College of Agriculture

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The College of Agriculture is committed to advancing agricultural education, research, and community service. It serves as a center for knowledge creation and dissemination in crop science, animal production, natural resource management, and sustainable agriculture.

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    AGRO-MORPHOLOGICAL VARIABILITY, GENOTYPE BY ENVIRONMENT INTERACTION, NUTRIENT AND LAND-USE EFFICIENCY, AND NUTRITIONAL PROFILE OF OAT (Avena sativa L.) GENOTYPES IN ETHIOPIA
    (Hawassa University College of Agriculture, 2024) GEZAHAGN KEBEDE BUNARE
    Agro-morphological variability, genotype by environment interaction, nutrient and land-use efficiency, and nutritional profile of oat (Avena sativa L.) genotypes in Ethiopia Oat (Avena sativa L.) is one of the useful annual cereal crops grown at higher altitudes in the tropics and temperate regions. It is a dual-purpose crop cultivated for fodder and grain production in the central highlands of Ethiopia. This crop is mainly cultivated for fodder production and the grain is also used for human food and animal feed in Ethiopia. Oat generally produces high amounts of fodder which has better nutritional quality and it can be used as a green feed and the excess production can be conserved as hay and silage to utilize during the feed scarcity period. Despite its significance, oat production, and productivity are highly influenced by genetics, environments, agronomic management, and their interactions. Therefore, developing high-yielding oat varieties with stable performance under diverse environmental conditions and improving the productivity of oat through various agronomic management are the major research areas for oat improvement in Ethiopia. However, studies on agromorphological based genetic diversity and yield stability of oat genotypes under diverse environmental conditions and the optimum nutrient requirements of oat for higher yield and nutritional quality under sole and mixed cultures with vetch have not been well studied and properly documented in the country. Thus, the overall aim of this study was to enhance the productivity of oat genotypes through proper exploitation of genetic variability and agronomic management under different environments and management conditions. The first experiment was conducted using 120 oat genotypes using a randomized complete block design with three replications at Holetta and Ada-Berga research stations in the 2020/2021 cropping season. The objectives of this study were to estimate the extent of agro-morphological based genetic variability, heritability, and genetic advance in oat genotypes, to investigate the phenotypic and genotypic relationships between the studied quantitative traits, to determine the direct and indirect effects of measured quantitative traits on fodder and grain yields, and to evaluate the genetic variations using cluster, genetic divergence, and principal component analyses for oat yield improvement. The results revealed that moderately high to very high heritability (62.9– 86.4%) coupled with high to moderate genetic advance as percent of mean (16.0–26.1%) were recorded for forage dry matter yield (FDMY), number of leaves at forage harvest (NLFH), stem dry matter yield (SDMY), forage yield production rate (FYPR), grain yield (GY), panicle length at grain harvest (PLGH), number of spikes per panicle (NSPP), and harvest index (HI). This result demonstrated that the selection of oat genotypes based on these traits could be effective for yield improvement. The genotypic and phenotypic correlation and path coefficient analyses indicated that the FYPR had a significant positive association and high direct effect on FDMY and also the biological yield production rate (BYPR) and HI had a significant positive association and high direct effect on GY. This indicated that selection based on FYPR and BYPR/HI would simultaneously improve the FDMY and GY in oat genotypes, respectively. The multivariate analysis revealed that the studied genotypes grouped into four clusters with the intra and inter-cluster genetic distances ranging from 2.3 to 4.3 and 11.7 to 63.2, respectively. The principal component analysis showed that traits such as FYPR, BYPR, PLGH, FDMY, and xxxi number of spikelets per panicle (NSLPP) contributed more for the first component whereas HI, GY, NLFH, and plant height at grain harvest (PHGH) had a high contribution for the second component. The presence of genotype by environment interaction (GEI) complicates the selection of genotypes with high yielding coupled with stable performance across environments. Twenty-four oat genotypes were selected and sown during the 2020/2021 cropping season at Holetta (E1), Ada-Berga (E2), Ginchi (E3), Jeldu (E4), D/Zeit (E5), Kulumsa (E6), Bekoji (E7), Kuyu (E8), and D/Markos (E9) agricultural research stations using a randomized complete block design with three replications. Thus, the second experiment aimed to assess the magnitude of GEI and to evaluate the fodder and grain yield stability performance of oat genotypes using univariate and multivariate statistical models. The additive main effects and multiplicative interaction (AMMI) analysis of variance for fodder yield showed that the total variation was highly contributed by the environment (E) main effect followed by GEI and genotype(G). Moreover, the GGE biplot analysis for fodder yield showed that G6 was the ideal genotype while G2, G3, G10, and G23 were desirable genotypes. Among environments, E7 was an ideal environment whereas E1 and E8 were favorable environments. The results of univariate stability analysis indicated that selection of oat genotypes using genotypic superiority index (Pi), yield stability index (YSI), coefficient of determination (R2 ), and coefficient of variation (CVi) stability parameters would be effective for fodder yield improvement. Similarly, the AMMI analysis of variance for grain yield showed that the E main effect was the highest contributor to the total variation followed by G and GEI. Based on the GGE biplot analysis for grain yield, G19 was an ideal genotype while G8, G11, G12, G14, G17, and G22 were desirable genotypes. Moreover, the ideal environment was E2 whereas E1, E4, and E5 were favorable environments. The univariate stability analysis for grain yield indicated that high grain yield-producing oat genotypes had stable performance using the stability parameters of Pi , the Perkins and Jinks adjusted linear regression coefficient (Bi), and YSI. The yield and nutritional quality of oat can be improved through the application of optimum fertilizer at the right time. Oat can be cultivated using the blanket recommended fertilizer rate in Ethiopia. Thus, the optimum fertilizer rate for fodder and grain production of oat has not been well studied and documented in the country. Therefore, this study aimed to assess the effect of fertilizer rates on agro-morphological traits, nutrient uptake and use efficiency, nutritive value, and economic feasibility of oat varieties at Holetta. The study was carried out during the 2020/2021 and 2021/2022 cropping seasons using a factorial arrangement of eight levels of the blanket recommended fertilizer (0, 25, 50, 75, 100, 125, 150, and 175%) and three oat varieties (CI-8251, SRCPX80Ab2291, and Sorataf) in a randomized complete block design with three replications. The results showed that variety, fertilizer, and year had significant effects on FDMY. The FDMY of oat varieties increased with increasing fertilizer rates and the highest (15.9 t/ha) yield was obtained from the application of 175% (71.8 kg N + 35 kg P/ha) fertilizer. Among oat varieties, the highest FDMY was obtained from CI-8251 (forage type oat) followed by SRCPX80Ab2291 (dual type oat) and Sorataf (grain type). The number of tillers per plant (NTPP), yields of morphological fractions (leaf, stem, and grain), FYPR, nutrient concentration, and uptake had significant positive associations with fertilizer levels and FDMY. However, all the nutrient use efficiencies except agro-physiological efficiency (APE) had inverse associations with fertilizer levels and FDMY. Similar to FDMY, the GY of oat varied significantly for variety, fertilizer, and year effects. Application of 150% (61.5 kg N + 30 kg P/ha) fertilizer rate produced the highest GY (6.5 t/ha) and grain nutrient uptakeGNU (141.7 kg/ha) while the lowest GY and GNU were recorded from oat sown without fertilizer application. Sorataf (grain type) variety gave the highest GY, GNU, partial factor xxxii productivity (PFP), and agronomic efficiency (AE) compared to forage and dual-type oat varieties. Oat varieties sown with 25% (10.3 kg N + 5 kg P/ha) fertilizer rate produced the highest PFP (346.6 kg/ha) and AE (164.8 kg/ha) while PFP and AE decreased with increasing fertilizer rates. The nutrient concentration and uptake had positive associations with fertilizer level and GY while nutrient harvest index (NHI) and nutrient use efficiency had inverse associations with fertilizer level and GY. The nutritional quality analysis indicated that digestible yield (DY) and total digestible nutrient yield (TDNY) varied significantly with variety, fertilizer, and year effects. Among oat varieties, CI-8251 gave the highest TDNY while SRCPX80Ab2291 gave the highest DY but the Sorataf variety gave the lowest TDNY and DY. Most of the measured nutritional quality parameters varied for the interaction effect of variety by fertilizer by year effect. Sorataf variety sown with 175% fertilizer rate in 2020 gave the highest crude protein-CP (113.9 g/kg DM), crude protein yield-CPY (1.66 t/ha), and digestible crude protein-DCP (68.2 g/kg DM). Application of fertilizer and FDMY had significant positive associations with CP, CPY, DY, DCP, and TDNY. The combined partial budget analysis for the three oat varieties showed that application of 125% (51.3 kg N + 25 kg P/ha ) fertilizer rate produced higher net benefit (83,440 ETB) and marginal rate of return (12,635.6%) from fodder production. On the other hand, the application of 150% fertilizer rate produced the highest net benefit from grain production. Oat can be also cultivated with vetch (annul forage legume) to improve the quantity and quality of feed in the central highlands of Ethiopia. The oat/vetch mixtures are sown with the same blanket recommended fertilizer rate that is used for the production of sole oat in the country. This indicated that the application of fertilizer on oat/vetch mixtures does not depend on the nutrient requirements of oat and vetch for better growth and development under a mixed cropping system. Accordingly, the optimum fertilizer rate for the oat/vetch mixed cropping system has not been well studied and documented in the country. Therefore, this study aimed to investigate the effect of fertilizer rates on agro-morphological traits, nutrient uptake and use efficiency, competitive ability, and economic feasibility of oat under oat/vetch mixed cropping and nutritive value of mixtures at Holetta Agricultural Research Center during the 2020/2021 and 2021/2022 cropping seasons. In this study, the oat/vetch mixture was sown with eight fertilizer rates (0, 25, 50, 75, 100, 125, 150, and 175%) and also sole oat and sole vetch were sown with their recommended fertilizer rate (100%) using a randomized complete block design with three replications. The results showed that fertilizer and year had significant effects on all measured agro-morphological traits, nutrient concentration, and nutrient uptake and use efficiency of oat. Accordingly, all the measured agro-morphological traits increased with increasing fertilizer rates, and the highest values were recorded in the second year. Application of 150% fertilizer rate increased the FDMY of oat/vetch mixtures by 107.4% compared to oat/vetch mixtures sown without fertilizer application. However, the highest nutrient use efficiency was recorded with the application of fertilizer at the rate of 25% while the nutrient use efficiency was the lowest with the highest fertilizer (175%) application rate. The FDMY of oat under oat/vetch mixtures was associated significantly and positively with all measured agro-morphological traits, nutrient concentration, and uptake while it had significant inverse associations with nutrient use efficiencies. The highest net benefit and marginal rate of return were recorded from the application of 150% fertilizer rate. The productivity of oat under oat/vetch mixed cropping was also assessed using different indices. The results showed that over-yielding oat (OYO), land equivalent coefficient (LEC), area-time equivalent ratio (ATER), and land equivalent ratio (LER) were higher in the first year while oat equivalent yield (OEY) and system productivity index (SPI) were higher in the second year. All xxxiii the aforementioned biological efficiency indices increased with increasing fertilizer rates and the highest values were recorded from the application of 150% fertilizer rate. Similarly, all the measured competitive indices such as crowding coefficient of oat (KO), actual yield loss of oat (AYLO), intercropping advantages of oat (IAO), and the competitive ratio of oat (CRO) were higher in the first year. All the values of competitive indices except aggressivity of oat (AO) increased with increasing fertilizer rates and the highest values were recorded from the application of 150% fertilizer. The economic efficiency indices of oat/vetch mixtures showed that the higher values of monetary advantages index (MAI), relative value total (RVT), replacement value of intercropping (RVI), and relative net return index (RNRI) were recorded in the first year. All the values of economic efficiency indices increased with increasing fertilizer rates and the highest values were recorded from 150% fertilizer rate. The nutritive values of oat/vetch mixtures also varied with fertilizer application and year of production. All the measured nutritive values except fiber contents (NDF-neutral detergent fiber, ADF-acid detergent fiber, ADL-acid detergent lignin, HC-hemicellulose, and C-cellulose) were higher in the second year. Application of fertilizer at the rate of 150% gave the highest ash, CPY, digestible dry matter (DDM), dry matter intake (DMI), in-vitro dry matter digestibility (IVDMD), DY, total digestible nutrients (TDN), TDNY, relative feed value (RFV), and relative feed quality (RFQ). On the other hand, oat/vetch mixtures sown without fertilizer gave the highest fiber contents. The person correlation analysis indicated that fertilizer application had significant inverse associations with fiber contents while it had significant positive associations with the remaining measured nutritional quality parameters. In conclusion, oat genotypes such as CI-715, CI-1463, SRCPX80Ab2806, A-505, CI-1480, S-122, Bona-bas, and CI-1674 were selected for fodder yield and grain yield improvement. Based on the AMMI, GGE, and univariate stability parameters, G6 (CI-1512), G9 (CI-1629), G10 (C-12), and G23 (CI-8235) were selected for fodder yield improvement while G8 (SRCPX80Ab2267), G17 (SRCPX80Ab2310), and G22 (SRCPX80Ab2691) were selected for grain yield improvement of oat. Application of 125% (51.3 kg N + 25 kg P/ha) fertilizer rate for fodder production and 150% (61.5 kg N + 30 kg P/ha) fertilizer rate for grain production could increase the respective yield and farm profitability in the study area. Similarly, application of 150% fertilizer rate would increase the fodder yield, competitive ability, and economic profitability of oat under oat/vetch mixtures and nutritive value of mixtures. However, the selected genotypes and fertilizer rates should be verified under diverse environments of oat-growing areas in Ethiopia.
