Research Progress on Effects of Continuous Cropping on Soil Microbial Florae and Its Restoration

Continuous cropping has become a common form of agricultural production at present, but with the increase of continuous cropping years, continuous cropping obstacles such as soil-borne diseases and plant growth potential decline are becoming more and more common. At present, the causes of continuous cropping obstacles and continuous cropping restoration have become a hot issue in agricultural research. This paper summarized the effects of continuous cropping obstacles on soil microbial community structure and main technical methods to repair continuous cropping obstacles, such as agricultural measure management, microbial balance adjustment and soil improvement, aiming to provide theoretical reference for protecting the sustainable utilization of soil ecosystem and ensuring the stability of crop production.

Effect of Different Cultivation Practices on Soil Physical and Chemical Properties for Greenhouse Vegetables under Long-Term Continuous Cropping

Five kinds of greenhouse vegetables( eggplant,loofah,tomato,cucumber and pepper) were selected in summer uprooting stage from greenhouse in Shouguang area,Shandong Province. Total nitrogen,ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium,organic matter content and p H,EC value of three soil layers were measured,respectively. The results showed that the total nitrogen,ammonium nitrogen,nitrate nitrogen,available phosphorus and available potassium in the soil were mainly accumulated in the upper soil,which made the soil acidification trend,because different farmers adopted different cultivation practices for different greenhouse vegetables in Shouguang region,but there was no significant effect on soil EC value. The input of ammonium nitrogen and nitrate nitrogen and other related fertilizers to greenhouse cucumber was higher than that of other greenhouse vegetables,but the amount of available potassium fertilizer and organic matter input to greenhouse tomato under different cultivation practices was lower than other greenhouse vegetables. In Shouguang area,the input of organic matter into greenhouse vegetables should be increased by increasing the proportion of manure input to increase the content of soil organic carbon,so as to achieve the balance of carbon and nitrogen ratio,and to provide a scientific basis for the establishment of an evaluation system for the environmental benefits brought about by chemical fertilizer reduction in greenhouse vegetables in Shouguang area.

Influence of rotation system on siderophere-producing microorganism(SPM) in rhizosphere soil of southern China

Soil siderophores are important for crop growth,benefit ferric iron absorption of root,and are affected by cropping patterns.The objective of this study was to evaluate the quantity of siderophores in soil of 2 continuous crop rotation patterns over 30 years in Anren country,China.Quantity and siderophore-producing capability of microorganisms in rice-riceoilseed rape(DDY)rotation and rice-rice(DD)rontinuous cropping rhizosphere soil were tested and analyzed by chrome azurol S method.Isolated strains were used to identify siderophore-producing microorganism(SPM)by PCR amplification and DNA sequencing.Results showed that 9 siderophore-producing bacteria strains were isolated from DDY rhizosphere soil while 7 strains were identified from DD rhizosphere soil.The mean solubility index which representing siderophore-producing capability of strains was 3.05.PCR amplification results indicated that bacterial were the major SPM in soil.This research indicates that crop rotation systems could drive microorganisms to produce siderophores and enrich them in bacterial communities.

A Sustainable Production Model for Potato at Low Latitude Plateau in Winter in Yunnan Province

[Objectives]To find a sustainable production model for potato at low latitude plateau in winter in Yunnan Province.[Methods]Xuanshu 2 potato variety was tested in prefectures of Yunnan Province.Soil covering experiment was conducted in two trials(open field experiment and green house potted experiment).Impacts of three cultivation factors were analyzed:(i)three cultivation models(T1,T2 and T3),(ii)planting density(T1,T2 and T3),(iii)soil covering(T1,T2,T3,T4)on plant growth,and yield production.[Results]The soil moisture content,temperature,roots growth,stems development,leaf area index,and number-weight of tubers per plant and per plot(g)have significantly increased with commercial yield average of 45 t/ha.[Conclusions]The combination of this method with modern agriculture mechanization should be further popularized and applied in large scale planting in regions with climatic conditions similar winter season in Yunnan Province,so as to make contribution to the satisfaction of the world population potato consumption.

