Browsing by Author "Muyinza, Harriet"

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    Capacity Building in Agronomic Practices, Waxing and Relative Humidity Storage Technologies for Shelf-life Extension of Fresh Cassava Roots
    (CGIAR Research Program, 2016) Nyamutoka, Pamela; Wanda, Kelly; Matovu, Moses; Aceng, Sharon; Muyinza, Harriet; Kaliisa, Robert; Menya, Geoffrey; Nuwamanya, Ephraim; Nyakaisiki, Elizabeth; Nanyondo, Rose; Abass, Adebayo
    Cassava is an important source of food and income in Uganda. Consumption of cassava has been increasing especially in the urban areas. Total consumption of fresh cassava in 2013 was estimated to be 1.32 MT per annum (RTB-ENDURE - Cassava Sub-Project scoping study, 2014). Market demand for fresh cassava in 2013 was estimated to be 309,528 MT per annum and was projected to increase to 387,074 MT in 2018, signifying a 25% increase. New market segments for fresh cassava roots have been emerging for both the niche and mass markets. Fresh cassava was found to be consumed in various forms. According to findings from the RTB-ENDURE Market Study (2015) high-end restaurants had introduced cassava recipes while fried cassava chips were a delicacy in road-side food catering services, a new phenomenon. Further, the study revealed that the most preferred consumption form was in fried form (37% of the study respondents), followed by boiled (35% of the study respondents) and steamed in banana leaves (25% of the study respondents). Cassava enjoys a unique position as a convenient food that is easy and fast to prepare. It is in recognition of this fact that cassava has been selected as one of the ten priority crops to assist Uganda transform its agricultural sector through provision of household incomes, employment and food security. However, despite this growth in demand, both utilization of and income derived from marketing of fresh cassava are being hindered by the rapid postharvest physiological deterioration (PPD) of the roots. Cassava suffers spoilage within two to three days of harvest. The implication is that it cannot be marketed over a long time and distance thereby reducing incomes to growers and traders, leading to less investments and hence low productivity. To address this challenge, the RTB-ENDURE Cassava Sub-Project also known as “Extending the Shelf life of Fresh Cassava Roots for Increased Incomes and Postharvest Loss Reduction” aimed at introducing, testing, validating and assessing the efficacy of two technologies for increasing the shelf-life of fresh cassava roots, and thereby assisting to increase the value to growers, traders and consumers along the entire value chain. These technologies included high relative humidity storage and waxing. Both relative humidity storage and waxing of fresh cassava roots are in commercial use elsewhere. However, their applicability and feasibility in Uganda was unknown since these technologies were new. Therefore, the approach used in RTB-ENDURE Cassava Sub-project involved knowledge sharing between the Ugandan research team and its counterpart at CIAT in Colombia, one of the countries where these technologies are being commercially adopted. CIAT has substantial experience in conducting research on PPD of cassava and on how to tackle the issue of the rapid deterioration of the roots by use of suitable varieties, agronomic practices and pre-harvest techniques such as pruning. CIAT scientists and value chain actors in Colombia trained the Ugandan research team in various aspects of high relative humidity storage and waxing, including varietal selection, PPD scoring, and the agronomic and pre-harvest techniques that reduce PPD. The project team conducted a scoping study and later a detailed market assessment, carried out on-station research on varietal selection (based on PPD susceptibility) and validation of the technologies for shelf-life extension, and established two pilot pack houses in western Uganda. These included one pack house in Kyenjojo district to test a farmer operated business model and another one that was established in Kabarole district to test a trader operated business model. Thereafter, the project built the capacities of both operators and their identified partners and potential suppliers to promote the adoption and adaptation of these shelf-life extension innovations. This report describes the capacity building process and activities that were done to enable the value chain actors adopt and adapt the pre-and post-harvest practices, and waxing and high relative humidity storage technologies in order to run a successful business enterprise.
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    Chemical basis for resistance in sweetpotato Ipomoea batatas to the sweetpotato weevil Cylas puncticollis
    (Pure and Applied Chemistry, 2009) Stevenson, Philip C.; Muyinza, Harriet; Hall, David R.; Porter, Elaine A.; Farman, Dudley I.; Talwana, Herbert; Mwanga, Robert O. M.
    The aim of this work was to determine the basis of resistance in a sub-Saharan sweetpotato variety, New Kawogo, to the African sweetpotato weevil Cylas puncticollis. This insect feeds on the roots, reducing quality and yield, and is the most important production constraint of sweetpotato in Africa. Laboratory bioassays were designed to determine how the performance of weevils differed on susceptible and resistant roots. Subsequently, liquid chromatography-mass spectrometry (LC-MS) analysis of the root surface and root latex identified quantitative and qualitative differences in the chemical profiles with higher levels of octadecyl and hexadecyl esters of hydroxycinnamic acids reported in the resistant variety. The compounds were synthesized to confirm their identity and incorporated into artificial diets for bioassays on C. puncticollis. High levels of mortality and developmental inhibition were recorded for larvae feeding on treated diets, and the effect was dose-dependent. Thus, in contrast to previous work on resistant African sweetpotato cultivars, resistance in New Kawogo is not only active, but is quantifiable and manageable for breeding. Work is underway to determine what effect these compounds have on the weevils at a molecular level. The inheritance of the root latex esters will be studied in new crosses and mapped in new populations using quantitative trait loci (QTLs) that are currently being developed.
