根系分泌物抑制连作障碍线虫病的根际调控机制及其应用

作物长期连作极易出现连作障碍(再生病害),本文围绕因传统耕作模式和种植习惯而诱发的新疆棉花、黑龙江大豆、河南花生、山东设施蔬菜、两广香蕉等连作障碍问题,对全国连作现象进行系统分析,发现全国连作现象普遍。按照耕地面积将连作障碍划分为五个等级,其中华北三省和东北的黑龙江省连作障碍等级最高,且各省连作现象均以大田经济作物为主。以香蕉、大豆(大田经济作物)、黄瓜(设施园艺作物)和三七(中草药)为代表,比对最低产量和正常产量在连作年份的变化,表明连作障碍发生规律成抛物线式,防控连作障碍需找到问题关键时期。单一根系分泌物介导的微生物多样性降低、病原菌富集,植物寄生线虫危害和土壤弱化是导致连作障碍的主要原因,其中线虫对植物的侵染危害作为土传病害是防治连作障碍中最难解决的问题之一,尤其是在设施蔬菜上。线虫在长期进化过程中形成了具有识别、寻找和侵染寄主的生物学功能,而不同植物根系分泌物对线虫发育和对宿主的识别侵染能力有不同的调控作用。针对根系分泌物–线虫互作为诱因的线虫病害,深入探讨易感作物和抗性/非寄主植物根系分泌物对线虫发育和对植物侵染的生物学机制,提出根际调控措施。在J2时期利用抗性/非寄主植物根系分泌物,调控根结线虫Mi-16D10、Mi-flp-18等基因和孢囊线虫的Hg-rbp-2等基因的表达控制线虫的发育、侵染和迁移,通过生物源功能物质定向防控线虫侵染作物。这些结果加深了我们对生物活性物质调控植物寄生线虫机制的认识。未来,以筛选和鉴定抗性或非寄主作物特异根系分泌物对线虫侵染的调控为依据,配置生物功能型肥料,利用植物源活性物质替代传统农药控制线虫病害的根际调控措施,定向调控植物根际生物学过程将成为国内外研究热点。此文将为未来深入系统地研究根系分泌物–线虫的相互作用及克服连作障碍提供理论基础,进而促进土壤健康和作物优质高产高效,对实现绿色农业和可持续发展具有重要的理论和实践指导意义。     

大豆连作障碍及产生机理

选择不同连作年限的地块设置试验小区，定期调查大豆根腐病发病程度，大豆收获后测产，并采用稀释平析以法测定大豆根际土壤中微生物组成及密度结果表明：连作导致大豆产量降低，根腐病加重，形成了明显的连作障碍现象，连作障碍产生的原因初步认为系由于大奶际病原真菌种类增加，有益真菌数量减少而致。同时连作导致大豆根际细菌放线菌密度下降，由此造成大豆根腐病加重。     

连作障碍发生机理研究进展

随着集约化种植程度的不断提高,作物连作导致产量和品质下降,土传病害严重发生,严重制约了现代农业的可持续发展,连作障碍发生机理一直是国内外学者研究的热点之一。近年来,国内外学者从多方面、多角度对连作障碍进行了研究,但这些研究多集中于单一因素分析,缺乏对不同因子内在相互关系和本质的了解,未能深入揭示连作障碍发生的真正原因。深入认识连作障碍的成因及各要素间的互作关系是防控作物土传病原微生物生长、缓解连作障碍、实现农药使用量零增长的基础。本文从土壤理化性状及生物学性状恶化、植物生理抗性下降和连作自毒作用等方面系统综述了连作障碍发生机理,分析了连作障碍因素间的相互关系并对该领域未来的研究方向进行了展望,以期为寻找安全、环保和有效的缓解措施提供理论依据。     

蚯蚓粪对作物连作障碍抑制作用研究进展

随着集约化生产的进一步发展,连作障碍已成为制约我国一些地区种植业可持续发展的瓶颈问题。蚯蚓粪是一种优质的有机肥,目前已成功应用于连作障碍防治,并取得了一定的研究成果。本文简要介绍了蚯蚓粪的理化性质和生物学性质,综述概括了其在抑制连作障碍方面的研究进展,并对以后的研究提出了展望,以期能为作物连作障碍综合防治提供一定的参考。     

