IITA Theses and Dissertations

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Foodgravity: understand food flows using classic gravity model and explainable artificial intelligence techniques
(Thesis, 2024-07) Dusabe, B.
Mapping food flows from production areas to consumption areas is essential and often challenging, especially at local scales (Moschitz & Frick, 2021). Knowing how food moves over space and time is crucial for policy-making to maintain food and nutrition security across scales. Nevertheless, there is a tendency to prioritize flows between countries at the global level i.e., Food and Agriculture Organization trade data (FAO, 2023a) whereas the internal food flows within a country are often neglected. This oversight can lead to less efficient spatial planning and agricultural interventions, particularly in less-developed areas where food and nutrition security remains a critical challenge. However, the food flow is a complex issue resulted from socio-ecological characteristics of both origin and destination areas, as well as the linkages in between. To untangle this complexity, this research combined concepts of classic gravity model with machine learning techniques, relying on Explainable Artificial Intelligence techniques (xAI) to enhance the transparency of the predictive models. The Irish potato was chosen as the focus crop to study its flow distribution among 30 districts of Rwanda. Objectives included compiling a comprehensive database of socio-economic and environmental factors along with district pair food flows, and leveraging machine learning methods to predict whether a particular district pair presents Irish potato food flows or not. Specifically, Random Forest (RF) and Support Vector Machine (SVM) were trained to predict Irish potato food flows, while the Local Interpretable Model-agnostic Explanations (LIME) xAI technique was used to further investigate particular district pair instance prediction and its most influencing features. Both RF and SVM models demonstrated high overall accuracy (both above 90%) in predicting district level Irish potato flow. However, it is important to note that the dataset presented imbalanced classes where district pairs that contained Irish potato flows were about 7% of the total data samples, while the remaining dataset comprised the absence of Irish potato flow. F1 score, which is the harmonic mean of precision and recall, was used to evaluate the class prediction accuracy of the models. On the both RF and SVM models, F1 score of class 0 (absence of flow) was 0.96 whereas on class 1 (Presence of flow) was 0.61 for RF and 059 for SVM. These F1 scores shows that both models were accurate at predicting the absence of Irish potato flows (class 0) than the presence of flow (class1), reflecting an imbalance in the dataset where instances of Irish potato flows were less frequent. Using Local Interpretable Model-agnostic Explanations (LIME) xAI technique it was observed that environmental factors notably at the origin district were the most flow influencers compared to socio-economic features. The study recommends the integration of market level flow data, the scope and temporal expansion for a more granular analysis.
Host plant resistance to infestation of Fall armyworm, Spodoptera frugiperda (J. E. Smith), in tropical maize, (Zea mays L.), germplasm
(Thesis, 2024) Udah, O.
The study evaluated early and extra-early maturing maize inbred lines to identify adaptive traits for resistance to Fall armyworm (FAW); determined the genetic control of resistance to FAW among selected early and extra early maturing maize inbred lines; identified the most critical stage(s) of different maize genotypes to FAW infestation; evaluated the effects of selected secondary metabolites on food preference of FAW; and determined the inhibitory efficacy of selected early maturing maize inbreds and hybrids against digestive enzymes of FAW. These were with a view to improving maize output and food security in Nigeria. A three-year study at Obafemi Awolowo University in Nigeria screened 1037 maize inbred lines for FAW damage. Early and extra-early maturing lines were divided into eleven groups based on maturity and endosperm color. Artificial infestation with FAW larvae was carried out two weeks after planting, with an average of four larvae per plant stand. Resistance was evaluated throughout the plants' growth stages using a rating scale. The study also included experiments on secondary metabolites and enzyme inhibition assays. Data from both resistant and susceptible lines were analyzed at the OAU Enzymology laboratory. Data obtained for each objective were subjected to analysis of variance and significant means were compared using least significant difference at p ≤ 0.05. Specifically, the adaptive traits were identified based on their significant relationships with the insect’s damage parameters using correlation and stepwise multiple regression analyses. The study identified 150 FAW resistant inbred lines as potential trait donors for breeding programmes. Nine adaptive traits were identified, with the number of days to anthesis and silking significantly correlated with FAW damage (p ≤ 0.05). The study revealed significant ((p ≤ 0.01) genetic variability among inbred lines, with both additive and non-additive gene actions influencing FAW damage. All tested maize hybrids contained flavonoids, triterpenes, and phenolics, while saponins were absent in all samples. The secondary metabolite profile of maize plant materials screened will be useful for selecting resistant germplasms, particularly for flavonoids. The genetic makeup of inbred lines and hybrids significantly influenced enzyme inhibition, with variability primarily due to genetic differences. Alpha amylase inhibition percentages in pro-vitamin A maize inbreds and hybrids revealed TZEIOR 192 as the most effective inbred line. TZEIOR 70, a FAW susceptible inbred parent, performed better than some potentially resistant lines, indicating multiple defense mechanisms may be responsible for resistance in the maize inbreds and hybrids studied. In conclusion, the study identified potential FAW resistant maize inbred lines. Male parents had additive gene action controlling FAW damage parameters, while pro-vitamin A maize inbred lines had non-additive gene action. Secondary metabolites played a crucial role in defense mechanisms against FAW, with flavonoids, triterpenes, and phenolics influencing FAW larvae's feeding preferences. Extracts from selected maize lines showed inhibitory activity against FAW digestive enzymes.
Effects of urbanization on avian diversity and human-nature interactions in tropical environments
(Thesis, 2025-03) Awoyemi, A.G.
