茴香轮作调控土壤细菌群落缓解三七连作障碍的效应及机制

三七是我国特有的中药材，但连作障碍严重制约了其产业发展，轮作是生产上最常用且有效的缓解措施。本研究在三七收获后的土壤上轮作茴香，通过测定轮作土壤水浸液对三七存苗的影响来评价轮作对三七连作障碍的缓解效果，并从轮作对土壤细菌群落的影响方面深入阐释轮作缓解连作障碍的机制。结果表明，茴香轮作后的土壤水浸液可以显著提高三七的存苗率。土壤细菌分析表明，茴香轮作后土壤细菌群落发生了明显改变。细菌的丰富度增加，相对丰度>1%的优势菌门变形菌门Proteobacteria和放线菌门Actinobacteria的相对丰度呈增加趋势。属水平上，轮作茴香使66个属的相对丰度显著增加，其中相对丰度>0.2%的优势菌属有14个；30个属的相对丰度显著降低，其中优势菌属有8个，总体上看相对丰度显著增加的属多于显著降低的属。在相对丰度显著增加的优势菌属中包含常见的拮抗菌属假单胞菌属Pseudomonas和芽孢杆菌属Bacillus细菌。本研究也分离到2株假单胞菌和1株芽孢杆菌对三七根腐病菌腐皮镰刀菌Fusarium solani和Monographella cucumerina具有明显的拮抗活性。因此，轮作茴香可以改善三七连作土壤细菌群落结构，增加土壤中拮抗细菌的丰度，提高三七的存苗率。生产上利用茴香与三七轮作对缓解连作障碍具有一定潜力。     

不同轮作方式对马铃薯土壤酶活性及微生物数量的影响

在连续种植2年马铃薯的土壤上进行不同轮作方式田间试验,探讨轮作方式对马铃薯土壤酶活性及土壤微生物数量的影响。试验结果表明:与对照(裸地)相比,小麦-豌豆-马铃薯轮作时土壤过氧化氢酶活性有增加的趋势;豌豆-马铃薯-豌豆轮作条件下,土壤的蔗糖酶活性提高,且在马铃薯成熟期提高幅度最大,为47.95%。轮作条件下土壤多酚氧化酶活性低于连作;轮作方式不同,土壤脲酶活性变化明显,在马铃薯块茎膨大期,豌豆-马铃薯-豌豆轮作方式的土壤脲酶活性比小麦-马铃薯-小麦高14.73%。马铃薯块茎膨大期根区土壤微生物数量测定结果显示:随着连作年限的增加,细菌数量及微生物总量降低,真菌数量升高了54.66%;小麦-豌豆-马铃薯轮作后,土壤中的细菌、放线菌数量最高,分别为6.40×106CFU·g-1和2.22×106CFU·g-1。     

不同连作年限硒砂瓜土壤细菌群落结构特征

应用高通量测序技术对宁夏中卫地区不同连作年限硒砂瓜土壤细菌群落结构和多样性进行研究,旨在揭示不同连作年限对硒砂瓜土壤细菌群落结构的影响。结果表明:随着连作时间的增加,细菌多样性指数和丰富度指数逐渐增加。从5份不同连作年限硒砂瓜土壤样本中共获得39门、98纲和620属的细菌;优势门为放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria);随着连作时间的增加,放线菌门、酸酐菌门丰度先增加后降低,变形菌门丰度逐渐降低,绿弯菌门丰度呈先降低后增加又降低现象;优势纲分别为放线菌纲(Actinobacteria)、酸杆菌纲(Acidobacteria)、α-变形菌纲(Alphaproteobacteria)、芽单胞菌纲(Gmmatimonadetes)、杆菌纲(Bacilli)、热原体纲(Themomicrobia)、γ-变形菌纲(Gammaproteobacteria)、β-变形菌纲(Betaproteobacteria);优势目为norank_c_Acidobacteria、芽孢杆菌目(Bacillales)、芽单胞菌目(Gemmatimonadales)、根瘤菌目(Rhizobiales)。RDA分析表明,有机质、速效磷是硒砂瓜连作土壤细菌群落组成的主要影响因子。研究表明,引起硒砂瓜连作障碍发生主要因素不是由于土壤理化性质变化引起的,而是随着连作时间的增加,放线菌门、变形菌门、绿弯菌门、酸杆菌门、厚壁菌门等有益微生物丰度下降造成的。     