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    ANALYSIS OF CLIMATE VARIABILITY AND CHANGE AND ITS IMPACTS ON WATER PRODUCTIVITY AND NUTRIENT USE EFFICIENCY OF MAIZE (Zea mays) IN THE GREAT ETHIOPIAN RIFT VALLEY BASINS
    (Hawassa University College of Agriculture, 2021) FITIH ADEME MAMO
    Climate variability and change are a global phenomenon affecting many nations. Smallholder farmers in Ethiopia have been facing severe climate related hazards, in particular highly variable rainfall and severe droughts that negatively affect their livelihoods. Anticipated climate change is expected to aggravate some of the existing challenges and impose new risks beyond the range of current experiences. This study aimed at understanding current climate variability and future climate change, and its associated impacts in particular for maize production. The climate analysis was conducted in the Great Rift Valley Basins (GRVB), which represents diverse agroecology and farming systems. The climate variability and change impact study were conducted in the Central part of the Rift Valley (CRV), which represent a major cereal-based farming system of the semi-arid environments of Ethiopia. Empirical statistical analyses using field experimental data in combination with crop-climate simulation modelling were used to achieve the objectives of the study. A high spatial resolution regional climate models and a well-known crop growth simulation model were used for the modelling analysis, which is an innovative feature of the methodology used in this thesis. The analysis revealed that rainfall exhibited high interseasonal variability (coefficient of variation 13-37%) during the period 1981-2010 in the GRVB. The mean annual temperature significantly increased by +0.43 ºC [0.27 ºC to 0.58 ºC] per decade in the same period. Projections for future climate suggested that annual rainfall will change by -25 to +6% and the annual temperature is expected to increase in the range of 2.5-5.1oC by the end of this century. A corresponding change in length of growing period (LGP) from -5.66 to -25.5% for central semiarid and +3.9 to -16.4% for central sub-humid highlands was simulated in the near century. Maize grain yield was strongly (P<0.01) and positively correlated with seasonal rainfall (r=0.67-0.69) in the CRV while day temperature affected grain yield negatively (r= -0.44) at Ziway (P<0.05) during the simulation period. Simulated water-limited yields showed high inter-annual variability (coefficient of variation, ~24%) and about 47% of this variability was explained by the xvii variation in growing season rainfall. The observed farmers’ yield was 28, 48 and 57% lower than the researcher-managed, water--limited and potential yield of the crop, respectively, indicating wide maize yield gap in the region. Analysis of climate change scenarios showed that maize yield will decrease on average by 16.5 and 23% by mid and end of this century, respectively due to climate change. Similarly, water productivity is expected to decline on average by 2.2 and 12% in the CRV by mid and end centuries with respect to the baseline. Nutrient uptake and corresponding nutrient use efficiency (NUE) might also be negatively affected by climate change. Phosphorus uptake probably will decrease in the CRV on average by 14.5 to 18% by mid-century. Nitrogen and P use efficiency indicators showed decreases in the range between 8.5 to 10.5% and between 9.3 to 10.5%, respectively by midcentury relative to the baseline average. The simulation under no water and nutrient limitation condition ensured improvements of both water and nutrient use efficiency in the changed climate which could ensure modest production in the future. The high estimated impact of climate variability and changes on crop yield and associated resources use in the CRV imply greater risks on rainfed crop production in the region. Hence, the study recommends further assessment of potential adaptation options and economic impact of climate related risks in the region to provide full-fledged evidence for better policy decisions.
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    ASSESMENT OF FACTORS INFLUENCING ADOPTION OF AGROFORESTRY TECHNOLOGIES IN HALABA SPECIAL WOREDA, SOUTHEREN ETHIOPIA
    (Hawassa University College of Agriculture, 2016) MIHRETU ERJABO
    Halaba special district is characterized by drought, soil erosion, high population pressure, poor livestock production, lack of feed for livestock, very deep water table, very low productivity of crops and food insufficiency. In order to address these problems, the woreda Agricultural Development office along with other management practices such as soil physical conservation measures agroforestry was introduced decades ago as a means to alleviate the problem. However, the level of agroforestry adoption remains low. The main objective of this study was to identify the factors that influence adoption of agroforestry technologies by farmers in the district. Random sampling procedure was employed to select two kebele administrations and respondents. Data collection was conducted by employing five different types of techniques such as rural household questionnaire survey, participatory rural appraisal, questionnaires for local and woreda extension staff, scanning government records & secondary data resources and field observation. A total of 12 key informants, 6 extension staffs and 182 households, samples were used in the data collection process. Chi-square test and t-test were used to determine whether there were statistically significant relationships between adoption of agroforestry and 15 selected variables. Out of which eleven were found to be significant to affect farmers’ adoptiveness. These were frequency of visits of farmers(13.39%), participation in training(11.49 %), farmers’ attitude towards agroforestry practices(10.61%), frequency of visits of extensionists(10.38%), participation in extension meeting(10.34%), participation in field day(10.28%), land holding size(9.29%), level of literacy(8.78%), awareness about the importance of agroforestry technology packages(7.06%), time taken from their residence to nearest extension(5.04%) and gender of respondents(3.34%). This study also identified various factors that may result in low adoption rates of agroforestry including fear of competition between trees & crops for water and nutrients uptake, seedling shortage, rainfall shortage, free grazing after crop harvest, financial problem, labor shortage, expecting trees as soil degrader & long span of trees and lack of need ranking of farmers by extension staff. To improve farmers’ adoption, the factors identified should be well addressed by launching a series and recurrent outreach extension program appropriate and suitable to farmers need.
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    CHARACTERIZATION, MAPPING, AND EVALUATION OF RECLAMATION RESOURCES FOR SOILS AROUND ABAYA AND CHAMO LAKES, SOUTHERN ETHIOPIAN RIFT VALLEY
    (Hawassa University College of Agriculture, 2024) AZMERA WALCHE MENGESHA
    Characterizing and understanding the nature of the soil and its management are crucial for successful crop production. With this in mind, experiments were conducted to (1) characterize of soils surrounding Lakes Abaya and Chamo, (2) analyze nutrient contents and map the fertility status of agricultural soils, (3) determine the intensity and types of soils and map their spatial distribution patterns, and (4) investigate the efficacy of gypsum and farmyard manure and their combined application in reclaiming sodic soil's chemical and physical properties. The first study revealed that the soil properties in the study site were highly heterogeneous in terms of morphological, physical, and chemical characteristics. Most of the studied soils were highly alkaline (>8.5), had very high sodium content (>20 cmolc kg-1 ), very high CEC value (> 40 cmolc kg-1 ), very low TN (<0.1%), and low levels of organic carbon (0.5-1.5%) and exchangeable calcium (2-5 cmolc kg-1 ). The study recommended removing sodium and salts from the soil depth to improve the productivity of agricultural soils in the area. Applying organic amendments such as manures and crop residues was also suggested to increase fertility and organic matter content. The second study showed the soil texture in the area was mainly clay, heavy clay (Ganta Kanchama site), and sandy clay loam. The surface soil had a higher available water holding capacity than the subsurface depth, indicating more plant water storing space. The soils in the studied area had an alkaline pH, moderately (2-4 dSm-1 ) to highly saline (4-8 dSm-1 ) EC values, high exchangeable sodium percentage (50-70%), high soil CEC, low OC, very low total nitrogen content, high potassium availability (>300 mg kg-1 ), and xxiii lower calcium carbonate content. The study showed the soils of the area were fertile, however, incorporating organic matter into the soil enhances its structure, water retention, and nutrient availability, reducing salinity and sodicity. The results of the third experiment revealed that the study area has moderately (7.9-8.4) to strongly alkaline soil pH (8.5-9.0), slightly (0.75-2 dS m-1 ) to moderately saline (2-4 dS m-1 ) EC values, and a high variability in soil ESP values, indicating a strong variability in soil sodicity across different parts of the study area. Out of 2274.65 ha of the studied area, 62.28%, 26.09%, 10.99%, and 0.63% were categorized as nonsaline non-sodic, saline-sodic, sodic, and saline, respectively. The results showed that almost all salt-affected sites were situated in relatively low-lying slope (0-2 %) areas, flat to almost flat slopes. The findings suggest that the place needs specific soil management strategies to address the salinity and sodicity problems. The last study investigated the impact of amendment resources on sodic soils. A pot experiment consisting of a factorial combination of four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha−1 ), with Complete Randomized Design (CRD and three replications was used. The results showed that applying gypsum (GYP) and farmyard manure (FYM) reduced exchangeable sodium percentage (ESP) in sodic soils. Specifically, using 10 ton FYM ha-1 and GYP at 100% GYP required (GR) rate resulted in a 99.8% decrease in ESP compared to untreated composite sodic soil. The study also indicated optimal amendment levels (combined application of 100% GYP and 10 ton FYM ha-1 ) for displacing exchangeable sodium from the exchange site using prediction models. Agglomerative hierarchical and K-means cluster analysis suggest that treatment levels and reclaimed soils with similar properties require application of comparable treatment levels and similar management. The study found that combined applications of GYP (at 100% gypsum requirement rate) and FYM (10 ton FYM ha-1 ) reduced ESP to less than 10% in agricultural soil. However, further research is needed to determine their effectiveness at the field level.
