European Journal of Sustainable Agroecosystems

Cyperus rotundus L., commonly known as purple nutsedge, has been regarded as the most problematic weed in the world since infested plants can result in losses above 80% in the yield of crops. Purple nutsedge competes for the same nutrients, water, and light with crops, while also releasing biologically active substances affecting the development of seeds of neighboring crops. The current study examines current research publications on the mechanisms of effect of purple nutsedge on crops in order to expand the knowledge about this phenomenon and suggest research directions in this field. The search was carried out in Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar for the period from 1974 to 2025. Finally, 35 studies were selected and analyzed according to the PRISMA methodology. According to literature, extracts, residues and root exudates of purple nutsedge exhibit negative effects on crops. The level of inhibition is largely influenced by concentration; tuber tissue is often more phytotoxic than the leaf tissue. The reason for this is the presence of phenolic acids (ferulic, p-coumaric, caffeic, chlorogenic, vanillic, and benzoic) and other components such as flavonoids and sesquiterpenes that can influence membrane transport, cell division, photosynthetic pigments and enzymes. There are big controversies regarding differences between resource competition and allelopathy, the importance of laboratory bioassays in comparison to field work, and whether allelochemicals can be truly measured on a field level. The conclusion of the review is that allelopathy of purple nutsedge is for sure real and agriculturally important. Indeed, there has been too much research done on it in laboratories, and not enough attention is paid to field studies.