Impacts of Drought Stress on Coffee (Coffea Arabica L.) Genotypes: Insights from Germination, Growth, Physiological, and Biochemical Responses
| dc.contributor.advisor | Asfaw Degu | |
| dc.contributor.author | Habtamu Chekol | |
| dc.date.accessioned | 2025-08-18T00:54:35Z | |
| dc.date.available | 2025-08-18T00:54:35Z | |
| dc.date.issued | 2024-05-20 | |
| dc.description.abstract | Drought stress is one of the major abiotic factors affecting crop growth and limiting production worldwide. Differences in drought tolerance among Coffea arabica genotypes have been observed, particularly in Ethiopia, where the effects of drought stress on coffee growth and yield have been documented. However, a comprehensive understanding of the morphological, physiological, and molecular processes in Ethiopian Arabica coffee genotypes under drought stress during germination, seedling, and adult development remains limited. This study delves into investigating the germination, growth, physiology, and molecular performance of three distinct groups of coffee genotypes categorized as relatively tolerant (Ca74140, Ca74112, and Ca74110), moderately sensitive (Ca74158, Ca74165, and CaJ-21), and sensitive (Ca754, CaJ-19, and CaGeisha), behaving differently in their physiological response to a dry soil condition. Therefore, a poly-propagator experiment under a shade house was conducted to investigate the impact of drought stress on the germination potential of the genotypes. Greenhouse measurements were then performed to evaluate the effects of drought stress on seedling development, encompassing growth, physiology, and molecular responses across coffee genotypes. Results indicated distinctive responses among coffee genotypes during germination, with relatively tolerant genotypes exhibiting swifter and more comprehensive germination, correlated with higher moisture content (Mc), greater seed surface area to volume ratio (SA/SV), and elevated coefficients of velocity and variation of germination (CVG, CVt), and germination index (GI). Furthermore, relatively tolerant genotypes displayed enhanced seedling vigor (VI). Under drought stress conditions, leaf, stem, and root development, leaf relative water content (RWC), water potential (Ψ), stomatal conductance (Gs), net assimilation rate (Anet), and transpiration rate (E) significantly declined across all genotypes. Nevertheless, relatively tolerant genotypes demonstrated better resilience compared to other groups. Metabolite analysis unveiled distinctive accumulation patterns, notably higher levels of certain compounds like glucose, maltose, tryptophan, L-cysteine, malic acid, oxalic acid, pyruvic acid, and shikimic acids, in relatively drought-tolerant genotypes, while other metabolites showed decreased accumulation. Osmotic adjustment via compatible solutes and energy-associated metabolites emerged as a significant mechanism associated with growth and physiological responses, emphasizing the role of osmotic potential modulation in drought tolerance among coffee genotypes. This study underscores the diverse tolerance levels to drought among Ethiopian coffee genotypes. Traits such as rapid and complete germination, higher growth, relative water content, water potential, gaseous exchange, and osmotic adjustment signify heightened tolerance to drought episodes. These attributes could serve as useful markers for identifying drought-tolerant genotypes in plant biotechnology. Overall, this study highlights the pivotal role of seed traits, germination, and post-germination events, encompassing growth, physiological responses, and metabolite dynamics, in delineating drought tolerance among coffee genotypes. | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/7006 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Ababa University | |
| dc.subject | Coffea Arabica | |
| dc.subject | Drought Stress | |
| dc.subject | Seed Germination | |
| dc.subject | Water Potential | |
| dc.subject | Gas Exchange | |
| dc.subject | Metabolites Alteration | |
| dc.title | Impacts of Drought Stress on Coffee (Coffea Arabica L.) Genotypes: Insights from Germination, Growth, Physiological, and Biochemical Responses | |
| dc.type | Thesis |