Urbanization is a rapidly expanding global phenomenon that poses significant threats to biodiversity. Despite its importance, the impacts of urbanization on biodiversity in certain regions remain understudied. Recent studies have highlighted the need for more research on the topic, particularly in Africa, where unprecedented urbanization overlaps with vast biodiversity. Thus, this thesis investigated the impacts of urbanization on socioecological systems in the Afrotropics, providing data useful in achieving sustainable urban development in line with SDG Goal 11 (Sustainable Cities and Communities) in the region. This thesis began with a comprehensive systematic literature review to assess the current state of urban ecology in Africa (Chapter 1). The review revealed a striking knowledge gap, with only 795 relevant papers published in the last century (1920—2020), much less than those from other continents. Notably, a disproportionate number of these studies (40%) were conducted in South Africa, indicating a significant geographical bias in our current knowledge on the topic. This review found that research efforts are driven by economic wealth (GDP) and the importance of conservation in African urban ecology. However, the review also exposed a surprising oversight: the Afrotropics, which is the most urbanized and biodiverse-rich African region, is not a primary focus of study. Furthermore, most urban ecology studies in Africa were conducted in a single city (55%), with substantial knowledge gaps persisting across taxonomic groups, scientific fields, and ecoregions. To partially address these important gaps, this thesis focused on investigating different research questions in multiple cities in Nigeria (Chapters 2—5), a typical Afrotropical country experiencing rapid urbanization. These additional chapters investigated the impacts of urbanization on bird taxonomic, functional and phylogenetic diversity (Chapters 2—3), avian-mediated regulating ecosystem services, including pest control, seed dispersal, pollination, and scavenging (Chapter 4), and human-nature interactions (Chapter 5). The results of these studies unequivocally demonstrated that urbanization has profound negative impacts on bird diversity and ecosystem services in the Afrotropics. Compared to non-urban areas, urban areas exhibited significantly lower bird taxonomic diversity (Chapter 2) and reduced provisioning of essential ecosystem services provided by wildlife, including pest control, seed dispersal and pollination (Chapter 4). Scavenging was the only bird-mediated ecosystem service enhanced by urban development (wet season). Furthermore, certain urban attributes, such as the presence of vehicles and pedestrians, were found to compromise bird phylogenetic divergence and ecosystem service provision, particularly pollination and seed dispersal. However, the results also highlight the potential for targeted conservation efforts to mitigate these negative impacts. Notably, the presence of water bodies and specific vegetation types, such as canopy and bush cover, can significantly enhance multiple components of bird diversity and crucial bird-mediated regulating ecosystem services (Chapters 2 and 4). By preserving and restoring these key habitat features, it may be possible to reverse the decline of bird diversity and the associated regulating ecosystem services in Afrotropical cities, particularly seed dispersal and pollination. Chapter 3 presents a novel application of machine learning and remote sensing techniques in estimating local habitat variables influencing bird diversity components across urban and non-urban areas. This study revealed that the Modified Chlorophyll Absorption Ratio Index (MCARI) is the most effective indicator of taxonomic and phylogenetic bird diversity in the Afrotropics. In contrast, the Normalized Difference Water Index 2 (NDWI2) and Soil Adjusted Total Vegetation Index (SATVI) were found to be the best predictors of functional diversity and phylogenetic divergence, respectively. Interestingly, the Normalized Difference Vegetation Index (NDVI), a commonly used predictor across regions and topics, ranked relatively low (25th percentile) in most cases. These results recommended the use of these alternative predictors (MCARI, NDWI2 and SATVI) rather than the NDVI in predicting bird biodiversity in urban and non-urban areas of the Afrotropics. This is likely due to NDVI's limitations, including scaling issues, saturation in high-biomass areas, and sensitivity to soil brightness, which can compromise its accuracy in diverse Afrotropical environments. The remote sensing approach employed in this study offers a potentially more efficient and cost-effective method for estimating local habitat variables compared to traditional manual estimation techniques. By leveraging machine learning algorithms and remotely sensed data, this approach can help reduce the labor, expense, and investigator error associated with manual data collection. In addition to the ecological impacts, urbanization also has significant social implications. By investigating the extinction of experience concept among urban dwellers in Nigeria, Chapter 5 found that most citizens had little or no contact with nature. The main reasons cited for this disconnection were lack of time, money, and nearby natural areas. The study also found that respondents with higher nature contact were more connected to nature, and that the perception of neighborhood safety was an important factor promoting nature contact. Furthermore, the study also found that respondents living in Lagos, and those with lower levels of income and education, showed greater dissociation from nature. These findings could be useful to fight against the worrying extinction of experience in the region, providing potential factors to consider and implement in future urban development plans in the Afrotropics. Overall, the Chapters of this thesis highlight the need for more research on the impacts of urbanization on biodiversity and ecosystem services in the Afrotropics. They also emphasize the importance of promoting nature contact and experience among urban dwellers, particularly in regions with rapid urbanization such as the study area (i.e. Nigeria). By addressing these knowledge gaps and promoting nature experience, we can work towards creating more sustainable and resilient urban ecosystems that will benefit both people and the environment.
Effect of hygiene status in maize storage facilities on pests, molds and aflatoxin contamination in Nakuru Country, Kenya
(Thesis, 2022) Makinya, K.J.
Infestation of harvested agricultural produce with pests, pathogens or contamination with mycotoxins during storage negates efforts to eradicate food and nutrition insecurity. Preventive measures, primarily suitable storage structures and cautious adherence to hygiene constitute key actions for effective control of pests and pathogens. However, contribution of recommended postharvest handling and hygiene practices as avenues for timely mitigation have never been examined. The aim of this study was to assess the effect of hygiene in maize storage facilities on pest infestation, mold and aflatoxin contamination. A cross-sectional survey was conducted in 2017 to assess postharvest handling practices, levels of hygiene and their effect on the magnitude of losses in maize farmers’ storehouses. A total of 342 rural farmers spread across the high potential moist transitional agro-ecological zone in Nakuru County were interviewed and data recorded in a semi-structured questionnaire and a checklist. In addition, the hygiene status of 40 storehouses where shelled maize grain was stored in bags was assessed and the grains sampled. The stores were ranked into ‘poor’, ‘average’ or ‘good’ hygiene categories depending on the level of adherence to recommended storage hygiene practices. Maize grains that had been harvested and stored in farmer’s stores were sampled at intervals of two months beginning April to October 2017. The samples were analyzed for moisture content, quality compliance, insect population, grain damage, weight loss, mold incidence and aflatoxin levels. The main storage bags were polypropylene used by 98.2% of the farmers. Bagged maize was stored either in granaries or designated rooms within dwelling houses. Overall, 90% of the farmers cleaned their storehouses before the most recent harvest was loaded, while only 50% cleaned the storehouses after the harvest had been loaded. Farmers reported 8.3 ± 0.5% weight losses resulting from insects, rodents, molds and theft. Laboratory analysis of maize sampled from farmers’ storehouses revealed a significant (P = 0.002) increase (from 12.2 to 14.2%) in moisture content of maize stored under poor hygiene conditions beginning from the second month of storage. Interaction between hygiene status, population of Sitophilus zeamais and storage time was highly significant (P <0.001). Good hygiene practices slowed the rate of grain damage and corresponding weight loss. The total population of molds across all the stores increased significantly after four (P < 0.001) and six (P < 0.001) months of storage. Additionally, stores adhering to good hygiene practices recorded significantly lower incidence of Aspergillus spp. at the fourth (P = 0.002) and sixth (P < 0.001) months of storage, respectively. This was followed by corresponding significantly (P = 0.041) lower levels of total aflatoxin (range 7 – 64 ppb) after four months of storage. Total aflatoxin levels increased approximately four fold for maize stored under hygienic conditions, six fold for storehouses characterized by average hygiene practices, and seven fold for grain stored under conditions of poor hygiene throughout the storage period. At the commencement of the trial, 15% and 22% of samples from hygienic and unhygienic stores respectively had total aflatoxin levels beyond the 10 ppb threshold set by the Kenya Bureau of Standards (KEBS). This proportion increased to 100% and 71% in unhygienic and hygienic stores respectively four months after commencement of the trial. From the Fractional Response Model, high hygiene scores correlated significantly with lower grain losses. Storing maize grains in the bedroom or living room correlated with lower losses by 2.8 and 4.6 percentage points, respectively; compared to storage in granaries, while storage in the kitchen correlated with higher losses by a margin of 19 percentage points. Storage of maize together with other grains or farm equipment was associated with higher losses by 2.8 percentage points. Storage of maize in hermetic containers did not result in significantly lower losses. In addition, repairing or disinfecting the store before introducing a new harvest did not significantly reduce grain losses. Training in grain storage did not have a significant effect either, while maize farming experience and younger age were associated with lower losses by 2.8 and 5.9 percentage points, respectively. Stores where majority of the postharvest handling decisions were made by women had lower losses by 2.8 percent points. This study demonstrates that storing grain under hygienic conditions can help smallholder farmers retard proliferation of molds, aflatoxin contamination and storage pests and consequently prolong safe storage duration of maize grains.
