Abstracts

Lemon balm (Melissa officinalis L.) is a perennial medicinal and aromatic plant traditionally used in the form of herbal teas, extracts, and fresh biomass. Although it has been extensively studied under conventional cultivation systems, information regarding its agronomic performance when grown as microgreens remains limited. The present study aimed to evaluate the effect of sowing density on germination dynamics, early growth, and fresh yield of lemon balm cultivated as microgreens under controlled environmental conditions. The experiment was conducted in 2025 under laboratory conditions using three sowing densities commonly applied in microgreen production: 3 g m⁻² (control, C), 6 g m⁻² (T1), and 9 g m⁻² (T2). Seeds were sown in plastic trays filled with a commercial peat-based substrate and grown under controlled temperature, relative humidity, and artificial lighting. Based on the thousand-seed weight (0.45 g) and seed use value determined according to ISTA rules (72%), the applied sowing densities corresponded to approximately 4.800, 9.600, and 14.400 plants m⁻², respectively. Germination, plant height, relative height increase, relative leaf area expansion, and fresh yield were monitored until harvest, which was performed 22 days after sowing at the stage of fully developed cotyledons and the onset of true leaf formation. Germination began on the 12th day after sowing and was completed by the 15th day in all treatments. Lower sowing density promoted earlier germination and faster early seedling development, whereas higher sowing density resulted in a greater number of established plants per unit area. Differences in plant height and relative leaf area were pronounced during the early growth stages but diminished by the time of harvest. Sowing density had a pronounced effect on fresh biomass yield, with the highest density (T2) achieving the greatest yield per unit area (approximately 90 g m⁻²) due to increased plant density, despite reduced individual plant weight. In contrast, the control treatment (C) produced heavier individual plants but resulted in the lowest total fresh yield (approximately 56 g m⁻²). The results indicate a clear density–yield trade-off in lemon balm microgreen production, suggesting that higher sowing density is more suitable for maximizing fresh biomass yield. This study provides new agronomic insights into the cultivation of Melissa officinalis as microgreens and contributes to the limited body of literature on medicinal and aromatic plants grown in this production form.

Keywords

Density, Germination dynamics, Early growth, Fresh yield

Acknowledgment

This study was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Grant: 451-03-136/2025-03/200003

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