Herbicidal Activity and Chemical Composition of Two Essential Oils on Seed Germinations and Seedling Growths of Three Weed Species

Abstract

The present study aimed to measure the herbicidal effect of Rue (Ruta graveolens L.) and Bergamot (Citrus bergamia Risso et Poiteau) essential oils against (Amaranthus retroflexus L., Convolvulus arvensis L., and Rumex crispus L.) in pre-emerge (in-vitro) and post-emergence (in-vivo) experiments. The chemical composition of essential oils was analyzed by gas chromatography (GC) and gas chromatography/ mass spectrometry (GC/MS). The major constituents were 2-undecanone (64.80 %) and 2-nonanone (13.78 %) for R. graveolens essential oil; linalool (41.62 %) and limonene (28.02 %) for C. bergamia essential oil. Four concentrations of the essential oils were studied in the laboratory (5, 10, 15, and 20 μL mL-1) and one (20 μL mL-1) concentration in the greenhouse applications. The results achieved demonstrate that an increase in the essential oil concentration leads to reduction of seed germination and seedling growth. In Petri dishes, R. graveolens essential oil reduced seed germination by 1.16-100 % whereas C. bergamia essential oil by 11.9-10 0 %. The average mortality rates of essential oils on weed seeds in greenhouse conditions were 33.3-68.3 % at 24 h and 20.8-45.8 % at 48 h after treatment. These results show that R. graveolens and C. bergamia essential oils may have the potential to be used as bio-herbicides against weed species.