## 3 Results and Discussion
### Chemical Composition of Plants  
#### 3.2.1 Macronutrient Content  
The macronutrient content of white cabbage, cauliflower, and broccoli leaves in the sixth true leaf unfolded stage was similar to that reported in the literature [37; 38; 39]. Macronutrients, namely essential nutrients that the human body needs in large amounts, include calcium, magnesium, potassium, sodium, iron, phosphorus, and chlorine [39; 40]. Microgreens are edible seedlings enriched with concentrated minerals and phytochemicals whose dietary potential as functional foods needs evaluation. In this study, comprehensive biochemical, mineral and metabolic [41]. The macronutrient content of leaves in the studied _Brassica_ plants is presented in Table 3 and Figure 4. The content of nitrogen and phosphorus in leaf dry matter was associated with the type of substrate, whereas the content of potassium, magnesium, and calcium in leaf dry matter was linked with plant species. The content of all analyzed macronutrients in leaf dry matter was influenced by the interaction effects of substrate and plant species. Similar interaction effects were reported in a study of tomatoes grown on substrates with different proportions of vermicompost [15]. The incorporation of coffee grounds (SCG) influenced the content of minerals accumulated in plants by an increase in nitrogen, potassium and phosphorus and a decrease in the content of magnesium and iron in _Brassica_ vegetables [42]. The content of nitrogen in leaf dry matter ranged from 1.46 g\(\cdot\)100 g\({}^{-1}\) DM in white cabbage grown on PRO3 to 2.85 g\(\cdot\)100 g\({}^{-1}\) DM in broccoli grown on PRO2. The nitrogen content of leaves was around 11% higher in broccoli grown on PRO2 and around 27% lower in broccoli grown on PRO3 relative to the control treatment. No significant differences in the nitrogen content of leaves were observed between broccoli seedlings grown on PRO1 and the control substrate. The substrates used in the experiment decreased the content of nitrogen in leaf dry matter by around 19-41% in white cabbage and by around 17-25% in cauliflower seedlings, respectively. In comparison with the control substrate, PRO1 increased phosphorus content in leaf dry matter only in broccoli (by approx. 22%), whereas no significant changes were noted in the remaining species. In vegetables grown on PRO2, the above parameter increased in broccoli (by approx. 17%) and cauliflowers (by approx. 12%), and decreased in white cabbage (by approx. 30%) relative to the respective controls. In turn, substrate PRO3 decreased the phosphorus content of leaves in all _Brassica_ species, and the observed decrease ranged from around 30% in broccoli to around 41% in white cabbage. These changes could be attributed to the fact that phosphorus concentration was nearly twice lower in PRO3 than in the control substrate (Table 1), which resulted in lower phosphorus uptake by the studied plants. The content of phosphorus in leaf dry matter ranged from 0.16 in 100 g\(\cdot\)kg\({}^{-1}\) DM (broccoli and white cabbage grown on PRO3) to around 0.29 in 100 g\(\cdot\)kg\({}^{-1}\) DM (cauliflowers grown on PRO2). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Factor** & **N** & **_p_** & **K** & **Mg** & **Ca** \\ \hline Substrate (A) & \textless{}0.001 & \textless{}0.001 & 0.454 & 0.475 & 0.004 \\ Species (B) & 0.002 & 0.426 & 0.003 & \textless{}0.001 & 0.080 \\ Interaction (A \(\times\) B) & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _p_-value in ANOVA of the macronutrient content of leaves in seedlings of the analyzed _Brassica_ species. Potassium levels were lower in substrates (PRO1, PRO2, PRO3) than in the control substrate, which led to lower leaf potassium levels in plants grown on these substrates.