Uganda Forestry Resources and Institutions Center (UFRIC) Collections
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ItemBegomoviruses infecting cassava and their interaction with brown streak viruses in Kenya(Makerere University, 2018-11)Cassava mosaic begomoviruses are known to occur together within the same host and have a high rate of recombination. CMBs have also been reported to co-infect cassava with CBSVs, resulting in enhanced symptom expression. Interaction of virus species within the same group may result in recombination or synergism while interaction between the different groups may result in synergism. This dissertation determined the diversity and level of co-infection of CMBs in Kenya and also examined the nature of interaction of East African cassava mosaic virusUganda (a variant of EACMV: a CMB), with CBSVs. For the first objective, a survey was conducted in the four major cassava growing regions of Kenya namely Eastern, Coastal, Nyanza and Western. The study reported for the first time the occurrence of East African cassava mosaic Cameroon virus (EACMCV) in all cassava growing regions and a high (82.96%) level of coinfection of all CMBs in Kenya. East African cassava mosaic Zanzibar virus (EACMZV) was the most prevalent CMB in all cassava growing regions and had spread from the coastal region where it previously occurred. For the second objective, two CMD resistant varieties and one susceptible variety were used to study the interaction of East African cassava mosaic virusUganda (EACMV-Ug) with the CBSVs: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). This study was conducted in a greenhouse at Jomo Kenyatta University of Agriculture and Technology in Kenya. Quantitative RT-PCR and PCR analysis were performed to compare viral titre in single and co-infection. In the susceptible variety, Mucericeri, EACMV-Ug was higher when in co-infection with CBSV but lower when in co-infection with UCBSV, compared to single infection. In CMD resistant variety, MM 96/5280, the titre of EACMV-Ug at 3 mpi was raised significantly by both CBSV and UCBSV. For CBSVs, the titre of UCBSV was lower at 3 mpi but higher at 6mpi when in co-infection in the susceptible variety Mucericeri. EACMV-Ug increased the viral titre of CBSV in MH 99/7296. Detection of a previously unreported CMB and the synergism of CMB in CMD resistant varieties call for stringent diagnosis of cassava viruses and development of new sources of resistance to CMD. The findings in this dissertation contribute to the knowledge gap on the complex nature of virus interaction and will contribute to the long term goal of managing and screening cassava viruses.
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ItemEnhancing the potential of organic and mineral fertilizers for bean production on contrasting soils(Makerere University, 2018)Smallholder common bean (Phaseolus vulgaris L.) farmers on Buganda Catena of Uganda predominantly use indigenous knowledge to describe and manage their soils. Low and declining soil fertility which varies along topo-sequence, limits bean production, hence farmers have to improve fertilizer use and grain yield on contrasting soils. The objectives of this study were (i) to characterize three local soil types commonly cropped to beans and (ii) establish the suitable combinations of organic and mineral N & P fertilizers for increasing bean production on different soils. It was hypothesized that (i) the three local soils cropped to beans have similar properties and (ii) combined application of organic and mineral fertilizers to the three local soils gives equal yields. Together with farmers in Masaka district, three local soils mainly cultivated to beans (Lidugavu-black, Limyufumyufu-reddish, and Luyinjayinja-Gravelly) were identified, characterized and scientifically classified. On-farm experiments were carried out during 2015A and B seasons consisting of N & P each at 0, 7.5, and 15 kg ha-1 applied as urea and TSP, respectively, and with three levels of manure (0, 2.5 and 5.0 t ha-1) replicated three times in a factorial RCBD. High and low fertility on black and red soils, respectively, observed qualitatively by farmers was in agreement with results from scientific field and laboratory characterisation. These were differentiated by variability in pH, N, P, Ca and Mg. Highly limiting major nutrients were N and P. Soils characterized as different by farmers were classified as Phaeozem (black), Cambisol (Red) and Umbrisol (Gravelly), topographically located at the bottom, middle and crest, respectively. There were significant (P<0.05) differences in yield in response to combinations of N, P and manure on the different soils. Highest grain yield was on Umbrisol (2495 kg ha-1) at 5.0 t manure ha-1, although this was not significantly different (P>0.05) from that observed at [7.5 kg N+15 kg P +5.0 t manure]. Phaeozem at [7.5kg (N+P) ha-1 +2.5 t manure ha-1] gave yield similar to the highest on Umbrisol. Highest yield on Cambisol (2023.1 kg ha-1) was at [15kg N ha-1 +5.0 t manure ha-1] and this was not significantly (P>0.05) different from that obtained with [15kg (N+P) ha-1 +2.5 t manure ha-1]. Relative yield increase from fertilizer application reached 36% mainly on Umbrisol and Phaeozem. Yield due to combining fertilizers did not necessarily increase significantly beyond what were observed when either input was applied separately at a nutrient rate equivalent to the combination. Resulting yield increase up to 476 kg ha-1 and 291 kg ha-1 on Cambisol and Phaeozem, respectively, were under different fertilizer rates. These results show best fit combinations of organic and inorganic N & P fertilizers to be more effective than application of either of the materials separately. However, determining optimum supplementary nutrients beyond N&P for better yields require an economic assessment for improved farmer decisions.
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ItemTree fruiting phenology variations under changing climate: Implications on primate foraging patterns in and around Budongo forest, Uganda(Makerere University., 2015-05)Due to observed declines in the number of fruiting trees in Budongo Forest Reserve (BFR), a study was conducted to investigate how the decline in fruiting would affect both primate foraging behaviors in and around BFR, Uganda. The study aimed at investigating the changes in tree fruiting phenology under changing climatic conditions and its implications for primate foraging patterns in and around BFR. It was hypothesized that changes in climate variables (temperature and rainfall) could be the cause of reduced tree fruiting. Tree phenology in different forest compartments was monitored by conducting monthly visits to over 7300 individual trees belonging to 97 tree species out of 465 tree species in BFR to record whether they were fruiting. Primate foraging patterns were explored by observing habituated monkey groups (Cercopithecus mitis, Cercopithecus ascanius and Colobus guereza) to record their dietary composition. Surveys were conducted among forest edge communities to assess the current spatial and temporal crop raiding patterns in relation to past crop raiding patterns. Analysis of phenology patterns showed continued reduction in the number of fruiting trees among different forest compartments. Results further indicate spatial differences in fruiting patterns with more in compartments comprising the primary forest types compared to compartments comprising secondary forest types. Climatic variability had a significant impact on tree fruiting. More fruiting was recorded at the end of rainy season (May) and highest minimum temperatures. Tree fruiting drastically fell and most times trees never fruited when there was no rainfall and temperatures went too high. A comparison of primate foraging patterns indicates that whereas fruits constituted over 60% of primate diet in the early 1990’s, there has been a gradual shift to leaves as main diet (over 45%) In addition, community edge residents (64%) agree that crop raiding around BFR has increased over the last 15 years both in frequency and intensity. It was noted that the reduction and differences in forest tree fruiting directly correlates positively to rainfall, minimum temperature and forest structure. Although reduction in fruiting has led to diet shifts among frugivorous monkeys, fruit availability within the forest seems not to have any impact on crop raiding behaviors of primates. There is thus a need for paradigm shift in management and conservation of BFR. There is also a need for more intense studies on the impacts of changes in tree phenology on other forest ecology components such as herbivores, pollinators, and seed dispersers.
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ItemEarly detection of tropical forest degradation: an IFIU pilot study in Uganda.(Environmental conservation, 1995)
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