Study on the Allelopathy Effects of Aqueous Extracts from Helianthus tuberosus on Echinochloa crusgalli (L.) Beauv.

【Objective】The allelopathic effects of aqueous extracts from different kinds of Helianthus tuberosus on barnyard grass were explored in order to reveal the mechanism of aqueous extracts from Helianthus tuberosus and provide a strong basis for their application in weed control.【Method】With the seeds of Echinochloa crusgalli (L.) Beauv. as experimental materials, a soil culture experiment was conducted to study the allelopathy of aqueous extracts from different organs of two H. tuberosus varieties from Xuzhou and Weifang on E. crusgalli. and to determine the root length, length of bud, germination rate, antioxidant enzyme activity, malondialdehyde (MDA) content of Echinochloa crusgalli (L.) Beauv, and the alkaline phosphatase, invertase activity and electronical conductivity(EC) of soil.【Result】With the increase of extract concentration, the germination rate of seeds decreased continuously, the highest inhibition rate reached 52.08%, and the maximum decrease of root length and length of bud reached 81.96% and 19.89%, respectively. The activity of POD, CAT and soil alkaline phosphatase increased first and then decreased with the increase of extract concentration and the SOD activity of E. crusgalli Beauv treated with aqueous extracts was generally inhibited. Aqueous extracts from Weifang H. tuberosus could induce MDA accumulation in E. crusgalli Beauv, while aqueous extracts from Xuzhou H. tuberosus made MDA content of E.crusgalli Beauv rise first and then drop. With the concentration of the aqueous extracts increased, the soil conductivity increased gradually and its maximum increase rate was 180.56%. The invertase activity showed a stimulating effect with the increase of the concentration of aqueous extracts from Weifang H. tuberosus.【Conclusion】 Aqueous extracts from H. tuberosus has certain effects on barnyard grass the growth, antioxidant capacity, MDA, and enzymes activity and EC in root soil of E. crusgalli Beauv. Therefore, aqueous extracts from H. tuberosus could be applied for weed control.