Browsing by Author "Nuwamanya, Ephraim"
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Item Assessment of Groundnut (Arachis hypogaea L.) Genotypes for Yield and Resistance to Late Leaf Spot and Rosette Diseases(Journal of Experimental Agriculture International, 2018) Elsiddig Mohammed, Khalid; Afutu, Emmanuel; Odong, Thomas L.; Okello, David K.; Nuwamanya, Ephraim; Grigon, Olupot; Rubaihayo, Patrick R.; Okori, PatrickGroundnut which is a major staple food crop in Uganda is constrained by late leaf spot (LLS) and groundnut rosette disease (GRD), accounting for major economic yield loss. This study was conducted to identify sources of resistance to LLS and GRD and yield potential of selected groundnut genotypes that could be used in breeding programs. Thirty-eight groundnut genotypes were evaluated at the National Semi Arid Resources Research Institute (NaSARRI)-Serere, Eastern Uganda during the first and second seasons of 2015. The experiment was arranged in randomized complete block design with four replications. The results showed highly significant (P < 0.01) genotype-by-season interaction for most of the traits studied. There were significant differences among the genotypes for 100 seed weight (P < 0.01), and dry pod yield and unshelled sample of 100 pods at P < 0.05. Late leaf spot severity (at harvest), GRD incidence (at 12 weeks) and severity (at harvest) were significantly (P < .01) different and positively correlated with Area Under Disease Progress Curve (AUDPC). GRD severity at harvest showed highly significant (P < 0.001) negative correlation with shelling percentage. Both 100 seed weight and unshelled sample of 100 pod showed highly significant (P < 0.01) negative correlations with LLS at harvest, LLS AUDPC, GRD at 12 weeks, GRD AUDPC, and GRD severity. Genotypes susceptible to both LLS and GRD recorded the lowest 100 seed weight. Nine genotypes (Serenut.2, SGV 0001, SGV 0005, SGV 0006, SGV 0019, SGV 0071, SGV 0082, SGV 0083, and SGV 89751T) showed resistance to both diseases with high yield potential. These genotypes could be used to introgress resistance to both diseases in acceptable cultivars which are susceptible.Item 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, AdebayoCassava 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.Item Early detection of plant diseases using spectral data(Las Palmas de Gran Canaria, Spain., 2020-01-08) Owomugisha, Godliver; Nuwamanya, Ephraim; Quinn, John A.; Mwebaze, ErnestEarly detection of crop disease is an essential step in food security. Usually, the detection becomes possible in a stage where disease symptoms are already visible on the aerial part of the plant. However, once the disease has manifested in different parts of the plant, little can be done to salvage the situation. Here, we suggest that the use of visible and near infrared spectral information facilitates disease detection in cassava crops before symptoms can be seen by the human eye. To test this hypothesis, we grow cassava plants in a screen house where they are inoculated with disease viruses. We monitor the plants over time collecting both spectra and plant tissue for wet chemistry analysis. Our results demonstrate that suitably trained classifiers are indeed able to detect cassava diseases. Specifically, we consider Generalized Matrix Relevance Learning Vector Quantization (GMLVQ) applied to original spectra and, alternatively, in combination with dimension reduction by Principal Component Analysis (PCA). We show that successful detection is possible shortly after the infection can be confirmed by wet lab chemistry, several weeks before symptoms manifest on the plants.Item Eleven years of breeding efforts to combat cassava brown streak disease(Breeding Science, 2016) Sezi Kawuki, Robert; Kaweesi, Tadeo; Esuma, Williams; Pariyo, Anthony; Kayondo, Ismail Siraj; Ozimati, Alfred; Kyaligonza, Vincent; Abaca, Alex; Orone, Joseph; Tumuhimbise, Robooni; Nuwamanya, Ephraim; Abidrabo, Philip; Amuge, Teddy; Ogwok, Emmanuel; Okao, Geoffrey; Wagaba, Henry; Adiga, Gerald; Alicai, Titus; Omongo, Christopher; Bua, Anton; Ferguson, Morag; Kanju, Edward; Baguma, YonaCassava (Manihot esculenta Crantz) production is currently under threat from cassava brown streak disease (CBSD), a disease that is among the seven most serious obstacles to world’s food security. Three issues are of significance for CBSD. Firstly, the virus associated with CBSD, has co-evolved with cassava outside its center of origin for at least 90 years. Secondly, that for the last 74 years, CBSD was only limited to the low lands. Thirdly, that most research has largely focused on CBSD epidemiology and virus diversity. Accordingly, this paper focuses on CBSD genetics and/or breeding and hence, presents empirical data generated in the past 11 years of cassava breeding in Uganda. Specifically, this paper provides: 1) empirical data on CBSD resistance screening efforts to identify sources of resistance and/or tolerance; 2) an update on CBSD resistance population development comprising