花生连作土壤障碍机制研究进展

花生是我国主要经济作物和油料作物,连作障碍问题严重影响花生的产量与品质,制约着我国花生产业可持续发展。已有研究认为自毒物质积累、病菌增加、土壤微生物群落失衡及土壤理化性质恶化是花生连作障碍的主要因子,但大多停留在单因子水平上,有的认识缺乏直接的证据。本文简要综述了花生连作障碍的危害、机制及调控措施,结合作者近几年来相关研究,主要从花生根系分泌物效应、化感物质存留特征、土壤生物群落演变等方面介绍了花生连作障碍机制研究进展,最后对花生连作障碍的进一步研究及防控技术发展方向提出展望。     

基于专利数据的连作障碍防治技术发展趋势分析

连作障碍严重影响着作物的产量和品质，研发高效的连作障碍防治技术是实现集约化农业可持续生产的关键。基于incoPat科技创新情报平台，检索并分析2000年至2019年期间国内外连作障碍防治技术的专利产出，对专利申请数量、技术构成、区域分布、主要申请人、法律状态等方面分析，揭示国内外作物连作障碍防治技术领域的研发状况、技术发展趋势和产学研情况。近年来，作物连作障碍防治技术领域专利数量急剧增加；结合现代生物和材料等新兴技术发展，新的研发充分考虑了连作障碍生物防治技术产品化和应用的结合；我国在作物连作障碍防治技术领域的专利申请机构多为企业和个人，高校和科研院所申请的专利转化率低，高校/科研院所与企业合作申请的专利数量少。连作障碍防治技术领域的应用成为焦点，生物和材料新技术成果正引入连作障碍生物防治技术的开发；中国在连作障碍防治领域的产学研合作和专利技术质量亟需加强。     

我国设施栽培连作障碍特征与成因及防治措施的研究进展

连作是目前我国设施农业的主要栽培方式,连作障碍是土壤修复的世界性难题。本文系统阐述了国内设施栽培出现的连作障碍特征(如酸化、盐渍化、养分失衡、重金属及其他有害物质积累、土传病害发生严重)与成因,并分别从农艺、生物、化学、物理4个方面简述了各种防治技术在缓解设施连作障碍过程中的作用效果。最后总结了设施连作障碍及防治技术研究中尚待解决的科学问题及研究方向,以为我国设施连作障碍的发生发展机理研究和防治技术提供科学依据。     

大豆专用肥对轮作、连作大豆土壤酶活性和有效养分的影响

采用盆栽、田间小区控制试验及室内分析相结合的方法 ,研究了施用大豆专用肥对连作、轮作大豆土壤酶活性和有效养分的影响。结果显示施用大豆专用肥后 ,土壤酶活性和有效养分总体均能达到或高于轮作土壤常规施肥水平 ,这表明大豆专用肥能调控大豆连作所引起的土壤酶活性和养分恶化 ,最终使得大豆专用肥能克服大豆连作所引起的大幅度减产     

药用植物连作障碍研究评述和发展透视

连作障碍作为现代农业生产中较普遍的问题,在药用植物栽培生产中表现尤为严重,据统计约70%以块根类入药的药用植物在种植过程中都存在严重的连作障碍问题。连作障碍已经成为制约药用植物品质和发展的关键性因素。本研究从药用植物连作障碍问题研究现状出发,分析了当前药用植物连作障碍形成的三大共性问题,即根系分泌物诱导根际土壤酸化、根际微生物群落结构失衡和植株病毒病严重,具体体现在:根系分泌物诱导根际土壤微生物差异性演化、土传病原菌的化感互作、根际微生物区系的失衡加大土壤酸化、根际病原菌增多和有益菌减少导致的土存真菌病害加重、病毒病伴生和发展。并分析了土壤灭菌法、功能微生物调控、作物多样性栽培和生物质炭改良的根际调控策略在减缓药用植物连作障碍中的潜在作用。作者呼吁从事连作障碍研究的工作者应重视从根际生态学角度出发,以土壤食物网为切入点,应用现代系统生物学和化学生态学技术与方法,全面系统探究根系分泌物介导下植物-土壤-微生物的相互作用过程与机制,并着重关注土壤线虫和土壤病毒在连作障碍发生发展中的生态位关系,以深入阐明连作介导土壤酸化的生态学机制和病原菌响应根系分泌物的协同进化机理,在此基础上,采用多种根际调控相结合的策略减缓连作障碍问题,全面考虑经济、社会和生态效益,做到"生态预防为主、综合治理为要"。     