种植模式对科尔沁沙地土壤微生物群落的影响

针对科尔沁沙地土壤质量退化、花生连作障碍问题,于辽宁省农业科学院章古台试验站进行田间定位实验,设置玉米(Zea mays L)-花生(Arachis hypogaea)-玉米轮作(L1)、花生-玉米-花生轮作(L2)、玉米连作(YL)和花生连作(HL)4种种植模式,采集0-20cm土层土壤样品,采用磷脂脂肪酸法(PLFA)分析土壤微生物群落结构组成及多样性,测定土壤可培养微生物数量及土壤微生物量碳氮磷含量。结果表明：L1和L2模式下土壤微生物群落总丰度、细菌群落丰度、真菌群落丰度、放线菌群落丰度均显著高于YL和HL。主成分分析与冗余分析结果表明,L1和L2与土壤微生物量碳氮磷含量、土壤微生物各菌群丰度呈正相关;土壤可培养微生物总量与土壤总PLFA含量正相关。综上,轮作引起的土壤微生物群落丰度的变化是土壤微生物量碳氮磷累积的驱动因素。花生-玉米轮作种植能有效改善土壤微生态环境、缓解花生连作障碍。     

柴达木盆地盐渍化土壤养分和酶活性特征

为探讨柴达木盆地不同程度盐渍化土壤养分和酶活性特征，沿察尔汗盐湖至昆仑山方向依次选择5个样点，分析土壤养分和酶活性特征及其二者的相关性。结果表明：除土壤全钾外，土壤盐渍化程度、土壤深度及其两者交互作用对土壤养分含量及土壤酶活性的影响均达到显著水平(P<0.05)。在盐渍化程度较低的土壤，养分有效性(速效钾除外)和酶活性较高，且随土壤深度的增加而降低。以有机碳和蔗糖酶为例，在盐渍化程度最低的S5样地中含量为13.83 g·kg^-1和21.01 mg·g^-1·d^-1(0～5 cm)、12.85 g·kg^-1和19.29 mg·g^-1·d^-1(5～10 cm)、9.83 g·kg^-1和12.19 mg·g^-1·d^-1(10～20 cm)，显著高于盐渍化程度最高S1中的8.56 g·kg^-1和1.41 mg·g^-1·d^-1(0～...     

不同种植年限对特殊药材土壤化学性质和微生物多样性的影响

以不同种植年限特殊药材根际土壤为材料,采用IlluminaNovaSeq高通量测序法和常规分析方法,分析了种植年限(0 a, 1 a, 4 a, 24 a)对根际土壤化学性质及微生物群落多样性的影响。结果表明：连续种植24 a后,土壤电导率、硝态氮含量显著高于其他种植年限。特殊药材连作对土壤细菌α-多样性指数均无显著影响,但土壤细菌丰富度和多样性减少;连续种植24 a真菌α-多样性指数中ACE指数、Chao1指数显著高于种植1 a,真菌丰富度和多样性增加。细菌群落Proteobacteria(变形菌门)、Acidobacteria(酸杆菌门)、Actinobacteria(放线菌门)为优势菌门,Sphingomonas(鞘氨醇单胞菌属)、Xanthomonadaceae(黄单胞菌科)相对丰度随着种植年限增加呈明显上升趋势,未知菌属RB41、Lysobacter(溶杆菌属)相对丰度呈下降趋势。土壤真菌群落Mortierellomycota(被孢霉门)、Ascomycota(子囊菌门)、Basidiomycota(担子菌门)为优势菌门,Mortierella(被孢霉属)相对丰度随种植年限增...     

