Abstract: The aim of the study was to assess some aspects of relative fitness of biotypes of A. spica-venti resistant and susceptible to ALS inhibitors, such as dynamics and germination capacity. Seeds were germinated on Petri dishes at two temperature combinations: 15/12 °C and 25/22 °C. Seeds of both biotypes germinated better in higher temperature. In both temperature combinations the susceptible biotype had higher germination capacity than the resistant biotype. Lower temperatures delayed germination of both biotypes. No significant difference was observed between germination time of resistant and susceptible biotypes.