Browsing by Author "Lapaka Odong, Thomas"
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Item Causal Link between Liberia’s Rice Imports and Income Changes(Agricultural and Environmental Sciences, 2018) Billy, Abraham; Bonabana-Wabbi, Jackline; Lapaka Odong, ThomasLiberia’s inability to produce enough rice to feed its population has led to massive rice imports, a high import bill, a negative balance of payment, vulnerability to shock and political instability (such as the 1979 rice riot that degenerated into civil unrest and the current economic crisis), increased food insecurity and high rate of poverty, among other effects. However, the effect of these massive rice importations on the national income has not been established. This provoked the need to determine the casual link between the imported rice volumes and income. To achieve this, the study models secondary annual time series data on Liberia’s agriculture subsector from 1979 to 2011. The Johansen cointegration technique, Error Correction Model (ECM) and the Granger Causality tests are used to determine the causal link between rice imports and income changes. Liberia’s imported rice volumes are observed to be sensitive to income changes in both the short-run and long-run periods. Based on the causation between imported rice volumes and income changes, this study recommends that the domestic rice production be improved and commercialized.Item Climbing beans in Uganda: A perspective of smallholder farmers on their determinants, associated challenges and implications for research(African Journal of Agricultural Research, 2018) Takusewanya, Rose; Namayanja, Annet; Adrogu Ugen, Michael; Nkalubo, Stanley; Lapaka Odong, Thomas; Bwogi, Godfrey VianneyIn many parts of the world including Uganda climbing beans are mostly grown in highland areas where population density is high and land is limiting. The objective of this study was to contribute to understanding the current status of the factors affecting productivity of climbing beans among smallholder farmers in Uganda. Kisoro and Kabale districts in the South West were selected for the study. Primary data was collected based on 150 households selected randomly in each district in January and June, 2014. In both districts, climbing beans was ranked as a major crop enterprise for income (72.7%). Most of the interviewed households (84 and 92%) in Kisoro and Kabale respectively appreciated that the major advantage of climbing beans was suitability to areas with limited land. The study revealed practices that seem to integrate the different factors and the various components within each factor promoting ecological or interrelatedness in the production system. Lack of staking materials was ranked by the majority (Kisoro 45% and Kabale 59%) as the most important constraint. Common bean diseases (49%) and pests (45%) were highly ranked in Kisoro as compared to Kabale (13 and 22%). Labour scarcity was ranked by the majority of farmers in Kabale (49%) as compared to Kisoro (19%). Given the importance of climbing beans in the two districts, the study recommends their continued and sustainable intensification.Item Combining Ability Analysis and Determination of Controlling Gene Action for Yield and Other Key Traits of Open Pollinated Maize (Zea Mays L.) Varieties and their Topcrosses with Inbred Line Testers in Uganda(Global Journal of Agricultural Research, 2020) Abera Muluneh, Netsanet; Lapaka Odong, ThomasThe study was carried out with 38 top crosses which were evaluated with parents and checks. The objective of the study was to determine combining ability and the type of controlling gen action for yield and yield related traits of 19 OPVs using their top crosses in terms of grain yield, days to anthesis, plant height and grain texture. Line x tester analysis result of mean squares of ANOVA revealed statistically significant interaction of genotypes (female, male and crosses) with environment variations for selected traits under study. Baker’s ratio of 1.00 for grain yield, suggests that additive genes were highly most important than nonadditive for the control of yield. The higher value of broad sense coefficient of genetic determination (H) was high for yield, days to anthesis, plant height and grain texture. Female parent KC2014 and male parent inbred line TA (CML536) had significantly positive GCA effect for grain yield. These parents were the best general combiners for grain yield across sites. Similarly, female parent OPVs (MM3, Longe 5, Longe 5D, SITUKA MI and VP MAX) and male parent inbred line TB (CML202) had highly significant negative GCA for days to anthesis, indicated that these parents can breed for earliness. Therefore, the exhibited variations between OPVs in terms of the GCA and SCA effects can be exploited to produce topcrosses which will help in selection of parents for hybrid development and variety improvement.Item Factors Affecting Liberia’s Imported Rice Volumes across Three Different Periods(Makerere University, 