连作西瓜的根际土壤酶活性和微生物多样性

以山东大鹏西瓜基地0,3,9,15 a的西瓜根和根际土壤为研究对象,采用野外调查和实验室分析方法分析连作对西瓜根际土壤酶活性和微生物多样性的影响。结果表明:随着连作年限的增加,土壤有机质和氮磷钾含量递减,连作第15年有机质及有效氮磷钾含量最低。在同一生长时期内,连作年限越长,西瓜根系活跃吸收面积和总吸收面积最低,根际土壤酶活性呈现先递增后下降的趋势,并且根际土壤酶活力幼苗期 < 抽蔓期 < 结果期。在连作前期土壤中可培养微生物代谢活力递增,连作后期微生物代谢活力递减,且连作越久土壤中微生物群落多样性降低,均匀度先增加后降低。相关性分析表明,土壤中过氧化氢酶（p < 0.05）、磷酸酶（p < 0.05）、蔗糖酶（p < 0.01）、速效磷（p < 0.05）、速效钾（p < 0.05）与真菌具有正相关性;脲酶与细菌正相关（p < 0.01）,与碱解氮负相关（p < 0.01）;过氧化氢酶（p < 0.05）、碱解氮（p < 0.01）与放线菌具有显著正相关。综上所述,连作0～9 a,土壤微生物代谢活力和酶活性增强,养分流失较小;连作9 a后,土壤养分流失严重,土壤酶活性和微生物代谢活力显著降低,产生连作障碍,说明减少连作年限可使西瓜优质丰产并且可持续发展,反之影响西瓜正常生长生产,损害经济效益。     

连作怀牛膝根际土壤微生物区系及酶活性的变化研究

本文从适宜连作的作物研究角度,以连作两年和多年的怀牛膝根际土壤为研究对象,对其微生物区系及酶活性的变化作了对比研究。结果表明,连作两年和多年的怀牛膝根际土壤中细菌总数占绝对优势,其平均占有率分别为62．27％和89．46％;放线菌次之,平均占有率分别为37．59％和10．45％;真菌最少,分别占总菌数的0．15％和0．09％。随着连作年限的增加,细菌数量和比例明显增加;其中亚硝化细菌、反硝化细菌、好气性纤维素分解菌、硫化细菌的数量均明显增加。同时,种植牛膝能够显著增加脲酶、蛋白酶、蔗糖酶的活性,但长期种植会使这3种酶活性呈不同程度减弱,多酚氧化酶活性却明显增强。最后对牛膝耐连作的可能机理作了进一步探讨。     

黄瓜连作对土壤微生物多样性和酶活性的影响

在相同管理措施下对日光温室黄瓜不同连作年限土壤微生物种类和数量以及酶活性的变化进行了分析。结果表明,随着连作年限的增加,土壤细菌数量和放线菌数量均呈先增加后降低的趋势,连作10 a时达到最高,随着连作年限的进一步延长又逐渐降低;真菌数量持续增加。土脲酶、碱性磷酸酶、蔗糖酶和多酚氧化酶活性均呈先增加后降低的趋势,在连作8～10 a时达到最大,土壤过氧化氢酶活性呈连续降低的趋势。在黄瓜生长季节,随着生育期的推移,3种土壤微生物的数量和5种土壤酶的活性均呈先上升后降低的趋势,3 — 4月份达到最大。     

山药连作对土壤微生物群落及土壤酶活性的影响

以山药连作（0 a,1 a,2 a）和轮作（山药—小麦）土壤为研究对象,探讨耕作模式对山药种植地耕层土壤（0—30 cm）微生物数量和酶活性的影响。结果表明:土壤耕层的有机质、全氮、有效磷和速效钾含量随山药连作年限的延长而逐渐降低,而山药—小麦轮作模式则有助于恢复地力。山药连作、轮作的土壤均以细菌所占比例最大,放线菌次之,真菌最少;与对照（0 a）相比,细菌、放线菌数量均随着山药连作年限增加呈递减趋势;但放线菌的降幅明显大于细菌,表现出对连作年限更强的敏感性;真菌数量随连作年限呈先升后降的趋势。山药连作可以明显降低土壤脲酶、碱性磷酸酶和蔗糖酶的活性,轮作模式则可以激发该三种酶的活性,其中轮作较连作2 a的处理可以明显提高脲酶和蔗糖酶活性,差异分别达显著水平（p < 0.05）和极显著水平（p < 0.01）。说明山药连作会破坏土壤耕层微生物种群结构,并抑制土壤酶活性,轮作可以在一定程度上改善土壤微生物群落结构及酶活性质量。     

