The experiment was conducted under laboratory and natural condition for evaluation of seed germination characteristics in 2 Bromus ecotypes and 5 Agropyron species collected from different parts of Iran. Seeds samples were treated with spores of Fusarium graminearum (114x104/ml and 57x104/ml) and F. avenaceum (152x104/ml and 76x104/ml). Germination percentage, and speed, root/shoot ratio, dry/fresh weight ratio and vigour index were determined in the inoculated seeds, as well as in control (non-inoculated seeds). Significant differences for the above characteristics were observed between plant genera, species and ecotypes and also between 2 Fusarium species. At both densities of F. avenaceum spores, all of triats were decreased in treated seeds at laboratory except for root/shoot ratio. At natural condition, there were no significant differences among agents of infection compared to control. In general, the seed contamination was higher in laboratory. Percentage and speed of seed germination and vigour index were higher in A. intermedium and A. elongatum comparing to other Agropyrone species and both B. persicus ecotypes. The higher density (114x104/ml) of F graminearum spores showed the highest effect on percentage and speed of germination and vigour index in all of species and ecotypes.