http://197.159.135.214/jspui/handle/123456789/955 2026-04-23T19:30:59Z http://197.159.135.214/jspui/handle/123456789/332 Title: Assessment of Loss and Damage induced by Waterlogging and Submergence Stress in Maize under Typical Ambient Conditions of the West African Sahel Authors: Daku, Elidaa Kossi Abstract: As the climate of the West African Sahel changes due to global warming, agricultural systems are facing stress due to the excess water induced by extreme rain events. Our first experiment, implemented in the suburbs of Ouagadougou (Burkina Faso), tested, the effects of different water levels above the soil surface (2-3 cm and 7-8 cm above ground) and their stagnation (1 - 3 and 3 - 6 days) on the growth, development and productivity of Obatampa maize cultivar, at three of its growth stages (stage at six leaves (V6), tasseling (VT) and the milky grain stage (R3)) during two years, under ambiant on-farm conditions. Hypoxia (1 to 3 days of soil saturation) and anoxia (4 to 6 days of soil saturation) at the tasseling stage reduced the grain yield by 53% and 54% respectively. At V6 stage, only anoxia caused 31% grain yield loss.Those grain yield losses were exponentially correlated with the stress days index (SDI) (R2 = 0.7 considering all the growth stages). The second experiment was carried out on the floodplain of Aniabisi (northern Ghana). The cumulative effect of the frequent waterlogging caused by precipitation, at different topographic locations (upslope, middle slope and downslope), associated water management techniques (presence or absence of bunds) and two planting dates for the Wang Data maize cultivar was tested. The results showed that the cumulative effect of waterlogging when it occurs from the vegetative stage to the end of the crop cycle can reduce the growth and productivity of maize drastically. Grain yield losses on downslope plots, represented 91% (2017) and 62% (2018). Under these conditions, a strong exponential relationship (R2 = 0.8) was established between the grain yield loss of Wang Data and the excess water stress factor (SEW30) in the vegetative stage. This factor could be useful as tool for assessing losses and damages associated with hazards due to excess rain events and also as tool in crop insurance scheme. By using the experiments for the calibration and validation of the EPIC model, it simulated well, the periods of waterlogging during these experiments. Indices generated from the simulated soil moisture appear to be a good predictor of grain yield decline during the tasselling stage of Obatampa. Nevertheless, the EPIC model was limited to simulating the reductions of yield, due to temporary waterlogging greater than 3 days at the V6 stage, occurring at the tasseling stage, or frequent from the vegetative stage. The improvement of the model should require the incorporation of different sensitivities to waterlogging at phenological stages. Description: A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the University of Cape Coast in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Agriculture 2021-02-01T00:00:00Z http://197.159.135.214/jspui/handle/123456789/331 Title: Cassava Bacterial Blight Development in the Agro-Ecological Zones of Cote D’ivoire Authors: Toure, Howélé Michaëlle Andrée Célestine Abstract: Cassava growth in Côte d’Ivoire is affected by the variation of climatic parameters and Cassava Bacterial Blight (CBB). CBB is a destructive disease influenced by climatic conditions which can lead to 100 % yield loss. For a better management of CBB in the context of climate change/variability, it was essential to study the evolution of the disease under different agro-ecological zones in Côte d’Ivoire. For this purpose, surveys were conducted out in cassava fields from 2014 to 2017 in the seven agro-ecological zones of Côte d’Ivoire and the varieties were assessed under natural and artificial conditions. Farmers’ knowledge on both climate change and CBB were also assessed. The results showed a prevalence of the disease in the agro-ecological zone 6, the agro-ecological zone 4 and the agro-ecological zone 1 with dieback incidence under extreme and favourable conditions. Cassava farmers interviewed were able to identify changes occurred in climate, their characteristics and their impacts on cassava. However, cassava bacterial blight was unknown by the majority. Three varieties were predominately recorded and are locally known as Akama, Yace and Yavo. Yavo was found more susceptible than Akama that was more susceptible than Yace to the disease. Cassava varieties are susceptible to the disease at different rates in the different agro-ecological zones. However, some of them appeared to be more tolerant than others. Climatic conditions constitute one of the major constraints to cassava cultivation in Côte d’Ivoire and are aggravating cassava bacterial blight expression. Therefore, the losses related to CBB remains unpredictable. All these aspects should be considered in the selection of tolerant varieties across different agro-ecological zones. It is therefore urgent to implement control strategies in response to the varying climatic conditions to prevent and reduce the impacts of both the variation of climatic parameters and the disease. Description: A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the University of Cape Coast in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Agriculture 2020-02-01T00:00:00Z http://197.159.135.214/jspui/handle/123456789/330 Title: Pearl Millet (Pennisetum glaucum L.) Hybrid Breeding in West Africa Towards High Productivity and Grain Iron (Fe) and Zinc (Zn) for Adaptation to Climate Change and Human Nutrition. Authors: Hassane, Zakari Abstract: Pearl millet (Pennisetum glaucum L.), the world’s sixth most important cereal crop is known as a climate smart crop due to its tolerance to drought, heat, soil salinity, low soil fertility, high nutritive and high capacity to buffer variable environmental conditions. Climate change and ecological production constraints is expected to increase the currently challenges facing by agriculture to ensure future food security for the growing population in West Africa (WA). Morever, the alarming status of micronutrient deficiency in the WA region exacerbates this situation and calls for effective strategies to combat malnutrition. Thereby, the main goal of this study was to identify the high yielding biofortified hybrids of pearl millet and establish an efficient scientific basis for hybrid breeding in WA with high adaptability