有机物料和氧化钙对连作花生土壤微生物与酶活性及产量的影响

  目的  研究复合肥分别配施商品有机肥、含腐殖酸有机水溶肥、氧化钙等对连作花生土壤可培养微生物数量、土壤酶活性、土壤养分含量及花生植株生长、荚果产量的影响,为连作花生合理施肥提供理论依据。  方法  在连作3年的花生田块,以施用复合肥600 kg hm?2（T0）为对照,分别在此基础上设置增施600 kg hm?2商品有机肥（T1）、75 L hm?2含腐殖酸有机水溶肥（T2）、600 kg hm?2氧化钙（T3）等3个施肥处理,测定不同施肥方式下连作花生土壤微生物数量、土壤酶活性、土壤养分含量、花生植株长势及荚果产量。  结果  与单施复合肥相比,增施有机物料（T1,T2）能够显著提升全生育期下连作花生田块可培养微生物总数量,并使得成熟期土壤可培养细菌数量与可培养真菌数量比值由48.59（T0）分别提升至58.93（T1）和59.94（T2）,缓解土壤向“真菌性”转变,显著提高土壤酶活性及土壤养分含量,促进花生植株生长,提高荚果产量。两种有机物料间比较,含腐殖酸有机水溶肥（T2）效果更佳,荚果增产达11.17%。増施氧化钙后,花生全生育期下土壤各项指标对照差异基本不显著,但花生植株仍表现出百果重、出仁率显著增加,荚果产量提升了5.12%。  结论  以复合肥配施含腐殖酸有机水溶肥（T2）对花生连作障碍缓解效果最佳,该施肥条件下,连作花生土壤微生物活力、土壤酶活性、土壤养分含量及花生荚果产量提高最为显著。     

氟磺胺草醚对大豆根际土壤微生物和酶活性的影响及其在根际的降解

【目的】 本研究旨在探讨不同浓度氟磺胺草醚在大豆根际土壤中的微生态效应,及其在根际土壤中的降解动态,为进一步研究除草剂的残留污染提供科学依据。 【方法】 以中黄13号大豆为材料,采用根箱进行了模拟栽培试验。设施用氟磺胺草醚3.75 mg/kg (低)、7.5 mg/kg (中)、18.75 mg/kg (高) 3个水平,以不添加氟磺胺草醚处理为对照,调查了大豆根际土壤细菌、真菌、放线菌数量,分析了根际土壤中过氧化氢酶、磷酸酶、脲酶、蔗糖酶4种酶活性,以及氟磺胺草醚在大豆根际土壤中的降解规律。 【结果】 低浓度氟磺胺草醚处理的大豆根际土壤细菌数量显著低于对照根际土壤 (P < 0.05),高浓度氟磺胺草醚处理在28 d时显著高于对照 ( P < 0.05);中浓度氟磺胺草醚处理与对照没有显著性差异。不同浓度氟磺胺草醚处理的大豆根际土壤真菌和放线菌数量与对照差异不显著。氟磺胺草醚处理的大豆根际土壤过氧化氢酶活性与对照没有显著差异;磷酸酶活性在取样初期略有降低;低浓度氟磺胺草醚处理的土壤脲酶活性显著降低,中浓度和高浓度处理对脲酶活性表现为先刺激后抑制;高浓度氟磺胺草醚处理的蔗糖酶活性在42 d和56 d时显著低于对照。高浓度氟磺胺草醚降解速率明显高于低浓度和中浓度,并且在试验初期降解迅速;3种浓度氟磺胺草醚在大豆根际土壤中的降解均符合一级动力学方程,降解半衰期由低浓度到高浓度逐渐变短。 【结论】 3种浓度氟磺胺草醚总体上降低大豆根际土壤中细菌的数量,而对大豆根际土壤真菌和放线菌的数量均没有显著影响。氟磺胺草醚对大豆根际土壤过氧化氢酶活性没有显著影响,在短期内对磷酸酶活性有一定程度的抑制作用,低浓度氟磺胺草醚可以显著降低大豆根际土壤脲酶活性,而高浓度氟磺胺草醚在试验后期可以显著抑制大豆根际土壤蔗糖酶活性。大豆根际土壤中氟磺胺草醚初始浓度越高,降解速率越快,半衰期越短。      