浅议农作物连作土壤改良措施

农作物连作障碍是农业生产持续发展所面临的一个重要问题,通过查阅有关克服农作物连作障碍的研究报告,结合作者从事相关研究的结论和进展,就农作物连作障碍产生的原因和克服的途径进行综述,以便为相关研究和类似技术的实际应用提供借鉴。研究表明,引起农作物连作障碍的主要原因有土壤中有害微生物的积累、土壤的次生盐渍化、农作物的自毒作用等。基于此,通过探究土壤的改良措施,探索消除或减低作物连作所产生的连作障碍,为农业生产提供一定的依据。     

Developing suppressive soil for root diseases of soybean with continuous long-term cropping of soybean in black soil of Northeast China

Field experiments were set up in 1991 to test if suppressive soil to soybean root diseases could be developed with continuous long-term soybean cropping in black soil of Northeast China. Based on the field observation in 2007, 2009, and 2011, soybean root growth was promoted, and the severities of root disease were reduced in a field with continuous long-term cropping with soybean. Population densities of the pathogens (Fusarium spp. and Heterodera glycines) in the soybean cropping field were significantly (P < 0.05) lower than rotation of soybean with wheat or corn. Higher levels of biological control agents (Trichoderma harzianum, Pochonia chlamydosporia, or Paecilomyces lilacinus) also were found in the long-term soybean cropping field. Therefore, continuous long-term cropping of soybean in black soil of Northeast China could develop suppressive soil to soybean root diseases.     

东北黑土区典型县域种植模式遥感识别与空间格局分析

种植模式对黑土地的土壤肥力和作物产量有显著影响，建立合理的种植模式是养好用好黑土地的重要措施。目前，黑土区种植模式的类型及其空间格局仍缺乏系统的分析，而遥感技术结合地学信息图谱方法则是监测黑土区种植模式的有效手段，但应用较少。该研究基于2012－2017年遥感反演作物分类数据，采用地学信息图谱方法识别种植模式，并使用核密度分析方法测度了各类种植模式的空间分布特征。结果表明：1）克东县可识别出5类种植模式，其中，主要的种植模式为无序种植模式、大豆连作模式和两年轮作模式，三者面积总和占比为83.90%。2）县域西部和北部以大豆连作模式为主，县域中部、东部和南部以无序种植模式为主，玉米连作模式呈东北-西南向带状分布，三年轮作模式和两年轮作模式呈"局部集聚、全局分散"的分布形态。3）行政村尺度的种植模式结构大体可以分为5种类型，总体呈现以"无序种植-大豆连作-两年轮作"类型为主并以其他类型为辅的空间结构特征，属于主要类型的行政村数量占比为32.08%。     

