https://hdl.handle.net/20.500.12478/15 2026-06-30T10:18:45Z 2026-06-30T10:18:45Z Ojuederie, T.C. https://hdl.handle.net/20.500.12478/8649 2025-01-07T10:48:12Z 2021-01-01T00:00:00Z

Delineation of tuber development in African yam bean (Sphenostylis stenocarpa (Hochst ex. A. Rich) Harms 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%).

2021-01-01T00:00:00Z Bedi, S.M. https://hdl.handle.net/20.500.12478/8633 2024-11-06T12:35:15Z 2021-01-01T00:00:00Z

Econometric analysis of disseminating sustainable intensification practices: evidence from Ghana Bedi, S.M. Adoption of sustainable intensification (SI) of agricultural practices is essential for increasing food production in more sustainable way. Dis-adoption of agricultural technologies is pervasive among smallholder farmers in sub-Saharan Africa after withdrawal of most programme interventions. Based on data collected from 700 farm households of an agricultural research for development programme in northern Ghana. This study i) examines alternative ways of inducing farmers into adopting new agricultural technologies, ii) determines the marginal farm household entrants that must be targeted during scaling-up and-out SI practices, and iii) identify the farm households that benefited most from SI adoption during diffusion. Myriads of econometric methods that account for sample selection bias were used while addressing the objectives of the study. The empirical results show that inducing farmers to adopt SI practices resulted in an increase in maize yield and net income of farmers. Results also suggest that the continuous inducement of farmers led to positive and significant increase in maize yield and net income of induced farmers. Point estimates reveal that stopping the inducement could have led to a decrease in maize yield and net income of induced farmers. The findings also indicate that farmers’ resource endowment and unobserved factors influence the marginal benefits of adopting SI practices, and that scalingup SI practices will favour marginal farm household entrants associated with the least probability of adoption based on observed socioeconomics characteristics. Finally, the results show that the adopters that benefited most from adoption based on the net income of maize and legume yield during SI diffusion are much more likely to live in highly resource endowed farm households with relatively younger household heads and fewer household members. In addition, they are much more likely to travel longer distances before reaching the nearest weekly market and motorable road. Overall, the study provides empirical evidence that the adoption of SI practices enhances farm performance and household welfare, and that scaling-up should be targeted. The study also suggests that the provision of support services is a necessary condition for sustaining adoption and thus collaboration between programme interventions with key government ministries and private business mechanisation firms are needed in the scaling-up policy decision making. Zusammenfassung Die Einführung nachhaltiger Intensivierung landwirtschaftlicher Praktiken ist für die Steigerung der Nahrungsmittelproduktion auf nachhaltigere Weise unerlässlich. Die Disadoption von Agrartechnologien ist häufig unter Kleinbauern in Afrika südlich der Sahara weit verbreitet, nachdem Programminterventionen eingestellt wurden. Diese Studie basiert auf Daten von 700 bäuerlichen Haushalten, die im Rahmen eines landwirtschaftlichen Forschungsprogramms zur Entwicklung im Norden Ghanas erhoben wurden. In dieser Studie werden i) alternative Möglichkeiten untersucht wie Landwirte dazu gebracht werden können, neue landwirtschaftliche Technologien zu übernehmen, ii) die marginalen landwirtschaftlichen Haushalte bestimmt, die bei der Einführung von SI-Praktiken angesprochen werden müssen, und iii) die landwirtschaftlichen Haushalte ermittelt, die am meisten von der Annahme von SIPraktiken im Norden Ghanas profitiert haben. Um die Ziele der Studie zu erreichen wurden mehrere ökonometrische Methoden eingesetzt, welche die Selektionsverzerrung der Stichprobe adressieren. Die empirischen Ergebnisse zeigen, dass die Anregung der Annahme der SI-Praktiken zu einem Anstieg der Maiserträge und des Nettoeinkommens der Landwirte führte. Die Ergebnisse deuten auch darauf hin, dass die kontinuierliche Anregung der Landwirte zu einem positiven und signifikanten Anstieg der Maiserträge und des Nettoeinkommens der geförderten Landwirte führte. Punktschätzungen zeigen, dass die Beendigung der Anreize zu einem Rückgang der Maiserträge und des Nettoeinkommens der angeregten Landwirte geführt haben könnte. Die Ergebnisse deuten auch darauf hin, dass die Ressourcenausstattung der Landwirte und unbeobachtete Faktoren den Grenznutzen der Einführung von SI-Praktiken beeinflussen und dass die Ausweitung von SI-Praktiken marginale landwirtschaftliche Haushalte begünstigt, die auf der Grundlage der beobachteten sozioökonomischen Merkmale die geringste Wahrscheinlichkeit der Einführung haben. Schließlich zeigen die Ergebnisse, dass die "Adopter", die auf der Grundlage des Nettoeinkommens aus Mais- und Leguminosenerträgen während der SI-Diffusion am meisten von der Adoption profitiert haben, sehr viel wahrscheinlicher in ressourcenstarken landwirtschaftlichen Haushalten mit relativ jüngeren Haushaltsvorständen und weniger Haushaltsmitgliedern leben. Außerdem müssen sie mit größerer Wahrscheinlichkeit längere Strecken zurücklegen, bevor sie den nächsten Wochenmarkt und die nächste befahrbare Straße erreichen. Insgesamt liefert die Studie empirische Belege dafür, dass die Einführung von SI-Praktiken die landwirtschaftliche Leistung und das Wohlergehen der Haushalte steigert und dass eine Skalierung und den Ausbau angestrebt werden sollte. Die Studie deutet auch darauf hin, dass die Bereitstellung von Unterstützungsdiensten eine notwendige Bedingung für eine nachhaltige Einführung ist und dass daher eine Zusammenarbeit zwischen wichtigen Ministerien und privaten Mechanisierungsunternehmen bei der politischen Entscheidungsfindung für die Skalierung und den Ausbau erforderlich ist.