连作土壤盆栽大豆的根际酸度和微生物数量变化

连作土壤条件下，不同抗性品种的根际微生物变化不同。盆栽试验结果表明，连作条件下，抗病品种绥农10号和抗线2号根际环境pH中性偏碱，不利病原真菌生长；感病品种合丰25号根际则处于偏酸环境，使作物易于感染根腐病。抗性大豆品种绥农10号和抗线2号的根际细菌数量增加，真菌数量减少；感病品种合丰25号的细菌和真菌数量变化不显著。     

不同土壤改良剂处理对连作西洋参根际微生物数量、土壤酶活性及产量的影响

以北京地区连作西洋参为研究对象, 通过3种土壤改良剂(熟石灰、EM菌剂、沼液)随机区组试验对其土壤理化性状、酶活性、根际微生物区系及产量进行了系统研究。结果表明: 低浓度熟石灰、中浓度EM菌剂及高浓度沼液处理最有利于提高西洋参产量; 施加熟石灰处理后, 土壤微生物主要类群数量显著减少, 土壤pH显著升高, 并对土壤脲酶活性有明显抑制作用; 施加沼液和EM菌剂处理后, 土壤有效微生物菌群显著增加(P<0.05), 土壤有机质和营养物质含量也显著增加(P<0.05), 并对土壤脲酶和多酚氧化酶活性有一定的促进作用。相关性分析发现, 土壤微生物主要类群的数量与蔗糖酶、脲酶、多酚氧化酶活性均有一定的相关性, 其中, 土壤细菌数量与蔗糖酶、多酚氧化酶活性呈极显著正相关(r分别为0.895^**和0.808^**), 土壤真菌和放线菌数量与蔗糖酶、脲酶、多酚氧化酶活性呈极显著正相关(r分别为0.932^**、0.769^**、0.840^**和0.837^**、0.891^**、0.797^**)。另外, 土壤细菌数量与有机质含量呈极显著正相关(r=0.863^**)。表明连作西洋参根际微生物区系及土壤酶活性与土壤理化性状之间紧密联系, 通过施加不同土壤改良剂, 可以为耐连作种植西洋参提供适宜的土壤环境。     

膨润土对花生连作根际土壤肥力和作物产量的影响

设膨润土施用量0、1.2、2.4、3.6、4.8 kg/m~2,共5个处理,研究膨润土基质对风沙地半干旱区花生连作土壤微生物量和酶活性的影响。结果表明:施用膨润土明显提高了风沙地花生连作土壤含水量、微生物量碳、氮、磷的含量以及土壤酶活性,在3.6 kg/m~2处理条件下土壤含水量、微生物量碳、氮、磷含量和土壤酶活性增加最显著。与不施膨润土相比,施用膨润土后花生产量分别提高了10.01%、11.83%、21.34%、9.05%,在3.6 kg/m2处理条件下花生增产显著。经相关性分析可知,花生产量与土壤微生物量碳、氮、磷含量均呈极显著正相关关系,与土壤蔗糖酶、磷酸酶、脲酶、蛋白酶、脂肪酶均呈显著或极显著正相关关系,与土壤过氧化氢酶活性相关性不显著。上述结果说明,在风沙地半干旱区花生连作土壤中添加适量膨润土能有效提高土壤微生物量和酶活性,对作物增产有明显的促进作用。     

