May essential oil of a native species inhibit seed germination of the invasive Acacia saligna?

MACCIONI, ALFREDO;MANCONI, MARIA;FALCONIERI, DANILO;PIRAS, ALESSANDRA;BACCHETTA, GIANLUIGI;MAXIA, ANDREA;SANTO, ANDREA

2016-01-01

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Abstract

Invasive Alien Species (IAS) are considered, after habitat loss and fragmentation, as one of the greatest threats to the conservation of native biodiversity and natural ecosystems worldwide. Acacia saligna (Labill.) H.L.Wendl. (Fabaceae) is native of South-Western Australia, but has been planted extensively in many areas of the world, among which the Mediterranean Region, becoming highly invasive especially in coastal habitats. In the Mediterranean ecosystems, several autochthonous species produce essential oils (EOs), in different concentrations in several parts of the plant, as adaptation to harsh environments. The ecological role of these compounds, named allelochemicals, may determine a positive influence and/or negative against other target organisms. The aim of this work was to test if the EO of Rosmarinus officinalis L. (Lamiaceae), perennial aromatic dwarf-shrub of the Mediterranean area, may be an effective method to inhibit the seed germination of the alien invasive A. saligna. In particular, variability in seed germination requirements and responses among populations from Sardinia and Sicily (Italy) were evaluated. Germination tests under light (12 hours of irradiance per day), constant temperatures (10, 15, 20°C) and several concentrations of R. officinalis EO (3.9, 7.8, 15.6 µl/ml) were carried out. Moreover, the ability of A. saligna seeds to recover their germination after the EO exposure was evaluated washing seeds with Tween 80 or sodium hypochlorite solutions. Among the examined factors, only the EO concentration and temperature had highly significant effect on seed germination. The lowest EO concentration did not show differences respect to the control (0 µl/ml), while the highest concentration inhibited significantly seed germination of all populations at all the tested temperatures. No seed recovered the ability to germinate after the EO exposure with none of the two methods of washing. Our results allowed to identify the minimum concentration of EO of an autochthonous species such as R. officinalis, able to inhibit the seed germination of the invasive A. saligna. In conclusion, these results may be useful to the biological control against the invasive alien species to allow the conservation of native biodiversity and the preservation of the Mediterranean habitats.