黄土高原马铃薯不同连作年限土壤 理化性质及微生物特性

以黄土高原旱作区马铃薯不同连作年限土壤为研究对象，采用空间代替时间序列方法，对撂荒（CK₁）、小麦/豌豆/马铃薯轮作（CK₂）、连作2 a、连作4 a和连作6 a等不同连作年限的土壤容重、结构分维、总有机碳、酶活性与微生物数量及变化规律进行研究。结果表明：(1）不同处理土壤容重差异显著，连作6 a土壤容重最小；(2）连作可以改变土壤中不同粒级团聚体的比例，各处理中＞4 mm粒径的土壤含量最高；(3）马铃薯长期连作显著降低土壤有机碳含量，连作6 a土壤总有机碳含量较撂荒降低14.27%； (4）马铃薯主要生育期内土壤转化酶、过氧化氢酶变化动态呈“S”型曲线，脲酶呈“M”型变化趋势，3种酶活性与土壤肥力因子均呈极显著正相关，与土壤容重呈极显著负相关；(5）细菌是连作土壤中优势菌，真菌和放线菌也占一定比重；细菌、真菌和放线菌数量在0～10 cm土层显著高于10～20 cm土层；马铃薯长期连作显著降低土壤微生物数量，群落结构随连作年限明显改变。     

马铃薯根系分泌物组分对不同种植模式的响应

作物根系分泌物与作物连作障碍密切相关,为寻求减小作物连作障碍的途径,在轮作(大豆-马铃薯)、固定间作(马铃薯/大豆)和马铃薯连作3种种植模式下,分离鉴定了马铃薯根系分泌物的主要组分。结果表明:与轮作处理相比,固定间作和连作处理马铃薯根系分泌物种类分别增加了13.79%和17.24%,烷烃类物质的相对含量分别增加了52.17%和52.60%,酸类物质的相对含量分别增加了65.41%和14.79%。连作处理马铃薯根系分泌物中鉴定出乙胺、N-乙基吗啉和邻苯二甲酸二丁酯的相对含量分别为1.46%、2.87%和5%,而在轮作和间作处理中均未检测到。与轮作处理相比,间作和连作处理N,N-二乙基乙酰胺相对含量分别高出123.29%和47.95%,棕榈酸相对含量分别高出23.18%和40.0%,硬脂酸相对含量分别高出27.36%和39.80%。说明大豆-马铃薯轮作可有效降低马铃薯根系分泌物组分的种类和含量。因此,生产实践中,可通过大豆-马铃薯轮作克服因某一种马铃薯化感物质累积而造成的毒害作用。     

葱轮作改善土壤微生物群落缓解三七连作障碍的潜力分析

明确葱轮作后对三七连作土壤微生物的影响,为利用葱与三七轮作缓解三七连作障碍提供依据。本研究在三七连作土上连续种植两茬小葱,以休耕连作土壤为对照,采用细菌16S rRNA和真菌ITS区测序,研究葱轮作后对土壤微生物多样性、物种组成及关键微生物的影响;然后分离可培养的关键细菌假单胞菌属,验证其对三七根腐病菌的拮抗功能。结果表明,葱轮作后显著提高了三七连作土壤细菌和真菌的丰富度,两种处理后的细菌和真菌在PCoA图上均能明显分开。门水平上,葱轮作后细菌变形菌门的相对丰度显著增加,酸杆菌门、绿弯菌门等显著降低;真菌子囊菌门的相对丰度显著降低,担子菌门显著增加。LEfSe分析表明,变形菌门及其下属的假单胞菌属等关键细菌在葱轮作后丰度显著增加,丛赤壳科中可以引起三七根腐的Fusarium和Ilyonectria等真菌在轮作后丰度降低。从轮作土壤中分离到22株假单胞菌,其中15株铜绿假单胞菌对三七根腐病菌有较好的拮抗效果。综上,葱轮作可以显著改善三七连作土壤的微生物状况,有益菌相对丰度增加而根腐病原菌相对丰度降低。利用葱与三七轮作对缓解三七连作障碍具有一定的潜力。     