Physiological basis for yield differences in maize (Zea mays L.) under varying nitrogen rates and planting windows in the savannas of Nigeria
(Thesis, 2024-06) Ahmad, N.M.
Maize Production in the savannas of West and Central Africa (WCA) is limited by intermittent drought during cropping season and low soil fertility which affects its productivity and the overall livelihood of smallholder farmers. This study aimed to determine the physiological basis of differential yield response of some maize varieties under varying level of nitrogen and different sowing windows in Guinea and Sudan savannas of Nigeria and identify stress surrogate traits for yield improvement in maize. Field experiments were conducted at Bayero University, Kano (11058`38.63892N, 80 25`7.01868E), altitude 451m above sea level in the Sudan savanna and Zaria (11.16050610N, 7.64535890E) in Northern Guinea Savanna. Treatments consisted of three sowing windows at two weeks intervals, two levels of nitrogen (30 and 100 Kgha-1) and four improved maize varieties (SAMMAZ15, SAMMAZ 16, SAMMAZ 40 and SAMMAZ 51). These were laid out in a Split-split plot design with three replications. Sowing window was allocated to the main plot, varieties to the sub plot and Nitrogen to the sub-sub plot. The results indicated that the most favorable sowing window identified for planting of maize is the mid-June to late June for Sudan Savanna and mid-June to early July for Northern Guinea Savanna. Furthermore, the choice of maize variety emerges as a critical factor influencing yield, irrespective of location. SAMMAZ 40 and SAMMAZ 51 varieties demonstrated superior performance in terms of both yield (3,814 kg/ha and 3,873 kg/ha, respectively) and biomass accumulation at both study locations. Additionally, while higher nitrogen application rates contribute to increased biomass, this effect is contingent on the interplay between planting period and variety selection, highlighting their combined influence on maize yield in terms of both quantity and weight. In instances of low nitrogen, specific surrogate traits such as leaf area index for grain yield, Intercepted photosynthetic active radiation for harvest index, and electrical conductivity, total dissolve salt, chlorophyll content, and leaf area index for hundred seed weight were identified as key indicators.
Performance of cassava planting materials produced using the "Semi Autotrophic Hydroponic" technology in the laboratory and across locations in the Democratic Republic of Congo
(Thesis, 2024) Binzunga, M.M.
Cassava (Manihot esculenta Crantz)) is a crucial food crop in D.R. Congo, sustaining over 70% of the population and serving as a primary income source. However, the cassava seed system faces the challenge of a low propagation rate associated with an extended growing cycle. This research aimed to contribute to the improvement of the cassava seed system in D.R. Congo using stem cuttings provided by SAH technology. Two experiments assessed plantlet performance using two types of substrates. Experiment 1, employing a split-plot design, used four genotypes (IB961089A, MM060083, Nase14, and Albert28) and four single substrates: KlasmannTS3 (K), Vermiculite (V), Local Peat (P), and Sawdust (S). It involved three subculture periods lasting four weeks, with data collection on survival, height, leaf, internode, and cutting numbers. Experiment 2, following a similar design, investigated the performance of three genotypes (IB961089A, IBA070520, and IBA980555) under single substrates (K, V, and P) and their combinations (K25P75, V25P75, and V10P90). The field experiment in Mulungu and Kiliba utilized SAH-derived plantlets employing a 4 x 4 split-plot design. Data were collected on survival, growth parameters, and stem length at different months after planting. Finally, a simple cost analysis was carried out, comparing the production cost of SAH-derived plantlets to that of producing cutting sunder the conventional propagation method. Experiment 1 revealed substrate significantly influenced survival rates, surpassing 90% (p<0.05), showing the highest number of cuttings of 70.4 in three months, representing a ratio of 1:4 with the genotype MM060083 (p<0.001). Experiment 2 showed K25P75 did not differ from single KlasmannTS3, with the highest survival rate and an increase of 80.5 cuttings, representing a ratio of 1:4 with IBA961089A. The superior effect of the substrates was attributed to their favorable properties, allowing rapid plantlet growth. Field results indicated that Kiliba recorded a higher survival rate of 81.3% compared to Mulungu's73.8%. Across locations, MM060083 had the highest survival, exceeding 80%, whileNase14 had the lowest. The check-cutting method demonstrated the highest survival of over 90% compared to SAH-derived plants, but KlasmannTS3 had the highest among the SAH at Kiliba (85.4%). The highest stem length was obtained at Mulungu (17.5 m) compared to Kiliba's 10.5 m at 12 MAPs. Nase14 achieved the highest stem length of 17.7 m per plot, while IBA961089A had the lowest at 9.3 m at 12 MAPs. SAH-derived plants caught up with conventional checks across locations by 12 MAPs. The use of combined substrates, particularly K25P75, demonstrated an equal unit cost to that of the conventional mini stem, both amounting to USD 0.07. These findings provide relevant insights into policymakers' decisions to promote efficient cassava propagation method for sustainable agriculture, enhance food security, and promote economic development in D.R. Congo.
Harnessing the potential of selected bio-agents for sustainable management of plant parasitic nematodes in coffee
(Thesis, 2024) Anyango, O.C.
East Africa confronts multiple challenges in coffee production, including aging plantations, subpar inputs, climate change, and pest-related issues. Among these threats, plant parasitic nematodes (PPN) pose a significant concern, contributing to estimated global losses of up to 15% in coffee production. Despite their impact, PPN often remain overlooked or underestimated as a major factor causing damage to coffee crops. In Kenya, specific symptoms of PPN damage are poorly understood, leading to their gradual manifestation over years and resulting in enduring losses to the industry. Biocontrol has been explored in management of PPN on other crops like horticultural, ornamental and other annual crops but has not been registered in coffee, a perennial crop. This study aimed to assess the potential of microbial antagonists in suppressing PPN and improving coffee production in Kenya. The effectiveness of three biocontrol agents namely Trichoderma asperellum, Purpureocillium lilacinum, and Bacillus subtiliswas evaluated under pot and field conditions, targeting Meloidogyne hapla, a prevalent nematode species affecting coffee in the Ruiru region of Kenya. In pot experiment, nematode-infested soil and roots from Chania Coffee Farm was utilized. Three Biocontrol agents, namely Bacillus subtilis, Trichoderma asperellum and Purpureocilium lilacinum were tested. Each of biocontrol agent was administered at three different rates: 6.67 × 103, 6.67 × 104, and 6.67 × 105 spores/ml, using a randomized complete block design with 20 treatments and five replicates. Drenching with 150 ml of the biocontrol agent occurred every two weeks for six months after transplanting, with assessments conducted at the experiment's termination. Two biocontrol agents, Trichoderma asperellum and Purpureocilium lilacinum, were tested in the field experiment. The recommended dose for other annual crops, 2 × 107 spores/ml, was applied in seven fields, each with three treatments and four replicates, spanning for two years. Drenching each plant with 40 ml of the respective product in 20 liters of water was done monthly after subsequent soil sampling. Monthly activities included soil sampling, nematode extraction, quantification, and identification, as well as fungal re-isolation. The nematode survey revealed ten genera of plant parasitic nematodes; Meloidogyne spp., Tylenchorhynchus spp., Helicotylenchus spp., Longidorus spp., Pratylenchus spp., Trichodorus spp., Scutellonema spp., Rotylenchulus spp., Paratylenchus spp., and Hemicycliophora spp., with varying densities based on coffee cultivar. Ruiru 11 exhibited a lower mean density of PPN, with 40, as compared to cv French Mission, which recorded 62, with the control group having 43 nematodes per 100cc of soil and 5 g of roots. Similarly, Ruiru 11 had a lower count of free-living nematodes, with 276, compared to cv French Mission, which recorded 326 nematodes per 100cc of soil and 5 g of roots. Trichoderma asperellum significantly colonized coffee roots with 2.45 × 106 cfu/g of soil and roots, a higher count compared to P. lilacinum, which recorded 3.22 × 103 cfu/g of soil and roots. In cv Ruiru 11, the percentage mean of PPN recorded per treatment was significant, with the untreated group having 36.7%, P. lilacinum 32.5%, and T. asperellum 30.8%. The study suggests that older plants associated with French Mission may contribute to this difference. Pot experiment results indicated a significant reduction in M. hapla on coffee with all bio-control agents at spore concentrations of 6.67 × 104 spores/ml and 6.67 × 105 spores/ml. Coffee cultivar Ruiru 11 exhibited higher efficacy in biocontrol agent uptake, resulting in a lower root galling index compared to French Mission. However, the galling index showed no significant variation among the bio-control agents. Trichoderma, at a spore concentration of 6.67 × 105 spores/ml, significantly reduced M. hapla densities in plant roots compared to P. lilacinum at a similar concentration. Additionally, the study demonstrated increased plant biomass in plants treated with biocontrol agents. This study recommends use of B. subtilis, T. asperellum, and P. lilacinum at a spore concentration of 6.67 × 104 spores/ml to effectively manage plant parasitic nematodes in coffee plantations. Further research should explore the use of different coffee cultivars and determine the optimal stage for exposing coffee to biocontrol agents. Additionally, there is a need to investigate the integration of these biocontrol agents into existing control practices for more effective and sustainable nematode management.
