REPLACING NITROGEN CHEMICAL FERTILIZERS WITH VERMICOMPOST: A SUSTAINABLE STRATEGY TO ENHANCE ROSMARINUS OFFICINALIS L. PERFORMANCE UNDER WATER STRESS

Abstract

A split-plot experiment using a randomized complete block design was conducted in Karaj, Iran (2023–2024) on Melissa officinalis (lemon balm), focusing on sustainable fertilization and irrigation. Three irrigation regimes were tested: optimal (I1), irrigation after 40% water depletion (I2), and after 55% depletion (I3). Six fertilizer treatments ranged from no fertilizer (F1) to varying mixes of urea and vermicompost (F2–F6). Results showed that higher water stress reduced seed yield, essential oil yield, chlorophyll content, and photosynthesis. Vermicompost improved soil quality and boosted plant biochemical and photosynthetic performance. This highlights the value of eco-friendly practices to enhance medicinal plant productivity while conserving resurces.

Plain Language Summary

(lemon balm), a valuable medicinal plant. The research aimed to develop sustainable cultivation practices by testing various combinations of water and fertilizers to determine which conditions promote better growth and higher essential oil production. Results showed that increased water stress reduced seed yield, oil content, and chlorophyll levels. However, using vermicompost (worm-produced organic fertilizer) improved plant health, enhanced photosynthesis, and supported better growth even under mild stress conditions.