Inhibitory Effect of Hydroalcoholic Extracts of Caltrop (Tribulus terrestris L.) on Germination and Growth of Avena fatua L., Chenopodium album L., Setaria viridis L. and Amaranthus retroflexus L.

Background: The use of allelopathic plant extracts as herbicide is being popularized in recent years. Objective: This research has been conducted to evaluate the allelopathic potential of caltrop (Tribulus terrestris L.) on seed germination and growth of Avena fatua L., Chenopodium album L., Setaria viridis L. and Amaranthus retroflexus L. Methods: This research was done to evalature the effect of caltrop on seed germination and growth of Avena fatua L., Chenopodium album L., Setaria viridis L. and Amaranthus retroflexus L. in the based of completely randomized design (CRD). The treatments were 0.1, 0.25, 0.5, 1, 2.5 and 5% extract of caltrop and distilled water (control). Results: The  results indicated that the different concentrations of caltrop extracts significantly inhibited the seed germination and seedling growth of weed species and the degree of inhibition increased with increasing concentration of extracts. The Laboratory results indicated that germination percentage and radical and plumule lengths of weed species were significantly reduced by the extracts in comparison with control. According to the results of greenhouse experiments, germination percentage, fresh and dry weight and height of weed species significantly reduced by using hydroalcoholic extracts. The greenhouse results confirmed that germination of Amaranthus retroflexus, Chenopodium album, Setaria viridis and Avena fatua seeds at 1% concentration reduced 64%, 84%, 43% and 85%, respectively in comparison with control. Conclusion: Therefore, extract of T. terrestris might be useful as natural herbicides and might contain numerous growth inhibitors that could be used for the development of biological herbicides.  [g1]متوجه نشدم؟!