不同作物轮作对谷田土壤酶活性和土壤细菌群落的影响

Effects of Soil Enzyme Activity and Bacterial Community under Different Crop Rotations

为探明谷子(Setaria italica)轮作后作物根际土壤细菌群落结构的变化特征,研究了谷子连作(CK)、谷子→黑豆(MRG)、谷子→籽粒苋(MRA)和谷子→藜麦(MRQ) 4种模式下土壤过氧化氢酶、脲酶、蔗糖酶和碱性磷酸酶活性,并利用Illumina MiSeq高通量测序法研究了细菌群落结构。结果发现:(1) 3种轮作模式下的土壤过氧化氢酶、脲酶和碱性磷酸酶活性均高于CK;(2)从20个土壤样品中共获得720 015条有效序列,归属于10 185个分类操作单元(OTU);(3)土壤细菌多样性指数以MRG处理最高,MRQ处理最低;丰富度指数以CK处理最高,MRQ处理最低;(4)不同模式下的优势菌门为放线菌门、变形菌门和绿弯菌门,优势属为鞘氨醇单胞菌属和拟诺卡氏菌属;(5)碳水化合物和氨基酸代谢菌群的相对丰度较高,为各模式下土壤菌群的主要代谢通路。结果表明,轮作能够改善土壤酶活性状况,降低谷茬地土壤细菌群落丰富度指数,籽粒苋和黑豆参与轮作能提高群落多样性指数,研究结果可为对谷子后茬轮作作物的选择提供理论支持。

To explore the changes of bacterial community structure in the rhizosphere soil of crops under the millet-based rotations,the activities of catalase,urease,invertase and alkaline phosphatase were studied under the rotations of millet→black bean(MRG),millet→amaranth(MRA)and millet→quinoa(MRQ)and compared with continuous cropping of millet(CK).The bacterial community structures under the four cropping patterns were also studied by high-throughput sequencing of Illumina miseq.The results showed:(1)The activities of soil catalase,urease and alkaline phosphatase under the three rotations were higher than those of CK;(2)A total of 720015 effective sequences were obtained from 20 soil samples,belonging to 10185 Operational Taxonomic Units(OTUs);(3)The highest diversity index of soil bacteria was found under MRG and the lowest value was found under MRQ while the highest richness index was found under CK and the lowest value was found under MRQ;(4)The dominant bacterial phyla under different rotations were Proteobacteria,Actinobacteria,and Chloroflexi while the dominant bacterial genera in soil were Sphingomonas and Nocardiopsis;And(5)the relative abundance of bacteria for carbohydrate metabolism and amino acid metabolism were higher than other bacteria,identifying that carbohydrate metabolism and amino acid metabolism were the main metabolic pathways of soil bacteria under each cropping patterns.These results illustrated that rotation can improve the soil enzyme activity and reduce the richness index of soil bacterial community,and improve the diversity index of soil bacterial community under some rotations(i.e.,millet→black bean and millet→grain amaranth).The results can provide theoretical support for the selection of millet-based rotation patterns.