Evaluation of Herbicidal Potential of Essential Oils and their Components under In vitro and Greenhouse Experiments

The present study aimed to evaluate the phytotoxic potential of essential oils. For this purpose, 18 essential oil samples extracted from Korean plants and 64 commercial essential oils were screened for their phytotoxic potential against the seedling growth of Brassica napus L. (rapeseed). Among the 82 samples, 11 commercial oils (cinnamon, citronella, clove, cumin seed, geranium, jasmine, lemongrass, palmarosa, pimento, rose otto and spearmint) strongly inhibited the seedling growth with $GR_{50}$ value < $150{\mu}g\;mL^{-1}$ . Major components from these effective essential oils were identified by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). GC-MS analyses revealed that the effective samples mainly consist of benzyl benzoate, carvone, citral, citronellol, eugenol, geraniol, D-limonene and terpinene. Subsequently, bioactivity of these individual components was evaluated against the seedling growth of B. napus, Echinochloa crus-galli and Aeschynomene indica. The components from different chemical groups exhibited different potency in inhibiting the seedling growth with varied $GR_{50}$ values ranged from $29{\mu}g\;mL^{-1}$ to > $1000{\mu}g\;mL^{-1}$ . In the greenhouse experiment, citral and geraniol completely suppressed the growth of all the tested 10 plants at $100kg\;ha^{-1}$ . In conclusion, the individual essential oil components geraniol and citral could be used as natural herbicides for weed management.