Allelopathic Effect of Artemisia annua Aqueous Extracts on Germination and Early Growth of Echinochloa crus-galli

Abstract

Weed infestation by Echinochloa crus-galli represents a major constraint in rice-based agroecosystems, necessitating exploration of eco-friendly suppression strategies. The present investigation evaluates the allelopathic potential of aqueous extracts derived from Artemisia annua on seed germination and early seedling growth of E. crus-galli under controlled laboratory conditions. Seeds were exposed to graded concentrations of leaf, stem, and root extracts, and germination percentage, mean germination time, root length, shoot length, and seedling vigor index were recorded. Results demonstrated a concentration-dependent inhibitory effect of A. annua extracts on all tested germination parameters. Leaf extracts exhibited the strongest allelopathic activity, followed by stem and root extracts, indicating differential distribution of bioactive compounds within plant tissues. High extract concentrations significantly delayed germination onset and reduced final germination percentage compared to control treatments. Seedling growth parameters, particularly root elongation, were more sensitive to allelochemical exposure than shoot growth, suggesting disruption of cell division and nutrient uptake processes in early developmental stages. Phytotoxic effects were attributed to the presence of secondary metabolites such as terpenoids and phenolic compounds known to interfere with metabolic and enzymatic activities in target weed species. Statistical analysis confirmed significant treatment effects across all growth parameters, reinforcing the suppressive potential of A. annua extracts. The findings highlight the prospective use of A. annua-derived allelochemicals as natural bioherbicide agents for integrated weed management systems. Further field validation and formulation development are required to translate laboratory efficacy into practical agricultural applications. Overall, the study supports the role of plant-based allelopathy as a sustainable alternative to synthetic herbicides in managing problematic weed species in cereal cropping systems.