, with higher disease severities recorded in Ethiopia followed by Zambia. Eight of the 59 entries were common to all nine locations and had severity ratings ranging from 1.6 to 2.9. The cultivar SC Signal had the lowest RLB severity ratings in the combined analysis over locations. Based on correlations of weather variables to RLB severity, mean rainfall from planting to 30 days before assessment date had a positive correlation (r = 0.70; P = 0.035), as did mean morning maximum wind speed (r = 0.88; P = 0.016). Other variables, such as temperature and relative humidity, did not correlate to RLB severity. This is the most comprehensive report to date on the occurrence of RLB in the region, which for the first time demonstrates an association between rainfall and wind speed with RLB severity. It also represents the first extensive report evaluating soybean genotypes for resistance against RLB in multiple environments.Item Soybean production in eastern and southern Africa and threat of yield loss due to soybean rust caused by Phakopsora pachyrhizi(Plant pathology, 2016-09-24) Murithi, H. M.; Tukamuhabwa, P.; Thomma, B. P. H. J.; Joosten, M. H. A. J.Soybean is a major source of oil and proteins worldwide. The demand for soybean has increased in Africa, driven by the growing feed industry for poultry, aquaculture and home consumption in the form of processed milk, baked beans and for blending with maize and wheat flour. Soybean, in addition to being a major source of cooking oil, is also used in other industrial processes such as in the production of paints and candle wax. The demand for soybean in Africa so far outweighs the supply, hence the deficit is mainly covered through imports of soybean products such as soybean meal. The area under soybean production has increased in response to the growing demand, a trend that is expected to continue in the coming years. As the production area increases, diseases and insect pests, declining soil fertility and other abiotic factors pose a major challenge. Soybean rust disease, caused by the fungus Phakopsora pachyrhizi, presents one of the major threats to soybean production in Africa due to its rapid spread as a result of the ease by which its spores are dispersed by the wind. Disease control by introducing resistant soybean varieties has been difficult due to the presence of different populations of the fungus that vary in pathogenicity, virulence and genetic composition. Improved understanding of the dynamics of rust ecology, epidemiology and population genetics will enhance the effectiveness of targeted interventions that, in turn, will safeguard soybean productivity.Item Evaluation of soybean genotypes for resistance against the rust-causing fungus Phakopsora pachyrhizi in East Africa(Plant Pathology, 2021-01-16) Murithi, Harun Muthuri; Namara, Mercy; Tukamuhabwa, Phinehas; Mahuku, George; Thomma, Bart P. H. J.; Joosten, Matthieu H. A. J.Soybean rust, caused by the biotrophic fungus Phakopsora pachyrhizi, is the most important foliar disease of soybean (Glycine max) worldwide. Deployment of resistant soybean cultivars is the best option for managing this disease. Genes conferring resistance to P. pachyrhizi have been identified, but pathotypes of the rust fungus overcoming these resistance genes have also been found. To identify novel resistance genes, soybean genotypes from both local and international sources were screened at multiple locations in Tanzania and Uganda in 2016 and 2017. The results from this screening revealed that infection types, disease severities, and sporulation levels varied among the genotypes and locations. The majority of the genotypes had tan-coloured (TAN) lesions and developed moderate sporulation, implying susceptibility, while only seven of the 71 lines had reddish-brown (RB) lesions and showed low disease severities in all of the screening environments. We identified seven genotypes that were the most resistant to rust in the most locations over the two years. These genotypes will be useful for further studies and, ultimately, for rust management, as they show broad resistance to various pathotypes of the rust fungus.Item Use of low cost near‑infrared spectroscopy, to predict pasting properties of high quality cassava flour(Scientific Reports, 2024-07-25) Mikidadi, Abubakar; Wasswa, Peter; Masumba, Esther; Kanju, Edward; Edema, Richard; Tukamuhabwa, Phinehas; Kayondo, Siraj; Kulembeka, HenerikoDetermination of pasting properties of high quality cassava flour using rapid visco analyzer is expensive and time consuming. The use of mobile near infrared spectroscopy (SCiO™) is an alternative high throughput phenotyping technology for predicting pasting properties of high quality cassava flour traits. However, model development and validation are necessary to verify that reasonable expectations are established for the accuracy