## 3 Results and Discussion
### Mycotoxins Occurrence  
Amongst the analyzed mycotoxins, deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-AcDON) were the most frequently detected in the barley grains tested (Table 6). Of  
Figure 2: Flavonoid concentrations in grains of four different barley varieties grown with four different N fertilization doses. Data are presented as means \(\pm\) standard errors (SE). Mean values followed by different letters (a–e) are significantly different at \(p<0.05\). Capital letters and numbers below bars indicate the name of the cultivar and the dose of fertilizer. Z—Zoom; H—Hobbit; G—Gation; S—Sandra; 60—60 kg N/ha; 90—90 kg N/ha; 120—120 kg N/ha; 150—150 kg N/ha. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**N-Dose/Variety**} & **Total Polyphenols** & **Lutein** & \(\beta\)**-carotene** \\  & **(mg/100 g)** & **(\(\mu\)g/kg)** & **(\(\mu\)g/kg)** \\ \hline
60 kg N/ha & 121.52 \(\pm\) 13.01 A & 11700.1 \(\pm\) 940.9 A & 1489.39 \(\pm\) 2.60 A \\
90 kg N/ha & 122.51 \(\pm\) 15.63 A & 11128.7 \(\pm\) 484.4 A & 1489.49 \(\pm\) 3.93 A \\
120 kg N/ha & 125.14 \(\pm\) 16.25 A & 11096.5 \(\pm\) 796.5 A & 1488.70 \(\pm\) 6.99 A \\
150 kg N/ha & 126.29 \(\pm\) 13.10 A & 10826.2 \(\pm\) 1036.6 A & 1487.52 \(\pm\) 3.22 A \\ \hline Zoom & 130.45 \(\pm\) 12.50 b & 11,869.7 \(\pm\) 896.3 b & 1491.98 \(\pm\) 5.61 a \\ Hobbit & 125.83 \(\pm\) 16.04 a & 11,099.5 \(\pm\) 814.3 ab & 1487.53 \(\pm\) 3.93 a \\ Galation & 115.51 \(\pm\) 14.31 a & 11,246.6 \(\pm\) 537.9 ab & 1488.84 \(\pm\) 2.89 a \\ Sandra & 123.67 \(\pm\) 10.68 a & 10,535.8 \(\pm\) 711.3 ab & 1486.74 \(\pm\) 3.27 a \\ \hline \multicolumn{3}{c}{\(p\)-value} \\ \hline N-dose (N) & ns & ns & ns \\ Variety (V) & ns & ns & ns \\ N \(\times\) V interaction & ns & ns & ns \\ \hline \hline \end{tabular}  
* Data are presented as means \(\pm\) standard deviations (SD); within columns and factors (N-dose/variety), mean values followed by different letters (capital letters for N-dose; small letters a,b for varieties) are significantly different at \(p<0.05\); ns—not statistically significant.  
\end{table} 
Table 5: Total polyphenols, lutein, and \(\beta\)-carotene content in four barley varieties grown in different conditions of nitrogen fertilization (N-dose) in the controlled field trial in Poland. the 14 mycotoxins analyzed, only four were detected in the tested samples. Aflatoxins B1, B2, G1, and G2 were not detected in any of the samples, and neither were OTA, 3-acetyldeoxynivalenol (3-AcDON), and nivalenol (NIV). Fumonisin B2 was detected in only one case, similarly to T-2 and HT-2 toxins. Among the barley varieties, Sandra was found to be the least susceptible to mycotoxin accumulation, and only at the highest nitrogen fertilization was it found to contain small amounts of DON. In contrast, the Hobbit, Zoom, and Galation varieties, irrespective of nitrogen fertilization conditions, contained mycotoxin DON, while in the case of the Hobbit and Galation varieties at fertilization levels of 90, 120, and 150 kg nitrogen per hectare, 15-AcDON mycotoxin was present in the grain (Table 6). However, DON concentrations were far lower than the maximum permissible levels defined for this mycotoxin in the current EU regulation (which is 1000 ug kg\({}^{-1}\) for unprocessed cereals) [62] which decreased from 1250 ug kg\({}^{-1}\) set in the previous EU regulation [63]. The detected concentrations of T-2 and HT-2 toxins were also far below the maximum limit, set as 150 ug kg\({}^{-1}\) for the sum of these two toxins in Commission Regulation (EU) No. 2024/1038 [64]. Regarding fumonisins, the current EU regulation No. 2023/915 does not set the maximum limits for barley [65]. Deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-AcDON) are produced by _Fusarium graminearum_ and _Fusarium culmorum_ during cereal production. Both species are considered significant contributors to _Fusarium_ head blight, a common fungal disease that often affects barley and other small-grain cereals [66].