Allelopathic Effects of Three Plant Species on the Germination and Growth of Agricultural Crops: Isolation and Spectroscopic Characterization of Active Allelochemicals

Abstract

Allelopathy plays a crucial ecological role in regulating plant interactions and maintaining ecosystem balance through the release of secondary metabolites known as allelochemicals. The present study investigated the allelopathic effects of three plant species — Taraxacum officinale, Malva parviflora, and Solanum nigrum — on the germination and early growth of three crops (Triticum aestivum, Vicia faba, and Lolium perenne). Aqueous and organic extracts from different plant parts were prepared and evaluated under controlled laboratory conditions to determine their inhibitory potential on seed germination, radicle elongation, and seedling biomass. The results revealed that all three donor plant extracts exhibited significant inhibitory effects, with S. nigrum extracts showing the strongest suppression on seed germination and root elongation, particularly in L. perenne. The degree of inhibition increased with extract concentration and varied according to both the donor and target plant species. Phytochemical screening and spectroscopic analyses (UV–Vis, FTIR, and NMR) identified several bioactive allelochemicals, including phenolics, flavonoids, and alkaloids, which are likely responsible for the observed allelopathic activity. These findings suggest that the tested plant species possess strong allelopathic potential, highlighting their ecological role and possible use as sources of natural bioherbicides. The study contributes to understanding plant–plant interactions in agroecosystems and supports the development of environmentally friendly weed management strategies based on allelochemical compounds.