不同有机物料对连作大豆土壤养分含量及生物性状的影响

选取畜禽粪便、天然有机物料、有机肥类有机物料3大类共9种有机物料进行大田试验,设正茬和连作2种种植方式,主要研究不同类型有机物料对土壤养分和生物性状变化特征的影响。结果表明:有机物料的施入对提高土壤养分含量和改善土壤生物性状作用效果明显。正茬土壤pH为5.70~6.00,连作土壤pH为5.50~5.90,施用有机物料小区均高于CK处理。畜禽粪便类有机物料,对提高大豆土壤速效钾含量效果显著,对正茬和连作土壤分别平均提高12.73%和17.09%;猪粪对正茬土壤呼吸提高11.30%;鸡粪对连作土壤中微生物量氮提高13.85%。天然有机物料,对提高土壤中碱解氮作用明显,正茬和连作分别平均提高6.31%和3.30%。有机肥类有机物料,对大豆土壤中速效磷含量正茬和连作土壤分别提高2.13%和2.27%,有机质含量分别提高1.98%和4.20%;鸡粪型有机肥对正茬土壤微生物量碳提高3.45%。所有有机物料处理整体效果均好于CK处理,这表明有机物料的施入具有提高大豆土壤养分含量,改善土壤养分性状的作用。     

Depth distribution of soil organic C and N after long-term soybean cropping in Texas

Crop management practices have potential to enhance subsoil C and N sequestration in the southern U.S., but effects may vary with tillage regime and cropping sequence. The objective of this study was to determine the impacts of tillage and soybean cropping sequence on the depth distribution of soil organic C (SOC), dissolved organic C (DOC), and total N after 20 years of treatment imposition for a silty clay loam soil in central Texas. A continuous soybean monoculture, a wheat–soybean doublecrop, and a sorghum–wheat–soybean rotation were established under both conventional (CT) and no tillage (NT). Soil was sampled after soybean harvest and sectioned into 0–5, 5–15, 15–30, 30–55, 55–80, and 80–105 cm depth intervals. Both tillage and cropping intensity influenced C and N dynamics in surface and subsurface soils. No tillage increased SOC, DOC, and total N compared to CT to a 30 cm depth for continuous soybean, but to 55 cm depths for the more intensive sorghum–wheat–soybean rotation and wheat–soybean doublecrop. Averaged from 0 to 105 cm, NT increased SOC, DOC, and total N by 32, 22, and 34%, respectively, compared to CT. Intensive cropping increased SOC and total N at depths to 55 cm compared to continuous soybean, regardless of tillage regime. Continuous soybean had significantly lower SOC (5.3 g kg⁻¹) than sorghum–wheat–soybean (6.4 g kg⁻¹) and wheat–soybean (6.1 g kg⁻¹), and 19% lower total N than other cropping sequences. Dissolved organic C was also significantly higher for sorghum–wheat–soybean (139 mg C kg⁻¹) than wheat–soybean (92 mg C kg⁻¹) and continuous soybean (100 mg C kg⁻¹). The depth distribution of SOC, DOC, and total N indicated treatment effects below the maximum tillage depth (25 cm), suggesting that roots, or translocation of dissolved organic matter from surface soils, contributed to higher soil organic matter levels under NT than CT in subsurface soils. High-intensity cropping sequences, coupled with NT, resulted in the highest soil organic matter levels, demonstrating potential for C and N sequestration for subsurface soils in the southern U.S.     

Impact of long-term continuous soybean cropping on ammonia oxidizing bacteria communities in the rhizosphere of soybean in Northeast China

Continuous cropping can be a serious problem in Chinese soybean production. This can result in yield reduction, root diseases, and changes in microbial community structure. We studied community structure, clone libraries, and abundance of ammonia oxidizing bacteria (AOB) in soybean fields there were in continuous soybean production for up to 17 years (SC17). Results showed that the potential nitrification rate (PNR) and amoA gene abundance of soybean in continuous cultivation for seven years (SC7) was 0.34 µg NO₃^? g^?1 and 4.71 × 10^?5 amoA gene copies/g dry soil, respectively. These values were lower than other treatments. Phylogenetic affiliation analysis based on blast results of amoA gene clone sequencing showed that the sequences belonged to seven clusters: Cluster 1, Cluster 3b, Cluster 3a.1, Cluster 3a.2, Cluster 9, Cluster 10, and Cluster 4. Correlation of AOB community compositions with environmental factors was performed using canonical correspondence analysis (CCA). Results indicated that the composition of AOB communities in maize–soybean (MS) rotation and continuous cropping of soybean for two years (SC2) were positively related to the PNR of soil, soil moisture, and soil total nitrogen content. Soybean fields continuously cropped for 11 years (SC11) and SC7 fields had AOB community compositions that were negatively related to these factors. The AOB community composition of SC17 was positively correlated to the soil total carbon content of soil. The results in this study indicate that the potential activity and abundance of AOB community in soil significantly changed after seven years continuous cropping compared to other continuous cropping intervals. Cropping systems have important effect on the diversity of functional microorganisms and associated nitrogen cycles.     

