不同地区稻虾综合种养系统的微生物群落结构分析

为研究不同地区稻虾综合种养系统的环境及克氏原螯虾肠道的细菌群落结构差异,为改进不同地区稻虾综合养殖策略提供依据,采用Illumina Miseq高通量测序技术,研究了武汉、永州和韶关地区稻田养殖克氏原螯虾的水体、底泥及虾肠道细菌群落结构,并对水体、肠道菌群与环境因子之间的关系进行了分析。结果显示,武汉地区稻虾综合种养系统的水体、底泥及克氏原螯虾肠道细菌群落的多样性均大于永州地区和韶关地区。武汉地区的稻虾综合种养系统的水体及底泥的细菌群落结构与永州地区和韶关地区均相似,其中水体的优势菌门均为放线菌门、蓝细菌门、变形菌门和拟杆菌门;底泥的优势菌门均为变形菌门。武汉地区的克氏原螯虾肠道的优势菌门为变形菌门、厚壁菌门和拟杆菌门;优势菌属为柠檬酸杆菌属(Citrobacter,10.85%)、气单胞菌属(Aeromonas,9.88%)和[Anaerorhabdus]＿furcosa＿group (8.43%)等。永州地区的克氏原螯虾肠道的优势菌门为厚壁菌门和放线菌门;优势菌属为ZOR0006 (9.78%)、拟杆菌属(Bacteroides,5.41%)和[Anaerorhabdus]＿fur...     

Agronomic performances of biodegradable and non-biodegradable plastic film mulching on a maize cropping system in the semi-arid Loess Plateau, China

Biodegradable plastic film mulch (PFM) is considered an alternative to non-biodegradable PFM to mitigate the negative impacts of residual film.However,the agronomic performance of biodegradable PFM in comparison to non-biodegradable PFM still needs to be tested.In this study,we evaluated the effects of biodegradable and non-biodegradable PFM on soil physicochemical properties,microbial community,and enzyme activities,as well as maize growth performance.Biodegradable and non-biodegradable PFM bot...     

Soil and microbial C:N:P stoichiometries play vital roles in regulating P transformation in agricultural ecosystems: A review

Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems,phosphorus(P) fertilizers(organic or chemical) are often applied to achieve high crop yields. However, P is readily fixed by soil particles, leading to low P use efficiency. Therefore, understanding the role of carbon:nitrogen:P stoichiometries of soil and microorganisms in soil P transformation is of great significance for P management in agriculture....     

沙柳沙障腐烂过程对土壤微生物生物量及酶活性的影响

为探究沙柳沙障腐烂过程土壤微生物生物量及酶活性的变化规律,以铺设10年的沙柳沙障为研究对象,采用野外原位取样和室内指标测定法,结合RDA多元数据排序分析,揭示影响土壤微生物生物量及酶活性的主要环境因子.结果表明:(1)随铺设年限的增加,土壤中的C∶ N与C∶ P呈上升趋势,10年后的C∶ N是1年的16.14倍,而N ...     

西安市北郊污灌区土壤中抗铅链霉菌的多样性分析

从西安市北郊污灌区采集土样,用添加K2Cr2O75 μg·mL-1和青霉素2 μg·mL-1的高氏1号、HV和SC固体培养基分离到120株具有链霉菌特征的放线菌.采用浓度梯度法,用含Pb2+培养基对分离菌株进行筛选,得到50株抗铅链霉菌.在抗铅能力实验结果的基础上,选取14株抗性较强链霉菌代表菌株进行形态培养特征、生理生化和16S rDNA基因序列相似性等分析.结果表明,14株代表菌株可归为6个不同的颜色类群,其表型特征与生理生化性质和链霉菌相符合,在系统发育树上处于8个不同的进化分支.菌株HQ0031与已知链霉菌相似性差异较大,可能为链霉菌属内1个潜在新种.研究表明西安市北郊污灌区土壤中抗铅链霉菌具有丰富的多样性,可为重金属污染环境的生物修复提供有益的微生物资源.     

