宁夏银北不同草田轮作模式对细菌群落组成特征的影响

Effect of Grass-crop Rotation Patterns on Soil Bacterial Community Composition in Northern Ningxia

摘要:

为研究不同草田轮作模式下宁夏银北地区典型盐碱地细菌群落组成特征，并确定影响细菌群落分布的环境因子，利用IlluminaHiSeq高通量测序技术，分析和比较了苜蓿连作、苜蓿休闲、苜蓿轮作油葵、苜蓿轮作饲料玉米、苜蓿轮作甜高粱5种典型旱作模式背景下的土壤细菌群落多样性，同时分析了土壤环境因子与细菌群落结构的关系。结果表明：变形菌门、放线菌门和酸杆菌门为5种草田轮作模式下土壤细菌群落的优势种类；变形菌门占总量的34.49%，变形菌门的相对丰度在苜蓿轮作油葵模式土壤中显著高于其他模式（P<0.05）；放线菌门占总量的17.02%，放线菌门的相对丰度在苜蓿休闲、苜蓿轮作饲料玉米模式土壤中最高；酸杆菌门占总量的10.96%，酸杆菌门的相对丰度在苜蓿轮作甜高粱模式土壤中最高。在属水平，节杆菌属(Arthrobacter)为优势菌属。土壤细菌多样性以苜蓿休闲模式最高，苜蓿轮作甜高粱模式最低。土壤全盐含量、pH值、碱化度、碱性磷酸酶活性在苜蓿轮作油葵模式中最低，速效磷、速效钾含量在苜蓿休闲模式土壤中最低。宁夏银北地区不同草田轮作模式下盐碱化土壤细菌群落组成特征存在差异，土壤速效钾含量、pH值、过氧化氢酶活性对此差异起主导作用。采用苜蓿轮作农作物模式可以提高宁夏银北地区盐碱化土壤养分含量及酶活性，并有效改善细菌群落的多样性，其中苜蓿轮作油葵模式细菌群落多样性显著高于其他模式，碱性磷酸酶活性和pH值是影响细菌群落结构组成和多样性最显著的环境因子。

关键词:盐碱地;草田轮作;细菌群落结构;环境因子;高通量测序

Abstract:

Aiming to understand the effects on the improvement of typical saline-alkali land in Northern Ningxia of China under different grasscrop rotation patterns, and on the composition characteristics and influencing factors of the bacterial community microbial diversity of saline-alkali soil,as well as discussing the possible mechanism of grass-crop rotation patterns to improve saline-alkali soil. A positioned experiment of crop and rotation system of Medicago sativa L. was carried out to discuss the effect on the mechanism for improving the saline-alkali soil through implementing different grass-crop rotation patterns, including continuous cropping(AA), fallowing after plowing(AF), rotating with Helianthus annuus L.(AO), Zea may (AC) and Sorghum dochna (AS). Total genomic DNA was isolated from the rhizosphere soils using a power soil DNA isolation kit. Then V4 sections of 16S rDNA were sequenced with the aid of the IlluminaHiSeq high-throughput sequencing technology and the diversity and structure of soil microbial communities in the rhizosphere soils were analyzed with QIIME. The relationship between soil physicochemical factors and bacterial community structure was also analyzed. The results showed that Proteobacteria, Actinobacteria, Acidobacteria were the dominant phylum in different grass-crop rotation patterns. Among them,the number of Proteobacteria was significantly higher in Helianthus annuus L. patternthan that of other grass-crop rotation patterns (P<0.05).The second dominant group, Actinobacteria, had the highest relative abundance in the pattern of fallowing after plowing, rotating with Zea mays. As of the third dominant group of Acidobacteria,the relative abundance of which was the highest in soils of rotating with Sorghum dochna. At the genus level, Arthrobacter was the dominant genus in saline-alkali soils of all grass-crop rotation patterns in Northern Ningxia. Alpha diversity index showed that the diversity and richness of soil bacterial community in fallowing after plowing pattern was significantly higher than that of other patterns, Sorghum dochna pattern were significantly lower than that of other patterns. The result of soil physicochemical properties showed that the values of total salt, pH value and alkaline phosphatase were the lowest in rotating with Helianthus annuus L. and the values of alkalyzable potassium, alkalyzable phosphorus were the highest in fallowing after plowing pattern. Speculating that alkalyzable potassium, pH value and catalase were the crucial factors influencing the bacterial community diversity among five grass-crop rotation patterns. Highthroughput sequencing analysis can obtain more comprehensive information of bacterial community diversity, and the changes of soil environmental factors after grass-crop rotation affected the structure of soil bacterial community, which provided correlations between bacterial composition and diversity with environmental factors.

Key words:saline-alkali soil;grass-crop rotations;bacterial community structure;environmental factor;high-throughput sequencing