Essential Oil-Loaded Montmorillonite Clay-Based Formulation for Sustained Bioherbicidal Activity

Abstract

Ocimum basilicum essential oil, with its rich composition of bioactive compounds like linalool and methyl chavicol, has shown promising weed control potential. Montmorillonite nano-clay (M-NC) can enhance the effectiveness of volatile essential oil herbicide through sustained release mechanisms. The oil of O. basilicum was loaded on M-NC (NC-OF) and examined for sustained-release and bioherbicidal properties. Results indicated that NC-OF show successful loading of key oil constituents, i.e., linalool and methyl chavicol. Characterization of the formulation suggested that binding between oil constituents and NC-OF occurred through hydrophobic, hydrogen bonding, and $\pi$--$\pi$ interactions. NC-OF demonstrated sustained release (t$_{50}\%$ up to 30 days) at 32 $\pm$ 1$^\circ$C. Different experiments revealed that the formulation disrupted weed stomata and epidermal cells, causing cellular damage and vascular irregularities in roots. Field tests demonstrated inhibitory effects on various weeds, NC-OF formulation showing 100% population reduction for A. arvensis and S. arvensis. In addition, the formulation did not harm soil enzymatic activity, suggesting a reduced ecological impact.