Evaluation of agronomic performance and genotypic mapping using SNP markers of grain iron and zinc content among rice accessions in Eastern Democratic Republic of Congo
(Thesis, 2024) Bukomarhe, C.B.
Rice (Oryza sativa L.) is among the most important food crop in the Democratic Republic of Congo (DRC). The crop has historically been neglected by local researchers. However, recent urbanization and changes in dietary habits have elevated its significance. The identification of rice varieties with high yield and reasonable micronutrient contents, especially iron (Fe) and zinc (Zn), could be important in rice varieties for the DRC. This study aimed to (a) determine agronomic performance of a subset of 36 rice accessions to identify high yielding and stable genotypes for cultivation in eastern DRC and (b) associate SNP markers with Fe and Zn content in rice grains for application in marker assisted selection. For the molecular markers study, 85 diverse rice accessions from the DRC maintained at the Kalemie were analysed for variation in Fe, Zn and SNP markers. The data were analysed using rMVP package of R software for Genome Wide Association Study (GWAS) to identify genomic regions linked to grain Fe and Zn content. Candidate genes associated with Fe and Zn content were identified and annotated from the Oryza sativa reference genome version 7.0 of the MSU-Rice Genome Annotation Project (RGAP) database. In the evaluated rice grains, Fe content ranged from 0.95 to 8.68 mg/100g (dry weight basis), while Zn content ranged from 0.87 to 3.8 mg/100g. Two significant SNPs were identified, with one on chromosome 11 associated with Fe and another on chromosome 4 associated with Zn. Candidate genes involved in transcription regulation and transporter activities related to Fe and Zn homeostasis, including the bZIP family genes and MYB family genes were pinpointed. For the agronomic trial, 36 rice accessions were evaluated in a 6x6 triple lattice design with three replications in Bwegera and Sange sites, in Eastern DRC. Data on various agronomic traits such as Day to Flowering (DTF), Plant Height (PH), Effective number of Tiller (ET), Panicle Length (PL), Grain per Panicle (GP), Thousand Grain weigh (TGW), Grain Length (GL), Grain Width (GW), Ratio Grain Length and Grain Weight (RGLGW), Grain Yield (GY) were recorded during growth and analysed using R software. Across locations, no significant differences were recorded in various agronomic variables, except for 1000-grain weight (TGW). Within locations, significant differences were observed for the evaluated variables except for panicle length, grain length, grain width, and the ratio of grain length to grain weight. Based on grain yield, accessions IR990-48-B-B-12, IR841, IR88638 and MR254 were the best across and within individual sites making them favorable recommendations for farmers. The identified markers and candidate genes can be utilized in Marker Assisted Selection (MSA) in rice breeding programs, aiming to enhance Fe and Zn content. The study is offering opportunities
Evaluation of agronomic trait of some cassava (Manihot esculenta Crantz) genotype using ground penetraiting radar
(Thesis, 2023-06) Omole, D.A.
The main economic value of the cassava rests in its starchy storage root, but limited information is available on the growth patterns of cassava roots as compared to the shoot. A non-destructive protocol that captures root bulking rate could facilitate selection and optimize varietal response to management practices. Therefore, this study aimed to evaluate the capability of ground penetrating radar (GPR) to estimate root bulking rate six months after planting. Ten varieties were planted in Ibadan and Ikenne in the 2021/2022 cropping season using a Randomized Complete Block Design (RCBD) with 3 replications in a mixed model with variety and harvest time as a fixed factor and location as a random factor. The plot size was 30 m2, with a plant spacing of 0.8m X 1m. Data were collected on the number of roots (n), dry matter content (%), Cassava Mosaic Disease (CMD) on a scale of 1 (no visible symptom) to 5 (severe mosaic, severe leaf distortion, and stunting), plant height(cm), shoot weight (kg), root volume (lt), root girth (cm), root length (cm), total root weight (kg) and Harvest Index (HI). Fresh yield (t/ha) and dry yield (t/ha) were estimated for each variety. GPR scanning was done to obtain GPR data and was processed using "RELEASE” software, a demo version produced by IDS Georadar. Data were subjected to ANOVA using R software at α0.05. Pearson’s product-moment correlation tests were performed to compare the relationship between GPR and agronomic data sets. Multiple linear regression was used to identify traits that are significantly related to fresh root yield. Results showed a significant correlation between root volume measured by GPR and root volume measured at harvest (r=0.90***), while the number of roots measured by GPR had a significant correlation with root number measured at harvest (r=0.60***). Regression analysis indicated that root volume and dry yield had a higher coefficient of determination multiple R-squared: 0.9837. Harvest time was also significant for all traits except root volume and fresh yield. Interaction between Variety and Location was significant for CMD, root length and HI. Interaction between Variety and Harvest time was significant for all traits except plant height, root number, and dry matter. Interaction between Location and Harvest time was significant for all traits except plant height, root number and dry yield. The three-way interaction between Variety, Location and Harvest time was significant between CMD and HI. Varieties such as Arubielu, Egecoutonou, and TMEB693 had the highest plant heights range of 240cm- 260cm. Arubielu and TMS13F1160P0004 had the highest harvest index (HI) values of 0.62. VarietyTMS13F1160P0004 had the highest dry matter content of 39%. Variety IITA-TMS- IBA000070 recorded the highest fresh yield of 26 t/ha. Variety TMS13F1343P0022 had the highest dry yield of 10.10 t/ha.
