Browsing by Author "Haileselassie, Teklehaimanot (PhD)"
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Item Characterization of Ethiopian Durum Wheat Landraces and Cultivars for Processing Quality Using Phenotypic Traits and Simple Sequence Repeat (SSR) Markers(Addis Ababa University, 2021-09-02) Dagnaw, Temesgen; Tesfaye, Kassahun (PhD); Haileselassie, Teklehaimanot (PhD); Geleta, Mulatu (PhD)Durum wheat (Triticum turgidum L. ssp. durum Desf.) is getting attention in terms of production and area coverage at the global level. Its unique characteristics to produce pasta and related end-products increased the preference for durum wheat by millers and processors. Ethiopia is considered as a center of diversity for durum wheat. However, in Ethiopia, durum wheat is facing serious genetic erosion due to the expansion of teff and bread wheat, and the cultivation of exotic durum wheat materials. The genetic resource of the Ethiopian durum wheat genotypes has been limitedly explored for its processing quality attributes at the level of both phenotypic and molecular diversity. Therefore, the present study was aimed to assess the genetic diversity and evaluate the processing quality attributes of Ethiopian durum wheat genotypes using phenotypic traits and SSR markers. The field experiment was conducted at two locations (Sinana in Bale zone and Chefe Donsa in East Shewa zone) to assess the phenotypic diversity. The phenotypic characterization of genotypes showed a wide range of variability for most quantitative and qualitative traits. The combined analysis of variance (ANOVA) showed highly significant (P<0.01) variations among genotypes for the majority of the traits studied. Gluten content (GL) and grain yield (GY) showed high and intermediate heritability, respectively, combined with moderate genetic advance, and grain protein content (GPC) showed intermediate heritability combined with low genetic advance. Both, GPC and GL showed a significant and negative correlation with GY. Cluster analysis based on quantitative traits grouped the genotypes into 5 major clusters. The first four principal components (PCs) explained 64% of the total variation. Based on qualitative traits, high genetic variation was observed among genotypes. Correspondence analysis discriminated cultivars from other populations of landraces. Finally, 104 best-qualified genotypes for processing quality traits were selected and assessed using quality traits associated 14 SSR markers, which had high mean polymorphic information content (PIC) of 0.56 and gene diversity (0.61). High levels of genetic diversity was obtained among all populations (I = 0.86; He = 0.46). Analysis of molecular variance (AMOVA) revealed high genetic variation within populations (88.35%) and among populations (11.65%). The Neighbor-joining (NJ) clustering and principal coordinate analysis (PCoA) grouped the genotypes into three major clusters. In addition, Bayesian model-based population structure analysis revealed two major genetic groups. Overall, this study revealed high genetic diversity among Ethiopian durum wheat landraces and cultivars, and these genotypes can be used to identify the best genotype/s for processing quality attributes and subsequent use in the Ethiopian durum wheat improvement programs.Item Genetic Diversity Assessment of Yams (Dioscorea Spp.) From Ethiopia Using Inter Simple Sequence Repeat (Issr) Markers(Addis Ababa University, 2015-04-04) Mohammed, Kedra; Tesfaye, Kassahun (PhD); Haileselassie, Teklehaimanot (PhD)The genetic diversity and relationships of 70 accessions of yam belonging to Dioscorea cayenensis/Dioscorea rotundata complex (55), Dioscorea bulbifera (13) and Dioscorea alata (2 as a reference) were assessed using six ISSR primers. DNA was extracted from a bulk of two plants per accession using a modified CTAB method. Six ISSR primers amplified 77 fragments with 75 (97.40%) polymorphism at genus level. The genetic diversity, estimated by Gene diversity and Shannon’s index were 0.36 and 0.53, respectively, revealing a high level of genetic variation at genus level. At species level 75 bands were amplified for D. cayenensis/D. rotundata complex, out of which 71 were polymorphic accounting for 92.2% polymorphism. Gene diversity and Shannon's index for D. cayenensis/D. rotundata complex were 0.33 and 0.49, respectively. In case of D. bulbifera a total of 64 bands were scored, out of which 55 were found to be polymorphic which resulted in 71.4% polymorphism. Gene diversity and Shannon's index for this species were 0.24 and 0.47, respectively. Genetic diversity analysis of D. cayenensis/D. rotundata complex accessions showed that Gedeo were the most diverse among populations