The topic of the thesis: Comparison of the seed and biomass yields of breeding vegetation cover This thesis was focused on yield ability of the selected ryegrass species grown in the Czech Republic. Experimental fields were based on the land of private working farmer Mr. Pavel Mimra in Slatina u Vysokého Mýta. There were grown three species of ryegrass on the farm in vegetational period of 2013/2014. Monitoring was primarily focused on the formation of yield aspects - the number of the ears, the number of the grains in the ear and the weight of thousand grains. In the vegetational period was also monitored presence of weeds, pests and diseasases and was evaluated total amount of plants and their offsets. The total amount and subsequent use of remaining biomass from breeding covers was also monitored. In the end, there were discovered results compared with theoretical yield. Costs, profits and economical relevance were evaluated in the final part of thesis