摘要：Amaranthus are a great source of phytochemicals important for nutritive and remedial benefits. However they are also great accumulators of anti-nutrients such as oxalates. Nitrogen (N), a vital plant nutrient is a strong determinant of plant nutritive value. The study therefore investigated the total flavonoids content (TFC) and phenolic content (TPC) accumulation, antioxidant activity and oxalates content in relation to different N forms in three vegetable amaranth varieties. Three N forms were used; ammonium, nitrate, ammonium/nitrate mixture {ammonium and ammonium nitrate were stabilized with Piadin® as nitrification inhibitor} and control on three amaranth varieties were AB5, AB6 and AB7 in randomized complete block design replicated three times. Sole ammonium and the control enhanced accumulation of both TFC and TPC, compared to the nitrate and ammonium nitrate mixture. Under ammonium treatment, TFC increased by 13.8% in AB5, 17.4% in AB6 and 14.7% in AB7 while TPC increased by about 19.5% in AB5, 23% in AB6 and 20% in AB7 in greenhouse. Similar trends were observed from the field experiment. Likewise, NH4+ - N form had higher antioxidant DPPH scavenging activity indicated by high inhibiting capacity and lower IC50 value (concentration which scavenged 50% of the DPPH radicals). Compared to control, nitrate elevated oxalate accumulation unlike ammonium treatment which on contrary inhibited oxalate buildup. It was therefore concluded that TFC, TPC and antioxidant capacity increased with N deficiency and ammonium-N provision while oxalate content was enhanced under nitrate treatment in leafy amaranth. This is relevant for nutritive wellbeing in human beings.
关键词：Amaranth; Nitrate; Ammonium; Flavonoids; Phenolics Oxalate and varieties
