Analysis Of Physicochemical Environment And Microbial Community Structure In Rhizosphere Soil Of Black Shank Tobacco

This experiment was conducted to study the Microbial biodiversity and the Physicochemical environment in tobacco rhizosphere soil,and learned the bacteria community structures,thus providing a theoretical foundation for formation and maintaining of healthy tobacco soil ecosystem.Taking the tobacco rhizosphere soil(35d,50 d and 65 d after transplanting)from Sichuan Liangshan prefecture in 2014-2015 as the sample,,through the technology of high-throughput sequencing on Illumina Miseq platform analysis the soil microbial's 16 Sr DNA of tobacco root.The result show that,The Rhizosphere Soil of Black Shank Tobacco p H was higher than the same type of healthy tobacco rhizosphere soil,after transplanting 35 days,50 days and 65 days.Soil available potassium,available phosphorus and soil water content showed significant difference.The content of available nitrogen,available phosphorus,available potassium and total nitrogen in the three periods showed a consistent of downward in the three periods for the four types of the soil samples.The rhizosphere soil available potassium content of black shank tobacco rhizosphere soil were higher than the same period of healthy tobacco.The rhizosphere soil available potassium content of black shank of tobacco rhizosphere soil were higher than the same period of healthy tobacco soil in the three period of yellow soil.The moisture content of tobacco rhizosphere soil showed an upward trend in the three periods after transplanting,and during the same period,the soil water content in rhizosphere of tobacco black shank was significantly higher than that of healthy tobacco rhizosphere soil.The number of bacteria,fungi and actinomycetes in tobacco rhizosphere soil showed an increasing trend in the three periods after transplanting.Comparison of Rhizosphere Soil and tobacco black shank healthy tobacco rhizosphere soil,there was no significant difference in the number of bacteria,fungi and actinomycetes in in the Resettling Growth Stage.But the same period of tobacco black shank and healthy tobacco rhizosphere soil microorganism quantity difference after vigorous growing period.The number of bacteria,fungi and actinomycetes in the tobacco black shank rhizosphere soil were lower than those of healthy tobacco during the same period,andthe number of soil fungi in the rhizosphere of tobacco black shank was significantly higher than that in healthy tobacco rhizosphere soil of the purple clay soi in the three periods.The number of bacteria,fungi and actinomycetes in the tobacco black shank rhizosphere soil were higher than those of healthy tobacco in 65 days after transplanting of the red soil.The number of fungi and actinomycetes in the tobacco black shank rhizosphere soil were higher than those of healthy tobacco after transplanting of the yellow soil.Based on the results of 16 Sr DNA sequencing,the coverage rate of bacterial libraries in each soil sample was 70%,and the coverage rate of fungal library was more than 85%,and The dilution curves of soil bacteria and fungi richness obtained from the selected sequencing depth tended to be smooth,so the library established by the experiment can be used to compare the true level of Microorganism communities in the rhizosphere soil of tobacco.The OUT number,ACE index of rhizosphere soil bacteria of tobacco black shank were higher than those in healthy tobacco rhizosphere soil,indicating the rhizosphere soil bacterial diversity of Phytophthora nicotianae were significantly higher than those in healthy tobacco rhizosphere soil in 50 days after transplanting.In the same soil types in susceptible varieties of tobacco rhizosphere soil fungi OUT,ACE index and Chao1 index were higher than those of healthy tobacco rhizosphere soil fungi,the infection of black shank of tobacco plant fungi in the rhizosphere soil of higher species diversity.The species diversity of bacteria and fungi in sandy soil was significantly higher than that of other three kinds of soil samples.The bacterial diversity of tobacco rhizosphere soil was high,the main colonies of different samples were relatively stable.On the level of phylum,there been 26 bacteria phylum and 7 fungal phylum were detected and classified in the healthy tobacco rhizosphere soil,and 28 and 7 in the rhizosphere soil of tobacco black shank,in which Proteobacteria(39.04%-53.71%)had clear superiority of bacteria phylum,followed by Bacteroidetes and Verrucomicrobia;Ascomycota(64.94%-91.61%)was distinct dominant of fungal phylum.On the level of guns,there had been 576 guns of bacteria and 277 guns of fungal were detected and classified of healthy tobacco rhizosphere soil,and 521 guns of bacteria and 265 guns of fungal in the rhizosphere soil of tobacco black shank,in which Sphingomonas had clear superiority of bacteria phylum,the Relative abundance ratio was 7.92%-15.76%;Ascobolus was the dominant genus of fungi in the rhizosphere soil of healthy tobacco,the averageabundance ratio was 20.66%;Ophiocordyceps was the dominant genus of fungi in the rhizosphere soil of black shank of tobacco,the average abundance ratio was 14.69% The larger environmental factors which had an important influence in healthy tobacco rhizosphere soil bacteria were available nitrogen,available phosphorus and Soil p H,and there was a positive correlation between the three indexes and the proportion of soil bacterial communities;The larger environmental factors which had an important influence in tobacco of black shank rhizosphere soil fungi were the soil p H and the content of total nitrogen,besides,there was a significant positive correlation among the majority of genus of fungi in the rhizosphere soil of black shank of tobacco.The microorganism information of tobacco rhizosphere soil was obtained by using the 16 Sr DNA sequencing technology of Metagenomics,this can study provide a new reference theory for the study of the soil mechanism of healthy tobacco planting.