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    Resistance to the Weevils Cylas puncticollis and Cylas brunneus Conferred by Sweetpotato Root Surface Compounds
    (Journal of Agricultural and Food Chemistry, 2013) Anyanga, M. Otema; Muyinza, Harriet; Talwana, Herbert; Hall, David R.; Farman, Dudley I.; Ssemakula, Gorrettie N.; Mwanga, Robert O. M.; Stevenson, Philip C.
    Seven resistant varieties of sweetpotato were compared with three susceptible varieties in field trials and laboratory bioassays and showed that resistance was an active process rather than an escape mechanism, as field resistant varieties also had reduced root damage and oviposition compared with susceptible varieties in the laboratory. Liquid chromatography−mass spectrometry (LC−MS) of root surface and epidermal extracts showed significant variation in the concentration of hexadecyl, heptadecyl, octadecyl, and quinic acid esters of caffeic and coumaric acid, with higher concentrations correlated with resistance. All compounds were synthesized to enable their positive identification. Octadecyl coumarate and octadecyl caffeate applied to the surface of susceptible varieties in laboratory bioassays reduced feeding and oviposition, as observed on roots of resistant varieties, and therefore are implicated in weevil resistance. Segregating populations from breeding programs can use these compounds to identify trait loci for resistance and enable the development of resistant varieties
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    Sweetpotato weevil (Cylas spp.) resistance in African sweetpotato germplasm
    (International Journal of Pest Management, 2012) Muyinza, Harriet; Talwana, Herbert L.; Mwanga, Robert O.M.; Stevenson, Philip C.
    Host-plant resistance could be a useful tool for managing the weevils Cylas puncticollis and C. brunneus, which are major insect pests of sweetpotato in Africa. There is currently little information on existing resistance mechanisms against Cylas spp. in African cultivars, except where lower levels of weevil damage were attributed to escape due to deep rooting and reduced soil cracking, limiting the exposure of roots to weevils. Here, we evaluate weevil resistance in 134 sweetpotato cultivars and landraces over two seasons in two agroecologically diverse locations. Several sweetpotato cultivars, including New Kawogo, expressed resistance to Cylas spp. The resistance characteristics have been demonstrated in previous laboratory experiments to be quantifiable and thus potentially useful in targeted plant-breeding against Cylas spp. We showed external root and stem base damage to be an accurate quantitative indicator of internal root damage, offering rapid and accurate evaluation of resistance in field trials for screening. Moreover, weevil resistance can be assessed earlier in plant development, so saving time in the selection of the progeny from breeding programmes.
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    Training Report: Capacity Building in Entrepreneurial and Business Skills for Operationalizing Fresh Cassava Roots Packhouse
    (The CGIAR Research Program on Roots, 2017) Nyamutoka, Pamela; Wanda, Kelly; Matovu, Moses; Kwagala, Innocent; Muyinza, Harriet; Kaliisa, Robert; Menya, Geoffrey; Nuwamanya, Ephraim; Nyakaisiki, Elizabeth; Nanyondo, Rose; Abass, Adebayo
    Cassava is an important source of food and income in Uganda. Consumption of cassava has been increasing especially in the urban areas. Market demand for fresh cassava in 2013 was estimated to be 309,528 MT per annum in 2013. It was projected to increase by 25% to 387,074 MT in 2018 (RTB-ENDURE-Cassava scoping study, 2014). New market segments for fresh cassava roots have been emerging for both niche and mass markets. Fresh cassava was found to be consumed in various forms. According to findings from the Market Study 2015 high-end restaurants had introduced cassava recipes. Fried cassava chips were a delicacy in road-side food catering services, a new phenomenon in urban areas. Further, analysis of respondent responses revealed that the most preferred consumption form was fried (37%), followed by boiled (35%) and steamed in banana leaves (25%). Cassava enjoys a unique position as a convenient food that is easy and fast to prepare. It is in recognition of this, among others, that cassava has been selected as one of the 10 priority crops with a high potential to transform the agricultural sector in Uganda through provision of household food security, incomes, and employment. . However, despite a growth in demand, both the utilization and income derived from marketing of fresh cassava roots are being hindered by the rapid postharvest physiological deterioration (PPD) that causes spoilage of cassava roots within two to three days of harvest. The implication is that it cannot be marketed over a long time and distance, thereby reducing incomes and food security to growers, consumers and traders. This in turn leads to less investments and hence low productivity.To address this challenge, the RTB-ENDURE Cassava sub-project also known as “Extending the Shelf life of Fresh Cassava Roots for Increased Incomes and Postharvest Loss Reduction” aimed at introducing, testing, validating the efficacy of two technologies for increasing the shelf-life of fresh cassava roots, and thereby assisting to increase the value to growers, traders and consumers along the entire value chain. These technologies included high relative humidity storage and waxing. This research also focused on investigating and establishing the business cases for the two technologies in Uganda since both technologies are in commercial use elsewhere but the commercial applicability and viability of the new technologies in Uganda was unknown. The next phase of the project, following on-station research and user validation therefore was to determine the commercial and institutional feasibility of these technologies in Uganda.In doing so, the project proposed to set up two packhouses in order to test their commercial viability. They included one packhouse managed by farmers and another managed by an entrepreneur. To facilitate the successful commercial operations of the packhouses, it was necessary to build the entrepreneurial and business skills of the operators. This report describes the capacity building process and activities that were done to enhance the business and entrepreneurial skills of packhouse operators.