长期施用绿肥对小麦玉米间作土壤微生物的影响

利用Biolog微平板法和高通量测序技术，研究小麦玉米间作条件下，不同长期施肥处理土壤微生物对不同碳源的利用差异以及土壤微生物群落在门、属水平上的变化，探明长期施用绿肥对土壤微生物群落多样性及代谢功能的影响。结果表明：长期施用绿肥可显著提高土壤有机质、速效磷和速效钾含量，降低土壤pH值，增强土壤微生物碳源代谢能力。不同施肥条件下，放线菌门(Actinobacteria)和变形菌门(Proteobacteria)为土壤优势菌群，绿肥处理的放线菌门丰度最高(29.94%),农家肥处理最低(22.95%);秸秆还田处理的变形菌门丰度最高(22.32%),对照处理最低(18.85%);酸杆菌门(Acidobacteriota)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)在各个处理中的相对丰富度较高，分别为13.39%～19.71%、10.85%～14.56%、3.54%～12.98%。长期施用绿肥有效提高了土壤放线菌门、厚壁菌门、芽孢杆菌属(Bacillus)以及假节杆菌属(Pseudarthrobacter)的丰度，降低了酸杆菌门的丰度，增加了土壤微生物种群数量。综...     

马铃薯长期连作对土壤真菌群落特征的影响

利用田间长期定位试验,2019年基于ITS高通量测序研究马铃薯/春小麦/碗豆轮作（R）、马铃薯连作1 a（C1）、3 a（C3）、5 a（C5）、7 a（C7）和9 a（C9）的土壤真菌群落结构的演替特征。结果表明：随着马铃薯连作年限的增加,土壤真菌菌群丰度和Chao1显著增加,C7和C9马铃薯土壤真菌菌群丰度最高,R土壤真菌菌群丰度最低,C7和C9真菌群落的相似度较高,C7、C9处理与R处理的真菌群落相似度低,C1、C3、C5的真菌群落结构介于C7、C9与R之间;土壤真菌群落的相似度在纲水平上分为两类,C7和C9为一组,R、C1、C3、C5为一组;在不同连作年限的马铃薯农田土壤中,共检测到273个真菌属,其中有13个真菌属处理间差异显著,其中,青霉菌(Penicillium)在C5、C7和C9土壤中数量显著高于R,绿僵菌属（Metarhizium）在C5、C7、C9中相对丰度显著高于R、C1、C3,镰刀菌属（Fusaruim）在C5中相对丰度达最高,显著高于R、C1、C3以及C7、C9;马铃薯连作5 a后引起农田真菌群落分布发生变化。青霉菌、绿僵菌属在长期连作农田中大量富集,镰刀菌属数量下降,连作障碍程度趋于减缓。     

Root exudates of potato onion are involved in the suppression of clubroot in a Chinese cabbage-potato onion-Chinese cabbage crop rotation

Clubroot, caused by Plasmodiophora brassicae, has emerged as a serious disease threatening cruciferous crop production throughout the world. Crop rotation with non-host species is commonly practised to avoid clubroot, but it is not known whether rotation crops can control clubroot when the resting spores of P. brassicae remain unaffected. Pot experiments were performed to investigate the response of clubroot in Chinese cabbage to crop rotation with potato onion. The results showed that Chinese cabbage rotated with potato onion exhibited less clubroot disease than Chinese cabbage monoculture. Compared with residues from potato onion, the addition of root exudates from potato onion significantly decreased the disease incidence and index of clubroot (p ≤ 0.05). Potato onion root exudates decreased the number of secondary plasmodia of P. brassicae and the expression of the PRO1 gene of P. brassicae. These results suggest that root exudates from potato onion may play an important role in suppressing clubroot in a Chinese cabbage-potato onion-Chinese cabbage rotation system.     

