The Influence of Nitrogen and Sulfur Fertilization on Oil Quality and Seed Meal in Different Genotypes of Winter Oilseed Rape (Brassica napus L.)

Abstract

Adequate nitrogen (N) and sulfur (S) fertilization of oilseed rape crops is necessary to obtain good-quality oil and post-extraction rapeseed meal. The aim of this study was to determine the effect of different doses of N fertilization (100, 160 and 220 kg ha−1) and S (0, 30, 60 and 90 kg ha−1) on the value of seeds of three winter oilseed rape genotypes. Two winter oilseed rape genotypes obtained by mutagenesis (cultivar Polka and breeding genotype PN440) were characterized by changed fatty acid profile. The cultivar Polka, type HO (high oleic), had a high content of oleic acid (C18:1, 78.0%) and the breeding genotype PN440, type HOLL (high-oleic and low-linolenic), had a high content of oleic acid (C18:1, 75.0%) and a low content of linolenic acid (C18:3, 3.0%). We also used the canola type of winter oilseed rape cultivar, Monolit. The analysed winter oilseed rape genotypes responded similarly to the N and S fertilization factors with regard to the content of crude fat and total protein in the seeds and the composition of fatty acids in the oil. N fertilization increased the content of glucosinolates (GLS-alkenyl, indole and total) in seeds, whereas S application decreased the content of saturated fatty acids (stearic acid-C18:0) in oil and increased the content of alkenyl and total glucosinolates (GLSs) in seeds. A significant interaction between N and S was observed for crude-fat and total-protein content. This study suggests that ensuring an adequate supply of both nitrogen and sulfur in the soil is essential for optimizing meal and oil quality in different types of winter oilseed rape cultivars. Proper management of these nutrients can lead to improved oil content and overall crop performance.