Allelopathic Effects of Aqueous Extracts of Eucalyptus occidentalis, Acacia ampliceps and Prosopis juliflora on the Germination of Three Cultivated Species

Abstract

This study concerns the effect of the aqueous extracts of Eucalyptus occidentalis, Acacia ampliceps and Prosopis juliflora on the germination of three species frequently cultivated in the South of Tunisia: Barley (Hordeum vulgare), annual lucerne (Medicago sativa) and jew's mallow (Corchorus olitorius). Aqueous extracts were obtained after a maceration of the dry plant material in distilled water (90 g/l) during 48 h at 60°C. The extraction was made from three vegetative organs (roots, twigs and leaves) for each species. The results showed a variable behavior between the species according to the origin of the extract. Barley is the most sensitive species, showing decrease of germination rate essentially with the leaf extracts of P. juliflora (52.5 ± 15.86%), E. occidentalis (61.5 ± 7.89%) and A. ampliceps (65.5 ± 5.7%). The annual lucerne showed a moderate tolerance; its germination rate was 76 ± 11.61, 81.5 ± 5.74 and 96 ± 2.82%, respectively, for the leaf extracts of A. ampliceps, E. occidentalis and P. juliflora. C. olitorius was found to be the most tolerant species to all extracts; only leaf extracts of E. occidentalis resulted in a lower germination than the control; it was 90 ± 4.32%. The extracts of the studied species affected the root system length; a reduction of the length was essentially observed for M. sativa and C. olitorius.

Keywords

• Acacia ampliceps
• allelopathy
• aqueous extract
• Eucalyptus occidentalis
• germination
• Prosopis juliflora