林下连作种植参根际土壤可培养微生物区系及细菌群落对酚酸类化感物质的响应

Response of Culturable Microflora and Bacterial Community to Phenolic Allelochemica in Rhizosphere Soil of Continuous Cropping Panax ginseng C.A.Meyer under Forest

关键词:  人参  根际土壤  土传病害  连作障碍  微生物多样性  酚酸  化感物质

Key words:  Panax ginseng C.A.Meyer  rhizosphere soil  soil-borne diseases  continuous cropping obstacle  microbial diversity  phenolic acid  allelochemicals

摘要:

为探究酚酸类成分对林下连作参根际土壤中微生物区系及可培养细菌群落的影响，以未栽培人参(Panax ginseng C.A.Meyer)林地土壤(1#样品)、连作未发病土壤(2#样品)和连作发病土壤(3#样品)为研究对象，探究根际土壤中微生物区系及可培养细菌群落结构、多样性的变化。同时，通过高效液相色谱(High Performance Liquid Chromatography,HPLC)分析方法对土壤样品中的酚酸进行定性和定量分析。结果表明，2#样品和3#样品土壤可培养微生物总数量与1#样品相比分别下降61.37%和68.24%；可培养细菌分别下降61.36%和68.18%；可培养放线菌分别下降72.97%和75.68%；可培养真菌分别为1#样品的1.40倍和0.47倍。3种样品共分离到193株细菌，分属于4门6纲13目19科39属96种。3种样品中最优势菌纲均为芽孢杆菌纲Bacilli(相对分离频率分别为51.67%、64.00%、48.28%)，1#样品、2#样品最优势菌属为芽孢杆菌属Bacillus(相对分离频率分别为15.00%、21.33%)，3#样品最优势菌属为链霉菌属Streptomyces(相对分离频率为24.14%)。多样性分析显示，3种样品土壤可培养细菌多样性差异小且分布均较为均匀。3#样品中大量积累的香豆酸可能是人参连作障碍的主导化感物质。连作和土传病害未导致人参根际土壤可培养细菌群落多样性下降。土壤微生物总量的减少、可培养微生物区系的变化、高丰度的链霉菌属，以及香豆酸的积累可能是导致人参土传病害严重和连作障碍的主要原因。

Abstract:

To explore the effects of phenolic acids on microflora and culturable bacterial community in rhizosphere soil of continuous cropping Panax ginseng C.A.Meyer under forest,taking uncultured P.ginseng C.A.Meyer woodland soil (sample 1#),continuous cropping soil without disease (sample 2#) and continuous cropping soil with disease (sample 3#) as the research objects,the changes of microflora,the community structure and diversity of culturable bacteria in rhizosphere soil were studied.At the same time,the phenolic acids in soil samples were qualitatively and quantitatively analyzed by High Performance Liquid Chromatography (HPLC).The results showed that the total number of culturable microorganisms in sample 2# and sample 3# decreased by 61.37% and 68.24%,respectively,compared with sample 1#.The culturable bacteria decreased by 61.36% and 68.18%,respectively.The culturable actinomycetes decreased by 72.97% and 75.68%,respectively.The culturable fungi were 1.40 times and 0.47 times that of sample 1#,respectively.A total of 193 strains of bacteria were isolated from the three samples,belonging to 4 phyla,6 classes,13 orders,19 families,39 genera and 96 species.The dominant phylum in the three samples was Bacilli (the relative isolation frequency was 51.67%,64.00% and 48.28%,respectively).The dominant genus in sample 1# and sample 2# was Bacillus (the relative isolation frequency was 15.00% and 21.33%,respectively).The dominant genus in sample 3# was Streptomyces (the relative isolation frequency was 24.14%).The diversity index analysis showed that the diversity of culturable bacteria in the three soil samples was small and distributed evenly.And a large amount of coumaric acid accumulated in sample 3# might be the important allelochemical of ginseng continuous cropping obstacle.Continuous cropping and soil-borne diseases did not lead to a decrease in the diversity of culturable bacterial communities in ginseng rhizosphere soil.The reduction of total amount of soil microorganisms,the change of culturable microflora and the high abundance of Streptomyces and the accumulation of coumaric acid may be the main reasons for the serious soil-borne diseases and continuous cropping obstacles of P.ginseng C.A.Meyer.