evaluation of the allelopathic potential of thymus kotschyanus boiss. extracts on seed germination, growth, and photosynthetic activity of convolvulus arvensis l. and cynodon dactylon l.

This study investigated the allelopathic potential of thymus kotschyanus boiss. on the germination, growth, and photosynthetic performance of cynodon dactylon and convolvulus arvensis. laboratory and greenhouse experiments were conducted in 2025 using a completely randomized design with four replications at a research farm in shirvan, north khorasan province, iran. treatments consisted of aqueous root and shoot extracts of mountain thyme prepared by soaking plant material in distilled water and shaking for 24 h at room temperature under continuous agitation (200 rpm), at concentrations of 10 and 20 g l-1, with distilled water serving as the control. the results indicated that the highest extract concentration (20 g l-1) significantly reduced germination percentage in c. dactylon by 19.8% and 36.6% and in c. arvensis by 31.2% and 51.3% following application of shoot and root extracts, respectively, compared with the control. under the same treatment conditions, germination rate decreased by 36.8% and 57.8% in c. dactylon and by 44.2% and 65.0% in c. arvensis, respectively. application of the root extract at 20 g l-1 significantly reduced several growth and physiological traits in both weed species, including plant height (34.4% and 31.7%), leaf area (41.8% and 43.0%), shoot dry weight (29.4% and 34.9%), total chlorophyll content (30.4% and 36.0%), net photosynthetic rate (41.0% and 50.4%), and stomatal conductance (50.5% and 56.6%) in c. dactylon and c. arvensis, respectively (p ≤ 0.01). overall, the findings demonstrated that root and shoot extracts of t. kotschyanus, likely containing water-soluble allelochemicals, markedly inhibited germination and growth of both weed species. these results suggest that t. kotschyanus may have potential for future development of bioherbicidal agents and could serve as a promising candidate for environmentally friendly weed management strategies.