Phytotoxic activities of essential oils and hydrosols of Haplophyllum tuberculatum

Phytotoxic properties of plants and their compounds against other plants or seeds are being increasingly reported. Moreover, essential oils may provide a new source of phytotoxic agents with possibly novel mechanisms of action. The aim of this study is to determine the chemical composition of the leaves, stems and leaves + stems essential oils by GC/MS and to assess their phytotoxic activities extracted from Haplophyllum tuberculatum A. Juss. (Forssk) as well as of the aromatic water obtained from these parts and of the roots. The phytotoxic activities of the essential oils and hydrosols were evaluated against Triticum aestivum L. and Raphanus sativus L. seeds. The GC–MS analysis revealed the presence of limonene, cis-p-menth-2-en-1-ol, trans-p-menth-2-en-1-ol, cis-piperitol, trans-piperitol, 1-octyl acetate, piperitone and isobornyl acetate as major compounds. Phytotoxic results showed that the assayed stems essential oils were active on the roots inhibition (IC50 = 1.09 mg/mL) for wheat. Leaves + stems essential oils had a significant activity against the tested seeds with IC50 ranged from 0.70 to 1.46 mg/mL for radical and epicotyls/coleoptiles percentage inhibition against T. aestivum L. and R. sativus L. While the hydrosols of leaves, stems and leaves + stems inhibited seeds germination at a higher concentration. The essential oils of this plants cannot be used as biologic herbicide with these cultivated plants.