Allelopathic Effect of Centaurea cyanus Aqueous Extracts on Germination and Radicle Elongation of Wheat Seedlings

Abstract

Allelopathic interactions of Centaurea cyanus aqueous extracts were evaluated on germination and early seedling growth of wheat (Triticum aestivum L.) to assess its phytotoxic potential under controlled laboratory conditions. Seeds were exposed to varying concentrations of leaf and flower extracts, and germination percentage, mean germination time, radicle length, plumule growth, and seedling vigor index were recorded. Results demonstrated a concentration-dependent inhibitory effect, with higher extract concentrations significantly reducing germination rate and delaying seedling emergence. Radicle elongation was more sensitive to allelochemical exposure compared to plumule growth, indicating stronger suppression of root development. A marked decline in seedling vigor index was observed with increasing extract concentration, suggesting impaired physiological and metabolic processes during early growth stages. Phytotoxic effects were attributed to the presence of water-soluble secondary metabolites likely interfering with enzymatic activity, cell division, and nutrient mobilization in germinating seeds. Leaf extracts exhibited stronger inhibitory effects than flower extracts, indicating variation in allelochemical composition across plant tissues. Statistical analysis confirmed significant differences among treatments, highlighting the dose-dependent nature of allelopathic interference. The study demonstrates that C. cyanus possesses notable allelopathic potential capable of influencing wheat seedling establishment under field-relevant exposure scenarios. These findings contribute to understanding plant–plant chemical interactions and their implications for crop performance in agroecosystems where wild flora coexists with cereal crops. Further studies are recommended to isolate and characterize specific allelochemicals and to evaluate their behavior under soil-mediated conditions for potential application in sustainable weed management strategies.