Format: ORAL

Maeleletse G. Mopai, Semakaleng Mpai, Ashwell R. Ndhlala

Department of Plant Production, University of Limpopo, Limpopo Province, South Africa

Amaranth species are a highly popular group of indigenous leafy vegetables (ILV) consumed in South Africa as a relish. Amaranth is rarely cultivated due to lack of protocols for optimum production. Climate change impacts on vegetable production has mandated farmers to resort to and develop sustainable, effective and efficient environmentally friendly growing practices. The Organic Medium Enclosed Trough (OMET) system is a non-drainable vegetable growing technique. The aim of the study was to investigate the effects of the OMET system on primary and secondary metabolites of two Amaranth species: A. caudatus and A. cruentus. Primary metabolites of the two species determined after harvesting included %protein, macro- and micro-elements using AOAC methods. Secondary metabolites, targeted (total phenolics, flavonols and tannins) and untargeted metabolites were analysed using photometric assays and UHPLC-MS-Q-ToF techniques, respectively. A. caudatus and A. cruentus grown under OMET system exhibited higher contents of nutrients including %protein, Ca, Mg, P, K, Mn, Cu, Fe, Se, Zn compared to non-OMET grown A. caudatus and A. cruentus, respectively. In contrary, A. caudatus and A. cruentus grown under non-OMET system recorded the highest total phenolics, flavonols and tannins compared to the same Amaranth species, A. caudatus and A. cruentus grown under OMET. The use of unsupervised PCA showed less metabolic variation and the use of supervised OPLS-DA showed clear metabolic variation based on treatments, OMET and non-OMET. The use of OMET system can be recommended to mitigate the climate change impacts in vegetable production as well as to combat the crisis of malnutrition hence it eliminate water and nutrient seepage, especially in developing countries whereby irrigation water is the most scarcest agricultural commodity.