Bioactive compounds content of New zealand spinach (Tetragonia tetragonoides (Pall.) o. kuntze syn. (Tetragonia expansa)) at different nitrogen concentrations

The aim of study was to determine the influence of different nitrogen concentrations (75, 140 and 205 mg L-1 NH4NO3) on the bioactive compounds content in New Zealand spinach (Tetragonia tetragonoides (Pall.) O. Kuntze syn. (Tetragonia expansa)) grown in floating hydroponic systems. Also, under the same conditions spinach (Spinacia oleracea L.) was grown and mentioned species were compared. Spinach as well as New Zealand spinach are nutritionally valuable leafy vegetables with high vitamin and mineral content. Both species are specific for the tendency of nitrogen accumulation, so it is necessary to be careful when consuming and processing it. New Zealand spinach is less known and mostly un-researched species in our region. By comparing the analyzed species significantly higher content of vitamin C (46 100 g-1 FW), phenols (108.04 mg L-1 FW), flavonoids (70.77 mg L-1 FW), non-flavonoids (37.27 mg L-1 FW), total chlorophyll (0.88 mg g-1 FW), carotenoid (0.17 mg g -1 FW) and antioxidant capacity (2172.63 μmol TE L- 1 ) were determined in spinach compared to New Zealand spinach. In spinach, nitrogen had a significant negative impact on the bioactive compounds content significantly reduced vitamin C content for 36.35 %, total phenols for 23.38 %, flavonoids for 26.08 %, non-flavonoids for 47.84 % and pigment compounds. In New Zealand spinach, with an increase of nitrogen in nutrient solution the opposite trend was determined. Namely, by increasing the nitrogen concentration significantly higher amounts of vitamin C even twice and total phenols for 5 % was determined in New Zealand spinach, while content of pigment compounds did not significantly change