## 3 Results and Discussion
### Cluster Analysis  
The effects of both the source of nitrogen and the nitrogen level were generally significant for the quality parameters of flowering Chinese cabbage. However, there is no clear answer as to which form of nitrogen supply offered the best results as the maximum values of quality parameters were observed for different nitrogen sources. Thus, a multivariate analysis in the form of cluster analysis was performed in order to better understand the dataset. The results are shown in Figures 4 and 5. Before clustering, all data were standardised within the cultivation system group.  
Based on the results from the cluster analysis, it can be concluded that the dataset could be divided into six distinct groups in the pot system (dendrogram in Figure 4) and three distinct groups in the hydroponic system (dendrograms in Figure 5) at a 70% distance using all the parameters tested as shown in the heatmaps in Figures 4 and 5. Distinct groups are shown in Table 5.  
In the pot system, the first cluster consisted of the plants treated with urea at N-90 with high pigment contents (chlorophylls and carotenoids) and a high a* colour coordinate value. The second cluster consisted of the samples fertilised with magnesium nitrate at the N-70 and N-90 doses, showing high DPPH activity and b*, h and C colour parameters as well as N, Zn and Cu contents. The third cluster consisted of the plants fertilised with calcium nitrate at N-90 and magnesium nitrate at N-50, showing a high Ca content and high or moderate P and K contents. The samples treated with urea at N-90 showing high pigment contents (chlorophylls and carotenoids) and a high a* colour coordinate value were in the fourth cluster. The fifth cluster consisted of the samples with the N-90 dose of ammonium and sodium nitrates. Those plants had high DPPH and TEAC activity and high N content and yield. The samples fertilised with the N-50 and N-70 doses of ammonium, sodium and calcium nitrates, all with low levels of all the parameters tested, were in the sixth cluster.  
Figure 4: Heatmap with a dendrogram for the flowering Chinese cabbage samples cultivated in the pot system.  
Figure 5: Heatmap with a dendrogram for the flowering Chinese cabbage samples cultivated in the hydroponic system.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**System** & **Samples** & **Cluster No.** \\ \hline \multirow{8}{*}{**Ca(NO3)2** N-90 & 1 \\  & & Mg(NO3)2 N-70 & 2 \\  & & Mg(NO3)2 N-90 & 2 \\  & & Ca(NO3)2 N-90 & 3 \\  & & Mg(NO3)2 N-50 & 3 \\  & & Urea N-50 & 4 \\  & & Urea N-70 & 4 \\  & & NH4 NO3 N-90 & 5 \\  & & NaNO3 N-90 & 5 \\  & & NH4 NO3 N-50 & 6 \\  & & NH4 NO3 N-70 & 6 \\  & & Ca(NO3)2 N-50 & 6 \\  & & Ca(NO3)2 N-70 & 6 \\  & & NaNO3 N-50 & 6 \\  & & NaNO3 N-70 & 6 \\ \hline \multirow{8}{*}{**Ca(NO3)2** N-70 & 6 \\  & & NH4 NO3 N-50 & 1 \\  & & NH4 NO3 N-70 & 1 \\  & & NH4 NO3 N-90 & 1 \\  & & Mg(NO3)2 N-50 & 1 \\  & & Ca(NO3)2 N-50 & 2 \\  & & Ca(NO3)2 N-70 & 2 \\  & & Ca(NO3)2 N-90 & 2 \\  & & Mg(NO3)2 N-90 & 2 \\  & & NaNO3 N-70 & 2 \\  & & NaNO3 N-90 & 2 \\  & & Mg(NO3)2 N-70 & 3 \\  & & NaNO3 N-50 & 3 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Results of cluster analysis for the pot and hydroponic system.  
In the hydroponic system, the first cluster was magnesium nitrate at N-50 and ammonium nitrate (all doses) with high or moderate pigment and P contents. The second cluster was calcium nitrate (all doses), sodium nitrate at the N-70 and N-90 doses and magnesium nitrate at N-90. Those plants had moderate or high TEAC and FRAP activities and phenolic content as well as moderate colour parameter values and N content. Finally, the third cluster was N-70 magnesium nitrate and N-50 sodium nitrate with low antioxidant activity and phenolic content.