Effect of crop rotation on the incidence of soil-borne fungal diseases of potato

Effects of crop rotation on the incidence of soil-borne pathogens and on the performance of potato were investigated in five field experiments. Rotations differed in cropping frequency of potato and in crop sequence.Incidence of stem canker caused byRhizoctonia solani was strongly influenced by the cropping frequency of potato and not by crops with which the potato was alternated in the rotation. Cropping frequency of potato also affected the occurrence of black scurf, but less pronounced than for stem canker. The antagonistVerticillium bigutatum slightly reducedR. solani (black scurf) in plots on sandy soil continuously cropped with potato. Incidence of stem canker was also strongly affected by granular nematicides applied to the soil, nitrogen level and the cultivar grown.     

Effects of different 3-year cropping systems on soil microbial communities and rhizoctonia diseases of potato

ABSTRACT Eight different 3-year cropping systems, consisting of soybean-canola, soybean-barley, sweet corn-canola, sweet corn-soybean, green bean-sweet corn, canola-sweet corn, barley-clover, and continuous potato (non-rotation control) followed by potato as the third crop in all systems, were established in replicated field plots with two rotation entry points in Presque Isle, ME, in 1998. Cropping system effects on soil microbial community characteristics based on culturable soil microbial populations, single carbon source substrate utilization (SU) profiles, and whole-soil fatty acid methyl ester (FAME) profiles were evaluated in association with the development of soilborne diseases of potato in the 2000 and 2001 field seasons. Soil populations of culturable bacteria and overall microbial activity were highest following barley, canola, and sweet corn crops, and lowest following continuous potato. The SU profiles derived from BIOLOG ECO plates indicated higher substrate richness and diversity and greater utilization of certain carbohydrates, carboxylic acids, and amino acids associated with barley, canola, and some sweet corn rotations, indicating distinct differences in functional attributes of microbial communities among cropping systems. Soil FAME profiles also demonstrated distinct differences among cropping systems in their relative composition of fatty acid types and classes, representing structural attributes of microbial communities. Fatty acids most responsible for differentiation among cropping systems included 12:0, 16:1 omega5c, 16:1 omega7c, 18:1 omega9c, and 18:2omega6c. Based on FAME biomarkers, barley rotations resulted in higher fungi-to-bacteria ratios, sweet corn resulted in greater mycorrhizae populations, and continuous potato produced the lowest amounts of these and other biomarker traits. Incidence and severity of stem and stolon canker and black scurf of potato, caused by Rhizoctonia solani, were reduced for most rotations relative to the continuous potato control. Potato crops following canola, barley, or sweet corn provided the lowest levels of Rhizoctonia disease and best tuber quality, whereas potato crops following clover or soybean resulted in disease problems in some years. Both rotation crop and cropping sequence were important in shaping the microbial characteristics, soilborne disease, and tuber qualities. Several microbial parameters, including microbial populations and SU and FAME profile characteristics, were correlated with potato disease or yield measurements in one or both harvest years. In this study, we have demonstrated distinctive effects of specific rotation crops and cropping sequences on microbial communities and have begun to relate the implications of these changes to crop health and productivity.     