2016) Billy, Abraham; Bonabana-Wabbi, Jackline; Lapaka Odong, ThomasThe purpose of this paper is to determine the factors that affect Liberia’s rice importation during the pre-war, war and postwar period. Design/methodology/approach – The study employs two stage least squares (2SLS) multiple regression analysis by modelling secondary annual time series data on Liberia’s agriculture subsector from 1979 to 2011. Findings – The study finds income, interest rate and inflation rate as factors affecting the volumes of imported rice; whereas, the exchange rate, population and imported rice price are found to have insignificant effects on rice imports. Additionally, Cassava is seen to have a strong negative significant relationship with imported rice. Practical implications – The short-term government food security strategies of tariff waiver on imported rice and import subsidies that encourage rice imports should be revised to prioritizing and upgrading cassava production as a substitute commodity to imported rice. Originality/value – cassava production and consumption could serve as important substitute to imported rice.Item Identification and mapping of quantitative trait loci associated with soybean rust (Phakopsora pachyrhizi) resistance in genotype UG 5(African Journal of Biotechnology, 2018) Gebremedhn, Hailay Mehari; Msiska, Ulemu Mercy; Weldekidan, Miesho Belay; Abate Asmamaw, Fentaw; Winnifred, Akech; Onziga, Dramadri Isaac; Lapaka Odong, Thomas; Rubaihayo, Patrick; Tukamuhabwa, PhinehasSoybean rust, Phakopsora pachyrhizi, is one of the most serious and widespread foliar diseases of soybean causing high yield losses world-wide. The objective of this study was to identify and map quantitative trait loci (QTLs) resistant to soybean rust in genotype UG 5. Ninety-seven F2 mapping plants, obtained from a cross between Wondersoya and UG 5, were used for this study. Quantitative trait locus analysis using QTL IciMapping software identified three putative QTLs associated with soybean rust (SBR) on chromosomes 6, 9 and 18 with logarithms of odds (LOD) scores ranging from 3.47 to 8.23 and phenotypic variance explained by the QTLs ranging from 18.3 to 25.6%. The putative QTL detected on chromosome 9 is novel and has not been reported elsewhere. The putative QTLs identified in this study could help to facilitate SBR resistance breeding towards efficient marker assisted selection approach and gene pyramiding leading to the development of durable resistance.Item Influence of Cassava Morphological Traits and Environmental Conditions on Field Populations of Bemisia tabaci(Insects, 2021) Katono, Kasifa; Macfadyen, Sarina; Omongo, Christopher Abu; Lapaka Odong, Thomas; Colvin, John; Karungi, Jeninah; Otim, Michael HilaryHigh populations of species in the whitefly complex Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) were reported to cause severe damage to cassava in East and Central Africa. However, reasons for B. tabaci population increases are not well understood. We investigated the effect of cassava morphological traits, temperature, rainfall and relative humidity (RH) on the abundance of B. tabaci. Five cassava genotypes with varying levels of resistance to cassava mosaic disease, cassava brown streak disease, and B. tabaci infestation were planted in three Ugandan agro-ecological zones. The experiment was conducted in 2016 and 2017 in a randomized complete block design. Across all locations, the tallest genotype Alado alado supported the lowest number of B. tabaci adults. In areas with high B. tabaci prevalence, leaf area, leaf lobe width, and leaf lobe number exhibited significant positive effects (p < 0.001) on B. tabaci adult count. Positive effects of relative humidity and negative effects of temperature and rainfall on B. tabaci adult and nymph counts were observed in 2016 and 2017, resulting in low populations in Lira. Evidently, temperatures of 28–30 C, rainfall of 30–150 mm and RH of 55–70%, and deployment of cassava genotypes of low plant height, large leaf area, and lobe width significantly enhanced B. tabaci population growth.Item Influence of environment on soybean [Glycine max (L.) Merr.] resistance to groundnut leaf miner, Aproaerema modicella (Deventer) in Uganda(Journal of Plant Breeding and Crop Science, 2018) Pembele Ibanda, Angele; Karungi, Jeninah; Malinga, Geoffrey Maxwell; Adjumati Tanzito, Georges; Ocan, David; Badji, Arfang; Mwila, Natasha; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickGroundnut leaf miner (GLM) [Aproaerema modicella (Deventer)] is a serious problem for soybean cultivation in Uganda causing yield losses of up to 100%. The use of soybean [Glycine max (L.) Merr.] cultivars resistant to GLM attack is an important strategy in the integrated pest management program. The aim of this study was to determine the environment × genotype interaction influence on the soybean resistance traits to GLM attack. Eighteen soybean genotypes were evaluated for resistance to GLM attack. The experiment was set up using