2021-01-01T00:00:00Z Iseghohi, O.I. https://hdl.handle.net/20.500.12478/8629 2024-11-04T12:42:06Z 2023-07-01T00:00:00Z

Genetic analysis and drought stress assessment of marker-based improved provitamin-A maize synthetics Iseghohi, O.I. Maize is an important staple in Sub-Saharan Africa (SSA) but most varieties are low in Provitamin-A (PVA) carotenoids, and the performance adversely affected by drought stress. Development and adoption of PVA carotenoids-enriched drought-tolerant Maize Synthetics (MS) could help improve maize yields and reduce vitamin A deficiency in SSA. Marker Assisted Recurrent Selection (MARS) could be used to improve the nutritional quality and resilience of maize. However, the effects of MARS on carotenoid contents of MS and performance of the PVA carotenoids-enriched MS in hybrid combinations and under drought stress have not been adequately documented. The level of improvement of carotenoid content of MS using MARS, combining ability and effects of drought stress on yield of PVA carotenoids-enriched MS were evaluated. Three selection cycles (C0, C1 and C2) of two MS (PVASYNHGA and PVASYNHGB) each improved through MARS were crossed to generate nine Varietal-cross Hybrids (VH). The genotypes [selection cycles, VH and a check (PVASYN13)] were evaluated at Ikenne, Mokwa, Saminaka and Zaria using a 4×4 lattice design with four replicates. The genotypes were also evaluated under Managed Drought Stress (MDS) at Ikenne following standard procedures. Days to Silking (DS), Plant Height (PH, cm) and Ear Aspect (EA) were measured and Grain Yield (GY, t/ha) was estimated. The α-carotene, β-cryptoxanthin and β-carotene contents (μg/g) of grains were determined using HPLC, and PVA content (μg/g) estimated. Data were analysed using descriptive statistics and ANOVA at α0.05. Genetic gain/cycle, Mid-parent Heterosis (MPH), Specific Combining Ability (SCA), General Combining Ability (GCA) and Drought Tolerance Index (DTI, where DTI of 0–0.49=low, 0.50–0.69=moderate and 0.70–1.0=high) were estimated. Genotype and location effects were significant for GY, DS, PH, EA and PVA carotenoids, while genotype×location effect was significant for DS, EA, β-carotene and PVA. The GY, DS, PH, EA, α-carotene, β-cryptoxanthin, β-carotene and PVA ranged from 3.7±0.3 (Ikenne) to 6.4±0.4 (Mokwa), 54.4±0.8 (Mokwa) to 63.0±0.8 (Zaria), 206.4±5.9 (Ikenne) to 222.5±8.0 (Saminaka), 2.4±0.2 (Saminaka) to 2.7±0.2 (Ikenne), 0.8±0.1 (Ikenne) to 1.0±0.1 (Mokwa), 2.4±0.3 (Ikenne) to 3.3±0.4 (Mokwa), 5.1±0.3 (Ikenne) to 6.5±0.8 (Mokwa) and 6.8±0.3 (Ikenne) to 8.7±0.8 (Mokwa), respectively. The MARS increased β-carotene and PVA by 25.0% and 15.0%, respectively in PVASYNHGA, and α-carotene by 5.0% in PVASYNHGB. Four VH (PVASYNHGBC0/PVASYNHGAC0, PVASYNHGBC2/PVASYNHGAC0, PVASYNHGBC0/PVASYNHGAC1 and PVASYNHGBC1/PVASYNHGAC2) had significant MPH and SCA for GY. Only PVASYNHGBC0/PVASYNHGAC0 (4.0%), PVASYNHGBC0/PVASYNHGAC2 (2.6%) and PVASYNHGBC0/PVASYNHGAC1 (2.3%) exhibited MPH for PVA. Three genotypes [PVASYNHGAC0 (0.7), PVASYNHGAC1 (0.3) and PVASYNHGBC2 (0.1)] had significant GCA for GY, while PVASYNHGAC2 (1.09) and PVASYNHGBC0 (1.27) had significant GCA for PVA. Under MDS, significant genotypic differences were observed for GY and DTI. Drought stress reduced GY by 31.4% (PVASYNHGBC1/PVASYNHGAC2) to 69.8% (PVASYNHGBC1/PVASYNHGAC0). The four VH with MPH for GY out-yielded the check by 12.7% to 16.4% and exhibited moderate to high DTI. Marker-assisted recurrent selection improved carotenoid contents of PVASYNHGA than PVASYNHGB. Genotypes PVASYNHGAC2 and PVASYNHGBC0 are suitable for provitamin-A inbred line development. Drought stress reduced grain yield of the maize synthetics but four varietal-cross hybrids (PVASYNHGBC0/PVASYNHGAC0, PVASYNHGBC2/PVASYNHGAC0, PVASYNHGBC0/PVASYNHGAC1 and PVASYNHGBC1/PVASYNHGAC2) were drought tolerant.

