Allelopathic effects of yellow cosmos (Cosmos sulphureus var. hirsuticaulis): Phytochemicals composition and its weed suppression potential
Allelopathic effects of yellow cosmos (Cosmos sulphureus var. hirsuticaulis): Phytochemicals composition and its weed suppression potential
- Author(s) H.L. Thi, N.T.T., Trang, T.T. Men and D.T. Khang
- Year: 2025
- Month: May
- Volume: 65
- Pages: 35-50
We evaluated the allelopathic effects of methanol extracts from different parts of Cosmos sulphureus var. hirsuticaulis (CS) on Brassica juncea (L.) Czern., used as an indicator species, to compare the inhibitory potential of flowers, leaves, stems and roots. The experiment was done in completely randomized design (CRD) with three replications and 6-extract concentrations (0, 0.03, 0.06, 0.12, 0.24 and 0.48 g/mL). Results showed that the inhibitory effects of CS extracts on germination and growth were concentration-dependent, with stronger suppression at higher concentrations. The flower and leaf extracts exhibited the highest inhibitory potential on root and shoot elongation, significantly stronger than those of stem and root extracts. Phytochemical analysis confirmed the presence of phenolic compounds (64.95 mg GAE/g) and flavonoids (1.96 mg QE/g fresh extract). Among plant parts, flowers contained the highest levels of phenolics (66.32 mg GAE/g) and flavonoids (3.39 mg QE/g). Greenhouse trials further demonstrated that leaf extracts at 0.96 g/mL significantly reduced weed growth, with Leptochloa chinensis and Fimbristylis miliacea exhibiting 50 % and 48.53 % inhibition, respectively. These findings suggest that CS leaf extracts may serve as an eco-friendly bioherbicide for sustainable weed management in rice production.
