Allelopathic effects of weeds extract on seed germination of Trachyspermum copticum L., Foeniculum vulgare and Cuminum cyminum

Seed germination stage is one of the most basic growth stages in medicinal plants that may be adversely affected by the chemicals released from other plants in the soil environment. The present study was performed to investigate the allelopathic effects of weeds, including (Xanthium strumarium, Amaranthus retroflexus and Chenopodium album) as common weeds in medicinal plant's farms, on seed germination parameters, total dry weight and allometry coefficient of Trachyspermum copticum L., Foeniculum vulgare and Cuminum cyminum L. in laboratory conditions. Treatments included extracts of all organs of three weed species, applied on the seeds of the medicinal plants at three concentrations of zero (distilled water), 50 and 100% by volume. The results showed that the extracts of mentioned weed species had a significant inhibitory effect on germination characteristics of the studied medicinal plants. The greatest negative impact on seed germination was recorded for the extract of Amaranthus retroflexus, but Trachyspermum copticum L. showed a better resistance to the extract of Amaranthus retroflexus as compared to Foeniculum vulgare and Cuminum cyminum.