Dobrudzha Agricultural Institute, 9520 General Toshevo, Bulgaria
Abstract. A field experiment was carried out with sunflower (Helianhtus annuss L.) hybrid San Luka during 2011 – 2013 in the trial field of Dobrudzha Agricultural Institute under conditions of slightly leached chernozem soil (Luvic phaeozem). The aim of the investigation was to find out what was the effect of foliar fertilizers on the qualitative and quantitative indices of sunflower seeds as a part of determining the elements which formed the optimal agronomy practices for this hybrid. The trial was designed according to the method of long plots, with four replications of the variants. The variants were the following: 1) Check (untreated); 2) Foliar fertilization with Bo-La; 3) Foliar fertilization with PTS (potassium tyosulfate); 4) Foliar fertilization with High-Phos; 5) Foliar fertilization with Foliar Extra. As a result from the experiment carried out it was found that all tested fertilizers had positive effect on the seed yield amounting to 7.9 – 18.4%. The fertilizers Bo-La and High-Phos had highest effect on yield and 1000 seed weight. The index oil content in seed was influenced positively and significantly only by the fertilizers Bo-La and PTS. The increase of content was with 3.7%.