## 4 Discussion
In this case, Amaranth species grown under the non-OMET system developed minor drought, leading to a significant reduction of photosynthesis [28]. These facts are authenticated by the chlorophyll contents on the leaves, which were reduced in non-OMET samples. Some in vivo studies demonstrated that water deficit results in damages of the photosynthesis II (PSII) oxygen-evolving complex [29]. [PERSON] and [PERSON] [30] reported a 4.46% protein content in _A. cruentus_, much lower than all the protein content of all the Amaranth species in the present study, ranging between 20.3 and 28.6%. The protein content of _A. cruentus_ (28.6%) is considerably higher than common vegetables such as spinach, cabbage, and kale consumed in RSA. [PERSON] et al. [31] measured a protein content % ranging from 0.9 to 2.1% in cauliflower, carrot, cabbage, lettuce, spinach. There are numerous factors such as nutrient and water conservation potential by the OMET system that influenced the accumulation of protein in all the three Amaranth species. [PERSON] et al. [32] revealed that maintaining a high level of soil moisture especially during the reproductive stage was beneficial to acquiring higher protein content. In this study, the OMET system, in comparison to the non-OMET system, was a moisture conserving growing technique that maintained a higher level of soil moisture content; this might have influenced highest accumulation of protein in OMET grown Amaranth species. Differences in species and treatment are probably attributable to different protein contents. Amaranth vegetables grown under OMET system can be an important source of dietary protein. In the study of [PERSON] et al. [19], Se concentrations for _A. caudatus_ was not quantified. [PERSON] et al. [19] reported the Zn concentrations of _A. caudatus_ (0.048 mg/kg DW), which was lower than the lowest Zn concentration of non-OMET grown _A. cruentus_ (1.66 mg/kg DW) in the present study. The low concentrations of all the microelements in the present study were found in non-OMET grown Amaranth species. _A. tricolor_ grown on non-OMET system had the lowest concentration of Cu (0.78 mg/kg), Fe (2.47 mg/kg), Se (6.36 mg/kg), and Zn (0.95 mg/kg) than the rest of the Amaranth species grown on both OMET and non-OMET system. In addition, the lowest concentration of Mn was found in non-OMET grown _A. cruentus_ (1.17 mg/kg), higher than the concentrations reported by [PERSON] et al. [19] for _A. caudatus_ (0.079 mg/kg DW). The _A. caudatus_ grown on both the OMET and non-OMET systems had average concentrations of the microelements when compared to other species. The OMET system enhanced the concentration of microelements (Table 3). Minerals are essential for plant growth, development, reproduction, and seed quality. Mineral deficiency and poor minerals uptake and transport due to abiotic stress such as drought especially at the reproductive stage result in yield loss and poor seed quality [33]. Lowered absorption of the minerals could be due to reduced transpiration flow, limited availability of energy for assimilation, and interference in the unloading mechanism [34; 35]. The OMET system has successfully increased the concentration of the mineral elements for Amaranth species than the non-OMET system. This could probably be due to its potential to eliminate leaching of nutrients, conserving and reserving them for uptake by the plant roots. The less to non-fluctuating temperatures of the OMET system is conducive for better nutrient absorption. The root exudates become useful for the plant since they are not leached. The non-OMET system, on the other hand, had little influence on the accumulation of mineral elements, probably due to its inability to conserve nutrients. The nutrients are leached during irrigation through deep drainage or seepage since there is no underlying plastic to inhibit drainage, the nutrients become out of reach for plant roots absorption. The mineral accumulation is also influenced by the degree of soil moisture stress.