连续施用不同氮量对半干旱地区马铃薯根际真菌群落结构的影响

针对马铃薯生产中因氮肥过量施用导致的土壤微生物群落结构失衡和多样性下降等问题,在始于2013年的不同氮肥用量(N0:不施氮,对照;N75:施氮量75 kg·hm~(-2);N150:施氮量150 kg·hm~(-2);N225:施氮量225 kg·hm~(-2);N300:施氮量300 kg·hm~(-2);N375:施氮量375 kg·hm~(-2))田间定位试验中,于2017年马铃薯成熟期采集根际土壤,应用Illumina PE250测序等分子生物学手段,研究连续5 a施用不同氮量对半干旱地区马铃薯根际真菌群落结构的影响。结果表明:不同施氮量对马铃薯根际真菌群落物种组成造成了显著影响,子囊菌门、Mucoromycota和担子菌门是3个优势门类真菌(相对丰度1.0%),以子囊菌门的相对丰度最大,占总序列的75.48%～83.95%,其优势属是Plectosphaerella(29.92%)和镰刀菌属(13.54%);马铃薯干腐病和枯萎病的病原菌——镰刀菌属的相对丰度随施氮量增加呈增大的趋势。马铃薯根际真菌Alpha多样性随施氮量的增加而降低。连续5 a超量施氮导致了0～20 cm表层土壤中NO~-_3-N含量显著增加,N375处理的NO~-_3-N含量是N0处理的3.76倍。连续5 a超量施氮也显著降低了根际pH值和速效磷含量,N375处理比N0处理pH值和速效磷含量分别降低了0.17个单位和32.10%。RDA及相关性分析结果表明,土壤硝态氮含量是影响马铃薯根际真菌群落结构变化的主要因素(F=1.571,P=0.043~*)。连续大量施用氮肥显著降低了马铃薯块茎产量,连续施氮5 a后,由于土壤剖面中NO~-_3-N的积累,最高产量施肥量由2013—2014年的N225减低为N75,其它施氮处理较N75分别减产了3.46%、22.81%、26.05%和25.32%。长期过量施用氮肥使马铃薯根际硝态氮大量累积,导致pH值降低,进而使根际真菌多样性降低;同时过量氮肥施用会使根际中土壤真菌病原菌相对丰度增加,不利于土壤的健康和马铃薯的高产。     

宁南山区膜下滴灌对马铃薯土壤酶活性、土壤养分及产量的影响

在宁南山区海原县关庄乡高台村试验田,采用膜下滴灌节水技术,研究了覆膜不滴灌、滴灌不覆膜、膜下滴灌和不滴灌不覆膜(CK)4种方式下马铃薯生育期的土壤养分、酶活性以及马铃薯产量的差异。结果表明:在0～20 cm和20～40 cm土层中,膜下滴灌种植条件下,与CK相比较,有机质含量分别提高了3.88%、18.23%,碱解氮提高了10.71%、18.75%,速效钾提高了5.92%、2.55%,生育期内土壤脲酶活性提高了27.05%～69.37%、0.17%～38.33%,碱性磷酸酶活性提高了12.70%～23.90%、 6.99%～28.93%,转化酶活性提高了5.65%～68.12%、8.41%～31.63%,纤维素酶活性提高了8.33%～32.94%、19.98%～108.82%,产量提高了107.90%;土壤养分与酶活性及马铃薯产量间存在显著正相关。研究得出,膜下滴灌可以改善土壤微生态环境,提高土壤酶活性,改善土壤养分循环能力,增加产量,是干旱半干区马铃薯旱作节水栽培的有效措施之一。     

Effect of crop rotation on Globodera rostochiensis and on potato yield1

A crop rotation field study was conducted in 1981–1989 to assess the effect of six crop rotation sequences on a soil population of potato cyst nematode (PCN), Globodera rostochiensis, and on potato yield. In the plots with potato monoculture, the tuber yield decreased from 35 to 4.6 t ha^?1. All other cropping systems maintained the yield at the original or an even higher level. In monoculture, the population density of the nematode was raised during the first 3 years from 0.1 to 265 larvae g^?1 soil, and the density fluctuated afterwards between 30 and 136 larvae g^?1 soil. Three of the cropping systems, (1) susceptible potato once in 5 years, (2) susceptible potato once in 4 years, and (3) potato once in 3 years using resistant (H1) and susceptible cultivars alternately, decreased the nematode density under the economic threshold or even under the level of detection. The nematicide treatments (oxamyl) did not control nematode multiplication but prevented yield losses. No nematicide is currently registered nor needed for the control of PCN in Finland. The nematode can be controlled effectively with crop rotation, resistant cultivars and early harvesting.