Nitrogen supply influences agronomic performance, essential oil yield, and phytochemical composition of basil (Ocimum basilicum L.) grown under hydroponic conditions

Abstract

Basil (Ocimum basilicum L.) is an aromatic and medicinal plant widely cultivated for its culinary, seasoning, and therapeutic applications, making it an economically important crop. Among its high-504 value products, basil essential oil (EO) is widely used to enhance the aroma and flavor of processed foods and beverages and for its pharmacological properties. Nitrogen (N) is one of the primary nutrients regulating plant growth, biomass accumulation, and secondary metabolism, thereby influencing EO yield and chemical composition. This study evaluated the effects of different N concentrations in the nutrient solution on the agronomic performance, EO yield, and phytochemical composition of hydroponically grown basil. Basil seedlings (~12 cm tall) were cultivated in a greenhouse using a completely randomized design with five N concentrations (4.0, 6.0, 8.0, 10.0, and 12.0 mmol L–¹) and three replicates. Plants received Hoagland and Arnon (1950) nutrient solution, and the pH was maintained between 5.8 and 6.2. Increasing N supply enhanced leaf and root biomass, root volume, and tissue N concentration. The highest N concentration (12 mmol L–¹) produced the greatest EO yield and increased the relative abundance of 1,8-cineole and eugenol, whereas the lowest N concentration (4 mmol L–¹) promoted greater germacrene D accumulation.