randomized complete block design replicated three times under natural pest infestation in Budaka (Eastern) and Arua (Northern) districts in Uganda. Data were subjected to analysis of variance, Pearson’s phenotypic correlation and cluster analysis. Highly significant (p < 0.001) differences among the genotypes were recorded for all the studied traits, except the number of pupae per plant which was significant (p < 0.05). GLM incidence and severity had significant negative correlations with rainfall and relative humidity. However, there were significant positive correlations between minimum temperature and GLM incidence as well as severity for most of the genotypes. Soybean genotypes VI046160 and VI046167 could be used as parents in breeding for resistance to GLM pest. Areas with high rainfall and humidity would be recommended for soybean production to minimize infestation by GLM.Item Influence of environment on soybean [Glycine max (L.) Merr.] resistance to groundnut leaf miner, Aproaerema modicella (Deventer) in Uganda(Journal of Plant Breeding and Crop Science, 2018) Pembele Ibanda, Angele; Karungi, Jeninah; Malinga, Geoffrey Maxwell; Adjumati Tanzito, Georges; Ocan, David; Badji, Arfang; Mwila, Natasha; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickGroundnut leaf miner (GLM) [Aproaerema modicella (Deventer)] is a serious problem for soybean cultivation in Uganda causing yield losses of up to 100%. The use of soybean [Glycine max (L.) Merr.] cultivars resistant to GLM attack is an important strategy in the integrated pest management program. The aim of this study was to determine the environment × genotype interaction influence on the soybean resistance traits to GLM attack. Eighteen soybean genotypes were evaluated for resistance to GLM attack. The experiment was set up using randomized complete block design replicated three times under natural pest infestation in Budaka (Eastern) and Arua (Northern) districts in Uganda. Data were subjected to analysis of variance, Pearson’s phenotypic correlation and cluster analysis. Highly significant (p < 0.001) differences among the genotypes were recorded for all the studied traits, except the number of pupae per plant which was significant (p < 0.05). GLM incidence and severity had significant negative correlations with rainfall and relative humidity. However, there were significant positive correlations between minimum temperature and GLM incidence as well as severity for most of the genotypes. Soybean genotypes VI046160 and VI046167 could be used as parents in breeding for resistance to GLM pest. Areas with high rainfall and humidity would be recommended for soybean production to minimize infestation by GLM.Item Inheritance of soybean resistance to soybean rust in Uganda’s soybean germplasm(International Journal of Agronomy and Agricultural Research, 2018) Gebremedhn, Hailay Mehari; Belay Weldekidan, Miesho; Msiska, Ulemu Mercy; Asmamaw, Fentaw Abate; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickUnderstanding the genetic mechanisms of soybean rust resistance is important for effective selection and breeding procedures. This study was hence conducted to determine the combining ability and gene action controlling soybean rust using a 10x10 half diallel mating design. The F2 segregating populations along with their parents were evaluated for rust severity and sporulation level at two reproductive stages (R4 and R6) in screen house and field conditions during the second season of 2016 and first season of 2017 at MUARIK using an alpha lattice design replicated thrice. Significant differences were observed among the parents and F2 generations for both disease severity and sporulation level. General and specific combining abilities were highly significant. The GCA/SCA ratio (1.50-2.30) and the Baker’s ratio (0.75-0.82) showed the predominance of additive gene action in the inheritance of soybean rust resistance. The broad-sense (0.94-0.99) and narrow-sense (0.73-0.82) heritability estimates indicated the possibility of improving resistance to soybean rust through selection in the early generations. UG 5, Maksoy 3N, Maksoy 4N and Maksoy 5N had negative GCA effects. The F2 populations derived from these parents crossed with Wonder soya and Nam 2 had also negative SCA effects. The use of these parents and F2 populations can, therefore, increase the response to selection for improving resistance to soybean rust.Item Molecular diagnostics of groundnut rosette disease agents in Uganda: Implications on epidemiology and management of groundnut rosette disease(Journal of plant breeding and crop science, 2017) Kalule Okello, David; Adrogu Ugen, Michael; Tukamuhabwa, Phinehas; Ochwo- Ssemakula, Mildred; Lapaka Odong, Thomas; Adriko, John; Kiconco, Faith; Male, Allan; Deom, Carl MichaelThe objective of this study was to use molecular diagnostic tools to detect the agents of groundnut rosette disease (GRD) to guide in varietal development and disease management. Samples were collected from both