Biomass accumulation and partitioning in cacao (Theobroma cacao Linn.) as affected by age, fertilizer application and canopy exposure
(Thesis, 2023) Ajibona, O.A.
Cacao is a plant known widely for its beans used in the production of chocolate and cocoa powder. Biomass production dynamics in cacao is an important process that needs to be understood for best management practices that guarantee maximum bean yield. This study investigated the accumulation and distribution of biomass in cacao as affected by age, fertilizer application and canopy exposure at the Cocoa Research Institute of Nigeria (CRIN) (7.36oN, 3.85oE) and the International Institute of Tropical Agriculture (IITA) (7.49oN, 3.90oE) in Ibadan, Oyo state, Nigeria in 2020. Principal Component Analysis was used as a selection tool to ensure that the trees used for the study fairly represented the whole plot. Fertilizer (300g of N.P.K 15:15:15 per tree) was applied using ring method to half of the selected trees while the other half had no fertilizer application. Split plot design was used with three replicates. A total of 18 trees of 8, 12 and 47 year old were harvested and measured. Data collected on shoot, root and leaf parameters were subjected to Analysis of Variance and means were separated using Least Significant Difference at 5% probability level. Regression analysis was carried out to establish allometric relationship between non-destructively obtained plant parameters (stem diameter, mean canopy diameter, height) and the total tree biomass and the biomass of specific tree organs. The age of the tree had significant effect on height (534.90 cm, 723.90 cm and 735.8 cm), leaf fresh weight (2.75 g/leaf, 2.99 g/leaf and 4.07 g/leaf) and leaf dry weight (1.22 g/leaf, 1.35 g/leaf and 1.88 g/leaf) of the 8-year, 12-year and 47-year old trees, respectively. Fertilizer application influenced total dry biomass of leaves (6.36kg/tree), leaf fresh weight (3.47 g/leaf) and leaf dry weight (1.58 g/leaf) with the non-fertilized trees having the highest values irrespective of their position in the canopy. Biomass accumulation in the leaves and branches decreased from 14-4% and 48-36% respectively. However, stem biomass increased from 20-33% and root biomass was maintained at 20% for the 8-year, 12-year and 47-year old trees. The highest contributor to total biomass were in the order of branch > stem > roots > leaves. The allometry between the components and the whole cacao revealed that the best predictor of biomass was stem diameter (R2 = 0.634-0.872). The position of the leaf in the canopy was discovered to have a significant effect on Specific Leaf Area (SLA) with leaves in the lower canopy portion of the tree showing a higher SLA than those in the upper portion. Leaf production in cacao was influenced jointly by their position in the canopy and exposure to sunlight. It was concluded that biomass accumulation increased with tree age and the woody organs were the major contributors to the total biomass. Stem diameter is recommended for use in predicting total biomass using allometric equation. Application of fertilizer to aged cacao trees is not recommended.
Mechanism of yield compensation in some accession of cowpea grown at different plant densities and environments
(Thesis, 2024-01) Odesina, I.S.
Grain yield of cowpea [Vigna unguiculata (L.) Walp.] in Nigerian savannas are low despite the cultivation of improved accessions. Amongst a host of production constraints, missing plant stand has been suggested to contribute to yield loss in cowpea. Gap-filling could be used as alternative to mitigate yield losses caused by stand reduction. This study, which was carried out in 2020, was aimed at investigating the mechanism of yield compensation in some accessions of cowpea in two savannah agro-ecologies at Minjibir and Shika in Northern Nigeria. The randomised complete block design in a split-plot arrangement in three replicates was used. The main plot consisted of four plant densities (33,333, 66,666, 99,999 and 133,333 plants ha-1) while the sub-plots consisted of six cowpea accessions (DANILA, IT08K-150-27, IT89KD-288, IT93K-452-1, IT98K-205-8 and IT99K-573-1-1). Results showed that plant density and environment affected grain yield. Total grain yield increased with increasing plant density. Generally, total grain yield was higher at Minjibir than at Shika. The highest total grain yield of 1,793.3 kg ha-1 was observed in the accession DANILA at 99,999 plants ha-1, while the lowest(1,100 kg ha-1) was observed in the accession IT98K-205-8 at 33, 333 plants ha-1. Stand count at harvest, leaf area index and intercepted photosynthetically active radiation and pod weight were positively correlated with total grain yield at both locations, suggesting that these traits could be considered for cowpea improvement. Cowpea growers and breeders could consider erect accessions (IT93K-452-1 and IT98K-205-8) and semi-erect accessions (IT99K-573-1-1 and IT08K-150-27) for cultivation at 133,333 plants ha-1 and prostrate accessions (IT89KD-288 and DANILA) at 99,999 plants ha-1 at Minjibir. The accession IT93K-452-1-1, IT98-205-8, IT99K-573-1-1 and IT08K-150-27 could be considered for cultivation at Shika, irrespective of plant density.
Genetic diversity in Nigeria taro [Colocasia esculenta (L.) Schott] germplasm
(Thesis, 2025-01) Oladimeji, J.J.
Taro is a resilient, underexploited tropical corm-producing crop that plays a vital role in the nutritional and economic livelihoods of many households in Nigeria. However, its production and productivity are constrained by the incidence of diseases, low-input farming practices and inadequate genetic improvement efforts. To improve the yield and quality of taro in Nigeria, adequate information is needed on the presence of heritable genetic variation among available collections. However, limited information is available on the level of variability among cultivated taro in Nigeria. This study was carried out to assess the extent of phenotypic and molecular diversity among some taro accessions collected from major taro-growing agroecologies in Nigeria. Four hundred and ninety taro landraces comprising 215 Dasheen and 275 Eddoe gene pools were assembled from farms and markets across seven States (Oyo, Kwara, Ekiti, Ondo, Akwa Ibom, Ebonyi and Anambra) in humid forest and derived savanna agroecologies in Nigeria. The 490 landraces were genotyped using 4,748 Diversity Array Technology sequence-based Single Nucleotide Polymorphism (DArTseq-SNP) markers, 3,047 of which were retained after quality filtering. A subset (114) comprising 65 landraces from the first collection and 49 landraces from the second collection were planted in September 2021 and March 2022 respectively, following their collection times using 27 agromorphological descriptors. Phenotypic data were subjected to descriptive statistics, cluster analysis and analysis of variance, while hierarchical clustering, population structure and analysis of molecular variance were carried out on the molecular data. The phenotypic and molecular characterization of the taro landraces revealed higher genetic diversity among the Eddoes than among the Dasheens. For all the quantitative traits, the estimates of genetic variance were higher than those of environmental variance. The total yield (TY) of the landraces ranged from 100 to 32,200 kg/ha (mean = 10,600kg/ha) for the phenotyped September 2021 set while the range was from 100 to 23,300kg/ha (mean = 6,800 kg/ha) for the March 2022 set. The taro landraces in both planting clustered into four groups based on 10 phenotypic traits at a threshold of 1.5. Highest yield was recorded in K-I-O1-S1 and A-I-IE Cormel 1 (32,200 kg/ha) from the September 2021 planting and AKN 1-P5 (23,300 kg/ha) from the March 2022 planting. Estimates of gene flow (Nm = 0.353) revealed intermixing of landraces among the States of collection. Gene flow was highest (1458.98) between landraces from Anambra and Ondo States and lowest (0.06) between Anambra and Kwara States. The population structure and hierarchical clustering based on the DArTseq-SNP markers delineated four clusters, one which comprised Dasheens, while three comprised Eddoes. The variation between gene pools (49%) was higher than within gene pools (32%). The variation among the States of collection was high (41%), while the variation among individuals within the gene pools (18%) and States of collection (19%) were relatively low. A wide level of genetic diversity was found between the taro gene pools and among the taro landraces from Nigeria. The findings constitute a valuable resource for the genetic improvement of taro in Nigeria.