甘薯连作障碍发生的土壤养分因素探讨

连作障碍是甘薯种植中的一个突出问题。为了阐明甘薯连作障碍发生的原因,分别采集了5、10和15年连作甘薯及其对照土壤,分析了土壤pH、有机质、阳离子交换量、全量和有效态氮、磷、钾含量、有效态中微量元素含量,并计算了土壤氮、磷、钾之间的比值。结果表明:相比于各自对照,5年甘薯连作显著提高了土壤pH,但是10和15年连作显著降低了土壤pH;5年连作对土壤有机质含量影响较小,但是10和15年连作提高了土壤有机质含量,其中15年连作达显著水平;5年连作对土壤全氮和碱解氮含量影响较小,但是10和15年连作均显著提高了土壤全氮和碱解氮含量;5、10和15年连作均显著提高了土壤全磷和有效磷含量;不同连作年限对土壤全钾、速效钾和中微量元素(钙、镁、硫、铁、锰、铜、锌、硅)含量的影响没有明显规律;甘薯多年连作后,土壤氮/磷降低,氮/钾和磷/钾升高,导致土壤氮、磷、钾失衡,氮磷过多可能引起钾的相对缺乏,也会破坏土壤微生态体系,引起病虫害发生。甘薯是一种耐贫瘠且喜钾植物,基于上述结果,甘薯连作一般不会造成土壤肥力的降低,土壤酸化和氮磷钾养分失衡可能是造成甘薯连作障碍发生的两个主要原因。

抗枯萎病香蕉品种宿根连作根际土壤微生物群落结构特征变化分析

【目的】分析抗枯萎病香蕉品种宿根连作根际土壤微生物群落结构特征变化,为深入研究抗枯萎病香蕉品种宿根连作抗性增强的作用机制及利用生防微生物进行香蕉枯萎病绿色防控提供理论依据。【方法】以抗枯萎病香蕉品种宝岛蕉为试验材料,在枯萎病发病严重土壤上宿根连续种植3造:组培苗第一代(第1造)、宿根第一代(第2造)和宿根第二代(第3造),调查各造枯萎病发病率,四分法采集各造土壤样本并测定土壤化学性质;采集第1造健康和发病植株、第2和第3造健康植株的根际土壤样本,分别编号为S1、V、S2和S3,重复3次,利用Illumina高通量测序平台对12个土壤样本的细菌16Sr RNA和真菌ITS区进行测序分析;采用样本复杂度(Alpha多样性指数)、主坐标(PCoA)和UPGMA聚类分析土壤样本细菌和真菌群落的丰富度和多样性、门和属水平上的群落构成及相对丰度差异;通过Spearman分析优势微生物群落与镰刀菌属的相关性。【结果】抗枯萎病香蕉品种宝岛蕉连续种植3造根际土壤化学性质未发生明显改变,种植第3造的香蕉枯萎病发病率显著低于第1和第2造(P<0.05)。随着种植年限的增加,根际土壤细菌群落的多样性整体呈逐年下降趋势,而真菌群落的多样性整体呈逐年上升趋势。连作改变了香蕉根际土壤微生物的群落构成,S2和S3细菌和真菌的群落结构相近,明显与S1和V群落结构分离。S2和S3的壶菌门(Chytridiomycota)的相对丰度较S1分别低88.02%和89.51%,Fungi_phy_Incertae_sedis的相对丰度分别高41.56%和82.81%,S3镰刀菌属(Fusarium)的相对丰度较S1、S2分别低45.60%和50.47%,与留芽种植宿根蕉抗性表现增强相关。发病植株根际土壤中变形菌门(Proteobacteria)和担子菌门(Basidiomycota)的相对丰度较高,而酸杆菌门(Acidobacteriota)的相对丰度较低。球囊菌门(Glomeromycota)、毛霉门(Mucoromycota)、隐真菌门(Rozellomycota)和壶菌门(Chytridiomycota)的相对丰度均与镰刀菌呈负相关。【结论】宿根第3造蕉的发病率最低,其根际土壤与第1造发病植株根际土壤的细菌和真菌群落差异明显,推测根际土壤微生物群落丰富度、多样性和群落构成改变是抗枯萎病香蕉品种宿根连作抗性增强的原因。

