evaluating allelopathic effects of some plant species in tissue culture media as an accurate method for selection of tolerant plant and screening of bioherbicides

plant tissue culture technique could provide sterile and controllable condition in order to assay direct effect of different compounds on plant growth accurately. in this study, the effects of aqueous extracts prepared from roots and shoots of goosefoot (chenopodium album l.), redroot pigweed (amaranthus retroflexus l.), fennel (foeniculum vulgare), and wormwood (artemisia absinthium l.) were evaluated on the seed germination and growth criteria in tissue culture media. the fennel root extract, nearly without phenolic content and with low antioxidant activity, showed the most drastic allelopathic effect on goosefoot, especially at 100 mg ml-1 concentration, which might be due to the presence of some substance potentially useful for biological control of goosefoot, an invasive weed. goosefoot was resistant to extract of fennel shoot, wormwood root, and shoot, while fennel and radish (raphanus sativus l.), at high concentration (100 mg ml-1), were not resistant to the root and shoot extracts of both goosefoot and redroot pigweed. in response to allelopathic components, shoot:root ratio was increased, and more peroxidase and superoxide dismutase activity were detected in roots. there was no direct relationship between allelopathic effects with total phenolic content and antioxidant activity. in conclusion, our results showed that allelopathic effects of extracts on growth and biochemical criteria depended on both the concentration levels and the plant parts from which the aqueous extract was derived. therefore, tissue culture media is an accurate and suitable tool to screen plants resistant to allelopathic components of weeds, and to identify high allelopathic plants as potential bioherbicide and invasive plant controller.