水稻化感品种根区土壤微生物群落反馈对伴生稗草的影响

Effects of Root Zone Soil Microbe Feedback Mediated by Allelopathic Rice Variety on Barnyardgrass

在分析水稻化感品种、非化感品种和稗草根区土壤微生物群落结构差异的基础上,采用土壤接种的植物-土壤反馈研究方法,探讨水稻化感品种、非化感品种和稗草根区土壤微生物群落对水稻和伴生稗草的反馈影响,以期揭示植物-土壤反馈在化感特性不同水稻品种与稗草种间关系中的作用。稗草根区土壤总磷脂脂肪酸(PLFA)含量以及细菌、真菌和放线菌PLFA含量均显著高于水稻化感品种根区土壤。对根区土壤PLFA的主成分分析表明,水稻化感品种、非化感品种和稗草根际土壤微生物群落结构明显不同。单种条件下,化感水稻品种根区土壤接种物处理稗草生物量高于非化感水稻品种根区土壤接种物处理,但添加根分泌物后,化感水稻品种根区土壤接种物处理稗草生物量低于非化感水稻品种根区土壤接种物处理,添加根分泌物影响了不同土壤接种物对稗草生长的反馈作用。水稻和稗草混种条件下,化感水稻品种根区土壤接种物处理稗草生物量显著低于稗草根区土壤接种物处理,化感水稻品种根区土壤接种物增强了水稻化感品种对稗草的抑制作用,调节不利于稗草生长的负反馈;非化感水稻品种根区土壤接种物处理稗草生物量显著高于稗草根区土壤接种物处理,非化感水稻品种根区土壤接种物调节有利于稗草生长的正反馈。无论是单种还是混种条件下,稗草根区土壤接种物和水稻根区土壤接种物对化感水稻品种生物量影响差异均不显著,但稗草根区土壤接种物显著降低了混种条件下非化感水稻品种的生物量,调节不利于非化感水稻品种生长的负反馈。可见,水稻化感品种根区土壤微生物群落调节不利于伴生稗草生长的负反馈过程,提高了水稻化感品种对稗草的竞争力。

Differences among microbial communities of root zone soil from allelopathic rice,non-allelopathic,and barnyardgrass and their feedback effects on the interference of allelopathic rice with barnyardgrass were tested by soil inoculums,so as to elucidatethe roles of soil microbial feedback in interspecific interactions between rice and barnyardgrass.The total PLFA content,bacteria mass,fungi mass and actinobacteria mass were much higher in barnyardgrassroot zone soil than those in allelopathic rice root zone soil.PCA scores for the PLFAs from different soil inoculums were clearly distinguished,indicating that there were significant differences of microbial community composition among root ozone soil from allelopathic rice,non-allelopathic,and barnyardgrass.The biomass of barnyardgrass of allelopathic rice soil inoculum treatment was higher than that of non-allopathic rice soil inoculum treatment and barnyardgrass soil inoculum treatment under monoculture.However,barnyardgrass had lower biomass in allelopathic rice soil inoculum with root exudates treatment than that in non-allelopathic rice soil inoculum,suggesting soil microbial feedback could be mediated through allelopathic rice root exudates.When competing with rice,more biomass of barnyardgrass in its own soil inoculum treatment compared to allelopathic rice soil inoculum treatment and less biomass compared to non-allelopathic rice soil inoculum treatment,indicated negative effects of soil microbial inroot zone soil of allelopathic rice on barnyardgrass,leading to the stronger inhibition on barnyardgrass in allelopathic rice soil inoculum treatment than non-allelopathic rice soil inoculum treatment.There were no significant effects of barnyardgrass soil inoculums on allelopathic rice biomass compared to its own soil inoculums under both monocultured and mixed-cultured treatments.However,the decrease of non-allelopathic rice biaomass in barnyardgrass soil inoculums in present of competition suggested negative feedback effects of microbial community of barnyardgrass root zone soil on non-allelopathic rice.The above results indicated that the microbe regulated the negative feedback in root zones of allelopathic rice variety on barnyardgrass,which improved the ability of allelopathic rice competing against barnyardgrass.