Effect of Integrated Fertilizer Management on Seed Oil Content, Protein and Fatty Acid Composition of Sunflower Under Rainfed Conditions in Hungary

Integrated nutrient management reduces reliance on chemical fertilizers by combining organic and inorganic inputs. A field experiment was conducted under rainfed conditions in Hungary from 2022 to 2024 to evaluate organic, inorganic and biological fertilizers applied to the high-oleic sunflower hybrid ES Emeric. Seven treatments were compared, namely, an unfertilized control, potassium (K), combined organic and inorganic nitrogen (GOIM), effective microorganisms (EM-1), and the combinations K+GOIM, K+EM-1 and GOIM+EM-1. Seed oil, crude protein and moisture content were determined, together with the fatty acid profile of the oil. Growing season influenced every measured variable far more strongly than fertilization, and all treatment responses were expressed as year-by-treatment interactions. Mean oleic acid content was 69.9% in the dry season of 2022 and 85.3% in 2024, but only 28.9% in the cooler and wetter season of 2023, when linoleic acid reached 59.8%. In 2022, K and K+EM-1 gave the numerically highest oil contents, 48.7% and 48.0%, less than one percentage point above the control, while GOIM+EM-1, GOIM and K+GOIM gave significantly higher protein contents than the remaining treatments. In the same season, EM-1 and K+GOIM raised linoleic and alpha-linolenic acids and, therefore, total polyunsaturated fatty acids, whereas GOIM+EM-1 and K increased oleic acid and total monounsaturated fatty acids. Integrated fertilization can therefore be used to shift the balance between monounsaturated and polyunsaturated fatty acids in sunflower oil, but the size and direction of the shift are governed by the conditions of the growing season.