连作障碍产生机理及防控现状

由于我国人口的迅速增长、耕地资源限制和粮食作物产区相对比较集中等各种因素的共同影响,在农业生产中作物长期连作已经形成了一个较为普遍的发展态势。随着连作年限的增长,作物的生产受到不同程度的影响,因此由连作所引发的一系列连作障碍已成为制约农作物生产可持续发展的一个重要原因,并引起了全球各方的广泛重视。许多作物在长期连作模式中都会发生连作障碍,这主要是由于植物的自毒作用、土壤中致病微生物的增殖、微生物区系失衡和土壤理化性质的劣变所引起的,目前科研工作者们根据连作障碍重要因子研究出了多种绿色有效的生物防控方法,主要通过研制生物菌剂、有机肥、土壤强还原措施以及噬菌体疗法等来防控连作障碍,各项试验证明这些方法都是切实有效的,而且绿色环保,符合我国绿色可持续发展理念。鉴于此,本综述针对目前连作障碍产生的主要因素,以及近年来提出的防控连作障碍的各种措施进行了阐述,并对该领域未来的研究方向进行了展望,为之后的连作障碍研究提供理论依据,以期克服作物连作障碍难题,促进新农业的健康可持续发展。     

Diversity of parasitic fungi from soybean cyst nematode associated with long-term continuous cropping of soybean in black soil

The soybean cyst nematode (SCN) is a major yield-limiting pest of soybean. In this study, experiments were conducted to examine the diversity of parasitic fungi from SCN associated with disease-suppressive soil fields in Northeast China. Soil samples were collected from three fields under different rotation systems that were established in 1991: (1) a continuous long-term cropping field with soybean (SSSS) that had been shown to be SCN-suppressive, (2) cycles of three-year rotation with corn, soybean, and wheat (WCS), and (3) continuous cropping field with three-year cycles of two years soybean and one-year corn (SSC). In the traditional method result, cyst densities of SCN declined as increase of parasitic fungi, and the percentage of parasitic fungi associated with cyst of SCN was higher in SSSS field than other two fields. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) also showed that parasitic fungi of SCN were also increased in SSSS field, compared with the other two fields. Principal component analysis based on PCR-DGGE data revealed that fungal communities on cysts could be divided into three groups: one group occurred in SSSS, and the other two groups were in WCS and SSC fields, respectively. Long-term cropping with soybean monoculture in the black soil field might increase parasitic fungi of SCN. These fungal communities may play an important role in the ecological suppression of SCN in disease-suppressive soil.     

长期轮作和连作对白浆土中氮素的影响

对轮作及大豆、玉米、小麦长期连作白浆土中氮含量及有机态氮组分变化进行研究。结果表明，在不施肥情况下，小麦连作区土壤由全氮、碱解氮降幅最大，酸解总氮、氨基酸态氮和氨基糖态氮降幅最小。在施有机肥情况下，土壤全氮、碱解氮及酸解总氮则以小麦连作区增幅最小，玉米连作区增幅最大；氨基酸态氮和氨基糖态氮在轮作区增幅最大。其他组分氮在轮作与连作小区间变化无规律。     

大豆连作障碍及调控技术研究进展

综述了近 15年来有关大豆连作引起的根分泌物及残茬腐解物的自毒作用、植株营养失调、病虫危害加重、土壤微生物种群数量和生物肥力及土壤某些理化性质改变等障碍因素方面的研究 ,总结了提高连作大豆产量品质的主要调控措施。在此基础上 ,对有关研究需进一步关注的几个问题进行了讨论