Reaction of Bulgarian varieties of perennial ryegrass (Lolium perenne L.) to glyphosate

The aim of this study was to determine and compare the sensitivity of new high yield Bulgarian varieties of perennial ryegrass (Lolium perenne L.) - Harmoniya, Tetrany and Tetramis to glyphosate in laboratory conditions. The effect of three doses of glyphosate - 360, 720 and 1440 g a.i./ha applied in the growth stage tillering (BBCH - 22-23) on perennial ryegrass on the dynamics of plant growth and formed fresh biomass in g per plant was studied. Genotypic differences were observed between the studied varieties of perennial ryegrass to glyphosate. With a relatively high sensitivity to glyphosate conditionally can be determined diploid variety Harmoniya in which the depression coefficients (B) on the dynamics of growth and accumulation of fresh biomass are in the range from-5.7 to - 4.7, while for tetraploids Tetrany (B) (average) is in the range of-3.3 to-3.9 and for Tetramis (B) (average) is within limits from-3.2 to-3.9, they have relatively high tolerance to glyphosate and can be used as components in future programs.