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    DIVERSITY OF CULTIVATED AND WILD YAMS (Dioscorea spp) IN SOUTHWEST ETHIOPIA BASED ON FARMERS MANAGEMENT PRACTICES, AGRO-MORPHOLOGICAL TRAITS AND NUTRITIONAL COMPOSITION
    (Hawassa University College of Agriculture, 2021) TSEGAYE BABEGE WOROJIE
    DIVERSITY OF CULTIVATED AND WILD YAMS (Dioscorea spp) IN SOUTHWEST ETHIOPIA BASED ON FARMERS MANAGEMENT PRACTICES, AGRO-MORPHOLOGICAL TRAITS AND NUTRITIONAL COMPOSITION Yam (Dioscorea spp) is a traditional crop that has long been cultivated in Ethiopia as a co-staple crop. Several yam species might have their origin in Ethiopia and are among those crops with wild relatives in the country. Though the genus Dioscorea is reported to show a wide range of variation, it has not been studied across its range of distribution. This study was investigated the diversity of wild and cultivated yams in Bench-Sheko and Sheka Zones, Southwest Ethiopia. Toward this effort, 5 studies were carried out. The first 2 studies were designed to investigate folk biosystematics, diversity and distribution and the local management practices of yams in Southwest Ethiopia. In the third study, accessions from South and Southwest Ethiopia were considered to investigate the diversity of yams based on agro-morphological traits. In the fifth study, we link two data sets to assess the knowledge of wild yam and the process of domestication. Lastly, we analyze the nutritional compositions based on selected yam landraces. We also have another study which is underway and was part of our initial project initiated with the objective of studying the true genetic diversity of yams using SSR marker. An ethnobotanical survey was conducted on 15 Kebeles in 5 districts of Bench-Sheko and Sheka Zones from Dec., 2016 to Nov., 2017. Data were collected using a semi-structured questionnaire from 272 households. Seventy-five yam accessions corresponding to 30 differently named landraces were used for morphological study. Sixty of the 75 accessions were collected in Kaffa, Bench-Sheko and Sheka Zones of Southwest Ethiopia. The rest represented previously collected accessions from Basketo, Gamo-Gofa and Wolaita areas of Southern Ethiopia. They were grown in RCBD with 2 replicates in 2018 at Hawassa University research field. The process of wild yam manipulation in Southwest Ethiopia was studied by linking two data sets derived from (1) ethnobotanical survey using 231 interviews and (2) morphological study using 47 selected accessions. Twelve landraces composed of different species and contexts were analyzed for nutritional composition in Addis Ababa at the Ethiopian Health and Nutrition Research Institute. Results obtained from ethnobotanical study suggest that there exists a systematic and welldeveloped folk naming and taxonomic system in Sheko and its environs. Sheko and Bench botany of yam recognizes 58 named individuals. These individuals are grouped into 3 well recognized ranks, namely sub-variety, variety and supra variety. Taxa assigned to each ranks have distinct features that mark them as members of a separate group. Farmers manage a wide range of morphological characters and some other attributes other than morphological ones for grouping of the taxa assigned to distinct groups. An account of each of these aspects and its link with the taxa recognized in the domain of formal science are presented. A folk biological classification of yam consisting of 4 taxonomic ranks is proposed. Our result showed much information of biological and functional aspects which can aid the taxonomic and genetic study of yams in Ethiopia. Our assessment also showed that there exists a wide range of yam diversity in Southwest Ethiopia. Altogether, 40 actually grown yam landraces, including those found in farms of unsampled households were recorded; making Bench-Sheko and Sheka Zones an area of notably high landrace diversity. The greatest number of these individuals had a narrow xviii distribution and low abundances, with a few being cosmopolitan. This was evident in a positive and significant correlation between distribution and local abundance, such that a few cosmopolitan landraces were locally more abundant. Maintenance and distribution range of landraces is related with the local management practices. A description of farmers’ decisions to the on-farm landrace maintenance is presented and implication for the collection and conservation of yam germplasm are suggested. Morphological diversity study based on 37 qualitative and 13 quantitative traits has shown a considerable variability among accessions of yam species studied. Our multivariate analysis showed that all the traits used were useful for capturing the variability among accessions, but 21 traits (17 of which are qualitative traits) were useful for capturing the variability among accessions of distinct species. The remaining traits were useful for capturing the variability among accessions within and between species, which could be exploited, if improvement need arises. The overall structure of morphological diversity is consistent with the locally perceived biota. Yet, no clear morphological variations were obtained among some differently/similarly named landraces, suggesting the need for DNAbased studies to show the full extent of the existing diversity. The observed manipulations of wild growing yams in Southwest Ethiopia suggest that yam domestication is still an active process. Knowledge of domestication was shared by 44% of the farmers, even by those that had never practice it. Farmers who have recent transplants in their garden varied from 4% in Bench to 10% in Sheko. The duration of domestication can take up to 6 years, but with most of the individuals it only takes 3 to 5 years. By linking two types of evidences, two divergent adaptation processes are distinguished: (1) parents of recent domesticate expressing a domestication syndrome belongs to wild D. abyssinica or D. praehensilis, and (2) populations of incipient domesticate that might be derived from feral or diverse types of hybrids. A description and analysis of each of these processes and their role on the adaptation process of yams is presented. Based on this account, the term adoptive transplantation is proposed to replace domestication. Although only a few landraces were used, a considerable variability existed in nutritional compositions among the studied samples. The results of nutritional study showed that landraces from D. alata contained high amounts of crude fat and ash contents that make them a good source of energy and minerals. Landraces from the D. cayenensis complex contained low moisture content that makes them suitable for prolonged storage and processing. The variability observed both among different species and among landraces in a single species highlights their potential in future breeding. More generally, this PhD study documented a great wealth of knowledge on distribution, the level of diversity within the yam, the taxonomic status, folk biosystematics and the local management practices. This constitutes an essential step towards setting development priorities and for enhancing the traditional yam farming in the studied areas. This study thus form an important part of an ongoing study aimed at designing an effective collection and conservation strategies for efficient utilization in future yam improvement.
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    ECOLOGY AND INSECTICIDE RESISTANCE MANAGEMENT OF THRIPS (THYSANOPTERA: THRIPIDAE) ON ONION (Allium cepa L.) IN THE RIFT VALLEY OF ETHIOPIA
    (Hawassa University College of Agriculture, 2020) BELETE NEGASH
    Ecology and Insecticide Resistance Management of Thrips (Thysanoptera: Thripidae) on Onion (Allium cepa L.) in the Rift Valley of Ethiopia Belete Negash1 , Ferdu Azerefegne1 and Gashawbeza Ayalew2 1Hawassa University, College of Agriculture, Hawassa, Ethiopia 2 Ethiopian Institute of Agricultural Research, Melkassa Research Center, Adama, Ethiopia ABSTRACT Decline in efficacy of registered insecticides to control thrips (Thysanoptera: Thripidae) on onion in Ethiopia stimulated studies on insecticide resistance, ecology and management of thrips on onion in the major onion production belt of the Central Rift Valley of Ethiopia (CRV). Several studies including farmers‟ insecticide use practices against thrips on onion, species composition and abundance, seasonal abundance of thrips and their effect on yield, insecticides resistance detection and management were conducted from 2015 to 2017. Diazinon, dimethoate, profenofos, lambda-cyhalothrin and spinetoram were widely used for thrips control on onion in the surveyed areas. Type and frequency application of insecticides use were different among the locations. Insecticide application frequencies were higher at Meki and Melkassa than in Werer areas. All the onion fields visited during the survey were infested by two thrips species namely, the western flower thrips, Frankliniella occidentalis (Pergande) and the onion thrips, Thrips tabaci (Lindeman). Thrips species compositions vary with locations. While, T. tabaci was dominant in Werer and Melkassa areas. The F. occidentalis thrips species was dominant at Meki location. Thrips population was higher during mid-growth stage of onion, 50 to 64 days after transplanting, than early and late growth stages in cool dry (October–January), hot dry (February – may) and rainy (June – September) growing seasons. Significantly lower thrips population recorded in the rainy season than the cool dry and hot dry seasons. Onion growth stage, growing seasons and sunshine hours were important factors for predicting thrips numbers. Cool and rainfall seasons significantly negative correlated with thrips numbers, while it was positively correlated with the onion growth stage, maximum temperature and sunshine hours. Thrips number was significantly greater on untreated plots than insecticide treated plots except in the rainy season. Higher percent yield losses were recorded on planting made in cool dry and hot dry 2 seasons in both years than rainy season with 8.24 to 40.17% yield losses. Commonly used insecticides on thrips were evaluated for their efficacy both in field and laboratory condition. Plots treated with spinosad, spinetoram, and imidacloprid resulted in better control, which was comparable higher marketable yield of onion both in cool and hot dry seasons. While, alphacypermethrin, diazinon, neem and λ-cyhalothrin insecticides treated plots poorly performed in both seasons and had lower marketable yield. Performances of dimethoate and profenofos were intermediate with the intermediate yield gains over the control under field condition. Laboratory bioassay confirmed that the poor efficacy of λ –cyhalothrin and diazinon under field conditions was due to thrips resistance to these insecticides. Higher level of resistance was recorded to λ – cyhalothrin and diazinon in Meki and Melkassa collected thrips populations, whereas no resistances to profenofos, dimethoate and spinetoram insecticides in all tested thrips populations were found. From insecticides resistance management studies, the sequential application of the more effective insecticides, imidacloprid and spinetoram, followed by less effective insecticide λ-cyhalothrin resulted in better control with higher economic return. Adding a penetrating surfactant improved the efficacy of insecticides compared to those without a penetrating surfactant in both seasons. Onion growers will continue to rely on insecticides as part of thrips management. Hence screening of new molecules periodically to identify effective insecticides and deploying a resistance management strategy through, among others, rotational application should form integral component in the integrated management of thrips (IPM) on onion. Studies on non-chemical control methods including cultural such as intercropping with other vegetables, host plant resistance should be conducted with the aim of strengthen thrips IPM
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    ECOLOGY OF THE AFRICAN MAIZE STALK BORER, Busseola fusca(Fuller) (LEPIDOPTERA: NOCTUIDAE) ON MAIZE (Zea maysL.) IN SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2020) ABRHAM TADDELE TEREFE