Caractérisation de la diversité génétique des bactéries Xanthomonas phaseoli pv. manihotis et Xanthomonas cassavae en RD Congo
(Thesis, 2024) Luzolo Tulomba, A.
Le manioc est l'une des principales cultures en République Démocratique du Congo, malheureusement il est affecté par divers agents pathogènes. Cette étude a exploré la diversité génétique des souches de Xanthomonas phaseoli pv. manihotis (Xpm) et Xanthomonas cassavae (Xc) en utilisant initialement la technique d'amplification de l'ARNr 16S pour confirmer l'identité des souches, puis la méthode MLVA (Multi-Locus Variable number tandem repeat Analysis) pour comparer les souches récentes aux anciennes souches du laboratoire SAVE, isolées en RD Congo dans les années 1970. La technique MLVA a permis de mettre en évidence la diversité au sein des souches comparées, tout en montrant certaines limites, notamment dans la comparaison des souches Lomami6 et UPB008, qui ont présenté des profils similaires. Le séquençage du génome entier de ces deux souches particulières a ensuite permis d'obtenir des informations plus précises. Les résultats ont confirmé que Lomami6 n'est pas une Xanthomonas cassavae, mais plutôt une Xanthomonas phaseoli pv. manihotis, tandis que UPB008 est effectivement une Xanthomonas cassavae. Par contre, aucun isolat de l’espèce Xanthomonas cassavae n’a pu être mise en évidence dans les souches récentes. Les résultats montrent que LOMAMI6 se rapproche de souches isolées en Colombie, au Nigeria et en Ouganda, tandis que UPB008 est génétiquement distinct des autres génomes de Xanthomonas cassavae déjà publiés sur la base des données NCBI. Les informations génomiques obtenues dans cette étude enrichissent notre compréhe...
Validation of single nucleotide polymorphism trait-markers and characterization of biofortified cassava (Manihot esculenta Crantz)
(Thesis, 2024-05) Ogungbesan, A.O.
Cassava (Manihot esculenta Crantz) is a vital industrial and staple crop in Sub-Saharan Africa (SSA) where it is valued for food security and consumer acceptability. Consumers with preference for white-fleshed cassava that lack Pro-vitamin A are prone to diseases associated with vitamin A deficiency. Biofortified cassava has great nutritional benefits in addressing micronutrient deficiency in resource-poor households. However, lack of adequate genomic information on local genetic resources has impeded the efficient conservation and improvement of biofortified cassava. The objectives of this study were to characterize 376 cassava accessions using Single Nucleotide Polymorphism (SNP) markers and to validate trait markers linked to Total Carotenoid Content (TCC), Dry Matter Content (DMC), and resistance to Cassava Mosaic Disease (CMD) for marker-aided selection in biofortified cassava breeding pipeline. In this study, 376 cassava accessions from three breeding programmes (International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, International Center for Tropical Agriculture, CIAT-Cali, and the University of Hawaii, USA – the origins) were phenotyped and genotyped to achieve the study objectives. The cassava accessions were selected from the clonal evaluation trial (219), elite parents (108), advanced yield trial (30), high-priority genotypes (14), and released biofortified varieties (3) established at IITA-Ibadan, Nigeria. The accessions were phenotyped for resistance to Cassava Mosaic Disease (CMD), Total Carotenoid Content (TCC), and Dry Matter Content (DMC). The accessions were also genotyped with Kompetitive allele-specific primer procedure using 46 SNP markers comprising 36 quality control and 10 traits-linked markers. Phenotypic data were subjected to descriptive statistics, normality tests, and trait relationships. Genotypic data were subjected to population structure, phylogenetic analysis, and F-statistics. Marker validation was done using the Kruskall-Wallis test. The mean performance of the color chart score was 3.37 with total carotenoid content being 10.83μg/g fresh weight basis. The average percent dry matter content was 34.31% while for cassava mosaic disease severity recorded was 1.5. Further results revealed a significant negative correlation between TCC and DMC (-0.64**), and CMD (-0.18**). Twenty-eight accessions combined lower than mean population CMD severity score, high DMC (>30%), and high TCC (>15μg/g). Genotyping results showed that the highest expected heterozygosity (He= 0.493) was found in the genotypes that originated from Hawaii which was comparable to genotypes from IITA breeding programmes (He= 0.43). The Principal Component Analysis (PCA) and hierarchical clustering revealed two genetic sub-populations within the 376 cassava genotypes with accessions connected to the accession origins. The analysis of molecular variance results based on origin and sub-population revealed higher genetic variations in accessions within origin and subpopulations than among origin and subpopulations. The CMD three resistance markers, one DMC marker, and the three PVA markers showed a good predictive ability indicating their usefulness in cassava forward breeding programmes. These results showed a high level of genetic variation among cassava accessions with good levels of prediction for the CMD, DMC, and PVA markers tested in this study. This will facilitate the incorporation of marker-assisted selection in accelerating the improvement for these traits.
Genetic characterization of cassava (Manihot esculenta Crantz) traits using argo-morphological characters
(Thesis, 2021-11) Iyanda, S.A.
Cassava (Manihot esculenta Crantz) is an important crop in Nigeria where leaves and tubers are eaten. However, its genetic variability remains unexplored in Nigeria. Local varieties are precious genetic resources because of their diversity. Mastery of this diversity is an important basis for crop improvement through plant breeding programs. Local cassava accessions (99) were collected mainly from the international institute of tropical agriculture (IITA), Ibadan, Southwestern part of Nigeria. These accessions have been planted with the objective to characterize them, based on morphological agro-morphological traits, and parameters were recorded at three, six, nine and twelve months after planting. The experiment was carried out in experimental station of IITA, and sixty-two (62) morphological were used. Significant differences (p<0.05) were observed for all the 62 analysed morphological traits. A total of twenty-one principal component analysis (PCA) in the trait sets accounted for eigen value range of 7.55 to 1.01 and a cumulative percentage variance of 83.95% to 11.45% of the total genetic variation. The Principal Component Analysis reveals traits with positive high dispersion of the accessions. On the cluster analysis, the accessions were classified in four groups. The matrices of genetic dissimilarity were used in the construction of dendrograms using the UPGMA method. We observed a high variation of agronomical descriptors which were capable to separate the accessions into four distinct clusters. This work showed the variation in agronomic traits existing among cassava accessions in IITA, Ibadan, Nigeria that could be exploited to enhance cassava breeding programs.
Genetic variability and association mapping for yield and yield-related traits in African yam bean [Sphenostylis stenocarpa (Hochst ex. A. Rich) Harms]
(Thesis, 2023-06) Olomitutu, O.E.
