Effects of Continuous Cropping on Soil Microbial Flora and Research Progress of Continuous Cropping Obstacle Reduction Techniques

Continuous cropping can bring economic benefits in a short time and meet the growing demand of agricultural products such as grain,but long-term continuous cropping will accelerate soil degradation,lead to the reduction of crop yield and the increase of disease rate,and destroy the balance of soil microbial structure.Therefore,it is not conducive to the sustainable development of soil ecosystem.In this paper,the problems caused by continuous cropping,such as imbalance of soil microbial flora,decrease of biodiversity,accumulation of root exudates and their effects on soil fertility and crop growth,were summarized,and some measures were suggested to alleviate the obstacles of continuous cropping,such as reasonable rotation,adjustment of intercropping planting mode and application of biological fertilizers.Moreover,the paper also looked forward to the development trend of continuous cropping obstacle reduction techniques,including the integration and application of biological techniques,the promotion of green ecological techniques and the application of intelligent management system.This study provides theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promote the healthy and sustainable development of modern agriculture.

Impact of Continuous Cropping on Soil Phenolic Acid Substances and Research Progress on Continuous Cropping Obstacle Reduction Techniques

At present,long-term continuous cropping in agricultural production has formed a relatively common development trend.With the increase of continuous cropping years,soil phenolic acids are also affected to varying degrees.This paper summarized the effects of continuous cropping on soil phenolic acids and the research progress of continuous cropping obstacle reduction techniques,aiming at providing theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promoting the healthy and sustainable development of modern agriculture.

Analysis of the Causes of Continuous Cropping Obstacles for Atractylodes macrocephala Koidz in Pingjiang County and Its Control Methods

First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provide guidance for pro- moting sustainable development of Atractylodes macrocephala Koidz industry in Pingjiang County, it put forward some control methods for eliminating continuous cropping obstacles of Atractylodes macrocephala Koidz, including breeding varieties with high resistance; applying rotation cropping and intercropping reasonable; rational fertilization and soil disinfection; introducing antagonistic bacterial and eliminating au- tointoxication.

Study on Obstacles to Continuous Cropping of Vegetables and Soil Remediation Technology

Firstly,this paper analyzes the cause of obstacles to continuous cropping of vegetables,and then introduces the soil ecological remediation technology used for overcoming obstacles to continuous cropping of vegetables. Finally,this paper analyzes the effect of applying soil ecological remediation technology in overcoming obstacles to continuous cropping of vegetables.

Effects of Allelochemicals on Root Growth and Pod Yield in Response to Continuous Cropping Obstacle of Peanut

Continuous cropping(CC)obstacle is a major threat in legume crops production;however,the underlying mechanisms concerning the roles allelochemicals play in CC obstacle are poorly understood.The current 2-year study was conducted to investigate the effects of different kinds and concentrations of allelochemicals,p-hydroxybenzoic acid(H),cinnamic acid(C),phthalic acid(P),and their mixtures(M)on peanut root growth and productivity in response to CC obstacle.Treatment with H,C,P,and M significantly decreased the plant height,dry weight of the leaves and stems,number of branches,and length of the lateral stem compared with control.Exogenous application of H,C,P,and M inhibited the peanut root growth as indicated by the decreased root morphological characters.The allelochemicals also induced the cell membrane oxidation even though the antioxidant enzymes activities were significantly increased in peanut roots.Meanwhile,treatment with H,C,P,and M reduced the contents of total soluble sugar and total soluble protein.Analysis of ATPase activity,nitrate reductase activity,and root system activity revealed that the inhibition effects of allelochemicals on peanut roots might be due to the decrease in activities of ATPase and NR,and the inhibition of root system.Consequently,allelochemicals significantly decreased the pod yield of peanut compared with control.Our results demonstrate that allelochemicals play a dominant role in CC obstacle-induced peanut growth inhibition and yield reduction through damaging the root antioxidant system,unbalancing the osmolytes accumulation,and decreasing the activities of root-related enzymes.

Screening and Verification of Genes Specifically Responding to Continuous Cropping Obstacle in Rehmannia glutinosa L.

Rehmannia glutinosa L.is one of the important medicinal crops in China.Continuous cropping obstacle severely restricts the yield and quality of R.glutinosa,but its molecular mechanism is still unclear.In this study,with widely-planted "Wen 85-5" as an experiment material,based on the digital gene expression profiling (DGE) data of previous five stress treatments (continuous cropping,phenolic acid,salt,drought and waterlogging) and the first cropping and continuous cropping treatments of R.glutinosa in five different periods (seedling period,elongation period,early expanding period,middle expanding period and later expanding period),80 candidate genes (|log 2 ratio|≥1,FDR <0.001) specifically responding to continuous cropping obstacle in R.glutinosa were screened.Functional analysis revealed that the differentially expressed genes were involved in the secretion and endocytosis of root cells,which may suggest that the recognition and absorption of allelopathic autotoxins by the roots of R.glutinosa is an important factor that restricts the development of roots in continuous cropping of R.glutinosa.In order to accurately lock genes specifically responding to continuous cropping obstacle in R.glutinosa,continuous cropping soil extract and ferulic acid and p-hydroxybenzonic acid were used to treat aseptic plantlets of R.glutinosa,respectively,and it was confirmed through qRT-PCR that the expression levels of some genes under phenolic acid treatment changed more severely than that under the continuous cropping soil extract treatment,and four key genes involved in the response of R.glutinosa to continuous cropping were finally locked.This study lays a foundation for further exploration of the molecular mechanism of continuous cropping obstacle.

