Monoterpenoids from Artemisia austriaca Essential Oil Disrupt Hormone-Mediated Reserve Mobilization to Suppress Avena fatua Seed Germination

BACKGROUND: The search for safe and effective alternatives to synthetic herbicides is crucial for sustainable agriculture. Essen- tial oils and their bioactive monoterpenoids are promising candidates owing to their potent phytotoxic properties. This study aimed to characterize the essential oil of Artemisia austriaca, investigate the absorption of its main components, camphor and 1,8-cineole, into Avena fatua (wild oat) seeds, and elucidate the mechanisms responsible for germination inhibition. RESULTS: The essential oil of A. austriaca was dominated by camphor (26.22%) and 1,8-cineole (20.15%). These monoterpe- noids were absorbed by A. fatua seeds, inhibiting germination in a concentration-dependent manner. Their mode-of-action involved disruption of hormonal balance, significantly decreasing the gibberellic acid level (by ≤46.22% at 150 ∼g mL−1) while increasing the abscisic acid content (≤22.25-fold at 150 ∼g mL−1). The compounds also inhibited key metabolic enzymes, ⊍-amylase and lipase, by ≤97.51% and 22.25% at 150 ∼g mL−1, respectively. This enzymatic inhibition led to the accumulation of energy reserves such as starch (≤9.92-fold at 150 ∼g mL−1) and a corresponding decrease in available free sugars (by ≤84.56% at 150 ∼g mL−1). CONCLUSION: Camphor and 1,8-cineole inhibit germination by disrupting hormonal signaling and blocking the metabolic pathways required for the mobilization of reserves in seeds. These findings clarify the specific phytotoxic mechanisms of these compounds, highlighting their potential as effective bioherbicides. This research advances the development of natural, eco- friendly alternatives for sustainable weed management.