of a prediction model. In the context of an ongoing breeding effort, we investigated the use of an inexpensive, portable spectrometer that only records a portion (740–1070 nm) of the whole NIR spectrum to predict cassava pasting properties. Three machine-learning models, namely glmnet, lm, and gbm, implemented in the Caret package in R statistical program, were solely evaluated. Based on calibration statistics (R2, RMSE and MAE), we found that model calibrations using glmnet provided the best model for breakdown viscosity, peak viscosity and pasting temperature. The glmnet model using the first derivative, peak viscosity had calibration and validation accuracy of R2 = 0.56 and R2 = 0.51 respectively while breakdown had calibration and validation accuracy of R2 = 0.66 and R2 = 0.66 respectively. We also found out that stacking of pre-treatments with Moving Average, Savitzky Golay, First Derivative, Second derivative and Standard Normal variate using glmnet model resulted in calibration and validation accuracy of R2 = 0.65 and R2 = 0.64 respectively for pasting temperature. The developed calibration model predicted the pasting properties of HQCF with sufficient accuracy for screening purposes. Therefore, SCiO™ can be reliably deployed in screening early-generation breeding materials for pasting properties.Item Artificial intelligence‑driven near‑infrared spectrophotometry model for rapid quantification of anti‑nutritional factors in soybean (Glycine max.)(Discover Applied Sciences, 2025-06-15) Palange, Norberto Jose; Obua, Tonny; Sserumaga, Julius Pyton; Ochwo-Ssemakula, Mildred; Edema, Richard; Tukamuhabwa, PhinehasAnti-nutritional factors can impact soybean nutrient bioavailability when consumed by monogastric animals. However, conventional methods available for quantifying anti-nutritional factors such as phytate and trypsin inhibitors in feeds are laboratory-intensive, time-consuming, expensive, and error-prone. This study developed near-infrared spectrophotometry (NIRS)-based models to quantify phytate and trypsin inhibitors in soybean. Thus, a set of 190 soybean genotypes assayed through conventional wet chemistry was used as a reference for model development and cross-validation. Using a benchtop NIR instrument (DS2500), spectra readings between 400 and 2500 nm were taken from each soybean sample. Mean values for phytate and total trypsin inhibitors (TTI) were 1.77 mg g−1 (SD = 1.23) and 0.89 mg g−1 (SD = 0.24), respectively. Predictive models were developed through partial least squares (PLS) and random forest (RF) regressions. The random forest models outperformed partial least squares regression with the best predictive performance of R2test = 0.97; RPD = 5.95 and R2test = 0.96; RPD = 3.62 for phytate and TTI, respectively. The high R2 and RPD values demonstrate the model's strong predictive capability and accuracy, suggesting that the NIRS-based models can effectively quantify phytate and TTI in soybean. Thus, breeders can efficiently select for low-anti-nutritional genotypes and accelerate the development of nutritionally beneficial legumes while reducing soybean processing costs. NIRS offers a promising alternative to traditional phenotyping methods due to its speed, simplicity, environmental friendliness, and cost-effectiveness. Its integration into breeding programs can streamline the screening process, especially in early selection stages.Item Genetic variability of anti‑nutritional factors among soybean (Glycine max.) germplasm(Discover Agriculture, 2025-04-28) Palange, Norberto Jose; Obua, Tonny; Sserumaga, Julius Pyton; Wembabazi, Enoch; Ochwo‑Ssemakula, Mildred; Tukamuhabwa, PhinehasSoybean is a vital source of vegetable protein, carbohydrates, oil, and minerals. However, anti-nutritional factors (ANFs) can diminish its nutritional value for monogastric animals, including humans. This study assessed the variability of phytate and trypsin inhibitors in Ugandan soybean germplasm. A total of 308 soybean genotypes were analyzed for yield, phytate, and total trypsin inhibitors (TTI) using spectrophotometric methods. Significant variation was observed for yield, phytate, and TTI levels (p < 0.001). Phytate levels ranged from 14.8 mg kg⁻1(BSPS 48A-6–3) to 6928.8 mg kg⁻1(NGDT 2.15–7), while TTI varied from 14.7 mg kg⁻1(DN 16_N) to 1534.8 mg kg⁻1(Duiker). Using a weighted selection index, the best-performing genotypes, Ux 990–044, Ux 990–102, and S 6.22B, combined high yield with low ANF levels. Broad-sense heritability (H2) was 0.68 for phytate, 0.84 for TTI, and 0.08 for yield. The phenotypic coefficient of variation (PCV) for phytate (203.1%) was significantly higher than the genetic coefficient of variation (GCV) (137.6%), indicating substantial environmental influence, while moderate for TTI (PCV = 34.6%; GCV = 29.2%). Genetic advance (GA) values were 1667.6 mg kg⁻1 for phytate