across the region. The experiments were conducted in replicated trials in different locations of WA. The experimental material consisted of L × T analysis of 9 lines and 12 testers, a full diallel of 6 restorers and 30 F1’s and evaluation of 68 single cross hybrids and 42 top cross hybrids including the checks. GCA effects revealed that, among the lines, ICMB 177004, ICMB 177005 and ICMB 177007 were good general combiners for days to 50% flowering; ICMB 177002 and ICMB 177090 for panicle length; ICMB 177111 for plant height, panicle circumference and grain yield. ICMB 177003 and ICMB 177001 were good general combiners for grain Fe and Zn content, respectively. Almost all the testers were good general combiners for plant height. Testers, ICMR 08888, ICMR 1301 and ICMR IS 16007 were good general combiners for number of days to 50% flowing; ICMR 157003 and ICMR IS 16008 for panicle length; ICMR 08666, ICMR 08777 and ICMR 157003 for panicle circumference, ICMR 08666, ICMR 08777, ICMR 157003 and ICMR 157004 for grain yield. ICMR 08666 and ICMR 1301 for grain Fe and Zn content. On the basis of SCA, the hybrids namely ICMH 177016, ICMX 187851, ICMX 187892 and ICMX 187895 were identified as superior for grain yield, grain Fe and Zn content simultaneously across locations. Five hybrids namely, ICMX 187807, ICMX 187851, ICMX 187998, ICMX 1871029, ICMX 1871046 exhibited positive heterosis both over mid-parent and better-parent for grain yield, grain Fe and Zn content across locations. Regarding the restorer’s improvement, the crosses ICMX 1770192, ICMX 1770193, ICMX 1770194, ICMX 1770197, ICMX 1770204 and ICMX 1770208 exhibited significant negative sca effects for days to 50% flowering with high grain yield. Positive and significant sca effects for grain Fe and Zn contents were expressed by crosses ICMX 1770197, and ICMX 1770204. Identified restorers with good GCA and crosses with good SCA, were useful in improving the restorer lines of pearl millet to promote the hybrid pearl millet breeding in WA. Grain yield is of economic importance for which considerable variable degree of standard xiv heterosis was registered in a number of crosses over CHAKTI and ICMV 167005 whereas, few hybrids showed positive heterosis over CHAKTI, check for grain Fe and Zn. Despite their yield advantage, top cross hybrids had shown some important characteristics like plant height and panicle length as important as grain yield for multiple purpose. While single cross hybrids were present better for biofortified hybrid of pearl millet. AMMI stability value (ASV) identified, the hybrids ICMX 1871018 to be the most stable for grain yield, ICMH IS 16187 for grain Fe content and ICMX 187778 for grain Zn. The stability index showed the hybrids ICMX 187827, ICMX 187026 and ICMX 1871037 as the hybrids that combined stability with high mean values for yield, high grain Fe and Zn content. The hybrids ICMX 187830 and ICMX 1871042 combined high mean value, adaptability and stability for grain yield whereas, ICMX 187895 combined high mean performance, adaptability and stability for grain Fe and Zn. ICMX 187766 and ICMH 177016 combined high grain Zn content with adaptability and stability. Parents which combine well for yield, Fe and Zn content and other traits will be used for the production of biofortified hybrids, while stable and adapted hybrids with high yields and Fe and Zn contents could be extended in WA. Description: A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the University of Cape Coast in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Agriculture 2020-01-01T00:00:00Z http://197.159.135.214/jspui/handle/123456789/329 Title: Assessing Deficit Irrigation and Supplemental Irrigation as Water Management Strategies for Improving Maize Production in Benin Authors: Allakonon, Marsanne Gloriose Bignon Abstract: Deficit Irrigation (DI) consists to provide the crop with water below its daily need (ETc) according to the sensitivity of its growth stages. The objective of this study was : (i) to assess the factors explaining maize response to irrigation water stress; (ii) assess the potential of supplemental irrigation and deficit irrigation for improving rainfed maize production; and (iii) to evaluate crop water productivity under irrigation water deficit in sub-humid climate of Benin. To achieve its objectives, the present study first reviewed through quantitative meta-analysis the overall response of maize to DI to identify the growth stage that will allow limited yield loss, and to understand the factors that explain maize response to water stress. Two field experiments were conducted under supplemental irrigation in 2018 and 2019 using four rates of fertilizers; and one experiment under deficit irrigation in 2019 using four (04) levels of DI (0, 25, 50, and 75% ETc). Irrigation water stress were applied based on daily crop evaporation determined from CropWat FAO database. For all experiments, a Randomized Bloc Design with 3 replications was used. The review showed that yield loss increases with increasing levels of DI at all growth stages, but yield loss was minimized in vegetative stage. In addition, the results from the review suggest that maize response to water stress is dependent on many factors such as climatic zone, cropping densities, and fertility management practices. The experimental results indicated that leaf area index (LAI) and plant height decreases in stressed treatments during the period of stress application, but the decrease was observed on different periods, suggesting a given sequence, or a process through which DI affect crop production. Grain yield decreases as water stress increases by 25%, 47%, and 82% respectively in D25, D50, and D75 treatments. There was no significant difference of stover yield between D0 and D25 in one side, and between D50 and D75 on the other side. Water Use Efficiency (WUE) and Irrigation Water Use Efficiency (IWUE) decreased as DI increases, respectively by 19% and 0.26% in D25 treatments, implying there’s an optimum deficit irrigation level for which yield loss would be reduced. Since farmers in West Africa context are more concerned about a sustained yield over a long period of time, that optimum deficit level should be determined, for instance through simulation on the long term base on scenario analysis, to make appropriate recommendations. Description: A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the University of Cape Coast in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Agriculture 2020-02-01T00:00:00Z