It is an effective way to develop integrated and ecological security weed management to control weedy rice using crop allelopathic varieties.However,there are few studies on the effects of allelopathy on competition in rice-barnyardgrass coexistence.We studied the resource competition ability of allelopathic rice and non-allelopathic rice compared to bamyardgrass using biomass,morphological plasticity,nutrient contents of plant and root zone soil in monoculture and mixed-culture in the field to test whether there were differences between allelopathic and non-allelopathic rice in response to competing bamyardgrass.When mixed with barnyardgrass,there was the increase of root biomass and leaf area of allelopathic rice,and decrease of biomass and leaf area of non-allelopathic fice.Mixed-culture with allelopathic rice did not lead to significant differences in morphological characteristic and nutrient content of bamyardgrass.However,there were significant increase of height,biomass,and leaf area of bamyardgrass in mixed-culture with non-allelopathic rice.Soil ammonium nitrogen in root zone and nitrogen content of allelopathic rice increased in presence of bamyardgrass,while non-allelopathic rice had lower nitrogen content of plant in mixed-culture with bamyardgrass than in monoculture.Allelopathic rice had more relative competitive ability and nutrient competition ratio of rice to bamyardgrass compared to non-allelopathic rice.All these results indicate morphological plasticity and effects on soil nutrient content in root zone of allelopathic rice improve its ability to compete with neighboring barnyardgrass compared to non-allelopathic rice.%利用作物自身的化感作用控制农田杂草是生态安全条件下农田杂草综合防治的有效途径,但在水稻Oryza sativa和稗草Echinochloa crusgalli的种间关系研究中化感作用对资源竞争的影响常被忽略.通过研究田间稗草伴生条件下,水稻化感品种和非化感品种生物量及形态特征的变化,结合水稻和稗草植株养分含量及根区土壤养分含量,分析水稻化感品种和非化感品种对稗草竞争的响应差异.稗草混种后,水稻化感品种根系生物量提高、叶面积增大;非化感品种生物量、株高、叶面积显著下降.与水稻化感品种混种,稗草株高、生物量、叶面积与单种对照差异不显著;而与非化感水稻混种,稗草株高、生物量、叶面积显著升高.水稻化感品种和稗草混种,水稻植株磷含量和根区土壤铵态氮含量增加,稗草根区土壤养分含量降低;而水稻非化感品种和稗草混种,水稻根区土壤铵态氮含量和植株氮含量下降,稗草茎叶氮含量增加,根区土壤养分含量与单种差异不显著.水稻化感品种对稗草的相对总产量和养分竞争比例显著高于非化感品种.可见,水稻化感品种和非化感品种对伴生稗草的响应和影响不同,水稻和稗草伴生系统中化感品种较非化感品种对稗草更具有竞争优势,二者形态特征及其对稗草根区土壤养分影响的差异,影响了其自身对伴生稗草的竞争能力.
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