Browsing by Author "Baguma, Y."
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Item Agro-pastoral choice of coping strategies and response to drought in the semi-arid areas of Uganda(African Journal of Rural Development, 2017) Akwango, D.A.; Obaa, B.B.; Turyahabwe, N.; Baguma, Y.; Egeru, A.Drought episodes have been on the increase in the semi- arid areas of Uganda with harmful effects like crop failure, and human and livestock mortality, among others. There are barely any studies that have examined why agro- pastoral communities take specific actions in coping with drought. This study examined the factors influencing the choice of coping strategies to drought and the reasons for response and nonresponse. The study was conducted in the semi-arid Karamoja sub-region of Uganda using a crosssectional household survey on 305 households. A multinomial logistic model was used to analyze the factors that determine the choice of coping strategy by households against drought events. The results indicate that coping was positively influenced by distance to the nearest water source, access to drought information and training on drought management. Livelihood support, amount of arable land owned and frequency of receiving information from Drought Early Warning Systems (DEWS) had a positive significant effect on response. To enhance response capabilities, there is need to improve livelihoods and frequent dissemination of information on impending drought.Item Effect of self-pollination with heat-treated pollen on parthenocarpy and homozygosity in cassava(African Crop Science Journal, 2020) Buttibwa, M.; Kawuki, R.S.; Baguma, J.K.; Nalela, P.; Eyokia, M.; Oshaba, B.; Ceballos, H.; Lentini, Z.; Baguma, Y.; Tugume, A.K.Cassava’s (Manihot esculenta Crantz) high heterozygosity complicates its genetic improvement via selective breeding. Double haploid (DH) technology can be used to improve the crop’s heterozygosity, thereby improving the capacity for genetic improvement. The objective of this study was to evaluate the effect of self-pollination using heated pollen on pollen tube penetration, fruit set, seed and haploid embryo development in cassava genotypes for the production of haploid cassava. Pollen from two cassava genotypes, NASE3 and NASE14, was heated at 40, 50 and 60 oC for 0.5, 1.0 and 2.0 hr each. The heated pollen was used in six rounds of self-pollinations. Pollen tube penetration was monitored by fluorescent microscopy, followed by early embryo rescue and ovule culture. Ploidy and zygosity were assessed using flow cytometry and single-nucleotide polymorphism analysis, respectively. Pollen germinated on the stigma, grew within the style through the nucellar beak, but did not reach the embryo sac, thus achieving no fertilisation in all the 5756 self-pollinated flowers. There was a reduction in pollen germination (in vitro and in vivo), pollen tube penetration and fruit set with increasing temperature. Heat-treated pollen stimulated division of the egg cell and induced development of parthenocarpic fruits. Up to 6 embryoids per ovule were observed and all regenerated plantlets were diploid, with up to 93.0% increased homozygosity. For the first time, plant regeneration from ovules, pollinated with fresh pollen at 14 days after pollination, was achieved indicating improved speed in plant regeneration. The data generated are important for the development of protocols for cassava DH plant production.Item Fruit Set and Plant Regeneration in Cassava Following Inter specific Pollination with Castor Bean(African Crop Science Journal, 2019) Baguma, J.K.; Mukasa, S.B.; Kawuki, R.; Tugume, A.K.; Buttibwa, M.; Nalela, P.; Eyokia, M.; Oshaba, B.; Ceballos, H.; Lentini, Z.; Baguma, Y.The increasing demand for cassava (Manihot esculenta Crantz) for food and non-food uses in the tropics necessitates that its breeding for increased root productivity be made faster. The characteristic long breeding cycle and heterozygous nature of this crop, pose a major obstacle to its rapid genetic improvement. This study aimed at inter-pollinating cassava with castor bean (Ricinus communis), with a purpose of inducing and regenerating cassava doubled haploids (DHs). A total of 3,349 flowers from twelve elite cassava varieties were inter-pollinated with caster bean. A total of 803 fruits were harvested for early embryo rescue and/or ovule culture. Of these, three were dissected to obtain seven unique embryos, while 800 were dissected to obtain 1312 young ovules, all of which were cultured in vitro. Overall, 82 (6.25%) of the cultured ovules formed callus that originated from the embryosac region, which is haploid. Four out of seven rescued embryos (57.1%) regenerated into plantlets. Ploidy analyses of 24 samples using flow cytometry revealed that 23 of the analysed samples were diploid. However, one callus sample was anueploid. Only one sample had an exceptionally high level of homozygosity ( 84.2%). These findings lay a foundation for future research aimed at induction of haploids in cassava.Item Genetic diversity among farmer-preferred cassava landraces in Uganda(African Crop Science Journal, 2012) Turyagyenda, L.F.; Kizito, E.B.; Baguma, Y.; Wanjala, B.W.; Osiru, D.S.O.Understanding of genetic diversity among a breeding population is an important requirement for crop improvement as it allows for the selection of diverse parental combinations and formation of heterotic pools for genetic gain. This study was carried out to determine genetic diversity within and among 51 farmer-preferred cassava (Manihot esculenta) landraces and 15 elite accessions grown in Uganda. Twenty six simple sequence repeat (SSR) markers used for genetic diversity assessment in this study revealed a total of 154 alleles, of which 24% were unique alleles present only in landraces. The genetic diversity and observed herozygosity in landraces were slightly higher than in elite accessions. Elite accessions clustered with some of the landraces indicating that there were some alleles in common. However, 58.8% of the landraces fell into 3 different clusters independent of the elite accessions. Including these landraces with unique alleles in cassava breeding schemes will increase the chances of producing farmer preferred