The essential oil of Dodonaea viscosa leaves is allelopathic to rosemary (Rosmarinus officinalis L.)

• Dodonaea viscosa is an aromatic and medicinal plant.
• Aqueous extracts of D. viscosa were influenced on composition of the essential oil of rosemary and major constituents.
• Allelopathic activity of D. viscosa on rosemary was confirmed.

The essential oil of Rosmarinus officinalis L. is widely used as a folk medicine. In this study, the allelopathic activity of Dodonaea viscosa (aqueous, and acetone extracts 0, 30, 60 and 100%) on R. officinalis L. was investigated under laboratory conditions. The essential oil of air-dried samples was obtained by hydro distillation and was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry. The effect of the of D. viscosa on the chlorophyll content, photosynthetic rate, total phenols content, proline content, and chemical composition in rosemary was evaluated. A significant reduction of chlorophyll content and photosynthetic rate was observed. On the other hand, an increase was detected in the total phenols and proline content. Aqueous extract increased the 1,8-cineol content from 4.6% to 7.0%, the camphor content from 4.8% to 8.9% and the borneol content from 4.1% to 7.2%. As a result, allelopathic activity of D. viscosa on rosemary was confirmed.