Laboratory assessment of <i>Lantana camara</i> L. extracts for selective inhibition of rice weeds: phytotoxicity, crop response, and phenolic composition

Weeds significantly reduce rice (<i>Oryza sativa</i> L.) yield and grain quality, highlighting the need for sustainable weed management strategies. This study evaluated the bioherbicidal potential of methanolic extracts from <i>Lantana camara</i> L. (LC) against dominant rice field weeds <i>Echinochloa crus-galli</i> (BY), <i>Leptochloa chinensis</i> (RS), and <i>Fimbristylis miliacea</i> (GF), and examined the recovery responses of rice varieties OM18 and OM5451. At 0.48 g/mL, LC extract markedly suppressed shoot and root growth in RS, and GF, with root inhibition reaching 95.14-100%. BY was less sensitive, especially in shoot growth (24.21% inhibition). Interestingly, low concentrations (0.01-0.06 g/mL) promoted early rice growth, suggesting hormetic stimulation. IC₉₀ values confirmed differential sensitivity: GF was most susceptible (0.129 g/mL), while BY was highly resistant (2.658 g/mL). OM5451 showed greater recovery after 168 h. HPLC analysis identified major phenolic compounds as veratric acid (5.605 µg/mL), <i>p</i>-coumaric acid (1.533 µg/mL), vanillic, salicylic, and gallic acids likely contributing to LC's phytotoxicity. While the findings underscore that LC may be potent as a selective natural herbicide, this laboratory-based study remains exploratory. Field-scale validation, ecological impact assessments, and formulation refinement are essential next steps. Nevertheless, this work highlights LC's dual role, as both an invasive species and a possible bioresource for eco-friendly weed control.