Primary Evaluation of Sesame Germplasm for Resistance to Charcoal Rot Disease in Laboratory Condition

Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid is a destructive fungal and soil-borne disease of sesame in Iran. To evaluate disease resistance in sesame germplasm، 26 isolates of the pathogen were prepared from infected plants collected from main sesame geowing areas of Iran. Pathogenicity test on cultivar Darab-14، carried out on water agar media in the plates، revealed a considerable pathogenicity in virulence of the isolates. To evaluate resistance of 75 entries of sesame germplasm، including improved cultivars، advanced lines and local genotypes، roots of seedlings were dipped into the hyphal suspension of mixed isolates for 5 minutes and maintained then at 32ᵒC in greenhouse. Reaction of each entry was recorded three days later، using a 1-5 scale. Calculated medians of scales showed that 14 genotypes were resistant and eight were moderately resistant. Using chi-square test، (Kruscal-Wallis method)، the statistical differences were sought. According to the calculations، genotypes Potak-e-Mousian، Mahalli Iranshahr and Safiabad line 3 had the highest level of resistance at the 95% confidence level. Although the rest of resistant genotypes showed the lower amounts of infection، a significant difference with the expected level of resistant and moderately resistant scores in the disease scale (score 1 and 2) was observed.