The research was carried out in 2018-2021 at the Zawady Agricultural Experimental Station, in Poland. The experiment was carried out in three repetitions in a split-plot system. The factors of the experiment were three morphotypes of winter oilseed rape: population, long-stemmed, semi-dwarf. The second factor of the experiment were three ways of using the preparations: 1. Control, 2. Soil conditioner, 3. Inorganic biostimulator containing PK, 4. Si biostimulant (plant resistant biostimulant). The aim was to investigate whether the use of soil preparations containing microorganisms and micro- and macro-elements or the foliar application of stimulants containing phosphorus, potassium and silicon would have a better effect on the quality of seeds, i.e.: total protein, crude fat and crude fibre of three different morphotypes of winter oilseed rape.The research showed that the highest concentration of total protein and crude fat was found in the semi-dwarf heterosis morphotype, while the population form had the highest content of crude fibre. In all tested cultivars, after the application of preparations containing potassium and phosphorus and on objects where silicon was used, there was a significant decrease in protein concentration. Research has shown that the best feed and utility value of seeds was obtained in areas where phosphorus and potassium were applied in a foliar manner. However, in the case of the traditional variety and the long-stemmed hybrid, the differences in fat content were statistically insignificant in all objects with biostimulating preparations, while in the case of the semi-dwarf hybrid, this tendency was demonstrated only in the objects with the organic and silicon-containing preparations. All of the tested cultivars were distinguished by the highest concentration of total protein, fat and crude fibre as well as fibre in the season with the lowest annual rainfall.