Chemical composition and in vitro herbicidal activity of five essential oils on Johnson grass (Sorghum halepense [L.] Pers.)

Abstract

The evaluation of the inhibition effect achieved by essential oils of dill ( Anethum graveolens L. ), oregano ( Origanum vulgare L.), juniper (Juniperus communis L.), sage ( Salvia officinalis L.) and winter savory ( Satureja montana L.)  on seed germination and shoot growth of Johnson grass ( Sorghum halepense L.) was tested in laboratory. The chemical composition of essential oils was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major constituents were carvon (40.5%) and limonene (32.2%) for A. graveolens essential oil, carvacrol (73.7%) for O. vulgare essential oil, α-pinene (43.5%) for J. communis essential oil, b-thujone (32.7%) and camphor (17.2%) for S. officinalis essential oil, thymol (44.6%) and p- cimene (13.4%) for S. montana essential oil. The in vitro study on herbicidal activity was carried out on seed germination and shoots length of S. halepense ; A. graveolens , O. vulgare , S. montana essential oils significantly inhibited the germination and shoot length and their herbicidal activity could be attributed mainly to their high content of carvone, carvacrol and thymol. A. graveolens , O. vulgare and S. montana essential oils reduced seed germination by 61.5%, 52.7% and 47.3%, respectively, while J. communis and S. officinalis essential oils stimulated germination (7.7% and 2.2%, respectively). The shoot growth reduction for almost all essential oils, except J. communis essential oil , was more than 30%. The solution of A. graveolens , O. vulgare and S. montana essential oils exhibited more powerful bio-herbicidal effect compared to J. communis and S. officinalis essential oils on the germination and shoot growth of S. halepense .