乙草胺对土壤微生物数量和酶活性的影响

采用室内瓶培养试验,研究了乙草胺施用对土壤微生物数量及酶活性的影响。结果表明:乙草胺施用初期对土壤细菌和放线菌数量有明显刺激作用,但施用30d时高施用量处理(30mg·kg-1)呈明显抑制作用,之后各处理放线菌恢复到对照水平,而对细菌的抑制作用一直持续到60d;乙草胺对土壤真菌数量呈"抑制-恢复-刺激"的作用趋势。乙草胺施用初期对土壤脱氢酶产生一定刺激作用,45d后高施用量处理呈明显抑制作用,一直持续到60d;土壤过氧化氢酶对乙草胺不敏感,而转化酶和脲酶对乙草胺施入初期较敏感;低施用量处理对转化酶有抑制作用,高施用量处理对转化酶有刺激作用,各处理对脲酶都有抑制作用。     

Impact of effective microorganisms and other biofertilizers on soil microbial characteristics,organic‐matter decomposition,and plant growth

Incubation and pot experiments were conducted to investigate the impact of commercially distributed biofertilizers (effective microorganisms [EM], BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B) on soil microbial‐biomass content and activity, net N mineralization in soil, and growth of Lolium perenne. According to the manufacturers, the products tested are based on microbial inoculants or organic growth stimulants, and are supposed to influence soil microbial properties and improve soil conditions, organic‐matter decomposition, and plant growth. In the incubation experiment (40 d, 20.6°C, 50% maximum water‐holding capacity), EM was repeatedly applied to soil together with different organic amendments (nonamended, chopped straw, and lupine seed meal). Under the experimental conditions of this study, no or only marginal effects of EM on organic C, total N, and mineral N in soil could be observed. In soil treatments without any organic amendment, EM suspension slightly enhanced microbial activity measured as soil CO₂ evolution. In soil with easily degradable plant residues (lupine seed meal), EM suspension had a suppressive effect on microbial biomass. However, comparisons with sterilized EM and molasses as the main additive in EM suspension showed that any effect of EM could be explained as a pure substrate effect without the influence of added living organisms. In the pot experiment with Lolium perenne (air‐conditioned greenhouse cabin, 87 d, 16.8°C, 130 klxh d^–1 light quantity), the products EM, BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B were tested in soil with growing plants. The products were repeatedly applied for a period of 42 d. Within this study, no effects of the different biofertilizers on mineral N in soil were detectable. There were clear suppressive effects of all tested biofertilizers on microbial‐biomass content and activity. Comparisons with sterilized suspensions showed that the effects were not due to living microorganisms in the suspensions, but could be traced back to substrate‐induced processes.     

一株大蒜根际细菌特性研究及其对田间大蒜产量和土壤酶活性的影响

植物根际促生菌(Plant growth-promoting rhizobacteria,PGPR)具有抵抗植物病害,促进植物生长等作用。以前期在山东省金乡县连作大蒜根际土壤中分离获得的根际细菌为研究对象,筛选获得对大蒜根腐病病原菌H5(Setophoma terrestris)和H9 (Fusarium solani)具有较好拮抗效果的菌株DS7,经16S rRNA基因序列分析初步鉴定,该菌株属于芽孢杆菌属(Bacillus)。功能特性研究显示:菌株Bacillus sp. DS7对H5抑制率达到51.72%,对H9抑制率达到42.31%;菌株DS7具有产IAA(19.29±0)μg/mL、产铁载体、水解蛋白、溶磷等能力,但不具有产ACC脱氨酶能力。田间接种试验结果显示:与不接菌的对照相比,接种菌株DS7后大蒜产量提高15.42%;土壤的蔗糖酶活性和脲酶活性高于对照土壤,过氧化氢酶活性低于对照土壤。综上,植物根际促生菌Bacillus sp. DS7具有多种功能特性,可以增加田间大蒜产量,改良土壤,是潜在的微生物肥料生产菌种。     