and 504.3 mg kg⁻1 for TTI, highlighting considerable genetic variability and heritability. These findings have practical implications for breeding programs; the identified genotypes that combine high yield and reduced ANFs can reduce processing costs for food and feed industries while enhancing nutritional security, especially in regions dependent on soybean as a protein source.Item Fruit Traits associated with Resistance to Fruit Pests of Hot Pepper(MUJAES, 2021-07-03) Ssekkadde, P.; Ribeiro, C.S.C.; Ochwo-Ssemakula, M.N.; Tukamuhabwa, P.; Karungi, J.Thirty-seven local and fourteen exotic hot pepper (Capsicum spp.) genotypes were screened under natural field conditions for resistance to two quarantine fruit pests; the fruit fly (Diptera: Tephritidae) and the false coddling moth (Lepidoptera: Tortricidae) at Makerere University Research Institute Kabanyolo for two seasons. The genotypes were grown in a randomised complete block design with three replications. Data on pest occurrence and damage; and fruit traits (fruit weight, length, width, flesh penetrability, and fruit wall thickness) were subjected to analysis of variance. The 51 genotypes showed variation in pest infestation and fruit traits. Five local genotypes (UG-WE02-1014, UG-WE02-0711, UG-EA06-0515 and UG-WE02-1608) and one exotic (CAP0408-12) showed resistance to fruit fly infestation. Fruit fly infestation correlated highly with fruit weight (r=0.59, p<0.001) and width (r=0.63, p<.001), among others. Similarly, FCM infestation positively correlated to fruit weight (r=0.50, p<0.001) and width (r=0.50, p<0.001). The identified hot pepper genotypes with resistance to fruit fly and FCM can be used in hot pepper improvement programsItem Pasting Properties of High-quality Cassava Flour of some selected improved Cassava Varieties in Tanzania for Baking(African Journal of Agricultural Research, 2023-01-03) Mikidadi, Abubakar; Wasswa, Peter; Masumba, Esther; Edema, Richard; Tulkamuhabwa, Phinehas; Kayondo, Siraj; Ongom,PatrickPartial substituting wheat with high-quality cassava flour (HQCF) in bread making would be economically beneficial in Tanzania. However, cassava varieties with the best pasting quality for this use are unknown. In addition, the appropriate time of harvesting the varieties to attain the best pasting quality is also unknown. This study, therefore, aimed at identifying the most appropriate cassava varieties and their appropriate harvesting time that could be used for production of HQCF for baking bread. Nine improved cassava varieties namely Kiroba, Mkuranga1, Pwani, Chereko, Mkumba, Hombolo, Orela, Kizimbani and Kipusa and two local varieties, Albert and Kibandameno were planted in 2020/2021 and 2021/2022 seasons at TARI-Ukiriguru using a split plot design. Harvesting was done at 10 and 12 months after planting (MAP). Pasting characteristics of the HQCF samples were determined at the International Centre of Tropical Agriculture, Dar es salaam, Tanzania using Perten Rapid Visco Analyzer (RVA) Tecmaster equipment, Model: N103802. The results indicated that KIPUSA had the lowest significant setback, while Hombolo had the highest significant setback both at 10 and 12 MAP suggesting that HQCF produced from KIPUSA should be considered for partial substitution of wheat in baking bread that is attractive to consumers.Item Regeneration Procedure for Three Arachis hypogaea L. Botanicals in Uganda through Embryogenesis(Br Biotechnol J, 2015-05-06) Okello, D. K.; Akello, L. B.; Tukamuhabwa, P.; Odong, T. L.; Deom, C. M.A procedure was developed for embryogenesis from embryo explants derived from mature seeds of freshly harvested Serenut 4T, Serenut 1R and Acholi-white groundnut cultivars representing the three broad groundnut botanical classifications. This study explored the use of mature embryo axes as explants for somaticembryogenesis, and determined the factors that affect regeneration of three Ugandan groundnut cultivars. Freshly harvested mature seeds of the three groundnut cultivars were collected and the embryo explants were initiated on 3 media namely; Murashige and Skoog (MS) basal media with varying concentrations of the growth regulator 2,4-Dichlorophenoxy acetic acid (2,4-D); Chu N6 basal medium with vitamins (N6); and Callus Induction Medium (CIM). The shoot formation and elongation medium contained MS basal medium supplemented with indolebutyric acid (IBA) and 6- Benzylamminopurine (BAP) in isolation, and BAP in combination with a-naphthaleneacetic acid (NAA) and indoleacetic acid (IAA). For root induction, elongated shoots were transferred to MS medium supplemented with various combinations of NAA with IBA, BAP and a combination of IBA and Kinetin. Different concentrations of 2,4-D elicited different callogenesis responses in the cultivars with Acholi white (Valencia botanical) and Serenut 4T (Spanish botanical) giving