    Maize (Zea mays L.) is an important crop in sub-Saharan Africa (SSA) and the developing world. In Ethiopia, smallholderfarmers almost in allregions of the country dominantly produce maize. In sub- Saharan Africa, maize suffers from various biotic and abiotic constraints resulting in considerable yield loss. Among the biotic factors, insect pests particularly fall armyworm and stem borers are currently the most important pests of maize. Stem borers attack maize from seeding up to maturity. The sampling number and unit are important features of any empirical study in which the goal is to make inferences about a population. The number of sampling number and unit could vary with insects being sampled, their distribution patterns purpose of sampling, infestation pattern and economic considerations. Diapausing B. fusca larvae live in maize stem during unfavorable conditions. Environmental factors such as temperature influence the duration of B. fuscalarvae development, intensity and time of pest out break varied between localities. Information on pest incidence, injury and yield loss in the different agro-ecologies will facilitate strategic decisions with regard to selection of management practices. This study provides information on B. fusca, spatial distribution pattern, sampling size, phenology, population density and termination of diapauses larvae, crop injury, and yields losses in maize in southern Ethiopia. xxii During the study periods, B. fusca was present and injurious to maize in all study areas. The spatial distribution pattern of B. fuscawas determined by using four distribution indices namely, Taylor’s power law, Iwao’s mean crowding regression, Lloyd's mean crowding, and index of dispersion. At the mid-whorl stage of maize, the distribution of B. fusca infestation was aggregated and uniform at both silking and maturity stages. At silking as well as mid-whorl stage of maize, B. fuscalarvae exhibited an aggregated distribution pattern but, larvae at maturity stage and pupae in both silking and maturity stages of maize found randomly distributed. To set control options for B. fusca at its economic threshold level in maize farm, required sampling units was determined using four precision levels and Iwao’s patchiness regression. The required sample units to estimate 5 to 30% mean infestation of maize by B. fuscaranged from, 101 - 73, 45 - 32, 25-18 and 16 to 12 in 2015 and 104-76, 42-30, 26-19 and 17 to 12 in 2016, for 10%, 15% , 20% and 25% precision, respectively. For 10% infestation, which is considered as action threshold level for stem borers management on maize, 22 sampling units (660 plants) per hectare at the precision of 20% are required. The phenology of B. fusca was studied at Hawassa and Wolaita Sodo using sowing date and pheromone traps.Three generations of B. fusca per year were observed in southern Ethiopia between May and September. In Hawassa, the first moth flight which emerged from diapause larvae was started at mid-April in 2015 and mid of March, 2016. In Wolaita moth flight started at early May and April in 2015 and 2016, respectively. The potential of crop residues as sources of carry-over populations of the insect was also assessed. Flight period and population density of adult B. fuscafrom diapause state were significantly varied between seasons. Access to water did not enhance pupation during the diapause. Planting of maize at the beginning of April and May xxiii in Hawassa and Wolaita Sodo, respectively could be no longer suitable for oviposition and consumption by second-generation B. larvae. Population density of B. fuscalarvae and pupae were significantly different among years, locations and crop stages. Early and highest infestation of B. fuscaon maize was observed in Gurage followed by Wolaita as compared in Sidama Zone. Higher population density, injury variables and grain yield losses due to B. fuscaon maize were recorded from chemical treated plots as compared with untreated. Tunnel length, hole number, bored internode, larvae and pupae population had a negative effect on grain yield of maize. Increase in altitude positively affected the population density of B. fuscaand the resultant infestation and yield loss. Cultural practice such as crop diversification; disposal of crop residues after maturity can reduce initial establishment of stem borer infestation. Chemical control is one of the components of integrated pest management and should be used only when necessary combined with other management practices. This study provides information on the distribution, biology, pest status and yields losses due to B.fuscaon maize in southern Ethiopia.
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    EFFECT OF ALTERNATE FURROW IRRIGATION UNDER DIFFERENT MOISTURE REGIMES ON WATER USE EFFICIENCY, GROWTH, YIELD AND YIELD COMPONENTS OF COMMON BEAN (Phaseolus vulgaris L.) AT ALAGE, CENTRAL RIFT VALLEY OF ETHIOPIA
    (Hawassa University College of Agriculture, 2020) HUNDE HAYILE TOLOSA
    The farmers use common traditional irrigation methods which at times lead them to over irrigate, resulting in high water losses and low irrigation efficiency. Under such conditions understanding and application use of deficit and alternate furrow irrigation systems on crop production would enhance food security through improved water use. Thus, this study evaluated that the effect of alternate furrow irrigation under different moisture regimes on water use efficiency, growth, yield and yield components of common bean, during 2019 at Alage ATVET College. The experiment was laid out in factorial combination of two factors, following randomized complete block design in split plot arrangement with three blocks consisting twelve treatments; four irrigation levels (100% ETc (I 0 ), 80% ETc (I 1 ) 60% ETc (I 2 ) and 40% ETc (I 3) as the main plot and three irrigation methods (fixed alternate furrow irrigation (FAFI), variable alternate furrow irrigation (VAFI) and conventional furrow irrigation (CFI)) as the sub plot. This experiment showed that deficit irrigation (DI) and AFI significantly (P<0.01) affected days to physiological maturity, No of nodules plant -1 , grain yield, CWUE and IWUE. DI also significantly (P<0.05) influenced days to 50% flowering, stand count, plant height, No of branch, shoot dry weight, nodule dry weight, No of pods plant -1 , No of seeds pod -1 , pod length, 100-seed weight and HI. The interaction effect of DI and AFI also significantly (P<0.05) influenced the biological yield. Maximum (5.16 t ha -1 ) and minimum (3.38 t ha -1 ) biological yield was recorded at I0 and I 3 respectively with combination of FAFI and CFI, in that order. The highest grain yield was obtained under I 0 (2.45 t ha -1 ) and the lowest (1.34 t ha -1 ) was at I 3 . On the AFI, the maximum grain yield (2.11 t ha -1 ) was obtained under FAFI and the minimum (1.78 t ha -1 ) was under CFI. The uppermost CWUE (1.03 kg m -3 ) was recorded at I 3 followed by I 2 (0.92 kg m -3 ) and the smallest was at I0 (0.70 kg m -3 ) followed by I1 (0.77 kg m -3 ). The maximum CWUE (0.92 kg m -3 ) was recorded under FAFI followed by VAFI (0.86 kg m -3 ) and CFI (0.79 kg m -3 ). The partial budget analysis showed that I 0 , I 1 and I 2 gave marginal rate of return above the acceptable threshold value with additional investment advantages for the later. However, there was significant yield difference between I 0 and I 1 ; farmers can save 20% of the irrigation water in the expenditure of the reduced yield (0.33 ton ha -1 ). The highest net benefit was obtained from FAFI, thus the farmers option allows for FAFI at which high yield was recorded. Generally this analysis indicates that farmers at study area and related agro-ecology can use I 0 (100% ETc) in order to maximize their income from increased investment, but if there is lack of adequate irrigation water they can use I 1 (80% ETc) in order to save and use irrigation water more economically.
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    EFFECT OF INTRA-ROW SPACING ON GROWTH PERFORMANCE AND YIELD OF ONION (Allium cepa L.) VARIETIES AT MIZAN-AMAN, SOUTHWESTERN ETHIOPIA
    (Hawassa University College of Agriculture, 2016) DIRO BUZAYO TOLESSA
    Onion is among the most important vegetable crops produced in Mizan-Aman for home consumption and as income sources. However, lack of site based varieties and inappropriate planting density have been the major bottlenecks of onion production and productivity in the area, since there are no recommended spacing and variety for that area specifically. Rather farmers use to practice non-uniform plant spacing. This study was thus conducted at Mizan ATVET College in 2015/2016 with the objective of investigating the effect of intra-row spacing on growth performance and yield components of onion varieties. Three varieties (Adama Red, Bombay Red and Melkam) were evaluated under four different intra-row spacings (6, 10, 14 and 18 cm) and constant inter-row spacing of 20 cm by using randomized complete block design replicated three times. Data on days to maturity, growth performance and yield were recorded and subjected to analysis of variance using SAS version-9 software. Results of the study indicated that, intra-row spacing and variety had significant effect on plant height, leaf number per plant, leaf length, days to maturity, bulb diameter and length, bulb dry matter, total bulb yield as well as, marketable and unmarketable bulb yield. Closer intra-row spacings enhanced early maturity, while wider spacing delayed maturity. The maximum plant height, leaf length and leaf number were recorded in 10 cm intra-row spacing. Bombay Red variety was early maturing with the highest mean value for growth and yield parameters. It had the highest total bulb and marketable bulb yield than Melkam and Adama Red onion varieties specially when planted at 10 cm intra-row spacing. Bombay Red with 10 cm intra-row spacing also gave highest total bulb and marketable bulb yield. The correlation values also confirmed the significant and positive association between growth parameters and bulb yield. Based on the result of this study, higher onion yield with better quality was attained when Bombay Red variety was planted with 10 cm intra-row spacing under Mizan-Aman condition, for recommendation, although additional verification trial is needed to substantiate the result.
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    EFFECT OF NITROGEN SOURCES ON GROWTH, YIELD AND YIELD COMPONENTS OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES AT MESKAN, SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2019) MESERET SHIFA
    Common beans (Phaseolus vulgaris L.) are an important cash crop and protein source for farmers in many parts of Ethiopia. However, lacks of adequate information on the use of nitrogen source fertilizers are the major yield limiting factors for common bean production in the study area. Thus, the field experiment was conducted at Meskan District in 2018 cropping season to evaluate the effect of nitrogen sources on growth, yield and yield components of common bean varieties; and to identify economically appropriate combination of nitrogen sources that give optimum yield of major common bean varieties. Factors studied includes four common bean varieties (Hawassa Dume, Gegeba, Rori and Ibado) and four level of N sources (T1= Control; T2=Rhizobium inoculated; T3=46 kg N ha -1 , T4= 46 kg N ha -1 + Rhizobium inoculated). The treatments were arranged using randomized complete block design in factorial arrangements with three replications. Results revealed varietal differences on growth, yield and yield components. The highest pod number plant -1 (29.1), seed number pod -1 (5.6) and grain yield (2.7 t ha -1 ) were recorded from variety Hawassa Dume. Similarly, nitrogen sources had significant effect on growth, yield and yield components. Significantly, higher number of pods plant -1 (27.5), seeds pod -1 (5.6), and grain yield (2.7 t ha -1 ) were recorded from combined application of Rhizobium inoculation+46kg N ha -1 . There was significant interaction effect of N sources with varieties on nodule number, root dry weight and straw yield, where by the highest nodule number plant -1 (40), root dry weight (11.6 ) and straw yield (4.5 t ha -1 ) were recorded from combined application of Rhizobium strain HB-429 and 46 kg N ha -1 with variety Hawassa Dume except number of nodule plant -1 . Grain yield was positively and significantly correlated with phenological, growth, nodulation, yield and yield components except maturity date. Partial budget analysis of the study revealed that the highest net return (32,748 ETB ha -1 ) was obtained from Hawassa Dume variety with combined application of inoculation and 46 kg N ha -1 . Based on the results of this study, it can be concluded that combined application of Rhizobium inoculation with 46 kg N ha -1 found to be appropriate for common bean variety Hawassa Dume in the study area. However, the result of the present study need to be evaluated and reconfirmed on farmers field across season and areas in order to reach to a conclusive recommendation.
