Seaweed-derived organic fertilizer enhances biomass, essential oil yield, and bioactive compounds in Pelargonium graveolens L’Hér.: A sustainable approach to agricultural productivity

The present study was conducted to evaluate the elicitation potential of red seaweed-based biostimulant (Solieria chordalis) on rose-scented geranium under mid hill conditions of the western Himalayas under modified cultivation conditions. Foliar application of seaweed liquid extract was applied at 0, 2.5, 5, 7.5, and 10 mL/L concentrations to assess its impact on plant growth, yield, and chemical constituents of this aromatic plant. The experiment was carried out in CSIR-IHBT, Palampur (H.P., India) for two years (2023-2025). The results encompassed an assessment of various parameters over four harvests revealed that application of S. chordalis seaweed aqueous extract (SWE) significantly improved the plant height (78.2 ± 6.5 cm), herb yield (39.2 ± 5.6 t ha-1), photosynthetic rate (14.2 ± 1.11 µmolm-2s-1), essential oil recovery (0.18 ± 0.02%) and percentages of volatile organic compounds as compared to control. There were 27.2% and 50.1% increase in herbage and essential oil yield respectively, with the application of seaweed at a higher concentration (10 mL/L) over control. The chemical profile of essential oil reveals that higher amounts of citronellol (55.8%), citronellyl formate (23.8%), geraniol (8.1%) and isomenthone (9.6%) were noticed in the treatment received 10 mL/L of SWE. The higher concentrations also improved the number of stomata along with the density of trichomes on the lower surface of the leaf, hence resulting in increased essential oil production. The current study suggested that application of 10mL/L of aqueous seaweed extract could improve the efficacy of rose-scented geranium both in quantitative and qualitative terms.