| Summary: | Background: Fruit peels are generally underutilized byproducts of the food industry, although they are valuable sources of bioactive compounds. The aim of this study is to evaluate a new application for three <i>Citrus</i> peel EOs as bio-herbicides. Methods: After a micro-morphological evaluation of <i>Citrus</i> peels by SEM analysis, the phytochemical composition of the EOs of <i>Citrus × bergamia</i> Risso & Poit., <i>Citrus × myrtifolia</i> Raf., and <i>Citrus limon</i> (L.) Osbeck was characterized by GC/FID and GC/MS analyses. The in vitro phytotoxicity against germination and initial radical elongation of several crop and weed species was evaluated. Furthermore, the eco-compatibility of these EOs has been assessed by the brine shrimp (<i>Artemia salina</i>) lethality assay. Results: SEM analysis highlighted the morphometric differences of the schizolysigenous pockets among the peels of the three <i>Citrus</i> species. Oxygenated monoterpenes are the main constituents in <i>C. × bergamia</i> (51.09%), whereas monoterpene hydrocarbons represent the most abundant compounds in <i>C. × myrtifolia</i> (82.15%) and <i>C. limon</i> (80.33%) EOs. They showed marked and selective phytotoxic activity in vitro, often at very low concentration (0.1 μg/mL) against all plant species investigated, without showing any toxicity on <i>Artemia salina</i>, opening the perspective of their use as safe bio-herbicides.
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