African Yam Bean (AYB) is an underutilised legume producing tubers and seeds rich in dietary proteins and minerals, but its Seed Yield (SY) is low. Landraces of AYB are repositories for potential beneficial alleles for the development of varieties with enhanced yield and qualities. However, limited information is available on the extent of genetic variation within available AYB landraces, the genetic basis of the variations and relative importance of SY-related traits, which are required for the development of varieties with improved SY and agronomic characteristics. Hence, genetic variability among some AYB accessions for SY and association of genomic regions with the yield-related traits were assessed. One hundred and ninety-six AYB accessions were evaluated for two years at Ibadan, Kano and Ubiaja following standard practices. The experimental design was 14×14 lattice with three replicates. Data were collected on Days to Pod Maturity (DPM), Pod Weight (PDW), Pod Length (PL), Seed Length (SL), Shelling Percentage (SP), 100-Seed Weight (HSW), Seeds Per Pod (SPP) and Seed Thickness (ST), while SY was estimated. Data were subjected to principal component analysis, cluster analysis, correlation analysis, path coefficient analysis, descriptive statistics and ANOVA at α0.05. Estimates of variance components, Genotypic Coefficient of Variation (GCV), Phenotypic Coefficient of Variation (PCV) and broad-sense heritability were computed for the traits. Yield stability index was used to identify superior and stable accessions. The 196 accessions were genotyped using 5,416 DArTseq-based Single Nucleotide Polymorphism (SNP) markers, from which 2,491 markers and 195 accessions were retained after quality filtering. Marker-trait associations were determined using the mixed linear model. Accessions, environments and accession×environment interaction effects were significant for all the traits. The DPM ranged from 118.5±14.3 (TSs-8, Ubiaja) to 220.0±6.0 (TSs-59, Kano), PW ranged from 4.2±0.3 g/plant (138A, Kano) to122.7±17.6 (TSs-421, Ibadan), while PL was shortest in accession TSs-22B (12.0±1.3 cm, Kano) and longest in TSs-51 (27.3±0.6 cm, Ibadan). The SY ranged from 1.3±0.1 (TSs-326, Kano) to 77.6±10.4 g/plant (TSs-421, Ibadan). Variances due to environment and accession×environment interaction were higher than the genotypic variance for all the traits. Also, estimates of PCV were higher than GCV for all traits. Broad-sense heritability ranged from 17.1±3.5% (DPM) to 66.4±0.2% (SL). The first three principal components accounted for 59.7% of the total variation among the accessions. Five major clusters were delineated based on phenotypic characteristics. Shelling percentage (rg=0.76), 100-SW (rg=0.29), DPM (rg=0.45), PW (rg=0.89), SPP (rg=0.20) and ST (rg=0.41) had significant genetic correlations with SY, and exhibited positive direct effects on SY. Accessions TSs-119, TSs-101, 138A, TSs-4, TSs-157A and TSs-61 were identified as superior and stable. Across locations, 24 SNP markers were significantly associated with the traits at a threshold of –log (p) =4, and explained 7.1 to 12.8% of the phenotypic variation among the accessions. A wide genetic variation exists among the African yam bean accessions. Selection criteria for improved seed yield in African yam bean should include shelling percentage, 100-seed weight, days to pod maturity, pod weight, seeds per pod and seed thickness.
Pollen fertility assessments on selected diploid genotypes of musa species in the IITA breeding collection
(Thesis, 2023-05) Taiwo, T.O.
Breeding of all types of bananas including plantain is dependent on the development of superior diploids with disease and pest resistance and better quality to be used as male parents. There has been a major challenge over the years on the selection of diploid parents with desirable traits for plantain breeding. Twenty-one diploid cultivars and hybrids in the International Institute of Tropical Agriculture musa germplasm collection were evaluated for male fertility to determine their suitability for use in hybridizations for plantain improvement. Pollen viability was assessed through staining with 2 3 5- triphenyl tetrazolium chloride and in vitro pollen germination on diploids, and the effect of number of male flower and anther size on pollen quantity was investigated, the genotype with the highest rating for percentage viability through staining was recorded in SH3362 (78.66%) and the lowest was recorded in Gu-nin-chio (0.41%) while Beram, Kasaska, Pari Jari Buaya and Morong Princessa has (0%). The highest pollen tube length among the twenty-one diploid genotype was 1448-1 (3024.1 µm) while the lowest pollen tube length was Yangambi (232.60 µm) and Beram, Kasaska, P. Jari Buaya and Morong princessa had no tube growth. The number of male flower and anthers length directly influence the quantity of pollen while anther width has no significant effect on pollen quantity. From the study, pollen viability via staining was correlated with the in vitro pollen germination and there was positive correlation between viable pollen and pollen tube growth, while viable pollen and pollen tube growth both has negative correlation on number of male flower and anther length and width for genotypes tested. 10 fertile lines for use in breeding from the observed genotypes were identified (1448-1, 2829-62, 8075-7, 9128-3, Awondaeke, Bieyeng, Calcutta 4, Higa, SH-3362 and Padri). This research work will help to identify genotypes for use as parents for plantain breeding, help to solve the problem of poor hybrid production due to low fertility, and help in successful implementation of breeding programs and ensure safe hybridizations
Genetic analysis of multiple-stress tolerant extra-early maize (Zea mays L.) inbred lines under contrasting environments
(Thesis, 2021) Obisesan, O.I.
This study evaluated grain yield performance and stability of 210 extra-early maize hybrids across stress and non-stress environments; established the mode of gene action controlling the inheritance of yield and other traits under Striga infestation, drought, optimal conditions and across environments; assessed the combining abilities of the inbreds; classified the lines to heterotic groups based on their combining ability; and determined the efficiency of inbred testers and interrelationship among traits measured. These were with a view to develop and deploy improved hybrids with combined tolerance to these stresses in West and Central Africa. Thirty-nine inbred lines were crossed to five inbred testers to generate 195 testcrosses. Ten single-cross hybrids were also generated by crossing the five testers in a diallel fashion. The 205 testcrosses were evaluated with five hybrid checks using a 14 x 15 lattice design under drought, artificial Striga infestation and optimal growing environments. In all evaluations, data were collected on yield and other agronomic traits. All data were subjected to analysis of variance to test for significant variation among genotypes and partition total genotypic effect into additive and non-additive components. Genotype main effect plus genotype by environment interaction (GGE) biplot analysis was employed to identify high-yielding and stable hybrids. Relationship among traits under each environment was assessed using path coefficient analysis. Significant (P ≤ 0.05) genetic variability for yield and other traits was obtained under each and across environments. Across research conditions, TZEEI 254 x TZEEI 29, TZEEI 377 x TZEEI 29 and TZEEI 243 x TZEEI 13 were high-yielding and most stable. Both GCA and SCA mean squares were significant (P<0.05) for grain yield under all research environments. While additive gene action was preponderant over non-additive for grain yield under Striga, non-additive gene action was preponderant over additive for grain yield and most other measured traits under drought, optimal and across stress environments. Eight inbreds under Striga infestation, two under drought, four under optimal and four across stress environments had significant positive GCA effects for yield. Of the five testers, TZEEI 21, TZEEI 29 and TZEEI 13 were efficient across stress environments. Inbreds were classified into four groups each under the two stress environments, and three groups each were identified under optimal and across stress environments. Path coefficient analysis identified ear aspect (-0.8), Striga damage rating (-0.1) and ears per plant (0.095) under Striga, ear aspect (-0.6), days to silking (-0.2), days to anthesis (-0.2) and stay-green characteristics (-0.1) under drought, ears aspect (-0.5), ears per plant (0.2), plant aspect (-0.2), root lodging (0.1) and stem lodging (0.1) had significant direct effects on yield. The study concluded that inbreds TZEEI 253 and TZEEI 386, and hybrids TZEEI 254 x TZEEI 29, TZEEI 377 x TZEEI 29 and TZEEI 243 x TZEEI 13 were promising multiple stress tolerant maize, and would be invaluable resources for improving maize productivity in the subregion.