连作木薯对土壤理化性质及细菌群落演替的影响

【目的】研究连作木薯对非根际和根际土壤理化性质变化及细菌群落演替的影响,为系统阐明木薯连作障碍形成机制及其缓解措施研发提供理论依据。【方法】以木薯品种华南205为试验材料,在撂荒地上连续种植3年,每年木薯块根成熟期(植后250 d)采集土壤样品。结合土壤农化分析、高通量测序技术和生物信息学手段,研究连作木薯对非根际和根际土壤理化性质及细菌群演替的影响。【结果】与种植第1年木薯相比,连作2年和3年的木薯非根际和根际土壤pH及有机质、碱解氮和速效磷含量降低,脲酶活性提高,除速效磷外,其他指标的变化均达显著水平(P<0.05,下同)。连作木薯会引起土壤细菌群落多样性及丰富度降低,其中根际土壤细菌群落多样性及丰富度下降速度比非根际土壤慢。连作木薯非根际与根际土壤细菌群落的分类和系统发育Beta多样性存在显著差异。连作木薯非根际和根际土壤的优势菌门均为放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)、酸杆菌门(Acidobacteriota),主要优势菌属均为芽孢杆菌属(Bacillus)、norank_f_Roseiflexaceae、norank_f_norank_o_Vicinamibacterales、norank_f_norank_o_Gaiellales。在操作分类单元(OTU)水平,不同连作年限木薯的非根际和根际土壤细菌群落组成存在显著或极显著(P<0.01)差异。土壤的细菌群落结构与理化性质相互影响,对细菌群落影响较大的环境因子排序为碱解氮含量>有机质含量>pH>速效磷含量>脲酶活性。【结论】连作会导致木薯非根际和根际土壤理化性质、细菌群落多样性和丰富度发生变化,土壤理化性质和细菌群落结构均在连作第3年出现明显劣化。木薯土壤理化性质变化与土壤细菌群落结构差异存在一定相关性,有益菌丰度降低可能是木薯连作造成土壤细菌群落劣化演替的重要原因之一。

作物根际激发效应:调控农田土壤碳动态及助力碳中和的关键因素

土壤碳是陆地碳库的重要组成部分,碳输入及输出、矿化与固定的动态平衡是实现碳中和的关键因素。根际激发效应(rhizosphere priming effect,RPE)是指活体植物的存在会显著影响植物-土壤系统碳动态,其微小变化都会影响宏观尺度上的土壤-大气碳动态。因此,作物RPE是调控农田土壤碳动态和碳中和的主导因子。本文通过文献回顾,首先阐述了农业实践过程中各种生物因素和非生物因素对作物RPE影响的研究现状;其次,归纳总结了当前作物RPE研究中的热点、难点,并分析其对土壤碳排放调控的意义,阐明了当前研究普遍存在案例特异性且缺乏普遍规律;最后,基于已有的研究提出农田生态系统中土壤碳调控和管理优化的潜在策略,为农业实践中有目的地调控作物RPE,在田间、种植模式及区域尺度上提出可能的方案指明了方向。本文可为生态农业实践中保障粮食安全的同时助力碳中和这一双赢方案提供理论参考。