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    EFFECTS OF IRRIGATION FREQUENCY ON YIELD RESPONSE OF TWO COMMONLY GROWN TOMATO VARIETIES AT SHASHOGO WOREDA OF SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2020) GETAHUN LENDABO HELAMO
    Tomato is one of the most important vegetable crops widely grown in Ethiopia. It has many nutritional values and considered as high value cash crop in the country. However, its productivity among small scale growers is far below its potential. This is partly due to lack of access and awareness to improved cultivars and agronomic packages. The objective of the study was to identify the response of two tomato cultivars under different irrigation intervals and to determine the optimum irrigation interval. The design was randomized complete block with factorial arrangement of two varieties (variety Galilea and variety Roma VF) and three irrigation intervals (4, 6, and 8 days), with three replications. The experiment was conducted from December 2018 to April 2019, at Shashogo Woreda of Southern Ethiopia. A Data were recorded on Phenological, growth and yield characteristics. Varieties differed significantly (P<0.05) in all characteristics, except in number of primary branches and fruit set percentage. Variety Roma VF was earlier by 8 and 13 days in days to first harvest and days to 50% maturity respectively than variety Galilea. Whereas variety Galilea had significantly (P<0.05) higher number of secondary branches per plant, clusters per plant, flowers per cluster, fruits per cluster, fruits per plant, marketable fruit yield and total fruit yield than Roma VF. Similarly, irrigation interval of 6 days resulted in higher values in all these characters than irrigation interval of 4 and 8 days. The highest net benefit of ETB 682,584 was obtained from Variety Galilea under irrigation interval of 6 days. Hence, economically attractive combination is to grow variety Galilea under irrigation interval of 6 days. Growing Roma VF under irrigation interval of 6 days might be considered when earliness is needed to meet special market demands.
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    EFFECTS OF INOCULANT AND NPS FERTILIZER ON NODULATION, GROWTH AND YIELDS OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES AT BILATE ZURIA DISTRICT, SIDAMA REGIONAL STATE, ETHIOPIA
    (Hawassa University College of Agriculture, 2021) ENJAMO NAGESSO SATO
    Common bean (Phaseolus vulgaris L.) is a major grain legume grown and consumed in subSaharan Africa, including Ethiopia. It is the most important food legume, fodder and cover crop. However, its cultivation is globally constrained mainly by low soil fertility and lack of improved agronomic practices. Four common bean varieties (Ibaddo, Hawassa Dume, Omo95 and Nasir were studied under three nutrient conditions (0kg ha-1 ,100 kg ha-1 NPS, Inoculation by strain HB-429) in three replication of randomized complete block design (RCBD) during the 2019 main cropping season (June to September). The objectives of the study were investigating the response these varieties to the three nutrient statuses in nodulation, growth, yield and yield components and investigating the variety X inoculant/fertilizer interaction in the same traits. There were significant differences between the four varieties in all traits (nodulation, growth, yield and yield components). Ibaddo had the highest grain yield (2.81 t ha-1 ) while Hawassa Dume had the highest mean in yield (2.53 t ha-1 ). The three fertilizer levels also differed significantly in all traits, 100 kg ha-1 NPS giving the highest means in all traits, while the control (no fertilizer application) had the lowest mean in all traits. Inoculation by rhizobium strain had intermediate mean of all traits. The variety X inoculant/fertilizer interaction was also significant for all traits except for nodule dry weight, leaf area index, shoot dry weight, grain yield, above biological yield and harvest index. Omo95 variety had the lowest means in all traits except leaf area index, plant height, number of primary branches where ranks first, second and third. The highest net return (48325 ETB ha-1 ) with acceptable marginal rate return (5993%) was obtained from Hawassa Dume variety with 100 kg NPS ha-1 followed by Hawassa Dume variety with strain HB-429 inoculation had net return of 41337 ETB ha-1 with 4895% marginal rate of return. This implies that the grower on the study area can gate additional benefit of 59.93 and 48.95 ETB for every 1 ETB expense by growing Hawassa Dume with the application of 100 kg NPS ha-1 and strain HB-429 inoculation, in that order. Moreover, the highest net benefits (37763.5) with MRR (%) of 3084 ETB and net benefits of 3935ETB with MRR (%) obtained from variety Ibaddo and Nasir grown with strain HB-429 and 100 kg NPS ha-1 fertilizer application. Therefore, use of both Hawassa Dume and Nasir varieties with 100 kg NPS ha-1 and Hawassa Dume and Ibaddo grown with strain HB-429 found to be economically feasible at the study area. However, verification of the result on farmers’ fields across season and similar areas could be required before wide use of this study to put the recommendation in firm ground.
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    EFFECTS OF NUTRITION EDUCATION AND EGG-BASED DIET INTERVENTIONS ON DIETARY INTAKE, NUTRIENT ADEQUACY AND NUTRITIONAL STATUS AMONG PREGNANT WOMEN AND BIRTH OUTCOMES IN THE SIDAMA REGION, ETHIOPIA: A CLUSTER RANDOMIZED CONTROL TRIAL
    (Hawassa University College of Agriculture, 2025) KALEB MAYISSO RODAMO
    This dissertation comprises of nine concrete chapters and annexes pertinent for the study. The first chapter is all about introduction containging background, problem statement, significance of the study, hypothesis and objectives of the PhD research. The second chapter is review of literatures relevant to the study. The third chapter comprehensively describes materials and methods of the dissertation research work. The chapters from IV to VIII deal with the findings of each of the four specific obejctives of the dissertation research, while, chapter IX contains general discussions, conclusions and recommendations. Background: Pregnancy is a unique period in a woman's life, characterized by anatomical, physiological, and biochemical changes that affect nearly all organ systems. During this time, a diverse diet is essential to provide the necessary nutrients to meet the increased nutritional requirements. Pregnant women should consume healthy foods, including chicken eggs, fish, lean meats, fruits, vegetables, legumes, whole grains, and healthy fats those are rich sources of essential nutrients. Among these foods, chicken eggs are particularly valuable. They are a nutritionally complete and naturally nutrient-dense option, supplying easily digestible nutrients, including high-quality protein, vitamin D, vitamin A, vitamin B12, folate, choline, and longchain omega-3 fatty acids. Specific nutrients, such as dietary iron and folate, are crucial during pregnancy. They play significant roles in achieving optimal birth outcomes and supporting the rapid growth and development of the fetus. Folate is essential for DNA synthesis and methylation reactions, while iron is vital for the function of red blood cells (RBCs) and white blood cells (WBCs), as well as for tissue oxygenation and blood formation. The requirement for folate during the first 28 days after conception is increased by 0% to 50% and the requirement for iron increases during the second and third trimesters. Globally, 28.8% of pregnant women met the minimum dietary diversity for women (MDD-W) indicating that large number of these women suffer from inadequate intake of micronutrients. The burden of intake of inadequate micronutrient is obviously higher in developing countries, resulting in adverse pregnancy outcomes. In Ethiopia, diets are typically dominated by starchy cereals, root crops and legumes and often include little to no animal products, as well as fresh fruits and vegetables. Consequently, micronutrient malnutrition becomes highly prevalent in the v country. Prior research studies concluded that inadequate micronutrient intake among pregnant women is attributable to poor dietary practices, poor knowledge, and wrong perceptions. This in turn leads low body mass index (BMI), micronutrient deficiencies, subsequent suboptimal weight gain, and increased risk of poor birth outcomes like preterm birth (PTB) and low birth weight (LBW). Several literatures denote that nutrition education is a well-established intervention to enhance optimal dietary practices and is crucial to designing appropriate diet interventions. However, the effects of integrated nutrition education and egg base diet intervention on improving nutrient adequacy, nutritional status and optimal birth outcomes were not well studied in Ethiopia. Objectives: This study was designed to assess the validation of food variety score (FVS) and dietary diversity score (DDS) as proxy indicators of nutrient adequacy; to evaluate the effect of nutrition education on improving nutrient adequacy and serum levels of ferritin and folate, and to examine the effect of an egg-based diet intervention coupled with healthy dietary advice on nutrient adequacy and nutritional status among pregnant women. The study also intended to determine adequate diet during pregnancy is associated with reduced risk of adverse birth outcomes and low serum ferritin and folate levels. Materials and Methods: This study employed a community-based cross-sectional, cluster randomized controlled trial (cRCT) and prospective cohort studies designs. The study was conducted on randomly selected pregnant women from two districts of Northern Zone, Sidama Region, Ethiopia. The women were selected at first trimester. A multiple-pass 24-hour dietary recall method with standard 10-food groups was used to estimate the DDS and FVS. Nutrient adequacy ratio (NAR) was estimated using the mean adequacy ratio (MAR) of the micronutrients. Receiver operating characteristic (ROC) curve analysis that gives maximum sensitivity and specificity was employed to define the cutoff points of DDS and FVS. Additionally, randomly selected pregnant women were recruited in a ratio of 1:1 of intervention and control group for cRCT. Nutrition education intervention (NEI) was delivered using health belief model (HBM) theory for the intervention groups, while the standard health care was given for control groups. Between group differences in mean scores on DDS, nutrient intake, nutrient adequacy and serum ferritin and folate levels were tested using an independent samples t-test. A linear mixed model (LMM) vi was used to evaluate the effect of interventions on adequacy and serum levels of the ferritin and folate accounting for the clustering effect. In egg-based diet intervention trial, chicken and nutrition messages were provided for intervention group at the health post for 12 weeks in two sessions per week, whereas standard healthcare was given to the control group. Between groups differences in mean scores for nutrient adequacy and nutritional status indicators were tested using Chi-square and independent samples t-test in addition to make alnalysis using LLM accounting for the clustering effect. For the prospective cohort study, a total of 438 pregnant women were recruited in the first trimester. The maternal weight and height were measured before 12 weeks‘ gestation. Prepregnancy BMI was calculated in the first trimester, and maternal weight and mid-upper arm circumferences (MUAC) were measured subsequently every trimester until delivery. Serum ferritin and folate levels were measured at first study visit in 12th week of gestation. Pearson‘s correlation test was employed to determine significant relationships between maternal anthropometric indicators. A poisson regression analysis with a robust variance estimate was used to identify predictors of PTB and LBW. Results: Chapter IV presents results on the validation of FVS and DDS as proxy indicators of nutrient adequacy. It was found that MDD-W showed a positive correlation (ρ = 0.159, 95% CI: 0.065-0.250) (p = 0.001), and had good predictive ability (AUC = 0.839, 95% CI: 0.80 to 0.88) (p < 0.001) of MAR of micronutrient. The sensitivity and specificity of the MDD-W in the ≥5 food group‘s standard cutoff were 69.9% and 5.3%, respectively. Chapter V shows results on effect of nutrition education on nutrient adequacy and serum levels of ferritin and folate during pregnancy. A significant difference was observed in mean serum ferritin and folate levels between the intervention and control groups (p < 0.001). NEI was positively associated with adequate intake of folate (β = 28.52, 95% CI: 14.671, 42.367, p< 0.001) and MAR (β = 344.019, 95% CI: 275.965, 412.073, p < 0.001). The nutrient intakes vii varied significantly among the study participating pregnant women. For instance, calcium and vitamin D were very low (1.97-19.9%), vitamin B12 42.1%, protein, folate, and vitamin A were moderate (64-80.6%), while iron intake was high, 95.4%. The MAR of individual nutrients were increased from 20.00 ± 0.0 to 161.36 ± 73.58 after introduction ofegg-based diet (p < 0.001). Chapter VII presents results on maternal consumption of inadequate diet during pregnancy are associated with an increased risk of low serum levels of essential micronutrients and adverse birth outcomes. The average gestational age at birth was 37.50 weeks and a low birth weight accounted for 37.3%. The prevalence of preterm birth was higher among women who had an inadequate DDS (AOR=0.52, 95% CI: 0.301, 0.890), consumed dietary folate below recommended level (AOR=1.48, 95% CI: 0.741, 2.932), undernourished women (AOR=1.105, 95% CI: 0.98, 1.24), a women with serum folate level < 23 cm were significant predictors of PTB. Similarly, being underweight, having short stature, malnutrition, experiencing PTB, low total GWG, and low serum ferritin levels were significant predictors of LBW. To address pregnancy-related malnutrition caused by micronutrient deficiencies, it is essential to integrate nutrition behavior change communication with egg-based interventions. Healthcare professionals should actively promote egg consumption during pregnancy through targeted communication efforts directed at families and communities. Enhanced public health initiatives that include nutrition support and anthropometric monitoring during antenatal care are crucial for improving birth outcomes.
