How to Increase the Nutritional Quality of Stinging Nettle Through Controlled Plant Nutrition

Research background. As food production faces major challenges, modern agricultural practices are increasingly focused on conserving resources, reducing negative environmental impacts, and sustainably producing foods high in health-promoting phytochemicals. During the production process, many factors can influence the quality and chemical composition of a final food product. Proper selection of cultivating conditions, especially a balanced nutrition, can significantly increase nutritional value resulting in foods with strong biological and functional properties. Stinging nettle is a rich source of minerals, vitamins, pigments, phenols and other bioactive compounds (BC) and can be consumed as a green leafy vegetable with beneficial effects on human health. Therefore, the aim of this study was to determine the nutritional quality and antioxidant capacity of stinging nettle leaves under the influence of different nutrient solution (NS) treatments during three mowings. Experimental approach. The experiment was performed in a floating hydroponic system, with different treatments of NS application during three mowings. After each mowing, the following treatments were differed: treatment 1 – depletion with water, treatment 2 - supplementation with standard NS, and treatment 3 - correction with nutrients. Of the BC minerals, ascorbic acid, phenols, and photosynthetic pigments content, as well as antioxidant capacity were analyzed spectrophotometrically, while individual phenols were determined by liquid chromatography. Results and conclusions. Different nutrition solution treatments and the number of mowings had a significant influence on the content of the analyzed BC. The highest contents of total phenols (377.04 mg GAE/100 g fm), total flavonoids (279.54 mg CTH/100 g fm), ascorbic acid (112.37 mg/100 g fm), and pigments (total chlorophylls 1.84, and total carotenoids 0.36 mg/g), as well as the highest antioxidant capacity (35.47 µmol TE/g) were recorded in the third mowing, with nutrient solution supplementation. Novelty and scientific contribution. This is the first time that stinging nettle leaves are produced in a floating hydroponic system by controlled plant nutrition. We establish this type of nutrition manipulation during multiple mowings as an innovative technique for the production of novel food with high and improved nutritional value suitable for consumption as green leafy vegetables.