不同连作年限马铃薯根际土壤细菌群落特征研究

采用长期定位试验,设马铃薯连作1~7 a(CP1~CP7)和轮作(RT)8个处理,通过高通量测序探究不同连作年限对马铃薯根际土壤细菌群落多样性的影响。结果表明:供试土壤中,放线菌门、变形菌门、厚壁菌门为主要的优势菌门。随连作年限的增加,土壤细菌数量表现出波动变化趋势,连作年限影响细菌群落结构。RT、CP1、CP2、CP3处理土壤细菌相似度较高,CP4、CP5、CP6、CP7处理土壤细菌相似度较高。马铃薯连作7 a土壤中的放线菌门相对丰度降幅最大,较RT降低10.47%;厚壁菌门相对丰度在连作6 a土壤中显著降低,较RT减少22.07%;类诺卡氏属相对丰度在连作7 a显著减少,较RT减少2.34%;芽孢杆菌属相对丰度在连作6 a时最低,较RT减少9.18%;连作7 a较RT减少5.14%;芽单胞菌属相对丰度在连作7 a土壤中达到最高(16.54%),较RT增加5.26%。长期连作改变了马铃薯土壤细菌群落结构,连作4 a土壤细菌群落种类开始变化,土壤细菌群落结构也随之改变。土壤中预防病害的菌类减少,增加了马铃薯染病风险。

农田土壤根际微生物群落多样性特征研究

以藜麦、蚕豆、油菜和马铃薯为供试材料,设置连作藜麦(HLMA)和藜麦轮作马铃薯(HLMLS)、油菜(HLYC)、蚕豆(HLCD)4种不同种植模式,通过测定土壤养分含量,并利用高通量测序技术(Illumina-HiSeq)对4种种植模式下藜麦根际土壤的基因组进行测序,研究不同种植模式对作物土壤养分和细菌群落组成特征的影响。结果表明:3种轮作种植模式下全钾、碱解氮、速效磷、速效钾含量和pH较连作种植模式显著下降。HLCD模式提高土壤细菌群落丰富度指数、多样性指数和优势度指数。细菌组成研究结果显示,4种种植模式下占优势的细菌均为放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、拟杆菌门(Bacteroidetes)和芽单胞菌门(Gemmatimonadetes)。HLCD处理下,放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、拟杆菌门(Bacteroidetes)和芽单胞菌门(Gemmatimonadetes)相对丰度均显著高于其他处理,分别达到50.48%、13.17%、11.90%、7.42%和4.50%,较HLMA处理分别增加44.21%、56.36%、36.19%、224.24%和53.16%。土壤细菌群落优势属以Subgroup、芽球菌属(Blastococcus)、67-14和土壤红杆菌属(Solirubrobacter)为主,但不同种植模式所占土壤各细菌属的相对丰度大小存在差异。HLCD处理下,Subgroup、芽球菌属(Blastococcus)、67-14和土壤红杆菌属(Solirubrobacter)相对丰度均显著高于其他处理,分别达到7.08%、5.48%、4.35%和3.49%,较HLMA处理分别增加51.99%、64.86%、49.89%和71.85%。聚类分析显示HLYC和HLMLS的组成最接近,其次是HLCD,HLMA的组成与前两者相差较大。土壤全钾、有效氮和速效磷是土壤细菌群落优势菌门变化的驱动因素。综上所述,连作藜麦后轮作蚕豆、油菜和马铃薯可改善土壤肥力,提高细菌群落组成丰富度。

连作根系分泌物加剧土传病害的机制和缓解措施研究进展

基于植物-土壤反馈理论,连作体系中的根系分泌物必然在加剧土传病害发生中起重要作用,但相关研究证据尚缺少系统总结。本文梳理了连作加剧土传病害发生的现象以及连作累积典型根系分泌物组分的案例。从有利于土传病原菌由土体向根际迁移、增殖和致病(“利病”)、破坏根际有益微生物群落防线(“压益”)和毒害根系免疫系统(“自毒”)等三个方面,阐述连作根系分泌物中某些物质促进土传病原菌入侵的机制。从根系分泌物的角度阐述轮作、间作、套作、伴生和嫁接等多样性种植方式缓解连作土传病害的发生机制。提出鉴定“利病”、“压益”和“自毒”物质以及构建对应的消减技术途径,可为土传病害绿色高效综合防控提供科学支撑。