2023-07-01T00:00:00Z Bakare, M.A. https://hdl.handle.net/20.500.12478/8593 2024-10-10T15:26:23Z 2023-08-01T00:00:00Z

Analysis of historical data for optimization of genomic selection pipeline in cassava Bakare, M.A. Breeding for high-yielding and broadly adapted varieties of cassava has been the primary target of the International Institute of Tropical Agriculture (IITA) cassava breeding program based in Nigeria. However, this target has been hindered due to the presence of genotype-by-environment interaction (GEI) and phenotypic recurrent selection as a traditional approach of breeding. This approach generates gains slowly due to long breeding cycle, resulting to low rate of realized genetic gain per unit time for complex traits like fresh root yield. Taking advantage of recent advances in computational resources, this study focused on exploring historical data using advance statistical techniques and stochastic simulation. The main objective was to identify a breeding scheme which optimizes the cost of field operation and rate of genetic gain. First, I used classical linear-bilinear model to dissect existing patterns of GEI of 36 elite cassava clones evaluated in 11 locations over 3 growing seasons. This aims to identify the optimum number of environments from target population of environments for future testing of genetic lines for key traits such as fresh root yield, dry matter content, and top yield. Second, I exploited the complex pattern of GEI from 96 varieties assessed in 48 trials using variance structure models on fresh root yield to identify an optimal model that captures GEI and stable clones, identify mega-environments and key environmental covariables driving GEI. Lastly, I used stochastic simulation to assess different breeding scenarios to identify an optimal breeding scheme which maximized genetic gain for cassava in Nigeria by investing the breeding resources in one breeding program for broad adaptation or splitting the resources into two sets of testing locations for narrow adaptation. Key lessons from these studies include: (1) Regardless the number of environments sampled to represent TPE, prediction accuracy of fresh root yield is lower than that of dry matter content and top yield. (2) The testing locations within the same geographic region were clustered and dissimilar from locations in other regions indicating some locations within each cluster may be dropped for field trial to maximize the budget cost. (2) A factor analytic statistical model with three factors was identified as the parsimonious model whose common latent factors captured 79.0% of total genetic variability. (3) Maximization of covariance between latent factor loadings and weather variables was an effective approach for identifying weather conditions driving genotypic response to testing environments. (4) The rate of genetic gain per unit time from genomic-enabled breeding programs were consistently higher than that of phenotypic-based conventional breeding program.

2023-08-01T00:00:00Z