[Chemical composition and allelopathic potential of essential oil isolated from Origanum vulgare]

This study aimed to explore the chemical composition of essential oil isolated from Origanum vulgare and investigated its allelopathic potential. The essential oil isolated by hydro-distillation from the whole plant of O. vulgare was analyzed by GC and GC-MS. Fourteen different components were identified, constituting 93.56% of the total area of peaks. The major components were methyleugenol (16.5%), myristicin (15.6%), carvacrol (15.0%), thymol (9.8%), and apioline (9.4%). We examined the inhibitory effects of essential oil on seed germination and seedling growth of wheat (Triticum aestivum), mung bean (Vigna radiata), and radish (Raphanus sativus). The results showed that essential oil of O. vulgare inhibited seed germination of all tested crops, with wheat being the most susceptible, followed by radish and mung bean. The inhibitory effects of essential oil on growth of the aboveground part of tested crops were greater than that of underground part. The inhibitory effects of essential oil on the seedling length of all tested crops increased in a dose-dependent manner, with the same pattern for radicle length of wheat and radish as well. Meanwhile, essential oil could stimulate radicle growth of V. radiata at low concentration, but inhibit the growth at high concentration. Our results confirmed the existence of allelochemicals in the essential oil of O. vulgare. However, what the compounds will be and how about their allelopathic mechanism needs further investigation.