EN
Commonly used method for weed resistance diagnostics relies on sampling a seed material from the fields with a very poor weed control, seeding it and testing weed seeding plants with herbicide under greenhouse conditions. Disadvantages of the above mentioned method are: a high cost and time consuming. In the paper a new method based on weed root’s system development on Petri dishes, containing agar medium jointly with a determined concentration of tested herbicides. Sulfonylurea herbicides affects both on green parts and roots of weed plants. The development of a root’s system of Apera spica-venti and Centaurea cyanus seedlings was conditioned by the presence of herbicides. Resistant weed biotypes of A. spica-venti and C. cyanus regenerated their root’s system, while the root’s development of susceptible biotypes was restricted. The assessment of weed resistance to herbicides on Petri dishes containing nutrient agar might be recommended for a purpose weed resistance detection as a reliable, simple, fast and less costly method.