Development of bio-nano-herbicide using Eucalyptus citriodora essential oil against a notorious weed Echinochloa crus-galli

BACKGROUND

Weeds are a menace in agriculture causing crop yield reductions to the tune of 40–50%. To overcome the problems of weeds, herbicides have been used excessively to the extent that they have caused resistance in weeds, in addition to the environmental hazards. Nano-herbicides are intended to exploit botanicals to develop novel bio-nano-herbicide formulations. Bio-nano herbicide was developed using Eucalyptus citriodora essential oil combined high-energy approaches such as ultra-sonication and high-pressure homogenization. The formulation has hydrodynamic and physical sizes of 95.5 and 32.3–57.7 nm, respectively. The product was tested for their pre-emergence and post-emergence herbicidal activity against Echinochloa crus-galli.

RESULTS

Increased concentration of bio-nano-herbicide inhibited the pre-emergence of weed seeds. Treated weed seeds registered lower dehydrogenase (0.80 to 0.32), alpha-amylase (1.349 to 0.101 mg maltose), catalase (3.87 to 3.52 μmol H₂O₂ min⁻¹ g⁻¹ protein), peroxidase (3.96 to 3.61 U mg⁻¹ protein min⁻¹) and super oxide dismutase (0.94 to 0.56 U mg⁻¹ protein min⁻¹) activities than control. Further, foliar spray of 1% nanoemulsion recorded significantly lower total chlorophyll content (1.62 mg g⁻¹ fresh weight), than the crude oil (2.58 mg g⁻¹). The antioxidant enzyme activities increased immediately after the first spray and the weeds wilted after the second spray.

CONCLUSION

This study is a maiden attempt to clearly demonstrate that bio-nano-herbicide can be developed using Eucalyptus citriodora essential oil which has both pre-emergence and post-emergence inhibitory activities against the notorious weed Echinochloa crus-galli. Field studies are to be taken up in the near future to validate the herbicidal efficacy of the novel nano herbicide formulation. © 2025 Society of Chemical Industry.