Allelopathic potential of invasive alien plant species, Xanthium strumarium L., water and methanol extracts on germination and seedling growth of Guizotia abyssinica (L.f.) Cass., and Linum usitatissimum L.

Abstract

The objective of this study was to investigate the allelopathic impact of Xanthium strumarium on the seedling growth and germination of Guizotia abyssinica and Linum usitatissimum. Plant specimens and samples of Xanthium strumarium were collected from the Minjar-Shenkora district in Ethiopia. In the laboratory, a series of dilutions of extracts from the leaves and roots of Xanthium strumarium were prepared using distilled water and methanol (99.85%) as solvents. Twenty-five grams of root and leaf samples were soaked separately in 250 mL of the specified solvent to create the stock solution. The experiment was carried out using Petri dishes in a completely random manner, with three replications repeated twice. Various concentrations of the extracts (25, 50, 75, and 100%) were applied as treatments, while distilled water served as the control. Each petri dish contained 25 seeds of each test crop and 5 mL of the corresponding extract. The number of Linum usitatissimum and Guizotia abyssinica seeds germinating was recorded every 24 hours until 12 and 14 days, respectively. Both descriptive and inferential analyses were conducted. When Guizotia abyssinica and Linum usitatissimum seeds were treated with 100% concentrations of water extract from leaf samples, germination percentages were inhibited by 72 and 77.4%, respectively. In methanol extracts, the entire inhibition of germination was observed in both test plant species at ≥ 50% and ≥ 75% concentrations of leaf and root samples, respectively. Therefore, the inhibitory effect of water and methanol extracts showed a concentration-dependent pattern, with increasing concentrations resulting in greater inhibition. The inhibitory effect of leaf extracts was more pronounced compared to root extracts, suggesting the presence of herbicidal activities. Further phytochemical and molecular studies are recommended to identify the active compounds in Xanthium strumarium. Additionally, utilizing isolated allelopathic substances as a means of controlling invasive alien species is suggested.