连作木薯对根际与非根际土壤真菌群落结构演替的影响

为揭示木薯连作障碍形成机制,该研究以定点大田连作木薯三年,利用高通量测序技术和生物信息学手段研究连作年限对木薯根际与非根际土壤真菌群落结构演替的影响。结果表明:(1)连作对木薯根际与非根际土壤真菌群落α多样性及β多样性影响显著。(2)木薯的主要优势菌门为子囊菌门、SAR超类群、担子菌门、毛霉门和unclassified_k Fungi,主要优势菌纲为粪壳菌纲、散囊菌纲、座囊菌纲。非根际土壤中,子囊菌门组成变化较大,从第一年的漆斑菌属、粪壳菌纲、座囊菌纲向单一的Knufia属演化;根际土壤的真菌则从子囊菌门的肉座菌目、刺盾炱目、漆斑菌属、座囊菌纲、粪壳菌纲向领鞭毛虫门Monosiga属演化。(3)土壤pH、有机质含量、碱解氮含量、有效磷含量、速效钾含量、脲酶活性对土壤真菌群落结构影响显著,尤其影响子囊菌门、SAR超类群、担子菌门和毛霉门的分布。综上认为,木薯连作会引起根系分泌物累积,改变土壤理化性质及真菌的生存环境,进而引起根际与非根际土壤真菌群落多样性和丰富度的变化。其中,非根际土壤中子囊菌由漆斑菌属、粪壳菌纲、座囊菌纲向单一的Knufia属演变;根际土壤中子囊菌门的肉座菌目、漆斑菌属、粪壳菌纲等有益真菌的相对丰度随连作年限的增加而降低,进而引发木薯连作障碍。

荞麦轮作对云南栽培马铃薯根际土壤酶活和微生物的影响

为探讨连作和与苦荞(KQ)轮作对云南省3个马铃薯主栽品种根际土壤酶活性、微生物数量和产量的影响,以马铃薯主栽品种‘合作88’(HZ88)、‘丽薯6号’(LS6H)、‘青薯9号’(QS9H)为试验材料,对不同处理下根际土壤的蔗糖酶、蛋白酶、脲酶、纤维素酶活性和微生物数量以及马铃薯产量、品质进行分析。结果表明,KQ-HZ88、KQ-LS6H、KQ-QS9H轮作处理的马铃薯单株产量分别较HZ88-HZ88、LS6H-LS6H、QS9H-QS9H连作处理显著增加76.32%、80.95%、90.91%,还原糖含量显著降低38.71%、18.42%、21.43%。与3年连作相比,HZ88-KQ-HZ88和KQ-HZ88-KQ、LS6H-KQ-LS6H和KQ-LS6H-KQ、QS9H-KQ-QS9H和KQ-QS9H-KQ轮作处理的土壤蔗糖酶活性分别较HZ88-HZ88-HZ88、LS6H-LS6H-LS6H、QS9H-QS9H-QS9H连作处理显著增加8.54%和14.00%、22.73%和34.25%、18.13%和25.12%;细菌数量显著增加19.05%(P>0.05)和92.86%、75.68%和72.97%、67.11%和73.21%。土壤酶活性及微生物数量的变化可能是引起云南地区马铃薯连作障碍的重要原因之一,轮作可有效改善根际土壤酶活性,增加土壤中有益菌数量,缓解连作障碍。

A review of research progress on continuous cropping obstacles

Due to the increasing global population and limited land resources, continuous cropping has become common. However, after a few years of continuous cropping, obstacles often arise that cause soil degeneration, decreased crop yield and quality, and increased disease incidence, resulting in significant economic losses. It is essential to understand the causes and mitigation mechanisms of continuous cropping obstacles(CCOs) and then develop appropriate methods to overcome them. This review systematically summarizes the causes and mitigation measures of soil degradation in continuous cropping through a meta-analysis. It was concluded that not all continuous cropping systems are prone to CCOs. Therefore, it is necessary to grasp the principles governing the occurrence of diseases caused by soilborne pathogens in different cropping systems, consider plant–soil-organisms interactions as a system, scientifically regulate the physical and chemical properties of soils from a systems perspective, and then regulate the structure of microbial food webs in the soil to achieve a reduction in diseases caused by soilborne pathogens and increase crop yield ultimately. This review provides reference data and guidance for addressing this fundamental problem.

