Koleva1*, Y. Stanoeva2, I. Kiryakov2, A. Ivanova1, P. Chamurlyiski1   1Shumen University “Bishop Konstantin Preslavski”, College Dobrich, Department of Crop Science and Plant protection, 9300 Dobrich, Bulgaria 2 Dobroudzha Agricultural Institute, 9500 General Toshevo, Bulgaria (M