不同种植模式对桑园土壤肥力和土壤细菌群落结构的影响

【目的】揭示间作下桑园土壤肥力、土壤微生物结构、多样性之间的关系,为改进桑园间套作模式和桑园培肥管理提供参考。【方法】以桑树净作为对照(CK),设桑树间作大豆(MSS)、桑树间作花生(MPP)和桑树间作甘薯(MST)3个间作模式,开展2年田间试验,分析4种种植模式下桑园土壤理化性状、细菌多样性指数和群落结构特征。【结果】土壤养分含量、OTU数量、α多样性指数和土壤细菌群落结构均随种植模式而变化。与CK相比,间作显著改变了土壤pH、速效钾含量,提高了土壤有机质、全磷和有效磷含量。α多样性分析结果表明,间作桑园土壤中细菌OTU数量及ACE、Chao1、Simpson指数均高于CK,其中间作处理的ACE指数与CK差异显著(P<0.05)。高通量测序分析结果表明,种植模式影响桑园土壤中大于1%的优势细菌门数量,在丰度前10的细菌门类中,变形杆菌门(Proteobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)、芽单孢菌门(Gemmatimonadetes)、硝化螺旋菌门(Nitrospirae)是间作土壤中的优势种群,相对丰度之和在62.32%~71.27%;在属水平上,鞘氨醇单胞菌(Sphingomonas)、Uncultured_bacterium_f_SC-I-84、Uncultured_bacterium_f_Chitinophagaceae、酸微菌(Ilumatobacter)、硝化螺旋菌(Nitrospira)、JGI_0001001-H03、砂壤土杆菌(Ramlibacter)和黄色土源菌(Flavisolibacter)是间作土壤的优势细菌属,较CK分别高60.9%、50.0%、19.1%、17.9%、11.3%、25.0%、50.5%和45.6%。此外,各模式下土壤细菌属群落相对丰度与土壤养分含量存在一定的相关关系。【结论】不同桑园间作模式显著改变了桑园土壤pH及碱解氮和速效钾含量,并影响桑园土壤中优势细菌分类水平组成(门、属)和优势细菌的相对丰度,改变了细菌群落结构和丰富度;发展桑园间作大豆和花生有利于改良土壤理化性状,提高土壤细菌多样性,维护桑园土壤肥力。

Effects of different planting patterns on soil fertility and soil bacterial community structure in mulberry field

【Objective】To reveal relationship between soil fertility,soil microbial structure and diversity,so as to provide reference for intercropping pattern and fertilization management in mulberry field.【Method】Mulberry monoculture group was taken as control(CK),and 3 intercropping patterns,mulberry-soybean intercropping(MSS),mulberry-peanut intercropping(MPP),mulberry-sweetpotato intercropping(MST)to conduct a 2-year field experiment. Soil physical and chemical property,bacterial diversity index and community structure characteristics under these 4 patterns were analyzed.【Result】Soil nutrient content,OTU number,α diversity index and soil bacterial community structure were different under various planting patterns. Compared with CK,intercropping significantly changed soil pH,available potassium content and increased content of soil organic matter,total phosphorus and available phosphorus. α diversity analysis showed that bacterial OTU number,ACE index,Chao1 and Simpson indexes in soil of mulberry field were higher than those in CK. ACE index of intercropping was significantly different from that in CK(P<0.05). llumina HiSeq highthroughput sequencing results showed that planting patterns influenced the dominant bacterial phyla accounting for more than 1%. Proteobacteria,Actinobacteria,Bacteroidetes,Gemmatimonadetes and Nitrospirae were dominant groups in intercropping soil among the top 10 phyla with the highest abundance,with a total of relative abundance of 62.32%-71.27%.At the genus level,Sphingomonas,Uncultured_Bacterium_f_SC-I-84,Uncultured_bacterium_f_Chitinophagaceae,Ilumatobacter,Nitrospira,JGI_0001001-H03,Ramlibacter and Flavisolibacter were the dominant bacterial genera in intercropping soil,which were 60.9%,50.0%,19.1%,17.9%,11.3%,25.0%,50.5% and 45.6% compared with CK,respectively. In addition,there was certain correlation between soil bacterial genera comunity relative abundance and soil nutrient content. 【Conclusion】Planting patterns significantly change soil pH,alkali-hydrolyzable nitrogen and available potassium content,and influence composition of soil dominant bacterial classification level(phylum and genus)and relative abundance in mulberry field soil,thus altering bacterial community structure and species richness. Soybean-peanut intercropping is beneficial to improve soil physical and chemical properties in mulberry field,soil bacterial diversity,and maintaining mulberry field soil fertility.