The effect of fertilizers on the yield and quality of sunflower seeds when grown in the conditions of the Left Bank Forest-Steppe of Ukraine

Abstract

The study of increasing the productivity of sunflower (Helianthus annuus L.) as one of the leading and most economically profitable oil crops in the agricultural sector of Ukraine is relevant. Taking into account the strategic importance of sunflowers on the global vegetable oil market, where Ukraine plays a key role, the research focused on optimizing the technological methods of its cultivation, in particular through the rational use of mineral fertilizers. The aim of the research was to determine the effect of different fertilization levels on the yield and quality parameters of seeds of sunflower hybrids of different biotypes. The research was conducted during 2024–2025 at the experimental field of the Poltava State Agricultural Research Station named after M. I. Vavilov. It was found that fertilizer application increased the yield of the Yarilo hybrid by 0.40–0.61 t/ha (26.5–40.4 %). The maximum result was obtained with the N₉₀Р₁₀₀К₉₀ rate. It was found that the exclusion of potassium (N₉₀P₁₀₀) did not lead to a significant yield loss, with a difference of only 3.9 %. The highest yield of the Ravelin hybrid (2.14 t/ha) was observed when N₉₀P₁₀₀K₉₀ was applied, which is 40.8 % higher than the control variant. Nitrogen-phosphorus fertilization also proved highly efficient, with seed yield increasing by 32.9–38.2 % compared to the control. The mid-season hybrid Guslar showed the highest sensitivity to the nutrient supply. The maximum yield (2.27 t/ha) was obtained with the application of mineral fertilizers at a dose of N₉₀P₁₀₀K₉₀, which was 32.0 % higher than the variant without fertilizers. Special attention in the study was given to analyzing the effect of mineral nutrition levels on seed oil content. It has been established that intensification of the sunflower fertilization system and increased yields lead to a gradual decrease in oil content. Even minimal doses of N₅₀P₆₀ fertilizers reduced oil content by 0.5–0.9 %, depending on the biological characteristics of the hybrid. The highest seed quality was observed in the control variant without fertilizers. It has been proven that although complete mineral fertilizer (NPK) is the most effective in terms of its impact on seed yield formation, the role of potassium in the soils where the study was conducted is less pronounced compared to nitrogen and phosphorus. The results prove that the optimal fertilizer dose should be based on the biological characteristics of a specific hybrid in order to achieve a balance between yield and oil content.