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    EFFECTS OF NUTRITION EDUCATION AND EGG-BASED DIET INTERVENTIONS ON DIETARY INTAKE, NUTRIENT ADEQUACY AND NUTRITIONAL STATUS AMONG PREGNANT WOMEN AND BIRTH OUTCOMES IN THE SIDAMA REGION, ETHIOPIA: A CLUSTER RANDOMIZED CONTROL TRIAL
    (Hawassa University College of Agriculture, 2025) KALEB MAYISSO RODAMO
    This dissertation comprises of nine concrete chapters and annexes pertinent for the study. The first chapter is all about introduction containging background, problem statement, significance of the study, hypothesis and objectives of the PhD research. The second chapter is review of literatures relevant to the study. The third chapter comprehensively describes materials and methods of the dissertation research work. The chapters from IV to VIII deal with the findings of each of the four specific obejctives of the dissertation research, while, chapter IX contains general discussions, conclusions and recommendations. Background: Pregnancy is a unique period in a woman's life, characterized by anatomical, physiological, and biochemical changes that affect nearly all organ systems. During this time, a diverse diet is essential to provide the necessary nutrients to meet the increased nutritional requirements. Pregnant women should consume healthy foods, including chicken eggs, fish, lean meats, fruits, vegetables, legumes, whole grains, and healthy fats those are rich sources of essential nutrients. Among these foods, chicken eggs are particularly valuable. They are a nutritionally complete and naturally nutrient-dense option, supplying easily digestible nutrients, including high-quality protein, vitamin D, vitamin A, vitamin B12, folate, choline, and longchain omega-3 fatty acids. Specific nutrients, such as dietary iron and folate, are crucial during pregnancy. They play significant roles in achieving optimal birth outcomes and supporting the rapid growth and development of the fetus. Folate is essential for DNA synthesis and methylation reactions, while iron is vital for the function of red blood cells (RBCs) and white blood cells (WBCs), as well as for tissue oxygenation and blood formation. The requirement for folate during the first 28 days after conception is increased by 0% to 50% and the requirement for iron increases during the second and third trimesters. Globally, 28.8% of pregnant women met the minimum dietary diversity for women (MDD-W) indicating that large number of these women suffer from inadequate intake of micronutrients. The burden of intake of inadequate micronutrient is obviously higher in developing countries, resulting in adverse pregnancy outcomes. In Ethiopia, diets are typically dominated by starchy cereals, root crops and legumes and often include little to no animal products, as well as fresh fruits and vegetables. Consequently, micronutrient malnutrition becomes highly prevalent in the v country. Prior research studies concluded that inadequate micronutrient intake among pregnant women is attributable to poor dietary practices, poor knowledge, and wrong perceptions. This in turn leads low body mass index (BMI), micronutrient deficiencies, subsequent suboptimal weight gain, and increased risk of poor birth outcomes like preterm birth (PTB) and low birth weight (LBW). Several literatures denote that nutrition education is a well-established intervention to enhance optimal dietary practices and is crucial to designing appropriate diet interventions. However, the effects of integrated nutrition education and egg base diet intervention on improving nutrient adequacy, nutritional status and optimal birth outcomes were not well studied in Ethiopia. Objectives: This study was designed to assess the validation of food variety score (FVS) and dietary diversity score (DDS) as proxy indicators of nutrient adequacy; to evaluate the effect of nutrition education on improving nutrient adequacy and serum levels of ferritin and folate, and to examine the effect of an egg-based diet intervention coupled with healthy dietary advice on nutrient adequacy and nutritional status among pregnant women. The study also intended to determine adequate diet during pregnancy is associated with reduced risk of adverse birth outcomes and low serum ferritin and folate levels. Materials and Methods: This study employed a community-based cross-sectional, cluster randomized controlled trial (cRCT) and prospective cohort studies designs. The study was conducted on randomly selected pregnant women from two districts of Northern Zone, Sidama Region, Ethiopia. The women were selected at first trimester. A multiple-pass 24-hour dietary recall method with standard 10-food groups was used to estimate the DDS and FVS. Nutrient adequacy ratio (NAR) was estimated using the mean adequacy ratio (MAR) of the micronutrients. Receiver operating characteristic (ROC) curve analysis that gives maximum sensitivity and specificity was employed to define the cutoff points of DDS and FVS. Additionally, randomly selected pregnant women were recruited in a ratio of 1:1 of intervention and control group for cRCT. Nutrition education intervention (NEI) was delivered using health belief model (HBM) theory for the intervention groups, while the standard health care was given for control groups. Between group differences in mean scores on DDS, nutrient intake, nutrient adequacy and serum ferritin and folate levels were tested using an independent samples t-test. A linear mixed model (LMM) vi was used to evaluate the effect of interventions on adequacy and serum levels of the ferritin and folate accounting for the clustering effect. In egg-based diet intervention trial, chicken and nutrition messages were provided for intervention group at the health post for 12 weeks in two sessions per week, whereas standard healthcare was given to the control group. Between groups differences in mean scores for nutrient adequacy and nutritional status indicators were tested using Chi-square and independent samples t-test in addition to make alnalysis using LLM accounting for the clustering effect. For the prospective cohort study, a total of 438 pregnant women were recruited in the first trimester. The maternal weight and height were measured before 12 weeks‘ gestation. Prepregnancy BMI was calculated in the first trimester, and maternal weight and mid-upper arm circumferences (MUAC) were measured subsequently every trimester until delivery. Serum ferritin and folate levels were measured at first study visit in 12th week of gestation. Pearson‘s correlation test was employed to determine significant relationships between maternal anthropometric indicators. A poisson regression analysis with a robust variance estimate was used to identify predictors of PTB and LBW. Results: Chapter IV presents results on the validation of FVS and DDS as proxy indicators of nutrient adequacy. It was found that MDD-W showed a positive correlation (ρ = 0.159, 95% CI: 0.065-0.250) (p = 0.001), and had good predictive ability (AUC = 0.839, 95% CI: 0.80 to 0.88) (p < 0.001) of MAR of micronutrient. The sensitivity and specificity of the MDD-W in the ≥5 food group‘s standard cutoff were 69.9% and 5.3%, respectively. Chapter V shows results on effect of nutrition education on nutrient adequacy and serum levels of ferritin and folate during pregnancy. A significant difference was observed in mean serum ferritin and folate levels between the intervention and control groups (p < 0.001). NEI was positively associated with adequate intake of folate (β = 28.52, 95% CI: 14.671, 42.367, p<0.001), iron (β = 9.320, 95% CI: 3.119, 15.536, P = 0.003), serum levels of ferritin (β = 12.107, 95% CI: 4.406, 19.809, p = 0.004), and folate (β = 2.263, 95% CI: 1.852, 2.675, p = 0.001). Chapter VI contains results on the effect of an egg-based diet intervention coupled with healthy dietary advice on nutrient adequacy and nutritional status among pregnant women. It was found that nutrition intervention was positively associated with MUAC (β =0.54, 95% CI: 0.281, 0.782, p < 0.001) and MAR (β = 344.019, 95% CI: 275.965, 412.073, p < 0.001). The nutrient intakes vii varied significantly among the study participating pregnant women. For instance, calcium and vitamin D were very low (1.97-19.9%), vitamin B12 42.1%, protein, folate, and vitamin A were moderate (64-80.6%), while iron intake was high, 95.4%. The MAR of individual nutrients were increased from 20.00 ± 0.0 to 161.36 ± 73.58 after introduction ofegg-based diet (p < 0.001). Chapter VII presents results on maternal consumption of inadequate diet during pregnancy are associated with an increased risk of low serum levels of essential micronutrients and adverse birth outcomes. The average gestational age at birth was 37.50 weeks and a low birth weight accounted for 37.3%. The prevalence of preterm birth was higher among women who had an inadequate DDS (AOR=0.52, 95% CI: 0.301, 0.890), consumed dietary folate below recommended level (AOR=1.48, 95% CI: 0.741, 2.932), undernourished women (AOR=1.105, 95% CI: 0.98, 1.24), a women with serum folate level <2.6–15 µg/L (AOR=0.760, 95% CI: 0.552–0.933). The prevalence of low birth weight was higher among women with underweight (AOR=1.126, 95% CI: 1.003, 1.23), short stature (AOR=11.341, 95% CI: 1.097, 11.421), under nutrition (AOR=1.141, 95% CI: 1.025, 1.270), intake of dietary iron bellow <27(EAR) (AOR=6.348, 95% CI: 4.144-9.724), serum ferritin of below <15 µg/L (AOR=1.588, 95% CI: 1.008, 2.502), and inadequate DDS (AOR=2.148, 95% CI: 1.778-2.596). Conclusions: The study demonstrated that NEI improved daily iron and folate intake as well as serum levels in pregnant women. Additionally, interventions that included egg-based dietary advice positively impacted nutrient adequacy and overall nutritional status. However, despite these benefits, there were still high rates of PTB and LBW. Factors such as low DDS, insufficient folate intake and serum levels, inadequate weight gain (less than 11.5-16 kg), and low MUAC < 23 cm were significant predictors of PTB. Similarly, being underweight, having short stature, malnutrition, experiencing PTB, low total GWG, and low serum ferritin levels were significant predictors of LBW. To address pregnancy-related malnutrition caused by micronutrient deficiencies, it is essential to integrate nutrition behavior change communication with egg-based interventions. Healthcare professionals should actively promote egg consumption during pregnancy through targeted communication efforts directed at families and communities. Enhanced public health initiatives that include nutrition support and anthropometric monitoring during antenatal care are crucial for improving birth outcomes.