of full-sibs, half-sibs and S1 families and their respective field performances; and 3) insights into chromosomal regions and genes involved in CBSD resistance based on genome wide association analysis. It is expected that this information will provide a foundation for harmonizing on-going CBSD breeding efforts and consequently, inform the future breeding interventions aimed at combating CBSD.Item Growth and Survival of Ripon Barbel (Barbus Altianalis) Larvae and Juveniles Fed Five Experimental Diets in Captivity(Aquaculture Reports, 2020) Aruho, Cassius; Walakira, John K.; Owori-Wadunde, Akisoferi; Nuwamanya, Ephraim; Bugenyi, Fred; Sserwadda, Martin; Rutaisire, Justus; Borski, Russell J.Mass production of quality seed is vital for commercial culture and requires prior knowledge of appropriate larval diets and their utilization. Four experiments were sequentially conducted at different periods to evaluate the effect of live and a processed microdiet on growth and survival of Barbus altianalis larvae and juveniles. Larvae were fed exclusively on live prey (Moina and Artemia nauplii), microdiet (57 % Crude Protein), decapsulated Artemia cysts and in combination (Moina + microdiet). The effect on growth was further evaluated in subsequent juvenile trial by co-feeding. Green water effect on larval growth was also evaluated. In the final experiment, 15 day old larvae were raised in fertilized outdoor concrete tanks. Results indicated that each diet affected larval growth significantly different (P < 0.05) with the combination diet (152.05 ± 2.51mg) and decapsulated Artemia (141.14 ± 2.43 mg) performing better than microdiet, Moina and Artemia nauplii in that order. In subsequent juvenile experiment, larvae originally fed decapsulated Artemia (510.13 ± 11.93 mg) and those fed a mixed diet (500.20 ± 11.8 mg) performed better than other diets. Ontogenetic pattern of amylase, lipase and protease activity identified larvae maturation age at 14–21 Days after hatching (DAH) (14.93 ± 0.36–31.5 ± 0.61 mg) with the combination diet. When larvae at 15 DAH were nursed in outdoor tanks, final survival and growth performance increased to 95.3 % and 1112 ± 42.70 mg compared to the indoor nursing at 90.9 % and 355.33 ± 6.44 mg respectively by 75 DAH. Therefore we recommend that any microdiet manipulations and or outdoor nursing be done during or after this period. Microalgae had no direct effect on larval growth (P > 0.05). In this study, larvae were confirmed to utilize the microdiet from exogenous stage but co-feeding produced best average weight (152.05 ± 2.51mg), specific growth rates (4.06 ± 0.19) and survival (90.9 %). This study provided guiding strategies for improved rearing of B. altianalis fingerlings in captivity.Item Identification of rice genotypes tolerant to submergence at seedling stage in Uganda(Journal of Plant Breeding and Crop Science, 2019) Bildadi Mlaki, Anna; Gibson, Paul; Edema, Richard; Habineza, Jean Claude; Mwanje, Gerald; Lamo, Jimmy; Nuwamanya, EphraimFloods have destroyed over 2000 acres of rice in Uganda which affected yield and caused losses to farmers. This problem is more pronounced when fields are not well leveled, and the mode of irrigation is by surface flooding. Majority of lowland rice fields in East African region are of this nature and are thus prone to yield losses. There are no submergence tolerance varieties identified in Uganda, so far. To address this problem, breeding for submergence tolerance is the most ideal and promising strategy in rice. As a first step, genotypes tolerant to submergence need to be identified which is the objective of this study. 29 rice genotypes were morphological characterized in screen house and field conditions while 34 rice genotypes were molecularly characterized. Results suggested significant differences in the performance of genotypes both in the screen house and under field conditions in which varieties Swarna, IRRI SUPA 3 and KOMBOKA showed approximately 80% and above survival rate with Swarna variety ranking first. Molecular characterization of rice genotypes revealed that, out of 34 genotypes, 30 genotypes scored presence for Sub 1A-2 allele while, four genotypes were neither Sub1A-1 nor Sub 1A- 2 alleles. None of the tested genotypes were carrying Sub 1A-1 allele.Item Influence of Weather and Purity of Plasticizer on Degradation of Cassava Starch Bioplastics in Natural Environmental Conditions(Journal of Agricultural Chemistry and Environment, 2019) Ahimbisibwe, Michael; Banadda, Noble; Seay, Jeffrey; Nabuuma, Betty; Atwijukire, Evans; Wembabazi, Enoch; Nuwamanya, EphraimThe threat posed by plastics to the environment has prompted the development of bioplastics. Starch plasticized by glycerol is a key renewable resource in the production of high-quality bioplastics. Previous studies have availed information on the mechanical quality of starch-based bioplastics however there is limited information about their degradation pattern in the natural environment which this research presents. Bioplastics were buried