and South among groups. Analysis of molecular variance (AMOVA) indicated the presence of higher proportion of variation within species (63.9%) than among species (36.1%) which could be due to presence of several shared bands. AMOVA for D. cayenensis/D. rotundata complex also showed higher within population variation (53.6) than among populations (46.4). This could be due to gene flow through seed materials exchange among local farmers. Cluster analysis showed grouping of most of the accessions according to their species. In addition, cluster analysis for relationship between D. cayenensis/D. rotundata complex accessions showed grouping of some of the accessions according to their population but it failed to produce clear species boundary between D. cayenensis/D. rotundata complex. The results suggested that there exists a high level of genetic diversity in yams of Ethiopia to be exploited for future improvement (breeding) of the crop.Item Genetic Diversity Study and Salt Tolerance Screening of Common Bean (Phaseolus Vulgar L.) Germplasm from Ethiopia(Addis Ababa University, 2013-02-02) Dagnew, Kefyalew; Haileselassie, Teklehaimanot (PhD)Phaseolus vulgaris L. (family Leguminosae), is a grain that provides protein. It is distributed in all parts of the world. P. vulgaris is a salt sensitive and one of a major export crop that can be grown in times of intermittent rainfall; also, it grows in the warm and low land areas of Ethiopia. Salinity as well as using less productive varaties make low production in Ethiopia. This research is aimed to investigate the salt tolerance and genetic diversity of P. vulgaris accessions from Ethiopia.The study was done on twelve accessions from Ethiopia. Shoot and Root Length (SL, RL) as well as Root Fresh and Dry Weight (RFW, RDW) were measured using 50, 100, 150, 200 mM NaCl salinity levels after germination.Tap water was used as a control. Studies were also carried out to estimate the genetic diversity among and within accessions of P. vulgaris using ISSR markers. Mostly, the growth of RL, SL, RDW and RFW were faster at 50 mM but they were significantly inhibited at high salt levels (150mM, 200mM). Accessions from Metekel (Dangure) and Harerge were found to be salt sensitive during shoot and root growth. However, accessions from Shinile and Metekel (Dibate) were relatively salt tolerant. The rest were intermediate. Besides, the highest RFW and RDW were recorded in West Wellega(F) variety at 200 mM NaCl. Seven selected ISSR primers yielded 69 reproducible bands from 96 individuals studied. All the loci were found to be polymorphic. The total genetic diversity (H) and Shannon’s diversity information index (I) for entire populations showed, 0.35, and 0.53, respectively. Individuals from Shinile site showed the highest level of gene diversity (H = 0.29, I = 0.43); while the lowest variability was showen by accessions from Metekel (L) (H = 0.10, I = 0.15). Variation within accessions was higher (62.55%) as compared to that of inter accessions (37.45%) based on AMOVA. Accession from Harerge (K) was quite separated to the rest of other accessions in UPGMA analysis. The accession from Hadiya had a closer genetic similarity with that of West wellega (F) while the two germplasm resources from Metekel (G, L) were closely related to their geographical distribution. In PCO, majority individuals of Metekel (L) tended to form their own separate grouping. The result of the present study confirmed the presence of salt tolerant and genetically diversified accessions that can be used to improve the productivity as well as calls for a combined effort for the collection, conservation and sustainable use of P. vulgaris.Item Genetic Diversity Study of the Brachiaria Brizantha (A. Rich.) Stapf Collected From Ethiopia Using Inter Simple Sequence Repeat (Issr) Markers(Addis Ababa University, 2014-02-02) Meheret, Fentahun; Tesfaye, Kassahun (PhD); Haileselassie, Teklehaimanot (PhD)Brachiaria brizantha is a C4 grass commonly used as forage in the tropics. Leaf samples from seven populations originating from Welega, Jimma, Omo, Gondar, Gojam, Borena and Ilu Ababora were collected from Zeway Regeneration and Conservation Site of ILRI, Ethiopia. Genomic DNA was extracted from 79 accessions each from three individuals using CTAB extraction method. A diluted genomic DNA was subjected to PCR amplification. From the ISSR primers tested, only six amplified 80 scorable bands from the 79 accessions used. 96.25% Percentage of polymorphic loci (PPL), gene diversity (h) = 0.366 and Shannon information’s index (I) = 0.539 were detected at species level. The number of bands identified by each primer ranged from 8 to 19, with an average of 13.3. The