## 5 Conclusions  
The purpose of this study was to determine the effects of different N sources and increased N supply on the yield and certain biochemical properties of flowering Chinese cabbage grown in two different cultivation systems (substrate and hydroponics). The factors studied had significant and multidirectional effects on the yield, growth and quality of plants. In general, the plants grown in hydroponic systems were characterised by higher yields than the plants grown in pots. Increasing levels of N nutrition significantly increased the average yield of the plants grown in pots, while in hydroponics, the average yields at N-70 were comparable to these at N-90. The nitrogen source modified plant nutrition in terms of N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu. For the pot cultivation system, the highest pigment contents (chlorophylls and carotenoids) were obtained in the samples treated with urea at the N-90 dose which correlated with the Mn level in the plants. However, in pot cultivation, the pigment content did not correlate with the colour parameters (L*a*b*). In the hydroponic system, the highest pigment contents were in the samples treated with magnesium nitrate at the N-70 dose. Moreover, Chl b correlated with L* and b*. The highest antioxidant activity and phenolic content were obtained in the samples from the pot system treated with magnesium nitrate at high N doses (N-70 and N-90), as well as with ammonium and sodium nitrates at the N-90 dose. In the hydroponic systems, the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) activity was observed after treatment with sodium nitrate at the N-70 and N-90 doses. In our experiment, with the exception of the TEAC (Trolox equivalent antioxidant capacity) activity in the urea treatment, the DPPH and TEAC scavenging of the samples in pot cultivation increased significantly as the N level increased from N-50 to N-70. The obtained results confirmed the research hypothesis. In conclusion, both the intensity of N nutrition and the fertiliser applied can significantly modify the yield of plants and their quality parameters. For pot cultivation, the most effective fertiliser was Mg(NO\({}_{3}\))\({}_{2}\) at the N-70/N-90 doses, while for hydroponic cultivation, it is difficult to indicate the most effective fertiliser as the responses varied depending on fertilisation. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13095691/s1](https://www.mdpi.com/article/10.3390/app13095691/s1)]([https://www.mdpi.com/article/10.3390/app13095691/s1](https://www.mdpi.com/article/10.3390/app13095691/s1)), Table S1. Two-way ANOVA of yielding and the chemical composition of flowering Chinese cabbage grown under various N nutrition sources and intensity. Table S2. Colour coordinates of flowering Chinese cabbage cultivated under various N nutrition sources. Table S3. Antioxidant activity (DPPH, TEAC (ABTS), FRAP) and phenolic content (TPC--total phenolic content and TFC--total flavonoid content) of flowering Chinese cabbage cultivated under various N nutrition sources. **Author Contributions:** Conceptualisation, T.K. and W.L. ; methodology, T.K. and M.M.-P.; investigation, W.L. ; formal analysis, M.M.-P., T.K. and W.L. ; visualisation, M.M.-P., T.K. and W.L. ; writing--original draft preparation, T.K., M.M.-P. and W.L. ; writing--review and editing, M.M.-P. and T.K. ; supervision, T.K. and M.M.-P.; project administration, T.K. ; funding acquisition, T.K. All authors have read and agreed to the published version of the manuscript. **Funding:** The study was financed by programme \"Maintaining research potential\" financed by the Ministry of Science and Higher Education. The publication was co-funded under programme \"Regional Initiative Excellence\" of the Ministry of Science and Higher Education in the years 2019-2023 (No. 005/RID/2018/19), with financing in the amount of PLN 1,200,000. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.