Optimization of In Vitro Cultivation for Enhanced Biochemical Properties of Geranium (Pelargonium graveolens) for Functional Use

Introduction: Pelargonium graveolens is a valuable aromatic and medicinal plant native to southern Africa, widely recognized for its essential oils rich in bioactive compounds with antiseptic, anti-inflammatory, and antioxidant properties. Its increasing cultivation in Armenia highlights its potential for use in natural health products and functional foods, where antioxidant-rich phytochemicals are highly sought after. Objective: This study aimed to optimize in vitro propagation protocols for P. graveolens by evaluating the effects of various plant growth regulators (PGRs) on morphogenic response, phenolic accumulation, antioxidant activity, and essential oil composition—specifically focusing on citronellol, geraniol, and linalool. Materials and Methods: Nodal explants were cultured on Murashige and Skoog (MS) medium supplemented with different PGRs, including 6-benzylaminopurine (BAP), kinetin (KIN), gibberellic acid (GA₃), and indole-3-butyric acid (IBA). After six weeks, growth parameters, chlorophyll content, total phenolic content (TPC), antioxidant activity, and essential oil profiles were analyzed. TPC was assessed using the Folin–Ciocalteu method, antioxidant activity via DPPH assay, and essential oils were identified by GC-MS. Data were statistically analyzed using one-way ANOVA (p < 0.05). Results: The PGR combination of 1.0 mg/L KIN + 1.0 mg/L GA₃ + 1.0 mg/L BAP + 1.0 mg/L IBA yielded the highest shoot number (3.9 ± 0.2) and length (6.3 ± 0.2 cm). Rooting was most effective with 1.0 mg/L IBA alone. This combination also significantly enhanced TPC (20.3 ± 0.9 mg GAE/g FW) and antioxidant activity (50.7 ± 1.8%). GC-MS analysis revealed increased concentrations of key essential oil constituents with known therapeutic and antioxidant properties. Conclusion: Targeted PGR combinations effectively improve in vitro regeneration and biochemical quality of P. graveolens, boosting its value as a source of natural antioxidants and functional ingredients. These findings support the use of optimized tissue culture methods in the sustainable production of plant-based compounds for health-promoting applications.