adapted elite cultivars. The study also revealed genetic differentiation among accessions from different regions providing an opportunity for establishment of heterotic pools within a breeding programme.Item Limits of phytosanitation and host plant resistance towards the control of cassava viruses in UgandaLimits of phytosanitation and host plant resistance towards the control of cassava viruses in Uganda(African Journal of Rural Development, 2017) Kawuki, R.S.; Adiga, G.; Orone, J.; Alicai, T.; Edimu, M.; Omara, T.; Pariyo, A.; Esuma, W.; Omongo, C.; Bua, A.; Kanju, E.; Baguma, Y.Cassava (Manihot esculenta Crantz) and the viruses that infect it, notably cassava mosaic virus and cassava brown streak viruses, have a unique history of co-evolution and co-existence. While cassava originated in South America, both viruses and the diseases they cause have largely been limited to the East African region, where they have, and continue to be key yield-robbing stresses. For sustainable control, we assume that deployment of resistant varieties when carefully combined with phytosanitation will combat these viruses. We have thus generated empirical data and tested the limits, i.e., how long this strategy can last. This entailed the comparison of elite cassava varieties, one set of virus-indexed tissue culture plantlets, and the other set, re-cycled planting materials under farmer’s cyclic propagation for 6-23 years. Trials were established at diverse sites in Uganda. We observed that both officially-released and unofficially-released cassava varieties are common in farmer’s fields; these varieties have varying susceptibility levels to viruses. Worrisome was that some officially-released varieties like NASE 3 registered cassava mosaic disease (CMD) incidences of up to 71% (virus-indexed), which was not any different from its re-cycled counterparts. Other varieties like NASE 14 have maintained high levels of CMD resistance six years after official release. Predominant re-cycled cassava varieties notably TME 204, I92/0057, TME 14, and to a limited extent NASE 14, are key reservoirs for cassava brown streak disease (CBSD) associated viruses. These findings highlight the limits of phytosanitation, i.e., in areas like Kaberamaido associated with high CMD pressure, varieties NASE 1 and NASE 3 can not be recommended; on the contrary, these varieties can be deployed in Kalangala, where they can survive with phytosanitation. And for CBSD, the findings justify the urgent need for phytosanitation (community-led) and development of varieties with higher levels of resistance and/or tolerance, as no immune variety has so far been identified.Item Local Varieties of Cassava: Conservation, Cultivation and Use in Uganda(Environment, Development and Sustainability, 2018) Nakabonge, Grace; Samukoya, C.; Baguma, Y.The study explored the theory that on-farm conservation of cassava germplasm is influenced by farmers’ traditional and cultural preferences of particular varieties. Traditional knowledge practices that are used for on-farm conservation of cassava germplasm as well as cassava attributes for selection were assessed. The findings obtained from the study indicated that farmers use traditional knowledge to select and preserve cassava germplasm for future use. It was also clear that farmers have their preferences such as culinary attributes, storability in the ground, early maturity and cooking quality to mention but a few that influence the decisions taken to retain or abandon cultivation of varieties. Therefore, by planting varieties in multiples plots, replanting immediately after harvesting, sharing with others in the community and planting disease-free materials, farmers ensure that they preserve varieties of interest for decades. The information generated during this study could inform development policies tailored toward ensuring sustainable on-farm conservation of cassava genetic resources.Item Participatory selection and development of drought tolerant cassava varieties for farmers in marginal areas(RUFORUM., 2010) Osiru, D.S.O.; Balyejusa-Kizito, E.; Bisikwa, J.; Baguma, Y.; Turyagyenda, L.Most breeding experiments suffer from the disadvantage that the major stakeholders are not involved in the selection and development of the varieties. This scenario leads to poor adoption and diffusion of the resulting technologies. Participatory plant breeding reduces the chances of developing varieties which, for reasons unknown or overlooked by the breeder, are not acceptable to farmers. Farmers’ participation in research and decision making in variety selection enhances adoption. Through participatory variety selection (PVS), farmers also gain skills, information and knowledge about improved varieties. Most previous research in cassava have not involved farmers in the development of the technologies. This research will involve farmers in the participatory selection of farmer preferred cultivars for breeding to improve their Water Use Efficiency (WUE) in drought prone environments of Uganda.Item Production of Virus-free Cassava through Hot Water Therapy and Two rounds of MeristemTip Culture(Cogent Food & Agriculture, 2020) Nakabonge, Grace; Nangonzi, R.; Tumwebaze, B.S.; Kazibwe, A.; Samukoya, C.; Baguma, Y.Cassava genetic resources are highly threatened by devastating viral diseases. It is therefore important to conserve the specifically farmer-preferred landraces/cultivars that are highly susceptible. The study assessed the efficiency of hot water therapy and meristem tip culture techniques in the elimination of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) causal viruses. Stems of symptomatic cassava genotypes confirmed infected with cassava brown streak viruses (CBSV) and cassava mosaic viruses (CMV) were subjected to hot water therapy at varying temperatures (25°C—60°C) followed by two rounds of meristem tip culture (MTC). Data on sprouting in the screen house and response in vitro were recorded and weaned plants were indexed for CMV and CBSV. The results indicated 100% elimination of CMV and a significant reduction in the viral load of CBSV. Thus, these techniques could be integrated into the cassava conservation strategy, for sustainable management of cassava genetic resources.