PHYSIOLOGICAL STUDIES ON STINGING NETTLE (URTICA DIOICA L.) PLANT

The experiment was carried out during two successive winter seasons of 2022/2023 and 2023/2024 at the Agricultural Research Center Farm, Gemmayzeh, Gharbia Governorate, Egypt. The investigation was to study the impact of three-hole distances (20, 25 and 30 cm), NPK fertilizer application rates 100 N: 50 P: 50 K, 200 N: 100 P: 100 K and 300 N: 150 P: 150 K (kg/fed as ammonium sulfate, calcium super phosphate and potassium sulfate fertilizers, respectively) and their interactions on the growth parameters and chemical constituents of stinging nettle (Urtica dioica L.) plants. The results indicated that the application of nettle plants thrives in tight growing environments with smaller quantities. The best results of plant height, fixed oil content in seeds, seed weight, carbohydrate content in leaves and potassium percentage, the highest fresh and dry weights of plant, carbohydrate content in seeds and phenolic content in leaves were obtained from 25 cm spacing + 100, 50 and 50 kg NPK fertilizers/fed. The biggest number of branches resulted from 20 cm spacing and 200, 100 and 100 kg NPK fertilizers/fed. Moreover, the treatment of 25 cm with 200, 100 and 100 kg NPK/fed gave the highest chlorophyll a, b and carotenoids contents in fresh leaves. While the wider spacing (30 cm) and the highest fertilizers (300:150:150 kg NPK/fed) gave the highest (chl. a/chl. b) ratio. However, the highest nitrogen percentage resulted from the interaction treatment of 30 cm with 100, 50 and 50 kg NPK/fed and the highest phosphorus percentage from the treatment of 25 cm with 300, 150 and 150 kg NPK/fed. during the two seasons. In brief, the study observed that inter-hole spacing significantly impacts Urtica dioica L. growth and yield. The optimal spacing is 25 cm, balancing resource use and competition. Middle NPK fertilization enhances productivity and metabolite accumulation. Combining 25 cm spacing with middle NPK fertilization improves vegetative growth and biomass. However, high rate fertilization can harm plant performance