This study used data on yields of grain triticale grown in a three-year field trial conducted in the experimental field of the Department of Crop Science at the Agricultural University – Plovdiv. The experiment was carried out after grain maize as predecessor in four replications with experimental plot size of 15 m2. The following varieties of triticale were used for the purpose of the study – AD-7291, Rojen, Sadovec, Rakita and Zaryad. Four nitrogen rates were tested – N0; N6; N12 and N18. The grain yield was determined directly from the harvested plots of 10 m2 equated to a standard humidity of 13%.
Having used the data for relative grain yield and relative fertilization rates, the degree of dependency for each of the studied varieties of triticale was established at R> 0.8. The change of the relative yield along with the increased rate of nitrogen fertilization could be traced by means of the resulting dependence, thus to make possible a more accurate economic analysis and precise fertilization of the crop. The mathematical processing of the results was carried out using the specialized computer program YIELD®.