P. Yankov*, M. Drumeva, D. Plamenov Abstract. The investigation was carried out during 2008 – 2010 on the trial field of Dobrudzha Agricultural Institute, General Toshevo, Bulgaria, on slightly leached chernozem. To clarify the effect of different types of main soil tillage on the ver

M. Drumeva, N. Nenova, E. Penchev Abstract. Sunflower, being one of the main oil seed crops in the world, is of special economic importance in East Europe. In sunflower breeding the heterosis effect is primarily used. The high yield and the quality properties of seeds depend on the in