Author
Naphat Somala
naphat.so@kmitl.ac.th
King Mongkut’s Institute of Technology Ladkrabang
Bangkok
Coauthors
Chamroon Laosinwattana, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Montinee Teerarak, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Nawasit Chotsaeng, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Jantra Dimak, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Abstract
The development of natural herbicides based on essential oils (EOs) from Cymbopogon nardus, Cananga odorata, Syzygium aromaticum, and Mentha piperita, represents a potential approach for sustainable agriculture. This is because EOs have multiple modes of action. To enhance their efficacy and stability, nanoemulsions were prepared using the high-energy methods micro-fluidization and ultrasonication, which reduced the particle size of EO droplets to a range of 20–200 nm. The C. nardus EO nanoemulsion presented droplet size of 33.2 nm while the C. odorata nanoemulsion had a droplet size of 43.98 nm. These nanoemulsions demonstrated high kinetic stability and exerted dose-dependent herbicidal effects, inhibiting germination and seedling growth of the weeds Echinochloa crus-galli and Amaranthus tricolor following both pre-emergence and post-emergence application. Foliar application caused severe visual toxicity symptoms. The mechanisms of action involve interference with seed imbibition and suppression of germination-related α-amylase activity, along with severe damage to cell membranes, as indicated by elevated electrolyte leakage and malondialdehyde accumulation. Additionally, a marked reduction in photosynthetic pigment content was observed. These results support the idea that EO-based nanoemulsions can serve as a highly effective and environmentally friendly bioherbicides for sustainable weed control.
Keywords
natural herbicide
nanoemulsion
Highlights
EO nanoemulsions with low particle size have enhanced permeability and herbicidal activity.
EO nanoemulsions have high weed inhibitory activity both pre- and post-emergence.
EO nanoemulsions at low temperatures retained their weed inhibition for 60 days.