Root and crown rot of wheat is caused by the fungus Gaeumannomyces graminis var. tritici. "Take-all" is an important disease affecting wheat, and its incidence has been reported in several provinces of Iran. To identify resistant cultivars, bread wheat germplasm should be evaluated. To evaluate bread wheat germplasm in response to Iranian isolate fungus (T-41) of Gaeumannomyces graminis var. tritici, 333 genotype of bread wheat, collected from different locations of Iran and other countries were evaluated to take-all in greenhouse conditions. Two experiments were conducted, the first with 89 and the second with 244 genotypes. The measured traits were amount of root and crown infection, disease intensity, wet and dry biomass, and height of shoots. Analysis of variance and means comparison for the parameters indicated that in the first experiment, two genotypes were resistant to the disease, and the rates of disease intensity in these genotypes were 0.13 and 0.06. In the second experiment, five completely resistant genotypes were identified with disease intensity ratings of '0'. The identified resistant genotypes screened from both experiments were re-evaluated, and the results were the same. Mean comparison between winter and spring types for dry weight and disease intensity showed that winter wheat is more resistant than spring type. The results of this research showed that there is resistance resource to take-all (T-41 isolate), in this germplasm.Since the experiment was conducted in greenhouse conditions, these genotypes should be tested against this disease in infected conditions at field. 

Keywords: Evaluation, Root rot, Spring and winter wheat, T-41 isolate

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