The eastern Africa region, Ethiopia and its surroundings, is considered as the center of origin and diversity for sorghum, and has contributed to global sorghum genetic improvement. The germplasm from this region harbors enormous genetic variation for various traits but little is known regarding the genetic architecture of most traits. Here, 1425 Ethiopian landrace accessions were phenotyped under field conditions for presence or absence of awns, panicle compactness and shape, panicle exsertion, pericarp color, glume cover, plant height and smut resistance under diverse environmental conditions in Ethiopia. In addition, F1 hybrids obtained from a subset of 1341 accessions crossed to an A1 cytoplasmic male sterile line, ATx623, were scored for fertility/sterility reactions. Subsequently, genotyping-by-sequencing generated a total of 879,407 SNPs from which 72,190 robust SNP markers were selected after stringent quality control (QC). Pairwise distance-based hierarchical clustering identified 11 distinct groups. Of the genotypes assigned to either one of the 11 sub-populations, 65% had high ancestry membership coefficient with the likelihood of more than 0.60 and the remaining 35% represented highly admixed accessions. A genome-wide association study (GWAS) identified loci and SNPs associated with aforementioned traits. GWAS based on compressed mixed linear model (CMLM) identified SNPs with significant association (FDR ≤ 0.05) to the different traits studied. The percentage of total phenotypic variation explained with significant SNPs across traits ranged from 2 to 43%. Candidate genes showing significant association with different traits were identified. The sorghum bHLH transcription factor, ABORTED MICROSPORES was identified as a strong candidate gene conditioning male fertility. Notably, sorghum CLAVATA1 receptor like kinase, known for regulation of plant growth, and the ETHYLENE RESPONSIVE TRANSCRIPTION FACTOR gene RAP2-7, known to suppress transition to flowering, were significantly associated with plant height. In addition, the YELLOW SEED1 like MYB transcription factor and TANNIN1 showed strong association with pericarp color validating previous observations. Overall, the genetic architecture of natural variation representing the complex Ethiopian sorghum germplasm was established. The study contributes to the characterization of genes and alleles controlling agronomic traits, and will serve as a source of markers for molecular breeding.

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Field experiments were conducted in Ethiopia to evaluate the effect of silicon fertilizer and sugarcane bagasse on tomato bacterial wilt (Ralstonia solanacearum). Silicon fertilizer significantly reduced the bacterial population, mean wilt incidence, percent severity index, and corresponding areas of disease incidence, and severity progress curves in the moderately resistant tomato cultivar (King Kong 2). Similarly, sugarcane bagasse resulted in a significant reduction of mean wilt and percent severity index, the corresponding areas under disease incidence and severity progress curves and the bacterial population at 5 days post inoculation, compared to the control, in cultivar King Kong 2. However, neither silicon fertilizer nor sugarcane bagasse resulted in any significant reduction of all disease parameters in the moderately susceptible cultivar Marglobe. Silicon fertilizer and sugarcane bagasse amendments also increased fruit yield for cultivar King Kong 2, but not for cultivar Marglobe. The total silicon content was also significantly increased in silicon fertilizer amendment, followed by sugarcane bagasse amended plants. The study recommends use of silicon fertilizer as a soil amendment under field conditions to augment resistance in moderately resistant cultivars where bacterial wilt disease problems prevail. However, a silicon fertilizer or silicon source was not found to substantiate or improve a susceptible cultivar. Sugarcane bagasse was demonstrated to possess a potential as an alternative soil amendment material and as an alternative silicon source.

Bacterial wilt caused by Ralstonia solanacearum is one of the most devastating plant diseases of economically important crops mainly Solanaceous family such as tomato, potato, pepper and eggplant. These crops play a significant role primarily as sources of income and food security for the small scale farming community in Ethiopia. The occurrence of bacterial wilt disease in Ethiopia was reported in 1956 and is known to cause significant yield loss on different Solanaceous crops in different parts of the country. On the basis of conventional characterization and classification, the strains of R. solanacearum found in Ethiopia have been identified as biovar 1 and 2. Recent characterization of R. solanacearum strains based on phylotype grouping using multiplex PCR and partial endoglucanase gene sequencing identified the occurrences of phylotype II and III. The association of biovar and phylotyping schemes indicated that phylotype II comprises only biovar 2, and phylotype III comprises strains of biovar 1 and biovar 2. The importance of the disease on Solanaceous crop is increasing from time to time specially in potato producing areas of the country. Apart from Solanaceous crops, the disease has also been posing a catastrophic damage to ginger production. Latently infected ginger rhizomes and potato seed tuber and decreasing of land holdings that limit crop rotation have contributed to the wider spread of the disease. In this review attempt has been made to summarize relevant scientific studies on this economically important disease in Ethiopia as well as its different disease management options, challenges and future considerations. Because, there is no single effective control measure against the target pathogen so far, a well-coordinated effort is required to develop an integrated disease management program that will help to minimize the damage and yield loss caused by the disease.