Yield, Polyphenol and Carotenoid Content, and Mycotoxin Occurrence in Grains of Four Winter Barley Varieties Grown in Different Nitrogen Fertilization Conditions in Poland

Barley has consistently been ranked among the four most grown cereals in the world. Integrated agronomic approaches, combining a selection of optimal genotypes and growing conditions, may help to provide high yields of quality and safe barley grains. This study aimed to assess the yield, polyphenol and carotenoid content, and mycotoxin presence in grains of four winter barley varieties—Hobbit, Zoom, Galation, and Sandra—grown under different nitrogen (N) fertilization levels. High-performance liquid chromatography (HPLC) was used to analyze bioactive compounds, while liquid chromatography tandem mass spectrometry (LC-MS/MS) was applied to determine mycotoxin occurrence. Results showed that Hobbit and Zoom had higher yields, with Hobbit benefiting from higher N fertilization levels. While no significant differences in phenolic acids (sum) were observed among the barley varieties tested (av. 80.50 ± 6.78 mg/100 g), higher N levels raised flavonoid content (46.78 ± 4.35 vs. 38.82 ± 3.54 mg/100 g). Zoom was characterized by the highest total polyphenol levels (130.45 ± 12.50 mg/100 g). Among the 14 mycotoxins tested, only two were frequently found in the grain samples (DON and 15-Ac-DON), with Sandra being the least and Galation the most susceptible. The N fertilization doses did not significantly impact mycotoxin levels in grains. The insights gained from this study can inform the development and selection of barley varieties and growing conditions that offer optimized yields, enhanced nutritional value, and reduced susceptibility to mycotoxin contamination, tailored to the producers’ and consumers’ expectations and to sustainable farming goals.