in holes in loam sandy soil and weekly photographic data and weight were collected to reveal the effect of degradation. Weather parameters of rainfall, temperature, relative humidity, sunshine intensity and sunshine hours were recorded to establish influence of weather on degradation. A control set up in the laboratory was used to compare the results. Over time the tests revealed that as the hydrophilic enzymes break down the bioplastic, its weight initially increases (up to 87%) due to absorption of moisture and after saturation, the bioplastic is disintegrated which initiates decomposition and the bioplastic weight is steadily reduced. Degradation was further enhanced by invasion of soil organisms like worms, termites among other soil microbes. Rainfall (r = 0.857) increased the moisture in the soil which initially increased the weight of the bioplastic up to a point when the hydrophilic enzymes set into breakdown the bioplastic then the weight started to drop. This was the same case for relative humidity (r = −0.04) however; the sunlight intensity (r = 515) and hours of illumination indirectly affect the process by influencing microbial activity. An increase in the sunshine intensity increased the activity of soil organisms up to a point beyond which increased exposure caused the organisms to burrow deeper in the soil. Increase in microbial activity increased the rate of degradation of the buried bioplastics which took five to ten weeks to fully decompose (98.3%). The reduced time of degradation means that starch-based bioplastics have a high potential as sustainable substitute for petroleum-based plastics.Item Near-infrared spectroscopy applications for high-throughput phenotyping for cassava and yam: A review(International Journal of Food Science and Technology, 2021-08-01) Alamu, Emmanuel Oladeji; Karima, Meghar; Nuwamanya, Ephraim; Fabrice, DavrieuxThe review aimed to identify the different high-throughput phenotyping (HTP) techniques that used for quality evaluation in cassava and yam breeding programmes, and this has provided insights towards the development of metrics and their application in cassava and yam improvements. A systematic review of the published research articles involved the use of NIRS in analysing the quality traits of cassava and yam was carried out, and Scopus, Science Direct, Web of Sciences and Google Scholar were searched. The results of the review established that NIRS could be used in understanding the chemical constituents (carbohydrate, protein, vitamins, minerals, carotenoids, moisture, starch, etc.) for high-throughput phenotyping. This study provides preliminary evidence of the application of NIRS as an efficient and affordable procedure for HTP. However, the feasibility of using mid-infrared spectroscopy (MIRS) and hyperspectral imaging (HSI) in combination with the NIRS could be further studied for quality traits phenotyping.Item Physicochemical analysis of Ugandan tea (Camellia sinensis) germplasm reveals potential commercial green and black tea varieties(Taylor & Francis, 2023-05) Grace Nalugo, Racheal; Kaweesi, Tadeo; Kawooya, Ronald; Nuwamanya, Ephraim; Mugisa, Charles; Namutebi, Vivian; Tumwine, Venansio; Turyahebwa, Vereriano; Tumuhimbise, RobooniTea (Camellia sinensis L.) is an important beverage consumed worldwide. In Uganda, it is the second-largest and highly priori-tized export crop after coffee and provides the much-needed jobs to more than 800,000 people. Despite its importance in the coun-try, the crop has received very limited research attention for its improvement and optimal utilization. This study was aimed at characterizing existing tea germplasm in Uganda to inform future breeding initiatives for market-preferred tea varieties. Fifty-eight advanced tea clones were randomly selected from the tea germ-plasm conserved at Uganda’s Tea Research Center in Rwebitaba and analyzed in the laboratory for eight physicochemical descrip-tors. Hierarchical cluster analysis performed on the 58 clones using Cluster-R package revealed four main clusters, indicating the exis-tence of variation for physicochemical parameters within tested germplasm. This variation can be exploited to select among and/or improve the studied germplasm genetically for quality. High fer-mentation rate, which is one of the key indicators for good-quality black teas, revealed 15 fast-fermenter tea clones. Clone “UTR12/12” was identified as the most rapid fermenter, fully fermenting within 30 min, which implies a good clone for black tea. The clone also had the highest polyphenol content (26.7%), higher than the high- quality clone “UTR6/8” (control). Other tea clones whose polyphe-nol content was within the range of the control black tea clone were: “UTR144/10” (20.9%) and ‘UTR144/17, (20.66%). The identi-fied promising black tea clones can be advanced to multi-location trials for further evaluation and selection for eventual variety release as commercial black-tea clones.Item Relationship between 2-acetyl-1-pyrroline and aroma in Uganda rice populations