the optimal response at 5mg/l whereas Serenut 1R (Virginia botanical) showed best response at a concentration of 30 mg/l. N6 and CIM supported callogenesis in Acholi white (AW) and Serenut 4T only. In all cultivars, maximum root production was gained when using MS medium supplemented with NAA- 1 mg/l and IBA -2.0 mg/l. On the other hand, for Serenut 1R and Serenut 4T, BAP 2.5 mg/l; NAA 0.5 mg/l combination yielded higher shoot regeneration percentage whereas for AW BAP 3 mg/l; NAA 0.5 mg/l supported maximum shoot production.This is the first ever report of successful regeneration of the three groundnuts botanicals in Uganda. These results are likely to facilitate genetic transformation of three preferred Ugandan groundnut varietiesItem Yield Loss Associated with Soya Bean Rust (Phakopsora pachyrhizi Syd.) in Uganda(Journal of Phytopathology, 2003-01-10) Kawuki, R. S.; Adipala, E.; Tukamuhabwa, P.Studies were conducted to quantify the yield loss attributable to soya bean rust, a relatively new disease in Uganda. This was carried out for three consecutive seasons in the central, eastern, northern and western parts of the country, using three commercial varieties (Nam 1, Nam 2 and Namsoy 3) and two elite varieties (UG-5 and GC-00138-29). The commercial varieties recorded higher yield losses (26.9–36.3%) and higher rust severities >50%, whereas the elite varieties recorded lesser yield losses of <10% and rust severities of <30%. Yield losses were highest in the central region (22.9%), and lowest in the northern region (15.1%). Yield losses differed significantly between seasons and were associated with reduction in seed weight and filled pod per plant.Item Soybean rust severity, rate of rust development, and tolerance as influenced by maturity period and season(Crop Protection, 2004-05-15) Kawuki, R.S.; Tukamuhabwa, P.; Adipala, E.Studies were conducted in Uganda for three consecutive seasons to evaluate soybean lines of different maturation periods against rust. All the lines were highly susceptible to rust with only two lines graded as moderately resistant: TGx 1835-10E (early maturing) and TGx 1838-5E (late maturing). These two lines were consistently associated with non-sporulating lesions. Within each maturation group, soybean lines differed significantly in rates of rust development (RRDs), rust severities at R6 growth stage, and yielding ability under rust stress. Most of the lines had RRDs higher than the local check. However, it was only the early maturing lines that yielded higher than the local check. Higher levels of rust tolerance were observed in the early maturing lines (yields >1000 kg/ha), and lowest in late maturing lines (yields<500 kg/ha). Most variation in yields was due to differences among soybean lines, except the late and medium maturing lines were it was due to seasonal variation. Most variation in RRDs was due to the seasons and not soybean lines, and rust severity increased with crop age.Item Genome-wide Association Mapping of Bruchid Resistance Loci in Soybean(PloS one, 2025-01-10) Mukuze, Clever; Obua, Tonny; Kweyu, Sharon V.; Kasule, Faizo; Tukamuhabwa, PhinehasSoybean is a globally important industrial, food, and cash crop. Despite its importance in present and future economies, its production is severely hampered by bruchids (Callosobruchus chinensis), a destructive storage insect pest, causing considerable yield losses. Therefore, the identification of genomic regions and candidate genes associated with bruchid resistance in soybean is crucial as it helps breeders to develop new soybean varieties with improved resistance and quality. In this study, 6 multi-locus methods of the mrMLM model for genome-wide association study were used to dissect the genetic architecture of bruchid resistance on 4traits: percentage adult bruchid emergence (PBE), percentage weight loss (PWL), median development period (MDP), and Dobie susceptibility index (DSI) on 100 diverse soybean genotypes, genotyped with 14,469 single-nucleotide polymorphism (SNP) markers. Using the best linear unbiased predictors (BLUPs), 13 quantitative trait nucleotides (QTNs) were identified by the mrMLM model, of which rs16_14976250 was associated with more than 1 bruchid resistance traits. As a result, the identified QTNs linked with resistance traits can be employed in marker-assisted breeding for the accurate and rapid screening of soybean genotypes for resistance to bruchids. Moreover, a gene search on the Phytozome soybean reference genome identified 27 potential candidate genes located within a window of 478.45 kb upstream and downstream of the most reliable QTNs. These candidate genes exhibit molecular and biological functionalities associated with various soybean resistance mechanisms and, therefore, could be incorporated into the farmers’ preferred soybean varieties that are susceptible to bruchids.