GRD infected and healthy plants and sites geo-referenced. RNA extraction, cDNA synthesis, polymerase chain reaction (PCR) amplification, electrophoresis, staining and visualization were performed according to standard procedures. Molecular diagnosis of the samples showed various combinations of the GRD agents, some in isolation and others a combination of two or three agents. This distribution is attributed to dependence on the aphid feeding behaviour and pathogenicity of GRD agents. Chlorotic and green rosette symptoms were observed throughout the sampling sites signifying the presence of satellite RNA (sat-RNA) variants. Some plants showing GRD symptoms tested negative for GRD, whereas some healthy-looking plants tested positive for the GRD complexes pointing to the ineffectiveness of phenotypic screening and the need for a molecular diagnostic tool that detects all three GRD agents both in absence or presence of disease symptoms. The absence of groundnut rosette assistor virus (GRAV) in some symptomatic samples signifies that they are epidemiologically dead end sources since GRV and sat-RNA must be packaged within the GRAV coat protein to be aphid transmissible. Oyado (Cassia obtusifolia) tested positive for all the GRD agents making it a potential alternative host. There is an urgent need for validation of the phenotypic screening with molecular tools in efficient diagnosis of the multi-pathogenic GRD in guiding both plant breeding and pathology work.Item New sources of cowpea genotype resistance to cowpea bruchid Callosobruchus maculatus (F.) in Uganda(International Journal of Agronomy and Agricultural Research, 2018) Belay Miesho, Weldekidan; Gebremedhin, Hailay Mehari; Msiska, Ulemu Mercy; Mohammed, Khalid Elsiddig; Malinga, Geoffrey Maxwell; Sadik, Kassim; Lapaka Odong, Thomas; Rubaihayo, Patrick; Kyamanywa, SamuelCowpea bruchid Callosobruchus maculatus (F.) is a major constraint to cowpea production throughout subsaharan Africa. The identification of sources of C. maculatus resistance and their incorporation into breeding programs would be a beneficial strategy to combat the devastation caused by the bruchid in stored cowpea. We evaluated 145 cowpea genotypes from Uganda and introductions from Kenya and Nigeria for resistance to bruchids. The mean number of eggs and number of holes, percentage pest tolerance, percentage weight loss, bruchid developmental period, bruchid growth and Dobie susceptibility index were significantly different among the 145 genotypes. Based on Dobie susceptibility index value, there were 18 resistant, 114 moderately resistant and 13 susceptible genotypes. Dobie’s susceptibility index correlated negatively with insect development period and percentage pest tolerance, and positively with number of eggs, growth index, number of holes and weight loss. The study identified new sources of cowpea from the studied genotypes that could be used by cowpea breeders to develop cultivars with relatively high resistance to cowpea bruchid. However, further investigations and identifcation of biochemicals that are responsible for cowpea seed resistance to bruchid are recommended.Item Yield Stability Analysis of Open Pollinated Maize (Zea mays L.) and their Topcross Hybrids in Uganda(World Scientific News, 2018) Abera Muluneh, Netsanet; Lapaka Odong, Thomas; Kasozi, Lwanga Charles; Edema, Richard; Gibson, Paul; Koime, DanielThe study was aimed at determining yield stability and adaptability patterns of a set of 65 open pollinated maize genotypes evaluated across four different agro ecologies in Uganda using 5 × 13 α-lattice design replicated twice. Individual location analysis ANOVA results showed mean squares of genotype were statistically highly significant in terms of days to 50% anthesis, anthesis silking interval, grain yield and maize streak virus disease severity score for all environments tested except for grain yield in Ngetta. The highest grain yield was recorded for topcross C9/TA (ECAVL1/CML536) of 9.60 t ha-1 in Bulindi, for top cross C3/TA (Longe5/CML536) of 9.56 t ha-1 in Namulonge. However, they were quite unstable as their ranking was not consistent across environments. The genotype Ambsyn5, C4/TB, FS85 and C9/TB were showed the lowest disease score for MSV. The parent OPV SITUKA MI was with the lowest day requirement for shading pollen and hence it can be utilized in breeding for earliness. The additive main effects and multiplicative interaction (AMMI) analysis results indicated that the tested genotypes were highly influenced by genotype main effects, environment effects and genotype x environment interaction effects; the magnitude of environment and its interaction effect for grain yield was 9.8 times greater than the variation attributed to genotype main effects thus these genotypes were more affected by the environment and their interaction. Based on Finlay and Wilkinson’s sensitivity estimate, genotypes G40, G58, G42, G44, G56, G23, G52 and G53 were identified as the most stable and widely adaptable.