highest genetic diversity was generated from accessions collected from Ilu Ababora (PPL= 58.75 %, h=0.210 and I =0.315) while the least was from those collected from Gondar region (PPL=28.75%, h=0.124 and I =0.183). Jaccard’s similarity coefficients ranged from 0.302 to 0.431 and analysis of molecular variance indicated the presence of higher proportion of variation within population (64.66%) than between populations (35.34 %). Cluster analysis using the un-weighted paired group method with arithmetic average (UPGMA) and Jaccard’s similarity coefficient (0.38) clustered the accessions into three major (I, II and III) clusters in their respective regional collection. Principal Component Analysis (PCO) showed accessions in populations formed their own cluster. Thus ISSR markers detected a range of genetic diversity from Brachiaria brizantha germplasm collections from Ethiopia.Item Genetic Variability and Genotype by Environment Interactions Among Released Varieties and Advanced Lines of Desi Type Chickpea Genotypes Under Acidic Soils of Western Ethiopia(Addis Ababa University, 2017-11-04) Alemu, Biru; Tesfaye, Kassahun (PhD); Haileselassie, Teklehaimanot (PhD); Lule, Dagnachew (PhD)GENETIC VARIABILITY AND GENOTYPE BY ENVIRONMENT INTERACTIONS AMONG RELEASED VARIETIES AND ADVANCED LINES OF DESI TYPE CHICKPEA GENOTYPES UNDER ACIDIC SOILS OF WESTERN ETHIOPIA Biru Alemu Addis Ababa University, 2017 The importance of pulses such as chickpea (Cicer airetinum L.) cannot be overstated because of their significant role in sustaining food security, balancing the ecosystem and generating revenue. A field experiment was conducted on sixteen desi type chickpea genotypes under field condition at five locations viz., Shambu, Hawa Galan, Mata, Alaku Belle and Badesso in western Ethiopia during the main cropping season of 2016/2017 to examine the magnitude and pattern of environmental effect on Desi-type chickpea genotypes and genetic variability at molecular and morpho-agronomic levels. Pooled analysis of variance indicated highly significant differences for genotypes, environments, and genotype by environment interaction. The combined mean of genotypes indicated that variety Natoli and advanced line DZ-2012-CK-20113-2-0042 were top yielders among the sixteen genotypes tested at five environments of western Ethiopia. Significant statistical differences among the genotypes were observed for a number of characters. Genetic similarity matrix based on Jaccard’s similarity coefficient using inter simple sequence repeat (ISSR) markers displayed an average range from 0.21 to 0.98. Based on yield performance, Additive Main Effect and Multiplicative Interaction (AMMI), AMMI stability value (ASV), Genotype selection index (GSI), Genotype main effect and Genotype by Environment Interaction (GGE) biplot analysis Natoli and DZ-2012-CK-20113-2-0042 were stable and high yielding genotypes and thus they are recommended for wider production in test locations and similar agro-ecologies.Item Molecular Characterization of Introduced Sugarcane (Saccharum officinarum L.) Genotypes in Ethiopia Using Inter Simple Sequence Repeat (ISSR) Markers(Addis Ababa University, 2015-03) Tazeb, Adebabay; Haileselassie, Teklehaimanot (PhD); Tesfaye, Kassahun (PhD)The major thrust of sugarcane (Saccharum officinarum L.) variety improvement programs is to increase sugar yield, while due to its genetic complexity, sugarcane has received very little research interest, despite its economic importance, and molecular techniques are being developed only in recent times. Furthermore, until the present date no molecular studies were carried out to evaluate sugarcane germplasm from Ethiopian fields. Therefore, the objective of this study was to evaluate genetic diversity and establish relationships among populations of sugarcane in Ethiopia using ISSR markers. Genomic DNA was extracted from leave samples of 82 sugarcane genotypes according to modified CTAB method. A total of 149 scorable and reproducible bands were generated using 12 ISSR primers among which 124 were polymorphic and attributed to PPL = 83.22 %, h = 0.31, and I = 0.45 at species level. Intra-population diversity based on polymorphic loci ranged from 28.86 % to 47.65 % with mean of 38.35 %, Nei’s gene diversity of 0.097 to 0.171 with mean of 0.137, Shannon’s information index of 0.147 to 0.255 with mean of 0.205, and within population AMOVA of 63.56 %. All diversity parameters confirm that, the highest diversity was obtained from those that were obtained from France and Cuba whilst the lowest was from those of Barbados and South Africa. AMOVA revealed 36.4 % among population variation which is significantly lower than that of within population