Allelopathic Effect of Lavandula angustifolia Mill. and Thymus serpyllum L. Essential Oils on Five Selected Plant Species

Abstract

In this study allelopathic effects of essential oils from English lavender (Lavandula angustifolia) and creeping thyme (Thymus serpyllum) on seed germination and seedling growth of mint (Mentha spicata), lemon balm (Melissa officinalis), tomato (Lycopersicon esculentum), cucumber (Cucumis sativus), and black locust seeds (Robinia pseudoacacia) was evaluated. The assessment of the allelopathic effect of essential oils was examined in a laboratory biological test. Working solutions of essential oils were prepared in three concentrations (10, 20 and 30 mg/mL). Both oils exhibited allelopathic effects, however, the concentrations that exhibited suppressing effects were different among the plants. It was noticed that English lavender and creeping thyme oils reduced the germination and growth of mint and black locust seeds and significantly suppressed tomato seed germination at higher concentrations (20 and 30 mg/mL), while it increased the lemon balm seed germination.