Abstract

The increasing demand for resilient and multifunctional crops in the Mediterranean region has renewed interest in Urtica dioica L. as a potential alternative crop. This study evaluated the combined effects of fertilization and row spacing on the growth, yield, and nitrogen use efficiency of nettle in Athens, Greece. A split-plot experimental design was employed in a three-year experiment, with three fertilization treatments (C = control, U = urea, and I = urea with urease inhibitor) and two different row spacings (D1 = 30 cm × 20 cm, and D2 = 50 cm × 20 cm). Agronomic traits, seed yield, nitrogen content, vegetation indices (NDVI), chlorophyll content (SPAD), and nitrogen efficiency indices were assessed. Fertilization significantly enhanced plant performance, with the application of I consistently producing the highest values for plant height (increased by 10–30%), biomass (increased by 10–20%), and seed yield (increased up to 30%) compared to C. Row spacing influenced crop performance, with D2 favoring plant height (up to 9% compared to D1), while D1 generally increased biomass production per unit area (up to 20% compared to D2). Nitrogen-related indices (NUE, NAE, and NUtE) were markedly improved under fertilized treatments, particularly when I was applied (up to 20%, 100%, and 19% compared to U). NDVI and SPAD values were also influenced by fertilization and row spacing at early growth stages. The findings demonstrate that both factors play critical roles in optimizing nettle cultivation under Mediterranean conditions, highlighting the importance of integrated agronomic management practices.

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