variation. From Jaccard’s pairwise similarity coefficient, those from Sudan and South Africa were most related populations exhibiting 0.70 similarity and USA and Barbados were the most distantly related populations with similarity of 0.53. With all clustering analysis, most of the genotypes clustered to their respective origins. Thus, ISSR markers detected a range of diversity from sugarcane varieties with their unique identity that deserve conservation attention and improvement programs. Key words: Commercial crop, genetic diversity, ISSR markers, Saccharum officinarumItem Morphometric, Photosynthetic and Molecular Markers Based Genetic Diversity Study of the African Wild Rice (Oryza Longistaminata Chev. Et Roher) From Ethiopia(Addis Ababa University, 2018-06-02) Melaku, Getachew; Haileselassie, Teklehaimanot (PhD)MORPHOMETRIC, PHOTOSYNTHETIC AND MOLECULAR MARKERS BASED GENETIC DIVERSITY STUDY OF THE AFRICAN WILD RICE (Oryza longistaminata Chev. et Roher) FROM ETHIOPIA Getachew Melaku Adane, PhD Dissertation Addis Ababa University, June 2018 Rice which feeds more than half of the world human population is affected by environmental changes. Therefore, its productivity should be supplemented by the genetic resources from other wild relatives. The African wild rice, Oryza longistaminata Chev. et. Roher, which possess AA genome as the cultivated rice, is hypothesized as a good candidate for widening the cultivated rice gene pool. However, its status of genetic diversity and relationship with other Oryza members is still unresolved. So far, the genetic resource from this African species is underutilized for the breeding of cultivated rice. Even, characterization and evaluation of the different agro-morphological and photosynthetic traits of O. longistaminata are still untapped. To this end, assessing the morphometric, photosynthetic and molecular markers based genetic diversity and regional differentiation of the African wild rice (O. longistaminata) in Ethiopia is very important for efficient breeding and conservation schemes. This study therefore, employed 67 SSR markers over 360 O. longistaminata accessions from 12 populations of Ethiopia, one O. longistaminata accession from Niger, 35 varieties of the Indica and Japonica subspecies of O. sativa, 25 accessions of four AA genome wild Oryza species, 8 accessions of five CC genome wild rice species and one Japonica weedy type for the assessment of genetic diversity and relatedness. In this study, evaluation of morphological differences and characterization of leaf gas exchange traits were done from the three replicates of 62 Ethiopian O. longistaminata accessions. The Restriction Associated DNA Sequencing xv data from 87 O. longistaminata accessions of Ethiopia was also analyzed for their phylogenetic relationships and region based differentiation. The eight morphometric and seven leaf gas exchange traits assessed in this study revealed a significant variation. Correlations between the evaluated morphological traits of the assessed accessions showed highly significant pairwise associations. The multivariate analysis from the eight morphological traits implicated population effect. In particular, the inter-population distances among the six populations of origin showed distinctness of the Amhara from the rest five Gambella populations. The Pearson pairwise correlation matrix for the seven leaf gas exchange traits revealed their inter-relationship. For instance, the rate of photosynthesis was positively and significantly (P < 0.001) correlated with all other traits except the intercellular CO2 concentration. Moreover, the accessions showed high photosynthetic rate with a minimum intercellular CO2 concentration, transpiration rate and stomatal conductance. When the 12 O. longistaminata populations from Ethiopia were pooled as one, the 67 SSR markers showed (Na = 4.35, Ne = 1.91, Ho = 0.15, He = 0.38, F = 0.53 and PIC = 83.82). Such diversity indices implicated higher diversity than the rest AA and CC genome rice types. A highly significant (P> 0.001) genetic differentiation (Fst) = 0.299 was also observed among the 12 O. longistaminata populations of Ethiopia. However, the Analysis of Molecular Variance (AMOVA) showed the highest variance (38%) among accessions with in a population. PCA of the whole 430 accessions showed five main clusters and a clear geographic pattern was emerged for the 12 populations of O. longistaminata from Ethiopia. Population structuring and clustering through UPGMA and hierarchical clustering clearly separated the 12 Ethiopian O. longistaminata populations from other wild and cultivated rice types. Moreover, structure analysis from the SSR data indicated genetic