Resistance evaluation of sesame cultivars and lines to charcoal rot disease in ‎greenhouse condition

Charcoal rot is one of the most important and destructive disease of sesame in Iran and worldwide. In order to evaluate reactions of different genotypes of sesame, infected plant tissues of sesame with charcoal rot symptoms collected and different isolates of the pathogen obtained, purified by hyphal tip method and finally using morphological criteria, 10 isolates identified as Macrophomina phaseolina. In order to determine virulence of the isolates, pathogenicity test was performed on 1% water agar plates at 30 C using pre-germinated seeds of Darab-1 cultivar. The result showed the variability of virulence of the isolates. Then reaction of the 26 cultivars and genotypes using the most virulent isolate (MP-3-13) was performed by the standard method of Cut-Stem in greenhouse condition. Mean of necrosis length of different genotypes were measured five days after inoculation. Statistical analyses indicated the significant difference among the necrosis length of sesame genotypes. The results showed that AT6, Dashtestan 2, Darab 1, AT1 and AT2 were the most tolerant ones, respectively. Yellow white had the most susceptible reaction to the charcoal rot disease in this experiment. The rest of genotypes showed a range of necrosis length in response to the pathogen.