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    EFFECTS OF SEED AND BLENDED FERTILIZER RATES ON YIELD AND YIELD COMPONENTS OF BREAD WHEAT (Triticum aestivum L.) AT DUNA DISTRICT, HADIYA ZONE, SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2021) BIRHANU ARASO LATEBO
    Bread wheat is one of the major staple and strategic food security crops in Ethiopia. However, the production and productivity of the crop are far below the global average. This is partly due to the low soil fertility and poor crop management practices including the use of suboptimal seed and fertilizers rates. Hence, this experiment was conducted to assess the effect of seed and blended fertilizer (NPSB) rates on the growth and yield of bread wheat; and determine the economically feasible seed and NPSB fertilizers rates for wheat production in the study area. Treatments consisting of four levels of seed rates (80, 100, 120, and 140 kg ha1 ) and four levels of blended NPSB fertilizers (0, 50, 100, and 150 kg ha-1 ), was laid out in a Randomized Complete Block design in factorial combinations with four replications. Data were collected on phenology, growth, and yield parameters and subjected to ANOVA using SAS software version 9.0. Results revealed that the days to heading, days to physiological maturity, plant height, spike length, thousand kernels weight, straw yield, and above-ground dry biomass were significantly (p<0.01) affected by the main effect of seed and NPSB fertilizer rates. The longest days to heading, days to physiological maturity, and spike length were recorded at 80 kg ha-1 seed rate. The maximum thousand kernels weight was obtained from the 120 kg ha-1 seed rate. However, the tallest plant height, straw yield, and above-ground dry biomass were recorded at 140 kg ha-1 seed rate. The tallest plant height, spike length, number of kernels spike-1 , thousand kernels weight, straw yield, and above-ground dry biomass were obtained from 150 kg ha-1 NPSB rate. However, the longest days to heading and days to physiological maturity were recorded from the control. The treatment interactions significantly (p<0.05) affected the number of total tillers, number of productive tillers, grain yield, and harvest index. The highest number of total and productive tillers were recorded at the combination of 140 kg ha-1 seed rate with 150 kg ha-1 NPSB fertilizer rate. However, the highest grain yield and harvest index were recorded from the combination of 120 kg ha-1 seed and 150 kg ha-1 NPSB fertilizer rates. Grain yield was strongly and positively correlated with plant height, number of total tillers, number of productive tillers, number of kernel spike-1 and above-ground dry biomass. As per the partial budget analysis the highest net benefit of 81,914 ETB ha-1 was obtained from the combined application of 120 kg ha-1 seed rate with 150 kg ha-1 NPSB fertilizer with a MRR of 988.2%. Hence, the combination of 120 kg ha-1 seed and 150 kg ha-1 NPSB fertilizer rates are profitable than other combinations, therefore this combination can be recommended for wheat production in the Duna District and areas sharing similar agro-ecology.
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    EFFECTS OF SEEDLING AGE AND VARYING RATES OF PHOSPHORUS ON GROWTH AND YIELD PERFORMANCE OF ONION (Allium cepa L.) UNDER IRRIGATION IN ALAGE DISTRICT, CENTRAL RIFT VALLEY OF ETHIOPIA
    (Hawassa University College of Agriculture, 2017) TILAYE ANBES WASIE
    Onion is an important cultivated crop used as a condiment as well as a source of income for many farmers in Ethiopia. However, the yield of the crop is constrained by a number of factors among which inappropriate transplanting age and poor fertilizer management practices are important factors. Therefore, a field experiment was conducted at Alage Agricultural Technical and Vocational Education and Training College (Alage) campus, Central Rift Valley of Ethiopia, during 2016/17 season to determine the effect of seedling age and phosphorus rate on growth and yield performance of onion. The treatments comprised of three seedling ages (6, 7 and 8 weeks of seedling age) and four phosphorus rates (0, 46, 92 and 138 kg ha -1 ). The experiment was laid out in randomized complete block design (RCBD) with four replications. The result showed that seedling age and phosphorus rate significantly affected plant height, leaf length, days to maturity, fresh bulb weight, bulb dry matter fraction, bulb length, marketable bulb yield, total bulb yield, harvest index, medium and large sized bulb yield. Among these parameters, marketable bulb yield, total bulb yield and harvest index were also significantly affected by the interaction of seedling age and phosphorus rate. On the other hand, leaf number per plant, bulb diameter, bulb dry weight, total biomass yield, small bulb sized yield, under sized bulb yield and unmarketable bulb yield were only influenced by the main effect of phosphorus rate. In this study result, transplanting at 8 weeks of seedling age fertilized with 138 kg P 2O5 ha -1 recorded the highest total bulb yield (50.6 t ha -1 ) and marketable bulb yield (48.33 t ha -1 ), but no significant difference was showed with that obtained at 92 kg P 2O5 ha -1 with the same seedling age. Treatment combinations of seedling age at 6 weeks and no P (control) produced the lowest amounts of total bulb yield (24.27 t ha -1 ) and marketable bulb yield (21.63 t ha -1 ). The partial budget analysis revealed that the highest net benefit with low cost of production was obtained in response to the application of 92 kg P2O5 ha -1 and the transplanting age of 8 weeks. The marginal rate of return for this treatment was 5657% which is found to be economically feasible for producing onion in the study area.
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    EVALUATION OF THE GROWTH, PHYSIOLOGICAL AND YIELD PERFORMANCE OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES UNDER SOIL MOISTURE STRESS CONDTITIONS
    (Hawassa University College of Agriculture, 2021) MITIKE MULATU ALEMU
    Common bean is one of the most important food crops, with significant economic importance and it is suitable for food security due to its short growing cycle and adaptability to different cropping systems. However, its average yield reported at the national levels remains far below the potential due to various biotic and abiotic constraints among which is moisture stress. The study was conducted to evaluate the effects of moisture stress on growth, physiological and yield and yield components of common bean varieties. A pot experiment was conducted under lath house from June to September 2020, at Hawassa University College of agriculture. Seven common bean varieties viz. Gofta, Fedis, Awash-2, Tinike, Awash-1, Dursitu and Nasir were grown under three irrigation intervals/moisture level viz. watered every day (waterlogging stress), watered every four days (control) and watered every eight days (moisture deficit), in factorial combination using Completely Randomized Design with three replications. The main and interaction effects were significant on Days to flowering, physiological maturity, plant height, leaf number, Shoot fresh weight, Shoot dry weight, root length, Transpiration rate, photosynthesis rate, stomata conductance, water use efficiency, stomata number, stomata width and length, chlorophyll concentration, Proline content, Length of pod, pods plant-1 , seeds pod-1 and yield gram-1 plant-1 . However, branch number and Internode length, leaf relative water content, hundred seed weight, total biomass (biological yield), straw yield and harvest index were significantly affected by main effects of moisture levels and varieties but chlorophyll fluorescence was affected by only moisture levels. Moisture stress significantly reduced growth, stomata conductance, photosynthesis, yield and yield components. Varieties performed differently in response to moisture stress. The highest hundred seed weight, biological yield, and straw yield were recorded for Awash-1 and Tinike varieties, respectively in control moisture stress. The highest yield was recorded from the variety Awash-1 and Gofta irrigated every 4 days of interval ( control); whereas the lowest yield was recorded from Fedis variety treated with daily irrigation ( water logging). Also Awash - 2 varieties is relatively better compared to the Tinike, Fedis, Dursitu and Nasir on yield and yield parameters at all moisture levels. Varieties Gofta, Awash-2 and Awash-1 appeared to be moisture stress-tolerant duo to maximum proline accumulation mechanism, high water use efficiency, low transpiration rate and better photosynthesis and yield performance by using different mechanisms.
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    GENETIC CONSIDERATIONS AND MOLECULAR TOOLS FOR FOREST CONSERVATION AND RESTORATION: EMPHASIZING Afrocarpus gracilior (Pilg.) C. N. Page IN SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2025) NIGUSSU BEGASHAW ABATE
    Large-scale tree planting initiatives and ambitious global forest restoration commitments aim to mitigate the impacts of deforestation. Ensuring the long-term success of these efforts requires integrating genetic principles into restoration practices. This study aims to enhance forest conservation and restoration by generating molecular genetic insights and tools, using Afrocarpus gracilior, a native dioecious conifer, as a case study. Specifically, it evaluates the extent to which genetic principles are considered in species selection and seed procurement, investigates the genetic consequences of population fragmentation, assesses inbreeding depression, and develops molecular markers for early sex identification. To achieve these objectives, the study combined a survey of tree nurseries and seed vendors with genetic analyses using DArTseq-generated SNPs to assess genetic diversity and population differentiation. Additionally, in vitro germination and early progeny growth experiments were conducted to evaluate inbreeding depression, while RAPD markers and bulk-segregant analysis were used for sex identification. Assessment of genetic considerations in forest restoration revealed that crucial guidelines are frequently overlooked in species selection and seed procurement, with exotic species dominating while native species remain underrepresented. Seed collection practices often neglect essential measures for preserving genetic diversity, heightening the risk of inbreeding and reducing adaptive potential. Notably, 84% of seed collectors sourced seeds indiscriminately, 87% of nurseries received seeds without passport data, 97% of seed collectors failed to meet the minimum required number of mother trees per collection event, and 88% ignored recommended spacing between selected mother trees. Genetic diversity analysis of A. gracilior populations showed overall low genetic diversity (Hₑ < 0.1), with progeny cohorts exhibiting even lower diversity than adults. Progeny from isolated or few mother trees had the lowest genetic diversity, indicating heightened genetic drift and inbreeding. In contrast, sacred forests and larger remnant patches harbored relatively higher genetic diversity, indicating their importance for in situ conservation. Further assessment of inbreeding depression in fragmented populations revealed significant reductions in progeny fitness, including 53% lower germination rates, 33% reduced acclimatization, 30% and 41% slower growth in diameter and height, respectively, and a 62% increase in leaf scorch. Screening for sex-linked markers identified OPD-18 (5’-GAGAGCCAAC-3’) as a 600 bp male-specific RAPD marker, providing a foundation for early sex determination in A. gracilior. xix The results highlight the critical role of genetic considerations in successful forest restoration, yet current practices often overlook these principles, increasing the risk of inbreeding and loss of adaptive potential. Very low genetic diversity was recorded across all fragmented populations of A. gracilior, with progeny from isolated or few mother trees exhibiting the lowest genetic diversity and significantly reduced fitness. These findings indicate increased genetic erosion, drift, and inbreeding depression, jeopardizing the species’ long-term survival. Recommendations include establishing and enforcing policies that promote the use of native species and genetic standards in seed procurement; sourcing seeds from diverse, larger populations; prioritizing in situ conservation of sacred sites; and further developing robust molecular markers to improve the reliability of early-stage sex identification in the dioecious A. gracilior. Implementing these measures would enhance the long-term success of restoration initiatives, fostering resilient forest ecosystems that support biodiversity conservation and sustainable land management.