distinctness in between the Amhara and Gambella regions. Dendrogram, DAPC, and population divergence xvi (Fst) analysis from the 30,256 Single Nucleotide Polymorphisms (SNPs) generated by the Restriction Associated DNA Sequencing also showed genetic differentiation among the two regions. In conclusion, the high diversity status of the Ethiopian O. longistaminata populations and their genetic distinctness to other Oryza species or in particular to O. sativa is an ideal opportunity for their utilization in diverse rice improvement programs. Moreover, the low transpiration rate and stomatal conductance records with a maximum Carboxylation Efficiency of the O. longistaminata accessions showed their environmental adaptability and high water use efficiency. The high Photosynthetic rate observed in the assessed accessions implicated that O. longistaminata could be used as a genetic resource for the photosynthetic improvement of rice cultivars. Therefore, the very efficient carbon balance mechanism and adaptation potential of O. longistaminata can be utilized for developing rice varieties and hybrids with higher yield even under harsh environment conditions.Item Morphometric, Photosynthetic and Molecular Markers Based Genetic Diversity Study of the African Wild Rice (Oryza Longistaminata Chev. Et Roher) From Ethiopia(Addis Ababa University, 2018-06-02) Melaku, Getachew; Haileselassie, Teklehaimanot (PhD)Rice which feeds more than half of the world human population is affected by environmental changes. Therefore, its productivity should be supplemented by the genetic resources from other wild relatives. The African wild rice, Oryza longistaminata Chev. et. Roher, which possess AA genome as the cultivated rice, is hypothesized as a good candidate for widening the cultivated rice gene pool. However, its status of genetic diversity and relationship with other Oryza members is still unresolved. So far, the genetic resource from this African species is underutilized for the breeding of cultivated rice. Even, characterization and evaluation of the different agro-morphological and photosynthetic traits of O. longistaminata are still untapped. To this end, assessing the morphometric, photosynthetic and molecular markers based genetic diversity and regional differentiation of the African wild rice (O. longistaminata) in Ethiopia is very important for efficient breeding and conservation schemes. This study therefore, employed 67 SSR markers over 360 O. longistaminata accessions from 12 populations of Ethiopia, one O. longistaminata accession from Niger, 35 varieties of the Indica and Japonica subspecies of O. sativa, 25 accessions of four AA genome wild Oryza species, 8 accessions of five CC genome wild rice species and one Japonica weedy type for the assessment of genetic diversity and relatedness. In this study, evaluation of morphological differences and characterization of leaf gas exchange traits were done from the three replicates of 62 Ethiopian O. longistaminata accessions. The Restriction Associated DNA Sequencing xv data from 87 O. longistaminata accessions of Ethiopia was also analyzed for their phylogenetic relationships and region based differentiation. The eight morphometric and seven leaf gas exchange traits assessed in this study revealed a significant variation. Correlations between the evaluated morphological traits of the assessed accessions showed highly significant pairwise associations. The multivariate analysis from the eight morphological traits implicated population effect. In particular, the inter-population distances among the six populations of origin showed distinctness of the Amhara from the rest five Gambella populations. The Pearson pairwise correlation matrix for the seven leaf gas exchange traits revealed their inter-relationship. For instance, the rate of photosynthesis was positively and significantly (P < 0.001) correlated with all other traits except the intercellular CO2 concentration. Moreover, the accessions showed high photosynthetic rate with a minimum intercellular CO2 concentration, transpiration rate and stomatal conductance. When the 12 O. longistaminata populations from Ethiopia were pooled as one, the 67 SSR markers showed (Na = 4.35, Ne = 1.91, Ho = 0.15, He = 0.38, F = 0.53 and PIC = 83.82). Such diversity indices implicated higher diversity than the rest AA and CC genome rice types. A highly significant (P> 0.001) genetic differentiation (Fst) = 0.299 was also observed among the 12 O. longistaminata populations of Ethiopia. However, the Analysis of Molecular Variance (AMOVA) showed the highest variance (38%) among accessions with in a population. PCA of the whole 430 accessions showed five main clusters and