黄顶菊入侵对土壤微生物、土壤酶活性及土壤养分的影响

通过采样分析,研究了外来植物黄顶菊入侵对非耕地和耕地,以及对玉米根系土壤微生物、土壤酶活性、土壤速效养分的影响,旨在揭示黄顶菊入侵农田和贫瘠荒地的机制。本试验比较了距根系不同距离土壤的微生态变化;分析了根系土壤3大微生物类群结构、5种土壤理化性质以及5种土壤酶活性之间的相关性。结果表明,非耕地黄顶菊根表速效氮、速效磷、速效钾的含量分别为对照的4.44、6.88、2.64倍,耕地中分别为对照的5.31、13.78、7.56倍;非耕地黄顶菊根表土壤细菌、真菌、放线菌数量分别为对照的13.23、6.67、21.40倍,耕地中分别为对照的9.27、2.15、2.24倍,可见黄顶菊对非耕地土壤中可培养的细菌、真菌、放线菌数量的影响更为明显;非耕地中黄顶菊根表土壤碱性磷酸酶、酸性磷酸酶、脲酶、脱氢酶、蔗糖酶的活性分别为对照的19.44、5.39、1.64、1.74、4.62倍,说明细菌非常活跃。耕地中分别为对照的2.26、3.45、1.53、0.95、4.89倍。另外在玉米与黄顶菊互作时,其根表土壤速效氮、磷、钾分别为非互作条件下的63.54%、64.70%、80.71%、,黄顶菊入侵明显降低了玉米根表速效养分。综上,黄顶菊入侵增加了其根系周围可培养土壤微生物数量、土壤酶活性及土壤速效养分含量;降低了附近玉米根表土壤中可培养微生物数量、土壤酶活性和速效养分含量。     

Micro-scale distribution of microorganisms and microbial enzyme activities in a soil with long-term organic amendment

Microbial ecology is the key to understanding the function of biodiversity for organic matter cycling in the soil. We have investigated the impacts of farmyard manure added over 120 years on organic matter content, enzyme activities, total microbial biomass and structure of microbial populations in several particle‐size fractions of a Luvic Phaeozem a few kilometres northeast of Halle, Germany. We compared two treatments: no fertilization (control) and 12 t farmyard manure (FYM) ha^?1 year^?1 since 1878. The fine fractions contained most C and N, microbial biomass, total amount of phospholipid fatty acids (PLFAs) and greatest invertase activity. Xylanase activity as well as fungal biomass increased only gradually with diminishing particle size, whereas the relative abundance of fungi decreased with diminishing particle size. The least diversity of the soil microbial community, indicated by the smallest Shannon index based on the abundance and amount of different PLFAs and small number of terminal restriction fragments (T‐RFs) of 16S rRNA genes, was in the sand fractions. The results supported the hypothesis that this microhabitat is colonized by a less complex bacterial community than the silt and clay fractions. Addition of FYM had enhanced the amount of organic matter, total microbial biomass, and xylanase and invertase activity, and induced a shift of the microbial community towards a more bacteria‐dominated community in the coarse sand fraction. Microbial communities in finer fractions were less affected by addition of FYM.     

Impact of monoculture of poplar on rhizosphere microbial communities over time

To date, research on the adverse effects of continuous cropping has focused on field crops; forest plantations, despite their very significant economic and ecological value, have received less attention. The evolution of microbial community in the rhizosphere of forest plantations, in particular, has rarely been examined. In this study, changes in the size, composition, and structure of bacterial and fungal communities in the rhizosphere of different generations of poplar (Populus deltoides) plantations were studied using real-time polymerase chain reaction (PCR) and PCR-denaturing gradient gel electrophoresis and compared with the composition of the microbial community in a bare land (control) adjacent to the plantation sites through sequencing analysis and by constructing phylogenetic trees. The numbers of bacteria and fungi increased significantly with successive poplar generations, although the increases in the two groups were not parallel. When compared with the control, the bacterial community increased greatly in the second generation, and the most significant increase occurred in the third generation. In contrast, the most significant increase in the fungal community occurred in the first generation, and the increase in the third generation was insignificant. In terms of community composition, the first generation showed little change in either community; however, the second generation showed remarkable changes in the bacterial community, and the third in the fungal community. The numbers of Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria increased by 10.92%, 7.38%, and 5.46%, respectively, whereas those of Acidobacteria decreased by 18.38% in the second generation. These changes in the number and composition of microbial communities in the rhizosphere could be one of the reasons for the decline in yield and quality associated with long-term monoculture.     