连作年限对紫苏根际土壤理化性质和植株生长指标的影响

连作障碍已成为制约紫苏产业发展的重要因素。为了探究不同连作年限土壤对植株生长及紫苏产量的影响,测定了连作1年、2年和3年紫苏根际土壤理化性质、酶活性和植株生长指标。结果表明,随着连作年限的增加,紫苏根际土壤pH、土壤有机质、全氮、全磷、全钾、有效磷和有效钾呈显著下降的趋势(P<0.05);有效氮呈逐渐上升的趋势,且连作1年与连作3年具有显著差异(P<0.05);土壤脲酶、磷酸酶、蔗糖酶和过氧化氢酶的酶活性均呈下降趋势(P<0.05);紫苏株高、茎粗、叶面积和产量均呈下降趋势(P<0.05)。相关性分析表明,土壤理化性质和酶活性与紫苏连作年限呈显著负相关。该研究获得的连续种植方式下紫苏根际土壤理化性质、酶活性和植株生长指标的变化,为今后解决紫苏连作障碍问题奠定了一定的理论基础。

Influence of Panax ginseng Continuous Cropping on Metabolic Function of Soil Microbial Communities

Objective To investigate the influence of Panax ginseng continuous cropping on the carbon substrate metabolic activity of microbes in soils sampled from Dafang,Huangni,and Wulidi in Jilin Province,China.Methods Soil metabolisms of soil communities were characterized by community level physiological profiles using BIOLOGTM EcoPlate.Results Soils sampled from the three sites were analyzed and their metabolic activities were compared.Principal component analysis explored the significant variance in metabolic function of microbial communities in soils,though the Shannon index and the evenness index of them were similar.Futhermore,two principal components(PC1 and PC2),which contributed 67.83% and 10.78% of total variance,were extracted respectively.And also,substrates significantly correlated with PC1 and PC2 at the three sampling sites were identified.Conclusion Characteristic of soil is the primary factor influencing microbial communities,and P.ginseng continuous cropping has significant influence on microbial community.Though soil samples show similar microbial metabolic profiles,microbial communities in rhizosphere soil are changed obviously during the cultivation of P.ginseng,which would finally result in the unbalance of microbial community.Phytopathogens would gradually be the predominants in rhizosphere soil and make P.ginseng sick.

Effect of Japanese knotweed(Fallopia japonica)Mulching on Continuous Potato Cropping:Modern Evaluation of Traditional Japanese Knotweed-mulch Farming in Nishi-Awa Steep Slope Land Agriculture System,Japan

Poaceae species such as silver grass or reed are commonly used in traditional mulch farming in Japan,where the Nishi-Awa area is a Globally Important Agricultural Heritage Systems(GIAHS)site.Farmers here have traditionally used silver grass for mulch farming;furthermore,local farmers have learned from long-standing experience that Japanese knotweed(Fallopia japonica,Polygonaceae)is better for cultivation of solanaceous crops in this area.However,it is unclear why Japanese knotweed mulching is beneficial for cultivation of solanaceous crops.Thus,in this study,we hypothesized that Japanese knotweed mulching may be effective in avoiding hazards associated with continuous potato cropping,as native potato used to be cultivated twice a year in the past.Therefore,we investigated the effects of Japanese knotweed mulching on continuous potato cropping and after tomato cropping,which is another solanaceous crop species.Field experiments were conducted in 2018.First,we compared Japanese knotweed mulching,silver grass mulching and no grass mulching(control)in a soil under continuous potato cultivation and in an uncultivated soil.As a result,the extent of the potato yield decrease was reduced by Japanese knotweed mulching.Secondly,we compared Japanese knotweed-mulching and no grass mulching in a soil after a tomato crop and in an uncultivated soil.The extent of decrease in potato growth and yield was also reduced by Japanese knotweed mulching.These findings indicate that mulching with Japanese knotweed helped to avoid the risks associated with continuous potato cropping.