Delineation of tuber development in African yam bean (Sphenostylis stenocarpa (Hochst ex. A. Rich) Harms
(Thesis, 2021) Ojuederie, T.C.
African yam bean (AYB) belongs to the family Fabaceae. It is an orphan crop with so many potentials that have not been well utilised. It produces both edible seeds and tubers with high nutritional values. However, the crop is grown mainly for the seeds in West Africa, but the tubers are mainly consumed in East and Central Africa. The dual food advantage of AYB is yet to be fully tapped, due to the irregular tuberization in accessions. This study therefore characterised tuber development in AYB accessions in vitro and on the field, visually and microscopically. The proximate analysis of the seeds and tubers of AYB accessions were also evaluated. Three tuber-forming (TSs 96, TSs 107, and TSs157) and three non-tuber forming (TSs 51, TSs 150, and TSs 152) accessions of AYB were collected from the Genetic Resources Centre of the International Institute of Tropical of Agriculture, Ibadan, Nigeria and evaluated on the field at two different periods: (June – December 2020) and (September 2020 – March 2021) for agromorphological traits. The field was laid out in a randomized complete block design (r = 3). Data was collected at peduncle initiation (50%, 75% and 100%), flowering (50%, 75% and 100%), and physiological maturity through destructive sampling. A microscopic cross image sectioning of freshly harvested AYB tubers was assessed using standard procedures. The six AYB accessions were evaluated in vitro in a completely randomized design (r=20) using a medium containing 4.43 g L-1 MS (Murashige and Skoog), 0.6 mgL-1 BAP (Benzyl amino purine), 0.03 mgL-1 NAA (Naphthaleneacetic acid), 0.1g L-1 Myoinositol, varying concentrations of Sucrose (30 gL- 1, 50 gL-1, 70 gL-1) and 7 gL-1 agar for microtuber formation. Proximate analyses of seeds and tubers produced were determined using standard procedures. Data were analysed using descriptive statistics and ANOVA at α0.05. TSs 107 was the only accession that produced tubers from 75% peduncle initiation to physiological maturity. Accessions that failed to produce tubers had few root nodules with less dense root architecture compared to TSs 107 which had the highest root nodule production with thicker root structure. A cross microscopic section imaging of the freshly harvested tuber of TSs 107 indicated that AYB tubers are derived from stem hypocotyl and not formed from the root. Analysis of variance of accessions planted in June 2020 indicated that pod length ranged from 22.1 ± 3.0 cm (TSs 152) to 25.3 ± 4.6 cm (TSs 107) and the number of seeds per pod ranged from 14.9 ± 4.0 (TSs 107) to 17.3± 2.5cm (TSs 157). Seed yield ranged from 9.3 ± 2.5 g (TSs 51) to 154.5 ± 12 g (TSs 96). TSs 107 which produced tubers had low seed yield (26.98 ± 4.83 g) and the longest number of days to first flowering (109 days) which was significantly different from TSs 96 (94 days) and TSs 157 (93 days). Nodulation in June 2020 was significantly highest in TSs 107 at both peduncle initiation (54.32) and flowering (43.56) stages of growth with the least number of nodules at both stages of growth (16.56 and 5.48) produced by TSs 152. Nodulation was significantly higher in accessions planted in June 2020 (10.69 ± 3.11) compared to those planted in September 2020 (0.38 ± 0.42). The moisture content in AYB seeds ranged from 9.63 ± 0.05% (TSs 152) to 10.17 ± 0.18% (TSs 51). The tuber of TSs 107 had lower moisture content (6.05 ± 0.22%) compared to the seeds (10.05 ± 0.10%). The crude protein in seeds ranged from 15.34 ± 0.70% (TSs 51) to 19.64 ± 0.08% (TSs 150) while the carbohydrate content ranged from 60.09 ± 0.16% (TSs 150) to 70.08 ± 0.54% (TSs 51) respectively. Only TSs 107 produced tubers out of the three tuber producing accessions. Accessions planted in June 2020 produced seeds, much nodules and tubers compared to those planted in September which failed to produce seeds, but TSs 107 produced tubers. Therefore, AYB accessions should be planted in the appropriate planting season (June) to avoid abortion of flowers during the late planting season. Nodulation decreased from vegetative stage to physiological maturity in all accessions. An inverse relationship exist between protein and carbohydrate contents in AYB seeds as observed in TSs 51 and TSs 150. The seeds of TSs 107 had higher protein content (17.65%), but the tubers still had appreciable amount of protein (15.41%).
Growth and nutrient uptake response of cocoa seedlings (Theobroma cacao) to different growth media at the nursery
(Thesis, 2024-08) Mornyuie, A.O.
A study was conducted in the nursery house of Mabang Megakarya Selection Programme, a substation of the Cocoa Research Institute of Ghana from April 2022 to September 2022 to determine the growth and nutrient uptake response of cocoa (Theobroma cacao) seedlings to different growth media at the nursery. The treatments comprised three base-materials viz: Topsoil (TS), Rice husk (RH) and Sawdust (SD) amended with three rates of rice husk biochar (RHB) at 75%: 25%, 50%:50% and 25%:75% and two rates of cocoa pod husk-based compost (CPHC) at 90%:10% and 80%:20% (base-media: amendment on v/v). The respective amounts of media combinations were mixed thoroughly and filled into polybags with dimensions 18 cm wide x 25 cm high. The treatments were arranged in a completely randomize design (CRD) with three replications. Seeds of cocoa hybrid clone C69 were sowed into the treatment pots. Cocoa seed germination was recorded at 14 and 17 days after sowing (DAS). Seedling growth and biomass production were measured at 2, 4 and 6 months after germination (MAG). Leaf nutrient concentration was analysed at six MAG and nutrient uptake calculated. Result indicated that at 14 DAS, seed germination was 100 % in potting media with TS50:RHB50 and 100 SD and these were significantly (p<0.05) higher than in all other treatments. The result showed that media type TS50:RHB50 significantly (p<0.05) increased number of leaves, plant height, stem diameter, tap root length, leaf chlorophyll content, leaf area and plant biomass production at 6 MAG. There was significant positive correlation between plant growth parameters at 6 MAG. Plant leave nutrients (N, P, K, Ca, and Mg) uptake were significantly (p<0.05) higher in potting media with TS50:RHB50 and TS90:CPHC10. Generally, TS50:RHB50 was the best growth media and produced vigorous cocoa seedlings.

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