Allelopathic effect of Heliotropium europaeum L. on seed germination and growth of Raphanus sativus L.

Some plants have negative effects on growth of the adjacent plants through excretion chemical Some plants have negative effects on the growth of adjacent plants through excretion chemical compounds known as allelopathy. In this study, the allelopathy effects of different parts of Heliotropium europaeum L. on seed germination and seedling growth of Raphanus sativus L. were investigated. The treatments included the extracts of root, stem, leaf, flower, fruit and distilled water (control) on seed germination of R. sativus. Also, 1% of stem powder, the whole plant as mulch and the whole plant mixed with soil were studied. To assess the allelopathic effects of different parts of H. europaeum, a number of growth parameters such as seed germination, stem length as well as dry and fresh weight were evaluated. The results indicated that all parts of the plant had a significant effect on germination of radish seeds, but their effects were different, so that the flower and stem extracts had the maximum inhibitory effect. The comparison of stem length, fresh and dry weight of R. sativus seedling in control and different treatments of H. europaeum showed that there was a significant difference between different treatments and control samples. Among different treatments, the inhibitor effects of stem extract was higher than other extracts. It was concluded that H. europaeum extract especially flower and stem extracts had a strong allelopathic effect and inhibited seed germination of R. sativus and could berecommended in production of natural herbicides.