Allelopatic effects of some medicinal plant essential oils on plant seeds germination

Abstract

The effect of essential oils from some medicinal plants on seed germination was studied with the aim of assessing their potential use as bioherbicides. The experiment was conducted as factorial based on completely randomized design (CRD) with three replications. Seeds of 3 summer crops including lettuce (Lactuca sativa), pepper (Piper longum) and tomato (Solanum lycopersicum) were exposed to essential oils of rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris) and anise (Pimpinella anisum) at 3 different concentrations (25 and 50% diluted and undiluted). Treated seeds were grown in a growth chamber at 25°C for 5 days. The number of germinated seeds in each Petri dish was daily counted. After five days seed germination percentage (Ge) was calculated. Biplot analysis was performed using genotype plus genotype environment interaction (GGE) method. Results showed that the allelopathic effect on Ge was varied among studied plants, which was mainly due to i) differences in the composition of the studied essential oils and ii) different allelopathic effects of the studied essential oils on Ge. Accordingly, compared to the individual use, combining several essential oils would have a greater inhibitory effect on Ge of weeds.

Keywords

• thyme
• rosemary
• anise
• lettuce
• tomato
• allelopathy
• pepper