a clear geographic pattern was emerged for the 12 populations of O. longistaminata from Ethiopia. Population structuring and clustering through UPGMA and hierarchical clustering clearly separated the 12 Ethiopian O. longistaminata populations from other wild and cultivated rice types. Moreover, structure analysis from the SSR data indicated genetic distinctness in between the Amhara and Gambella regions. Dendrogram, DAPC, and population divergence xvi (Fst) analysis from the 30,256 Single Nucleotide Polymorphisms (SNPs) generated by the Restriction Associated DNA Sequencing also showed genetic differentiation among the two regions. In conclusion, the high diversity status of the Ethiopian O. longistaminata populations and their genetic distinctness to other Oryza species or in particular to O. sativa is an ideal opportunity for their utilization in diverse rice improvement programs. Moreover, the low transpiration rate and stomatal conductance records with a maximum Carboxylation Efficiency of the O. longistaminata accessions showed their environmental adaptability and high water use efficiency. The high Photosynthetic rate observed in the assessed accessions implicated that O. longistaminata could be used as a genetic resource for the photosynthetic improvement of rice cultivars. Therefore, the very efficient carbon balance mechanism and adaptation potential of O. longistaminata can be utilized for developing rice varieties and hybrids with higher yield even under harsh environment conditions.Item Morphometric, Photosynthetic and Molecular Markers Based Genetic Diversity Study of the African Wild Rice (Oryza Longistaminata Chev. Et Roher) From Ethiopia(Addis Ababa University, 6/2/2018) Melaku, Getachew; Haileselassie, Teklehaimanot (PhD)Rice which feeds more than half of the world human population is affected by environmental changes. Therefore, its productivity should be supplemented by the genetic resources from other wild relatives. The African wild rice, Oryza longistaminata Chev. et. Roher, which possess AA genome as the cultivated rice, is hypothesized as a good candidate for widening the cultivated rice gene pool. However, its status of genetic diversity and relationship with other Oryza members is still unresolved. So far, the genetic resource from this African species is underutilized for the breeding of cultivated rice. Even, characterization and evaluation of the different agro-morphological and photosynthetic traits of O. longistaminata are still untapped. To this end, assessing the morphometric, photosynthetic and molecular markers based genetic diversity and regional differentiation of the African wild rice (O. longistaminata) in Ethiopia is very important for efficient breeding and conservation schemes. This study therefore, employed 67 SSR markers over 360 O. longistaminata accessions from 12 populations of Ethiopia, one O. longistaminata accession from Niger, 35 varieties of the Indica and Japonica subspecies of O. sativa, 25 accessions of four AA genome wild Oryza species, 8 accessions of five CC genome wild rice species and one Japonica weedy type for the assessment of genetic diversity and relatedness. In this study, evaluation of morphological differences and characterization of leaf gas exchange traits were done from the three replicates of 62 Ethiopian O. longistaminata accessions. The Restriction Associated DNA Sequencing xv data from 87 O. longistaminata accessions of Ethiopia was also analyzed for their phylogenetic relationships and region based differentiation. The eight morphometric and seven leaf gas exchange traits assessed in this study revealed a significant variation. Correlations between the evaluated morphological traits of the assessed accessions showed highly significant pairwise associations. The multivariate analysis from the eight morphological traits implicated population effect. In particular, the inter-population distances among the six populations of origin showed distinctness of the Amhara from the rest five Gambella populations. The Pearson pairwise correlation matrix for the seven leaf gas exchange traits revealed their inter-relationship. For instance, the rate of photosynthesis was positively and significantly (P < 0.001) correlated with all other traits except the intercellular CO2 concentration. Moreover, the accessions showed high photosynthetic rate with a minimum intercellular CO2 concentration, transpiration rate and stomatal conductance. When the 12 O. longistaminata populations from Ethiopia were pooled as one, the 67 SSR markers showed (Na = 4.35, Ne = 1.91, Ho = 0.15, He = 0.38, F = 0.53 and PIC = 83.82). Such diversity indices implicated higher diversity than the rest AA and CC genome rice types. A highly significant (P> 0.001) genetic differentiation (Fst) = 0.299 was also observed among the 12 O. longistaminata populations of Ethiopia. However, the Analysis of Molecular Variance (AMOVA) showed the highest variance (38%) among accessions with in a population. PCA of the whole 430 accessions showed five main clusters and a clear geographic pattern was emerged for the 12 populations of O. longistaminata from Ethiopia. Population structuring and clustering through UPGMA and hierarchical clustering clearly separated the 12 Ethiopian O. longistaminata populations from other wild and cultivated rice types. Moreover, structure analysis from the SSR data indicated genetic distinctness in between the Amhara and Gambella regions. Dendrogram, DAPC, and population divergence xvi (Fst) analysis from the 30,256 Single Nucleotide Polymorphisms (SNPs) generated by the Restriction Associated DNA Sequencing also showed genetic differentiation among the two regions. In conclusion, the high diversity status of the Ethiopian O. longistaminata populations and their genetic distinctness to other Oryza species or in particular to O. sativa is an ideal opportunity for their utilization in diverse rice improvement programs. Moreover, the low transpiration rate and stomatal conductance records with a maximum Carboxylation Efficiency of the O. longistaminata accessions showed their environmental adaptability and high water use efficiency. The high Photosynthetic rate observed in the assessed accessions implicated that O. longistaminata could be used as a genetic resource for the photosynthetic improvement of rice cultivars. Therefore, the very efficient carbon balance mechanism and adaptation potential of O. longistaminata can be utilized for developing rice varieties and hybrids with higher yield even under harsh environment conditions.Item Screening and Identification of Potential Striga [Striga Hermonthica (Del.)] Suppressing Rhizobacteria Associated With Sorghum [Sorghum Bicolor (L.) Moench] in Northern Ethiopia(Addis Ababa University, 2020-06-06) Tsega, Urgesa; Haileselassie, Teklehaimanot (PhD)Sorghum (Sorghum bicolor (L.) Moench) is one of the globally important cereal crops well adapted to Sub-Saharan Africa (SSA) agro-ecologies. However, the productivity of sorghum is hindered by both abiotic and biotic factors including drought, Striga, insect pests, poor soil fertility and diseases. Among the constraints, Striga (genus), also called witch weed is the most important production problem in the area. Out of Striga species, Striga hermonthica can cause a complete yield loss making it the most economically important weed. Control methods including cultural, chemical, biological and breeding for resistance have been practiced for years. To date, none of these strategies have become practically effective to eradicate Striga. Some of the existing control methods mentioned are not easily accessible for small holder farmers, while still some are not environmentally friendly. Therefore, this thesis focused on an alternate control of Striga hermonthica that employ rhizobacteria whose application is scanty in the study area. Hence, study was designed with the objective of identifying potential Striga suppressing rhizobacteria associated with sorghum. Soil samples were collected from three Striga infested sorghum fields with different levels of Striga infestation in northern Ethiopia. In order to activate the microbes, the sample was mechanically homogenized and various sorghum varieties grown on it in the greenhouse for four weeks. One hundred seventeen rhizobacteria were isolated from the root surface of the sorghum and these were then screened for their Striga suppressive traits, namely hydrogen cyanide and indole acetic acid production ability. Accordingly, 40.2% and 46.8% were capable of producing hydrogen cyanide and indole acetic acid, respectively. Twenty two isolates (18.8%) could produce both hydrogen cyanide and indole acetic acid in common. These elites were considered for further in vitro effect on Striga seed germination, in the presence and absence of susceptible host plant, and all of them, with varying ranges, showed a statistically significant germination inhibition. Finally, shortlisted most effective isolates RI6, RI9, RI19, RI23, RI26, RI38, RI54 and RI72 were morphologically and biochemically identified to belong to the genera of Pseudomonas, Klebssiella, Bacillus and Entrobacter. The result of the study demonstrated the existence of promising soil born bacteria that could be exploited as a bioherbicides to control Striga infestation on sorghum provided that broader samples from various parts of the country are explored.