连作对菊花根际土壤化学性质及酶活性的影响

[目的]研究连作对菊花物质积累、根际土壤化学性质、养分含量及酶活性的影响,探究根际土壤酶活性及其与土壤化学性质之间的关系。[方法]以连作菊花根际土壤为对象,以无连作(CK)、连作2年(CM2)、连作9年(CM9)的菊花及其根际土壤为研究对象,测定菊花物质积累、根际土壤化学性质及酶活性。[结果]经长期(9年)连作,菊花地上、地下干物质积累较对照分别降低47%、44%。菊花根际土壤有机质、速效氮、速效磷、速效钾含量较对照分别提高64%、74%、348%、67%。随着连作年限的增加,蛋白酶活性逐渐升高;纤维素酶、脲酶、硝酸还原酶活性逐渐下降;亚硝酸还原酶、磷酸酶、过氧化氢酶活性均先下降后上升。[结论]纤维素酶、脲酶、蛋白酶、硝化还原酶及亚硝酸还原酶与pH、有机质、速效氮、速效磷、速效钾等土壤化学性质之间存在显著相关性。连作导致菊花物质积累降低、根际土壤养分失调、酶活性紊乱。该结果能为菊花连作的形成原因和有效防治提供参考。

发生马铃薯立枯病土壤中立枯丝核菌的荧光定量PCR快速检测

连作马铃薯根际土壤中立枯丝核菌的大量累积可能是导致马铃薯连作障碍发生的主要原因之一。为了解根际土壤中土传病害病原菌的积累与连作障碍之间的关系,进一步寻求缓解和克服马铃薯连作障碍土传病害的有效途径,本研究建立优化了荧光定量PCR（real-time PCR）方法,对引起马铃薯立枯病的病原菌立枯丝核菌进行了快速监测和绝对定量,对马铃薯连作1~5年根际土壤立枯丝核菌的动态变化趋势进行了检测分析。结果显示,研究建立优化的荧光定量PCR检测方法,可直接应用土壤DNA进行病原菌的定量检测,能检测到土壤中浓度为1×102个拷贝/g土的马铃薯立枯丝核菌,扩增效率为1.04,具有检出限低、扩增效率高的特点,实现了不通过病土分离培养方法,就可掌握病原菌在根际土壤中的累积状况;在马铃薯立枯病发病严重的连作根际土壤中,立枯丝核菌的累积数量随连作年限的递增呈上升趋势;病原菌的累积随生育进程的推进呈下降趋势;病原菌累积量最大的是连作5年的播前土壤,每g土壤达3.75×107个拷贝数,由此可见,连作导致了土壤微生物种群结构发生改变,土壤致病真菌数量增加,相应地也增加了马铃薯立枯病的初侵染机率。

马铃薯连作田土壤中主要病原真菌的种群动态变化规律

作物长期连作后出现土壤肥力不平衡,病原物种类及其数量不断累积,表现出严重的连作障碍。连作障碍影响马铃薯的产量和品质,已成为马铃薯产业发展的主要限制因素,土壤微生物作为连作障碍的主要因素之一,研究土壤中病原菌种群动态变化具有重要的意义。为了深入研究土传病原真菌与马铃薯连作的关系,探明马铃薯连作障碍的机理,采用稀释平板法和残渣分离法研究了马铃薯连作对土壤病原真菌种群动态变化的影响。结果表明,甘肃省定西市渭源县会川镇半阴坡村马铃薯的主要土传病原真菌为镰孢菌、轮枝菌和立枯丝核菌;3种病菌主要分布于0～10cm土壤层,10～20和20～30cm土壤层则较少,其中0～10cm土壤层中每克土壤中的菌落数均随连作年限的增加而增加,镰孢菌(Fusariumspp.)为3 900,900,2 100和5 900个/g土,轮枝菌(Verticilliumspp.)为200,400,600和1 600个/g土,立枯丝核菌(Rhizoctonia solani)为7.80,9.58,20.60和22.40个/10g土;建议通过翻耕或药剂处理重点防治表层土传病菌。