Screening of Allelochemicals in <i>Miscanthus sacchariflorus</i> Extracts and Assessment of Their Effects on Germination and Seedling Growth of Common Weeds

There is increasing interest in the application of bioherbicides because they are less destructive to the global ecosystem than synthetic herbicides. Research has focused on reducing the dependence upon synthetic herbicides by substituting them with environmentally and economically sustainable bioproducts. Allelopathic phytochemicals may be an efficient method for controlling weeds, benefitting both the environment and human health. This study addressed the allelopathic potential of <i>Miscanthus sacchariflorus</i> (MS) extracts on the germination, plant growth, biomass, and biochemical parameters (electrolyte leakage, photosynthetic pigments, and antioxidant enzyme activities) of weeds using laboratory and field experiments. Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) showed the presence of 22 phenolic compounds, including Orientin, Luteolin, Veratric acid, Chlorogenic acid, Protocatechuic acid, <i>p</i>-Coumaric acid, and Ferulic acid. Leaf extracts of <i>M. sacchariflorus</i> either completely suppressed or partially reduced seed germination and affected the development of weed seedlings (root and shoot length), in a dose-dependent manner. Aqueous extracts of <i>M. sacchariflorus</i> reduced the fresh weight and dry weight, affected the photosynthetic pigment content (chlorophylls, carotenoids), influenced the electrolyte ion leakage, and stimulated the activity of antioxidant enzymes in a species-specific manner. Pearson’s correlation analysis showed that the phenolic compound composition of <i>M. sacchariflorus</i> correlated with the variables tested, indicating that the phytochemicals present in the plant extracts of <i>M. sacchariflorus</i> are a potential source of bio-herbicides.