Allelopathic analysis of four ecotypes of Ajowan

Document Type : Regular Paper

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Plant physiology

Abstract

In order to study the allelopathic effects of seed extracts and essential oil of four ecotypes of Ajowan, (Trachyspermum copticum) on seed germination and shoot and root length, proline and sugar concentration of Zea mays (as monocotyledon) and Lepidium sativum (as dicotyledon) were evaluated Three levels of Ajowan seed ethanolic extract (2.5, 5 and 10mg/mL) and three levels of essential oil (2.5, 5 and 10%) were prepared. Seed germination and shoot and root length were significantly reduced by all concentrations but proline and sugar were increased. The lowest increase and the highest decrease were for Kerman ecotype extract, whereas the Mashhad ecotype extract showed the highest increase. Ajowan seed extract effects on L. sativum was more than Z. mays. Ajowan seed essential oil completely inhibited the germination and seedling growth of the two examined plants. The inhibitory effects may be related to the presence of allelochemicals, including thymol, γ-terpinene and p-cymene of ajwain seed. Maybe optimum concentrations of ajwain seed extracts could be used in herbicides against weeds. The significant effects of four ecotypes of Ajowan indicate that there was variation in allelopathic activity among the Ajowan ecotypes.

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