**5. Conclusions**

The results of this study showed that there is a significant advantage of using nutrient solution incorporated with NaCl to increase yield, mineral composition, and antioxidant activity in dune spinach. Plants irrigated with nutrient solution incorporated with 50 mM NaCl revealed a significant increase in growth parameters and FRAP capacity. As the plant grew beyond week 6, an increased level of salinity caused a decrease in chlorophyll content (SPAD), while the phenolic content, as well as nitrogen, phosphorus, and sodium, increased. Based on this study, it is evident that there is potential for brackish water cultivation of dune spinach for consumption as a leafy vegetable and as a natural source of nutritional antioxidants. This could be a water-saving option in provinces experiencing the adverse effect of drought and salinity, where seawater or underground saline water could be diluted and used as irrigation water in the production of this vegetable.

**Author Contributions:** A.S.: investigation, data collection, documentation and analysis, methodology, and writing the original draft of the manuscript. M.O.J.: referencing and statistical software, critical review of the article with technical input, final approval of the article, and manuscript preparation. L.K.: validation of experimental design, supervision, and critical revision of the article. C.P.L.: conceptualization, supervision, funding acquisition, and critical revision of the article. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Research Foundation of South Africa (Grant numbers: 117032 and 121087).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article.

**Acknowledgments:** The authors would like to thank Xatyiswa Salukazana, Sihle Ngxabi, Lizeka Gana and Nomnqophiso Zantanta for their valuable assistance in data collection and experimental setup. To Deborah Erasmus and Phumlani Roto (Technicians in Horticultural Department) thank you for your assistance in procuring the needed equipment for this research.

**Conflicts of Interest:** The authors declare no conflict of interest.
