Allelopathic effect of cumin (Cuminum cyminum L.) on seed germination of three weeds

The allelopathic effects of cumin (Cuminum cyminum L.) were evaluated on seed germination of velvet flower (Amaranthus retroflexus L.), flixweed (Descurainia sophia (L.) Webb ex Prantl) and wild oat (Avena fatua L.) in laboratory using the aqueous extracts of dried powdered of cumin leaves. The treatments were 1, 2, 5, 10 and 15% extract of cumin and distilled water control. According to the results, extracts significantly inhibited seed germination of weed species and the degree of inhibition increased with increasing concentration of extracts. Germination of Amaranthus retroflexus seeds was inhibited at concentrations greater than 5%. (In addition, radicle and plumule lengths of Amaranthus retroflexus were significantly reduced at 1% compared to the distilled water. Results indicated germination percentage, germination rate and radicle and plumule lengths of Avena fatua were significantly reduced by the extracts compared to the distilled water. Results confirm germination of Descurainia sophia seeds was inhibited at concentrations greater than 2%. Accordingly germination rate and radicle lengths of Descurainia sophia were significantly reduced by the extracts compared to the distilled water. Therefore, extract of cumin might be useful as natural herbicides and might also contain numerous growth inhibitors that could be used for the development of biological herbicides.