Links between pseudometallophytes and rhizosphere microbial communities in a metalliferous soil

Short-term improvements in soil health derived from pseudometallophytes growth and metal phytoremediation were quantified based upon specific microbial properties of potential value as bioindicators of soil functioning. To this aim, plant consortia, consisting of 1–3 pseudometallophytes with different metal-tolerance strategies (hyperaccumulator: Noccaea caerulescens; accumulator: Rumex acetosa; excluder: Festuca rubra), were grown in a mine soil. At the end of the experiment, soil microbial biomass, activity, structural and functional community profiling, and stability were determined. Growing together with N. caerulescens stimulated the growth of the other two pseudometallophytes. The combination of R. acetosa and N. caerulescens extracted the highest amounts of Zn. Except for β-glucosidase, a negative correlation was found between enzyme activities and number of pseudometallophytes present in the study pots. Microbial biomass C was highest in the presence of all three pseudometallophytes. The combination of different pseudometallophyte species, which may allow for a greater exploitation of potential niche space, appears promising for phytoremediation. When quantifying soil health, the importance of measuring various types of soil microbial properties has been highlighted, as the response observed was different in each of them.     

小分子有机物对土壤酶活性及微生物多样性的影响

目前对小分子有机物的研究主要集中在叶面肥方面,较少在土壤肥料的应用方面,而对土壤酶活性以及微生物功能多样性的研究就更少。以分别添加葡萄糖、甘油以及甘氨酸的土壤(25℃培养)为试材,采用酶活性(每15 d取样)测定方法与Biolog-Eco板技术(取培养45 d的土样),研究小分子有机物对土壤微生物及酶活性的影响。结果表明,3种小分子有机物处理土壤的4种酶活性在15～75 d内,变化规律基本一致;在45 d时葡萄糖处理土壤的过氧化氢酶活性显著高于清水对照(CK)、甘油以及甘氨酸,而碱性磷酸酶活性显著低于其它处理。与CK、葡萄糖以及甘氨酸相比,甘油处理土壤微生物平均吸光度值和功能多样性指标(除指数D外)显著提高,而CK、葡萄糖以及甘氨酸处理之间没有显著性差异。葡萄糖、甘油以及甘氨酸处理改变了土壤的微生物功能多样性以及碳源利用比分,其中甘氨酸和葡萄糖处理土壤胺类利用百分比(AM)几乎为零。土壤微生物多样性与酶活性冗余分析表明,碱性磷酸酶与微生物功能多样性指数S、U、H′、碳水化合物利用百分比以及AM呈显著正相关,相关系数分别为0.588、0.669、0.616、0.678及0.603,与指数D及蔗糖酶活性呈显著负相关,相关系数分别为-0.737和-0.741。由此可知,不同种类小分子有机添加物对土壤酶活性以及微生物功能多样性影响不一,其中甘油显著提高了土壤微生物代谢活性以及多样性指数(除指数D外),而土壤酶活性与微生物功能多样性的主成分分析表明甘氨酸与另外两种小分子有机物存在明显差别。     

有机无机复混肥施用量对热带水稻土微生物群落和酶活性的影响

[目的]研究一次性施用不同量的有机无机复混肥对热带地区水稻产量及土壤微生物群落与酶活性的影响,为该区域水稻高效肥料管理提供科学依据.[方法]水稻田间试验连续进行了3季(2018年早稻-晚稻,2019年早稻).施肥设5个处理:不施肥对照(CK),常规化肥分3次施用(CF),采用一次性基施的等量、减10％和减20％氮磷钾养...