The experiment was carried out in the experimental field of the Department of Plant Growing at the Agricultural University – Plovdiv in the period 2009–2012, by the block method with four replications and size of the yield plot 20 m2. Three hybrids were studied – Hamar, Merano and Vektra.
Hamar was the most suitable for cultivation for green mass. It formed a smaller persentage of stems, more leaves and flowers. During the three years of the experiment as well as averagely for the period of study the highest green mass yield was obtained from hybrid Hamar (72 687kg/ha).