巨菌草不同生长时期对砒砂岩地区土壤理化性质及细菌群落结构的影响

目的]揭示巨菌草种植前及其不同生长时期对砒砂岩地区土壤基本理化性质及细菌群落结构的影响，为更好应用巨菌草改良砒砂岩地区土壤提供理论依据。方法]运用Illumina MiSeq高通量测序技术，在门、属水平上比较砒砂岩地区巨菌草不同生长时期对土壤细菌结构及多样性的影响。结果]巨菌草种植后，三块样地的含水量在巨菌草分蘖期最低，在成熟期达到最高，土壤有机含量有所增加，土壤pH值变化不明显。细菌菌群结构：各样地的土壤细菌在巨菌草种植前及其生长的四个时期，门水平上的优势菌群均为放线菌门（Actinobacteria）、变形菌门（Proteobacteria）；在属水平上，含量最高的是未分类（unidentified）的细菌。Alpha多样性及群落组成丰度分析表明，三块样地种植巨菌草后，其细菌多样性和物种丰度均比种植前高，农田地土壤细菌多样性和物种丰度在巨菌草拔节期达到峰值，在分蘖期土壤细菌数量最大，比种植前土壤细菌数量高出8倍多，达2.09×10⁷ CFU/g干土，山顶地土壤细菌多样性和物种丰度在巨菌草分蘖期达到峰值，河滩地土壤细菌多样性在巨菌草苗期达到峰值，其丰富度在拔节期达到最大。结论]砒砂岩地区土壤细菌群落结构在巨菌草不同生长时期相似，巨菌草能明显促进砒砂岩地区土壤细菌菌群多样性和丰富度，能有效提高土壤有机质含量，但砒砂岩地区各样地土壤细菌多样性、数量和有机质含量达到峰值的时期不同。

Effect of Pennisetum sp. and its different growth periods on physical-chemical properties and bacterial diversity in sandstone areas

Objective] This study aimed to analyze the effect of Pennisetum sp. in different growth stage on soil physical-chemical properties and bacterial community structure, and provide a theoretical basis for better application of Pennisetum sp. to improve soil in Pisha sandstone area. Methods] We used Illumina MiSeq sequencing to compare the effect of Pennisetum sp. in different growth stage on soil bacterial community structure. Results] After planting Pennisetum sp., the water content of each plot was lowest in tillering stage and highest in maturity period. The soil organic content increased and soil pH did not change significantly. The dominant bacteria of every plot obtained at phylum level were Actinobacteria and Proteobacteria. At genus level, the highest abundance was unidentified. Bacterial diversity and species abundance in three sample plots were higher than those before planting Pennisetum sp. The soil bacterial diversity and species abundance of farmland were highest in jointing stage, the amount of bacteria was highest in tillering stage. The soil bacterial diversity and species abundance of hilltop were highest in tillering stage. The soil bacterial diversity of flood and was highest in seedling stage, the species abundance was highest in jointing stage. Conclusion] The soil bacterial community structure in Pisha sandstone was similar in different growth stage of Pennisetum sp. Pennisetum sp. can obviously promote soil bacterial diversity and species abundance and improve soil organic matter content effectively. However, the soil bacterial diversity, amounts and organic matter content reached a maximum in different growth stage.