with Oryza (barthi, glaberrima and sativa) backgrounds(African Journal of Biotechnology, 2019-11-30) Ocan, David; Odoch, Martin; Ibanda, Angele Pembele; Nuwamanya, Ephraim; Rubaihayo, Patrick RutimbanziguThe sweet popcorn aroma conferred by 2-acetyl-1-pyrroline (2AP) is a highly economic trait of rice grain attracting premium price worldwide. This research study was conducted to determine the levels of 2AP in Ugandan rice lines with the aim of establishing a better understanding on the level and classes of 2AP and aroma phenotype. Concentration of 2AP was assayed using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF-MS) in tandem with sensory evaluation. Substantial variations in aroma intensity within and between the Uganda rice families were recorded. However, the levels of aroma variation were strongly influenced by the type of rice, and the breeding population it was derived from. Hence, three aroma based categories, namely, nonaromatic, moderately aromatic and highly aromatic were identified. GC with complementary sensory evaluation suggested a highly complex nature of rice aroma, as several rice lines were re-classified on the basis of this study. The 2AP contents and aroma intensity for genotypes with O. glaberrima were low compared to O. sativa and O. barthi. Genotypes of Supa 5, Supa 1052, Yasmin aromatic and MET 3 contained high 2AP levels whereas MET 16, MET 6, AGRA 78, AGRA 55, AGRA 41 and Sande TXD 306 exhibited moderate 2AP contents. Therefore, in developing an optimal breeding strategy aimed at improving the aroma in rice, quantitative information about 2AP and complementary sensory evaluation are a prerequisite.Item Starch quality traits of improved provitamin A cassava (Manihot esculenta Crantz)(Heliyon, 2019-02-16) Atwijukire, Evans; Hawumba, Joseph Ffuna; Baguma,Yona; Nuwamanya, EphraimProvitamin A cassava clones were analysed for starch yield and critical starch quality attributes, to understand possible applications in the food industry. Total carotenoids content in the test clones ranged from 0.03-11.94 μg g-1 of fresh root. Starch yield ranged from 8.4-33.2 % and correlated negatively (r = -0.588, P < 0.001) with carotenoids content. Amylose content (16.4–22.1%) didn't differ significantly (P ≤ 0.05) among the cassava clones. Meanwhile, total carotenoid content had significant negative correlations (P ≤ 0.05) with starch pasting temperature, peak time, setback viscosities and peak area. The reduced peak time and pasting temperatures in high-carotenoid cassava signifies reduction in energy requirements in yellow-fleshed roots when compared to white-fleshed cassava. This attribute is desirable for the food industry as it would reduce the overall cost of processing the cassava. Furthermore, final viscosities of starch from carotenoid-rich cassava were lower than those of white-fleshed roots, making provitamin A cassava suitable for soft food processing.Item 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, AdebayoCassava 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.Item Volatile Organic Compound Based Markers for the Aroma Trait of Rice Grain(Journal of Agricultural Science, 2020) Ocan, David; Rongrong, Zhang; Odoch, Martin; Nuwamanya, Ephraim; Ibanda, Angele P.; Odong, Thomas L.; Lamo, Jimmy; Fitzgerald, Anne M.; Daygon, Venea D.; Rubaihayo, Patrick R.A study was conducted to determine the volatile organic compounds (VOCs) associated with rice grain aroma in 37 commonly grown lines within Uganda, as well as elites. The aim of the study was to identify potential volatile biochemical markers, if any, for the rice grain aroma trait. Certified rice seeds were obtained from the Uganda National Crops Resources Research Institute germplasm collection. The seeds were sown into experimental plots, under field conditions and the mature paddy harvested. Polished rice grains were heated to 80 oC and the liberated VOCs subjected to untargeted metabolite analysis using gas chromatography-time-of-flight mass spectrometry. In total, nine functional groups were present; hydrocarbons, alcohols, ketones, aldehydes, N-containing compounds, S-containing compounds, esters, oxygen heterocycles and carboxylic acids. More specifically, 148 VOCs were identified across the 37 rice lines, of which 48 (32.4%) including 2-acetyl-1-pyrroline (2-AP) appeared to elucidate the difference between non-aromatic and aromatic rice. Furthermore, 41 (27.7%) VOCs were found to be significantly correlated with 2-AP abundance, the principle rice aroma compound. Amongst the 41 VOCs, only ten compounds were found to contribute highly towards variation in 2-AP abundance, indicative of their possible modulation roles in regard to rice aroma. Within the ten influential volatiles, three aroma active compounds; toluene, 1-hexanol, 2-ethyl and heptane, 2,2,4,6,6-pentamethyl- were established as the most reliable biochemical surrogates to the rice aroma trait. Thus, the aforementioned compounds may be used in rice breeding programme for enhancing development of the grain aroma trait.