Evaluation of sesame genotypes for resistance to bacterial blight (Xanthomonas campestris pv. sesami) under field conditions

Sesame is an important lowland oilseed crop cultivated in the tropical and subtropical regions of the world. In Ethiopia, the intensity of sesame bacterial blight varies depending on topography, altitude, and weather conditions. The study was initiated to evaluate the resistance level of sesame genotypes against bacterial blight disease. An inoculum suspension was prepared in sterile distilled water and standardized turbidometrically to an inoculum size of approximately 10⁷ CFU/ ml (1 × 10⁷ cfu/ml). A total of 77 treatments were laid out in an alpha lattice design (7 × 11) having seven blocks. Two rows were designated for one genotype, with three replications, and one block includes seven genotypes. Disease severity was determined from 8 per-tagged plants as an estimate of the percentage of total leaf area covered by bacterial blight lesions. Out of the 77 genotypes evaluated during the 2019 cropping season, no any genotypes showed resistance, while 54 were identified as moderately susceptible (20.1 –50% severity) and 8 sensitive (50.1–70% severity). During the 2021 cropping season, among 77 genotypes, similar to the first year none were found immune or resistant but, 23 genotypes were found to be moderately resistant (10.1–20% severity), 57 genotypes were found to be moderately susceptible (20.1–50% severity index), and 7were found to be susceptible (50.1–70% severity). It was investigated that significant variation was observed in bacterial blight, growth, grain yield, and yield components among the 77 genotypes evaluated at Bako. Some sesame genotypes found as potential sources of resistance and better yield performance.