锌镉污染区植物根际与非根际土壤微生物区系研究

本文研究锌镉污染的区植物根际与非根际土壤微生物区系,为污染土壤生物修复提供理论基础。现场采样和室内培养分析的结果表明,污染区内土壤重金属锌镉含量大大超过土壤环境质量标准。植物根际土壤中锌镉含量低于非根际土壤锌镉含量,污染区根际与非根际土壤微生物区系组成发生了明显变化,土壤三大类微生物细茵、真茵、放线茵的数量均显著降低。微生物数量与土壤全锌、镉都呈显著的负相关,锌对微生物的抑制作用比镉显著。     

Soil degradation processes and plant colonization in abandoned terraced fields overlying pumice tuffs

The state of soil degradation/regeneration in abandoned agricultural terraced fields over pumiceous tuffs has been assessed in this paper. In an initial stage, the relationships between soil types, surface microfeatures as indicators of soil degradation, physicochemical properties, plant colonization and vegetation structure were studied by means of multivariate statistical analyses (PCA, DCA, CCA and TWINSPAN®). Aerial photographs interpretation, DEMs and field surveys allowed us to identify 47 different environments for abandoned fields along 7 altitudinal transects (33 abandoned field terraces). In each study site, an inventory of the existing plant species and of morphological surface microfeatures were also made, by the line‐intercept method. Plant colonization in the field plots studied relates to the variation of soils properties according to a climatic altitudinal gradient. The soil properties most closely related to the abandonment age (decrease of soil salinity and clay content, and increase of soil alkalinity and total organic C and N), have contributed to the growth of plant communities with a high degree of climacity. The protection degree offered to the soils by the different vegetation types as a function of their structure and life‐forms strongly determines the occurrence of the different soil surface microfeatures as indicators of soil degradation or recovery. The acceleration of the early stages of succession by active planting of seeds from shrub species in the lower and upper areas, followed by reforestation in the latter ones, may be the best improvement practices to achieve an effective ecological recovery of the fields and simultaneously to attenuate soil degradation. The reassuming of agriculture may be desirable in those fields placed in middle heights, provided they show the best soil and climate conditions. Copyright © 2006 John Wiley & Sons, Ltd.     

Mineralisation of atrazine, metolachlor and their respective metabolites in vegetated filter strip and cultivated soil

In vegetated filter strips (VFS) the presence of perennial vegetation, rhizodeposition of labile organic substrates and the accumulation of an organic residue thatch layer may enhance microbial numbers and activity, thereby increasing the potential for mineralisation of herbicides and herbicide metabolites retained during run-off events. The objective of this laboratory experiment was to compare the mineralisation of atrazine and metolachlor with that of their respective metabolites in VFS and cultivated soil. With the exception of total bacteria, propagule density of the microbial groups, endogenous soil enzymes and microbial diversity were higher in the VFS soil. This correlated with increased mineralisation of metolachlor and its metabolites in the VFS soil and indicates potential for VFS to curtail the subsequent transport of these compounds. In contrast, the mineralisation of atrazine and the majority of its metabolites was substantially reduced in VFS soil relative to cultivated soil. Consequently, the potential for subsequent transport of atrazine and many of its metabolites may be greater in VFS soil than in cultivated soil if reduced mineralisation is not offset by increased sorption in the VFS.     

Combined Effects of Nutrient and Pesticide Management on Soil Microbial Activity in Hybrid Rice Double Annual Cropping System

Combined effects on soil microbial activity of nutrient and pesticide management in hybrid rice double annual cropping system were studied. Results of field experiment demonstrated significant changes in soil microbial biomass phospholipid contents, abundance of heterotrophic bacteria and proteolytic bacteria, electron transport system (ETS)/dehydrogenase activity, soil protein contents under different management practices and at various growth stages. Marked depletions in the soil microbial biomass phospholipid contents were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also induced slight changes, and the lowest microbial biomass phospholipid content was found with pesticides application alone. A decline in the bacterial abundance of heterotrophic bacteria and proteolytic bacteria was observed during the continuance of crop growth, while the lowest abundance of heterotrophic bacteria and proteolytic bacteria was found with pesticides application alone, which coincided with the decline of soil microbial biomass. A consistent increase in the electron transport system activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or combined with pesticides increased it, while a decline was noticed with pesticides application alone as compared with the control. The soil protein content was found to be relatively stable with fertilizers and/or pesticides application at various growth stages in both crops undertaken, but notable changes were detected at different growth stages.     

中国长江三角洲地区及日本水稻种子细菌多样性研究

1997～1999年,分别从中国长江三角洲稻区的276份和日本稻区30份水稻种子样本中分离出3 200余个及303个非致病菌株。经细菌学、菌落形态及致病性测定后,对386个格兰氏阴性菌及30个阳性菌进行Biolog鉴定,并用3个水稻病原菌进行了拮抗性筛选。从中国的水稻种子中测得假单胞杆菌属的10个种及5个非假单胞杆菌属中的14个种;从日本的水稻种子中测得假单胞杆菌属的6个种及5个非假单胞杆菌属中的10个种。这5个非假单胞菌属中的14个种尚未有从中国稻谷上分离出来的记录。从中国的14个细菌种及日本的10个细菌种中测得拮抗菌,其中占拮抗细菌种总数64%的种来自假单胞杆菌属和芽孢杆菌属。