The aim of the study was to evaluate the effect of nitrogen nutrition on the content of fatty acids and selected qualitative parameters (nitrogenous substances, ash, crude fiber) in winter oilseed rape (Brassica napus L.). The experiment was carried out at the Vígľaš—Pstruša Research and Breeding Station in 2008–2009 and 2009–2010 by complete block design with four repetitions. Nitrogen fertilization was applied at four levels, plus an untreated control (after agrochemical soil analysis) by DAN 27 (Dolomite Ammonium Nitrate): 100, 120, 140, and 160 kg/ha N. Application date was in BBCH scale phase 59–60. The fatty acid contents (MUFA—monosaturated fatty acids; PUFA—polyunsaturated fatty acids) were determined by gas chromatography in the extracted fat, which is determined by extraction method. Within the result evaluation, statistically significant increases in the contents of linoleic and linolenic acids were recorded in all variants treated by nitrogen fertilizer, which is positive in terms of the use of rapeseed oil for food and energy purposes. The statistically significant decrease of oleic acid after the application of nitrogen fertilizers is negative for industry use of rapeseed oil.

The effect of phosphorus (P) and nitrogen (N) application on yield, oil and fatty acids content (especially oleic acid, linoleic acid and linolenic acid) in rapeseed was investigated in the field experiment. Also effect of weather conditions was evaluated. The polyfactorial trial was realized in experimental years 2013/2014 and 2014/2015 in terms of agricultural cooperative in Mojmírovce. The experiment was based on three variants of fertilization treatments by the block method in three replications. The size of each block was created by plots with size 600 m2. The first level of treatment 10 was non-fertilized control. The second level of treatment 2U was fertilized by nitrogen in dose 240 kg.ha-1. The third level of treatment 3P was fertilized by the same dose of nitrogen 240 kg.ha-1 and by phosphorus in dose 88 kg.ha-1. The highest average yield 3.9 t.ha-1 was achieved at treatment 3P, where phosphorus was applied. It means statistically significant yield increase by 30% compared to treatment 2U, where no phosphorus was not applied. There was statistically non-significant difference in oil content, in the range of treatments. The content of oleic acid fluctuated from 63.3% to 65.9% and the highest was reached at unfertilized control treatments in both experimental years. The linoleic acid content ranged from 20.3% to 21.2% and content of linolenic acid varied between 6.9% and 8.9%. Application of nitrogen and nitrogen + phosphorus high statistically significant decreased oleic acid content in both experimental years. Opposite effect was observed, where content of linoleic and linolenic acid was high statistically significant increased after nitrogen and nitrogen-phosphorus fertilization. Effect of unequal weather conditions and treatments of nitrogen and nitrogen-phosphorus nutrition can influence the percentage ratio of higher fatty acids composition.

Small field plot experiments were carried out at the testing station of the Central Control and Testing Institute in Agriculture in Veľký Meder (Slovakia) in the experimental years 2014/2015, 2015/2016 and 2016/2017. Selenium salts in the form of sodium selenite and sodium selenate were applied in growth phases: end of tillering (BBCH 29) and flag leaf ligule and collar visible (BBCH 39). The effect of experimental years 2014/2015, 2015/2016 and 2016/2017 on the yield of wheat grain was not statistically significant within the observed variants. The achieved mean yields were in the range from 10.06 ± 0.81 to 11.07 ± 0.29 t/ha in 2014/2015, from 9.82 ± 0.54 to 10.32 ± 0.10 t/hain 2015/2016 and from 11.23 ± 0.76 to 11.64 ± 0.51 t/ha in 2016/2017. Selenate in comparison with selenite influenced the selenium accumulation in wheat grains more positively. However, a significant difference was recorded in variants with selenite application in the flag leaf growth phase in comparison with the end of tillering phase. The influence on the content of macroelements P, K, Ca and microelements Cu and Fe was observed in sodium selenite only; its application decreased the element content in comparison with the control variant. Statistically significantly higher values of fiber and fat were achieved after application of selenium in the flag leaf growth stage in comparison with the end of tillering.

The article deals with the effect of foliar Se application on macro-and micro-elements and selected quantitative parameters (the content of ash, starch, and fat) in oat grains. The three-year experiments were carried out on Research and Breeding Station Vígľaš – Pstruša in the years 2014, 2015, 2016. The used oat variety was Valentin. The experiment was performed by a block method within a parcel size of 10 square meters (8 x 1.25 m) with the span of rows amounting to 0.125 m in four replications. Alfalfa was grown as forecrop. A potato and wheat production area (III-C2) with a height of 375 m above the sea level. The experimental area is characterized by warm, slightly wet weather with an average annual temperature of 7.8 °C and average annual precipitations of 666 mm. Basic fertilizing was planned before the sowing in the form of 100 kg of Ammonium nitrate containing dolomite (27% N), 100 kg of 60% KCl (60% of K2O), and100 kg of MAP (Monoammonium phosphate 12% N and 52% P2O5). Selenium was foliar applied in doses 25 g and 50 g Se per hectare in a solution form of sodium selenate (Na2SeO4). The harvest was realized by a small plot harvester in BBCH 91. The results of the experiments showed a statistically non-significant effect on microelements and most macroelements. Only sulfur content in oat grains was statistically significantly influenced by Se foliar treatment. The contents of ash, starch, and fat in oat grains were monitored, which showed statistically significant effect only in fat. Se content in grains showed a statistically significant increase by both Se foliar treatments.

Sunflower (Helianthus annuus L.) is grown in Slovak growing conditions for edible oil of high quality, its composition of unsaturated fatty acids affects the human health positively. Influence of year, hybrids (Marbelia CS and Reasun DS-5) and biostimulating preparations (Florone and Fertisiline) on yield, oil content, and amount of selected fatty acids (oleic, linoleic, palmitic, and stearic acids) was find out in this study. Also evaluate the relationship within the achieved yield and oil content with the obtained amount of selected fatty acids. Field small-plot experiments were established by randomized split plot method during the growing years of 2018 and 2019. The experimental field is situated in a warm maize production area, while the course of weather conditions during individual growing seasons was different.On an average for experimental period of 2018-2019, more favorable course of temperatures and precipitation was recorded in 2018. Significantly higher achene yield (3.29±0.35 t/ha) and a higher amount of selected fatty acids (oleic acid 62.11±4.33%; linoleic acid 45.32±4.62%; palmitic acid 5.26±0.33%; stearic acid 4.21±0.20%) were found in Reasun DS-5 hybrid. Both biostimulating preparations had a significant effect on the yield and oleic acid content, when both biostimulators were applied in BBCH 15 and BBCH 55. The amount of linoleic acid decreased by both biostimulating applications in BBCH 15 (Florone 33.88±10.57%; Fertilisine 34.11±13.37%) and BBCH 15, 55 ((Florone 34.08±12.34%; Fertisiline 34.26±13.40%) compared by control treatments (38.43±6.01%). The contents of linoleic acid on treated variants by both preparations in BBCH 55 (Florone 38.26±9.47%; Fertisiline 39.03±8.95%) were statistically nonsignificant with comparison to untreated control. The height of yield was negatively correlated (r= -0.310; P<0.01) with the oil content in the average of 2018 and 2019. A significant positive correlation was found in the relationships between the yield and palmitic acid (r=0.35; P<0.01), linoleic acid and palmitic acid, and stearic acid (r=0.51; P<0.01) (r=0.86; P<0.01), palmitic acid and stearic acid (r=0.45; P<0.01).