PHD-School of Agriculture And Enterprise Development

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This collections contains bibliographic information and abstracts of PHD theses and dissertation in the School of Agriculture and Enterprise Development held in Kenyatta University Library

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Browsing PHD-School of Agriculture And Enterprise Development by Subject "adaptation"

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    Phenotypic characterization and evaluating the response of sweetpotato genotypes for drought tolerance as an adaptation to climate change in Ethiopia Selamawit Abebe Gitore
    (Kenyatta University, 2023) Gitore, Selamawit Abebe
    Sweet potato plays a major role as a food security crop in many countries particularly in the sub-Saharan Africa and Asia. Despite its importance, current identification is still limited, which is one of the reasons for low sweet potato productivity at the moment. Drought susceptibility is perceived as one of the major drawbacks of orange fleshed sweet potato genotypes that have been so far released. The objectives of this study are; to characterize sweet potato genotypes present in Ethiopia for selection of those possessing optimal dual-purpose characteristics, to assess the drought stress tolerance of orangefleshed sweet potato genotypes and to identify sweet potato cultivars with good yield and quality, and assess various drought stress tolerance selection indices and choose the appropriate ones for use in identifying drought tolerant sweet potato cultivars in Ethiopia. The experiment was conducted at Boloso sore district, Wolaita region, and southern parts of Ethiopia. 40 selected sweet potato genotypes advanced from crossing experiment and 10 orange fleshed sweet potato genotypes planted on the field using Alpha lattice design for characterization and drought evaluation experiment. Characterization of the genotypes performed using international potato center standardized morphological descriptors. Classification of dual-purpose use varieties was done according to Leon- Velarde approach, based on root to vine ratio. Parameters related with a storage root yield such as vine length, vine Internode length, vine internode diameter, number of branch, vine fresh weight, root yield, Leaf area index were collected for drought evaluation study. The generated data in this study were subjected to analysis of variance using R software, agricolae package. The significantly different means were compared using tukey test at the level of p< 0.05. Principal component analysis and cluster analysis performed to separate and group the genotypes based on their differences and similarities. Phenotypic variability observed among the 40 genotypes for almost all leaf, vine and root parameters except for central leaf lobe, petiole length, and root thickness. The research finding showed that 30 genotypes out of 40 qualified for dual-purpose based on their index value of root to vine ratio. The study revealed that the genotypes MUSG014065-21-13, MUSG014065-21-14 and MUSG014019-7-50 showed the lowest rank sum and standard deviation of rank sum and considered as a drought tolerant genotypes. Stress tolerance index, geometric mean productivity, yield index, stress intensity index and tolerance indices were shown to be the best in identifying drought tolerant genotypes based on their strong correlation with yield under stress conditions. Efforts should be made to promote the adoption of these dualpurpose sweet potato genotypes among farmers to enhance the economic and nutritional benefits of sweet potato cultivation. Further research could also be conducted to identify the molecular markers associated with drought tolerance in sweet potato genotypes to facilitate marker-assisted selection in breeding programs. Moreover, collaboration between researchers, farmers, and policymakers is essential to promote the adoption of drought-tolerant sweet potato varieties and support sustainable agricultural practices.