Phytotoxic effects of several essential oils on two weed species and Tomato
Abstract Essential oils (EOs) composition of Rosmarinus officinalis L., Satureja hortensis L. and Laurus nobilis were analyzed by GC and GC–MS instrument. Then phytotoxic activities of mentioned EOs and a combination of R. officinalis and L. nobilis EOs (R+L) were evaluated against germination and growth of two weeds species, A. retroflexus (dicot), B. tectorum (monocot) and tomato. Applied EOs strongly inhibited the germination and seedling growth of the tested species, in a dose dependent manner with A. retroflexus being significantly more sensitive than others. Indeed, at 400 μL.L−1μL.L−1 EO of R. officinalis, germination of A. retroflexus decreased 91.3%, while for the same dose, germination and seedling growth of B. tectorum and tomato were reduced by 56.7% and 26.7%, respectively, compared with control. R. officinalis EO caused the most germination inhibitory for A. retroflexus and tomato while B. tectorum germination was well inhibited by S. hortensis EO. Seedling growth were also affected by EO application in a dose response manner. A. retroflexus shoot length was inhibited by the R+L EO more than other EOs while most root growth inhibition caused by S. hortensis EO. For B. tectorum, and tomato, S. hortensis had the strongest inhibitory effect on root and shoot elongation.
Keywords: Weed control; Inhibitory effect; Essential oils; Allelopathy; Monoterpenes
Ecotoxicology and Environmental Safety (Impact Factor=3.7)
Natural herbicide activity of Satureja hortensis L. essential oil nanoemulsion on the seed germination and morphophysiological features of two important weed species
The aim of the present study was to obtain an oil/water (O/W) nanoemulsion (NE) containing garden savory (Satureja hortensis) essential oil (EO) and evaluating its herbicidal activity against Amaranthus retroflexus and Chenopodium album. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were employed to determine the chemical composition of the EO. Carvacrol (55.6%) and γ-terpinene (31.9%) were the major EO components. Low energy method was applied, allowing achievement of EO nanodroplets. The NE also presented low polydispersity, and the mean droplet was below 130 nm even after storage for 30 d Laboratory tests showed that the NE at different concentrations (100, 200, 400, 800, and 1000 μL.L−1) significantly (P≤0.05) reduced the germination indices and the seedling’s growth in dose-response. The inhibitory effect was the greatest at 800 μL.L−1 NE. Overall, root length was more inhibited as compared to shoot length. Post-emergence application of NE at different concentrations (1000, 2000, 3000, 4000 and 5000 μL.L−1 of EO) on 2–4 true leaves’ stage of the weeds caused significant (P≤0.05) decrease in the growth factors in dosedependent manner. Complete lethality was observed by 4000 μL.L−1 NE sprayed on the weeds. Spraying of NE significantly (P≤0.05) reduced chlorophyll content in the tested weeds. Increasing in relative electrolyte leakage (REL) 1 and 5 d after treatment represented significant cell membrane disruption and increased cell membrane permeability. Transmission electron microscope (TEM) pictures confirmed NE droplet size and demonstrated membrane destruction. The study approved that the NE of S. hortensis EO has herbicidal properties as it has high phytotoxic effect, and interferes with the germination, growth and physiological processes of the weeds. The production of NE from S. hortensis EO is a low energy method that offers a promising practical natural herbicide for weed control in organic agricultural systems
لینک برای دانلود کامل مقاله: