European Journal of Sustainable Agroecosystems

Background: Background: Invasive plants have spread to different ecosystems around the planet to an extent that the role of allelopathy is one of the dominant reasons for their success. Allelopathy refers to the ability of plants to secrete certain chemicals (allelochemicals) that affect the ability of other plants to germinate and metabolise crop species. The development of gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and similar methods has made it possible to formulate chemical profiles of different invasive plant species and ecosystems, but the application of chemical fingerprinting in understanding the ways toxic chemicals influence plants remains limited.
Objective: This review summarises the literature sources published between 2015 and 2025 (important studies published before 2015 have been included where appropriate) discussing the identification of allelochemicals of eco-economically important invasive plant species and their biochemical influence on germination and metabolism of crops.
Sources of literature: A meticulous combination search of Scopus, Web of Science, PubMed and Google Scholar resulted in a total of 116 studies included in qualitative thematic analysis after screening based on PRISMA.
Main findings: Phenolic acids (including ferulic, p-coumaric, gallic and vanillic), sesquiterpene lactones (parthenin), quinones (sorgoleone) and flavonoids repeatedly show up in large quantities among alien species such as Parthenium hysterophorus, Mikania micrantha, Chromolaena odorata, Ageratum conyzoides and Sorghum halepense. These various components contribute to inhibition of α-amylase and protease activities during soaking which lead to ROS accumulation, superoxide dismutase, catalase and peroxidase disturbance, as well as lipid peroxidation resulting in diminished germination, radicle growth and growth score in crops.
Research gaps: Reviewed evidence is dominated by laboratory bioassays using aqueous or organic extracts at arbitrary concentrations, with limited field-scale validation, inconsistent dose standardisation, sparse integration of multi-omics platforms, and negligible attention to soil-microbiome-mediated transformation or climate-change interactions.
Conclusion: Allelochemical fingerprinting offers a mechanistically grounded route toward both improved invasive weed management and the rational design of selective bioherbicides, but the field requires methodological standardisation, field validation and multi-omics integration before this promise can be translated into applied crop protection.