S13 - Session O3 - Macroelements composition of nettle in hydroponic production

Authors: Marko Petek *, Sanja Radman, Nevena Opacic, Sandra Voca, Lepomir Coga, Sanja Fabek Uher, Bozidar Benko, Nina Toth, Jana Sic Zlabur

Nettle ( Urtica dioica L.) is a perennial plant used as a medicinal herb and also as a food. Besides numerous phytochemicals, nettle is great source of macro and microelements which are important for human health. In the last 2 decades, global world population is more and more aware of problems caused by climate change which affect both the decrease in yield and the lower quality of the final product. Therefore, hydroponic production is good solution for optimal nutrient supply in order to produce nutritionally high quality nettle. In this way excessive application of nitrogen is avoided and reduced negative effect on other nutrients and quality itself. The aim of this research was to determine macromineral compostion of nettle in hydroponic production system according to different nutrient solutions in order to obtain the highest possible mineral status. The experiment was conducted in a greenhouse following randomized complete block design with three replicates. Four different nutrient solutions (Johnson, Jensen, Larson, Cooper) which differ in EC value (1.72, 2.34, 2.50 and 3.42 mS/cm, respectively) were tested. Nettle was sown on 11 March 2021 in polystyrene plates filled with perlite and placed in basins filled with nutrient solutions after germination. Harvest was performed manualy on 20 May 2021. Samples were first dried, then homogenized which was followed by digestion in the microwave oven with HNO 3 and HClO 4 . Phosphorus was determined spectrophotometrically, potassium phlamorphotometrically and calcium and magnesium by atomic absorption spectrometry. Nitrogen was determined by Kjehldal method. Results showed differences between nutirent solutions and harvest. The content of macroelements varied as follows 6.15-7.14 % N DW, 0.87-0.93 % P DW, 4.21-4.75 % K DW, 4.95-5.40 % Ca DW, 0.72-1.13 % Mg DW.