Phytochemical screening and herbicidal properties of aqueous extract of Eucalyptus cinerea F.Muell. Ex Benth.: source of phenolic molecules with allelopathic potential

In this study, aqueous leaves extract of Eucalyptus cinerea F.Muell. ex Benth. were screened for its phenolic composition and herbicidal activity on germination, seedling growth, physiological parameters (chlorophyll content, net photosynthetic activity, transpiration, stomatal conductance) and biochemical parameters (malondialdehyde, membrane integrity and proline content) of Triticum durum Desf., Vicia faba L., Phaseolus vulgaris L., Sinapis arvensis L., Eruca vesicaria L. and Scorpiurus muricatus L. Phenolic compounds were identified using liquid chromatography mass analysis and 15 components were identified. In pre-emergence stage, germination and seedling growth of tested species were significantly reduced in a dose-response dependent manner. In post-emergence stage, tests were conducted in a greenhouse, observation of leaf fading symptoms was recorded at 6 h after treatment. Chlorophyll content was decreased after extract application. In addition, E. cinerea aqueous extract induces an electrolyte leakage revealing membrane damage and loss of integrity and enhanced the level of proline suggesting induction of oxidative stress. The tested plants responded differently to E. cinerea extract exhibiting a differential species-specificity. In fact, weeds were damaged more strongly than cultivated crops. These results indicated that E. cinerea extract exhibited potential as natural herbicides and provide helpful information to develop new and potent bioactive chemicals from natural products.