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    GENETIC DIVERSITY AND DROUGHT TOLERANCE IN ETHIOPIAN DURUM WHEAT (Triticum turgidum subsp. durum) GENOTYPES
    (Hawassa University College of Agriculture, 2025) BANTEWALU HAILEKIDAN DUKAMO
    Durum wheat (Triticum turgidum subsp. durum), the second most widely cultivated wheat species after common wheat, plays a crucial role in global food security. Ethiopia, recognized as a secondary center of origin and diversity for durum wheat, harbors a broad and unique genetic reservoir well adapted to diverse agroecological conditions. However, productivity remains low due to limited availability of improved, drought-tolerant varieties and insufficient exploitation of genetic diversity. This study aimed to characterize Ethiopian durum wheat landraces, identify drought-tolerant genotypes, and assess their potential for breeding programs by integrating field, greenhouse, and molecular analyses. The research involved three interlinked components. The first was a field experiment conducted at Dera (1500 masl) and Debrezeit (1920 masl), where 104 genotypes (100 landraces and 4 checks) were evaluated under drought-stressed and non-stressed conditions using an augmented design. Thirteen agronomic traits related to yield, phenology, and canopy status were measured across both environments. Additional data were collected from an extended growing season, and drought tolerance was assessed using various indices. ANOVA, correlation, principal component analysis (PCA), and clustering were used to identify promising genotypes and trait associations. The second component involved a greenhouse experiment at Hawassa University using 20 top-performing landraces and four checks selected from the field study. Genotypes were grown under well-watered (70% field capacity) and drought-stressed (35% field capacity) conditions in a completely randomized design with three replications. Data on morphological, physiological, and biochemical traits were collected, including grain yield, relative leaf water content (RLWC), chlorophyll content, canopy temperature, and proline accumulation. Statistical analyses were employed to evaluate drought responses, including correlation, PCA, cluster, and path coefficient analysis. The third component focused on the molecular characterization of 94 genotypes (86 landraces and 8 improved varieties) using SNP markers generated through DArTSeq technology. Genotyping was performed by SEQART AFRICA, producing 17,092 highquality SNPs. Genetic diversity, population structure, and linkage disequilibrium (LD) were analyzed to assess genome-wide variation and support genotype selection. Field results revealed significant genetic variation among landraces across all measured traits. Genotypes ETDW/15DZ23, 34493, ETDW/15DZ4, 34522, MCD3-14, 34217, and 31831 demonstrated superior grain yield under stress and non-stressed conditions. High heritability (h²b = 32.84–97.87) and genetic advance estimates for traits such as spike length, kernel number per spike, and tiller number indicated strong potential for selection. Drought indices, including stress tolerance index (STI), mean productivity (MP), and yield stability index (YSI), identified ETDW/15DZ23, 34493, and ETDW/15DZ4 as topperforming, drought-resilient genotypes. Strong positive correlations (r = 0.88) between grain yields under stressed and non-stressed conditions further confirmed their stability and xviii adaptability. The greenhouse experiment revealed significant effects of genotype, treatment, and their interaction (P<0.001) for most traits. Under stress, grain yield decreased by up to 68%, RLWC dropped from 93.07% to 44.91%, and proline content increased markedly, indicating drought response. Cluster analysis grouped genotypes based on resilience, with one cluster showing the highest yield (5.99 t/ha) under well-watered conditions, while another showed superior RLWC (65.80%) and yield (2.90 t/ha) under stress. Path analysis underscored the importance of RLWC, proline, and chlorophyll content in drought tolerance. Molecular analysis revealed 14,136 informative SNPs distributed across the A and B genomes, with chromosome 2B having the highest marker density. Population structure analysis indicated considerable variation within and among landraces, with AMOVA showing 51.75% of genetic variation within populations and 48.15% within individuals. The genome-wide LD decay threshold was 4.58 Mbp, with the highest LD values on chromosome 4B. Average polymorphic information content (PIC) and gene diversity values were moderate, indicating a diverse and informative marker set for future breeding applications. This study highlights the significant phenotypic and genotypic diversity within Ethiopian durum wheat and identifies promising genotypes for drought tolerance and yield stability. The integration of field performance, physiological traits, and genomic data provides a robust platform for developing improved durum wheat cultivars. These findings support the use of landraces in breeding programs targeting climate resilience and food security. Future work should focus on multi-environment trials, genome-wide association studies (GWAS), and marker-assisted selection to accelerate genetic improvement and enhance drought tolerance in Ethiopian durum wheat
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    GENETIC DIVERSITY AND GENOME-WIDE ASSOCIATION MAPPING IN TETRAPLOID WHEAT (TRITICUM TURGIDUM SPP.) GERMPLASM OF ETHIOPIA
    (Hawassa University College of Agriculture, 2024) MIHERETU FUFA GELETA
    Genetic Diversity and Genome-Wide Association Mapping in Tetraploid Wheat (Triticum turgidum spp.) Germplasm of Ethiopia PhD Dissertation Miheretu Fufa Geleta Hawassa University, 2024 Ethiopia is a center of diversity for Tetraploid wheat (Triticum turgidum spp.) species, which hold ample genetic variation; howevr, the country remains a net importer of wheat due to a huge gap between production and consumption. The present study was aimed to investigate the extent and pattern of diversity based on phenotypic traits, grain quality traits, and molecular markers; and Genome-Wide association studies for phenotypic and grain quality traits. Diversity assessment at the entire genotypes based on the qualitative traits revealed intermediate (0.60±0.01) diversity and high diversity concerning glum color (0.78), spike density (0.61), and seed color (0.86); however, low diversity for awndness (0.15). All qualitative traits showed highly significant (p<0.001) variation across regions of collections and altitudinal classes; however, only spike density was significantly (p<0.05) different at the species level. Within populations diversity was higher than between population diversity. Analysis of variance based on the quantitative traits revealed highly significant variation (p<0.001) among genotypes and for genotype by location interaction in all traits except for the number of effective tillers per plant. The observed mean and range values of the phenotypic traits revealed high variability in the accessions. Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) values were high for grain yield, biomass yield, and harvest index. The estimates of heritability (H2 ) ranged from 41.78 to 84.62 % respectively for grain yield and the number of seeds per spikelet. High genetic advance as a percentage of mean was observed for the number of seeds per spikelet, the number of effective tillers per plant, grain yield, biomass yield, and harvest index. The number of seeds per spikelet gave a high value of genetic advance and heritability implying high genetic gain from its selection. Grain yield showed a highly significant (p<0.001) negative correlation with days to booting and days to maturity and a positive correlation with the remaining quantitative traits. The combined ANOVA based on the grain quality traits revealed a highly significant variation (p < 0.001) among the genotypes and for genotype by location interaction for all traits. The genotypes showed a wide range in their thousand kernel weight, zeleny index, and vitreousness percentage. Grain yield and protein content, respectively, showed high and low values of PCV and GCV; however, an intermediate value of PCV and GCV was observed for gluten content and thousand kernel weight. Zeleny index and vitreousness percentage showed high PCV and intermediate GCV; however, protein content showed low PCV and GCV. The estimate of broad sense heritability (H2 ) ranged from 33.57 % for vitreousness percentage to 66.36 % for zeleny index. The values of genetic advance and GAM observed were respectively high for grain yield (31.94, 26.91) and zeleny index (31.89, 29.34); intermediate for thousand kernel weight (18.27, 16.59), gluten content (15.70, 13.55), and vitreousness percentage (15.75, 12.97) and low for protein content (9.81, 8.44). Grain yield showed a highly significant positive correlation with thousand kernel weight (0.43***) and vitreousness percentage (0.19**) and positive correlation, but not significant, with protein content, gluten content, and zeleny index. xxi Principal component analysis (PCA) based on phenotypic traits showed that the first and second principal components (PC) respectively accounted for 19.74% and 15.96 of the total variation in the entire genotypes, respectively. The first five principal components combined explained 61.21 % based on the entire genotypes. On the other hand, PCA of grain quality traits showed that the first and second PCs respectively accounted for 34.12 % and 20.65% of the total variation and the three PCs explained 69.11% of the total variation in the entire genotypes. Eleven landraces and eleven improved varieties were top performing based on their grain yield and grain quality traits. Clustering based on phenotypic traits and grain quality traits respectively grouped the whole genotypes into seven and six clusters without clear regional grouping. Furthermore, the genetic diversity and population structure were investigated for the study panel as well as the landraces based on 10349 DArTSeq markers distributed across A and B genomes. The study panel was clustered into two populations: pop1 and pop2 respectively comprising 150 landraces and 3 released varieties and 19 released varieties and 12 landraces pop2 being more diverse than pop1; likewise, landraces were clustered into two subgroups. Analysis of molecular variance (AMOVA) revealed highly significant (P<0.001) variation between populations and within populations the latter being higher than the former implying that more attention should be given to individual accessions within populations to explore the existing genetic diversity. Little to moderate genetic differentiation (Fst) was respectively reported for the landraces (0.028) and the study panel (0.117) implying no significant differentiation among populations. High gene flow (1.297-8.818) was recorded based on DArTSeq markers at all level. PCA based on DArTSeq markers grouped the released varieties and the landraces separately in the study panel; however, PCA of the landraces did not show clear groupings. 127 genotypes were reported to have one or more private alleles at 755 loci, an indication of key adaptive genes at these loci to be exploited in breeding programs. In conclusion, high genetic diversity was detected in Ethiopian tetraploid wheat germplasm, which could be utilized for future wheat breeding programs. The landraces ETW115 and ETW135 and the released varieties (Tesfaye and Bekelcha) could be used in a crossing program owing to their maximum genetic distance. Analysis of genome-wide LD in the whole collection showed that 44.98% of the total marker pairs had a significant LD (p<0.01) with a mean r2 value of 0.129791. 44.59% (18668) and 8.62% (3609) of the significant marker pairs showed r2 values above 0.2 and 0.7, respectively, indicating a higher level of LD in the genome. The number of significant marker pairs observed was higher in the B genome (24.44%) than the A genome (20.54%). GWAS identified 44 SNPs, two of which are pleiotropic, across chromosome 1A, 2A, 2B, 3A, 3B, 4B, 5A, 5B, 6A, 6B, and 7B that were significantly (FDR <0.05) associated with some of the traits studied. Thirty-five QTLs were reported while the remaining 9 QTLs were found to be novel, which need to be validated for further use in the breeding program. We also identified several candidate genes, potentially regulating the traits, and encoding various proteins involved in plant growth and development. Hence, this study highlights the significance of the Ethiopian tetraploid wheat gene pool for improving tetraploid wheat globally; thus, a breeding strategy focusing on accumulating favorable alleles at these loci could improve tetraploid wheat production in Ethiopia and beyond