## 4 Discussion  
The quest for improving food security in South Africa entails scouting for strategies that will be adapted to the changing climate and further contains adequate nutrients for human health nourishment. In this study, the interactive effect between Amaranth species and growth condition (OMET and non-OMET) were shown to be crucial factors for manipulating growth, yield, nutrients, and secondary metabolites contents. The obtained results on the growth and yield section may be attributed to variation of species and OMET system influence. The results can be assimilated with those mentioned in mulding studied due to the similarities of the concepts. [PERSON] and [PERSON] [21] reported that mulch is effective for vegetable growth and yield by improving moisture content of soil and heat energy. Furthermore, reasons related to the potential of OMET to conserve water and nutrients, which causes a moderate availability of water resulting in good nutrient dissolution and absorption by the plants, could also be attributed to the results obtained [22; 23]. Recently, [PERSON] et al. [10] reported the efficacy of OMET on improving growth and yield attributes in okra seedlings. Plant height and stem diameter have a major impact on biomass. Early flowering in _A. caudatus_ and _A. tricolor_ grown under the non-OMET system could be due to abiotic stress such as water and nutrient stress. The exposure of the plant to a shortened drought period induces early flowering and halts the production of leaves [24]. In this case, the non-OMET system had high rates of water and nutrients loss through evaporation, drainage, and leaching. Irrigation water used for the OMET system was less than that used for the non-OMET system, irrespective of the studied species. This could be due to the underlying plastic on the OMET system, which is water impermeable, therefore, water loss through seepage/deep drainage was eliminated, unlike the non-OMET system. The high evaporation rate in the OMET system is eliminated by the top plastic covering the growing medium [9]. Furthermore, this can be due to species type in response to different conditions and growing condition factors such as moisture and nutrient availability associated with plant growth and development under each treatment. Although Amaranth is drought resistant, it performs optimally under irrigation [24] and sufficient supply of nutrients, especially nitrogen (N). One of the essential elements, and one which participates directly as an indispensable requirement for normal plant growth, is N. Application of the multi-feeder made N and other vital nutrients readily available for uptake by the plants. Probably due to the potential of OMET system to conserve irrigation water and nutrients, it prolonged the availability and uptake of water, N, and other nutrients by the plants, thus prompting vigorous vegetative growth and high yielding in Amaranth species. The increased yield of Amaranth was probably due to the ability and potential of OMET to supply frequent and enough water, as Amaranth is said to yield optimally under sufficient irrigation. [PERSON] and [PERSON] [25] reported that organic materials increase soil organic matter by directly improving soil properties and ultimately better plant growth and biomass. Given the response of Amaranth species to OMET and non-OMET, bioactive compounds including total phenols, total flavonoids, and tannins showed a decrease in OMET conditions. These results suggest the efficacy of OMET in keeping water and nutrition (fertilizers) at the plant rooting zones. According to the known carbon-nitrogen theory [26], nitrogen fertilizer enhances the accumulation of nitrogen containing metabolites such as amino acids and protein, while reducing the production of compounds such polyphenols (phenols and flavonoids) [27]. On this basis, the OMET grown Amaranth had fewer bioactive compounds and higher contents of amino acids and proteins. Minor drought stress is associated with major causes for crop loss and poor performance.