根系分泌物在‘热研2号’柱花草与鬼针草生长早期种间干扰中的作用

为探究根系分泌物在牧草与杂草种间相互干扰中的作用，采用营养液水培和土壤盆栽法研究‘热研2号’柱花草(Stylosanthes guianensis Sw. ‘Reyan No.2’)和鬼针草(Bidens pilosa L.)根系分泌物对彼此生长的影响。结果表明：无植株体接触情况下，柱花草根系分泌物对鬼针草表现出化感抑制作用，而鬼针草根系分泌物对柱花草表现为化感促进作用;柱花草和鬼针草在根系不完全接触时的根长、根体积、生物量均高于根系自由接触(P<0.05)，根系无接触时二者的根长、分枝数、生物量也均高于根系自由接触(P<0.05);竞争效应分析发现，根系不完全接触时柱花草的竞争能力强于鬼针草，而根系自由接触时竞争能力弱于鬼针草。说明土培伴生生长时柱花草根系分泌物也可以抑制鬼针草的生长，但鬼针草能通过增强地上部竞争能力来抵御柱花草根系分泌物的化感干扰，二者的种间关系是资源竞争和化感作用共同作用的结果。

Effects of Root Exudates on Interspecific Interference Between Stylosanthes guianensis Sw. ‘Reyan No.2’ And Bidens pilosa L. at Early Growth Stage

To explore the role of root exudates in the mutual interference between forage and weeds,the effects of root exudates from S. guianensis Sw. ‘Reyan No.2’ and B. pilosa L. on each other’s growth were studied by hydroponic culture with nutrient solution and pot culture in soil. The results showed that in the absence of any contact between the two plants,the root exudates of S. guianensis showed allelopathic inhibition on B. pilosa,while the root exudates of B. pilosa showed allelopathic promotion on S. guianensis. The root length,root volume,and biomass of S. guianensis and B. pilosa in incomplete root contact were higher than those under free root contact (P<0.05),and the root length,branch number,and biomass of two plants in no root contact were also higher than those under free root contact (P<0.05). According to the competitive effect analysis,the competitive ability of S. guianensis was stronger than that of B. pilosa under incomplete root contact and was weaker than that of B. Pilosa under free root contact. The results indicate that the root exudates of S. guianensis can inhibit the growth of B. pilosa in soil culture,but B. pilosa can withstand the allelopathic interference of the root exudates from S. guianensis by enhancing the competitive ability of the aboveground,and the interspecific interaction between them is the result of resource competition and allelopathy.