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.

THE HLDER CONTINUITY FOR THE GRADIENT OF SOLUTIONS TO ONE-SIDED OBSTACLE PROBLEMS

The Hǒlder continuity is proved for the gradient of the solution Jo the one-sided obstacle problem of the following variational inequality in the case 1<p<2

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.

湿垃圾来源的蚯蚓粪肥对连作障碍土壤质量和黄瓜产量的影响

随着城市化的发展,湿垃圾产量与日俱增,湿垃圾资源化利用迫在眉睫。利用蚯蚓处理湿垃圾制作蚯蚓粪肥用于农田土壤改良,是一项有效的湿垃圾资源化利用途径以及有利于缓解蔬菜连作障碍方面问题。该文以常规有机肥为参照,选取以湿垃圾及其厌氧沼渣为原料制作的蚯蚓粪肥为研究对象,研究连续3年施加蚯蚓粪肥对黄瓜(Cucumis sativus)土壤综合质量和作物产量的影响。结果表明,经过3年的改良后,施加60.0 t/hm^(2)蚯蚓粪肥的黄瓜产量提高了5.60%,土壤有机质含量提高了50.0%,且蚯蚓粪肥的效果要高于常规有机肥;土壤全氮含量达到最高,高于背景值33.0%;土壤的养分含量(硝态氮、速效磷、速效钾)也得到了提高,其中速效钾含量升高了94.0%。经过3年的改良,土壤中的细菌数量在施加了有机肥后明显增加,其中以添加30.0t/hm^(2)蚯蚓粪肥的细菌数量最多;土壤细菌/真菌的比值有所提高,土壤生物性状得到改善。土壤的呼吸强度随着有机肥的施入而升高,以施加60.0t/hm^(2)蚯蚓粪肥的最大;土壤pH略有降低,盐度无明显变化。因此,湿垃圾来源的蚯蚓粪肥能改善土壤的理化和生物学性质,可在一定程度上缓解连作障碍的发生,可作为化肥替代品或与化肥相配合在农业生产中进行推广。

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。

不同土壤改良剂对川党参连作障碍的防控效果

以川党参种子为试材,采用大田试验的方法,研究了有机肥(OM)、生石灰(QL)和钙镁磷肥(CMP)3种改良剂对川党参连作障碍的防控效果,以期为通过土壤改良消减川党参连作障碍提供参考依据。结果表明:1)OM、QL和CMP处理均显著提高了川党参产量,增幅分别为37.9%、77.9%、117.4%。2)OM、QL和CMP处理均提高了叶绿素和类胡萝卜素含量,增幅分别为31.6%、18.2%、25.3%和28.7%、18.0%、24.0%。3)OM和QL处理下过氧化氢酶活性较CK显著提高,而O_(2)^(·)含量均显著降低。4)QL和CMP处理下川党参的黄酮含量较CK分别提高了31.5%和17.6%。OM处理下川党参生物碱含量显著提高了58.7%。5)QL和CMP处理的pH较CK分别提高了10.9%和9.8%,碱性磷酸酶活性分别提高了95.4%和69.1%。OM、QL和CMP处理下土壤过氧化氢酶活性较CK分别提高了16.7%、21.0%和20.1%。6)3种改良剂处理对川党参形态发育、产量和光合色素积累均具有一定的促进作用,其促进效果由大到小依次为生石灰(CE=1.31)>钙镁磷肥(CE=1.11)>有机肥(CE=1.02)。综上,土壤改良剂能够通过调控光合代谢、抗氧化系统及土壤酶活性来消减川党参连作胁迫。3种改良剂对连作川党参的促生增产效果由大到小依次为生石灰(3 000kg·hm^(-2))>钙镁磷肥(3 000kg·hm^(-2))>有机肥(4 500kg·hm^(-2))。

农业废弃物基生物炭的应用效应研究进展

生物炭因结构和理化性质独特、原材料丰富及应用前景广阔等特点,在农业及环境污染治理等领域的应用较为广泛。基于相关文献,综述了农业废弃物基生物炭在改善土壤理化性质、提高土壤养分、改善土壤微生态环境、促进作物生长、修复污染土壤及缓解连作障碍等方面的效应,旨在为农业废弃物基生物炭在农业生产中的应用提供参考。

异源双根缓解咖啡连作障碍及其机制初探

为明确异源双根是否能缓解咖啡连作障碍及其可能机制,本研究以大粒种咖啡1号(Caffealiberica,No.1)和中粒种咖啡热研1号(Caffea canephora, Reyan No. 1)靠接形成大粒种-中粒种异源双根咖啡,通过咖啡连作障碍园土壤培养幼苗,评价植株苗木质量,明确异源双根对咖啡连作障碍的缓解作用。通过双根无分隔、尼龙网分隔、双盆分隔等不同分根方式试验,明确异源双根缓解咖啡连作障碍机制,并探讨双根间在缓解连作障碍上的差异及协同作用。结果表明:较连作障碍咖啡园非根际土,异源双根咖啡或同源双根咖啡经根际土培养后苗木质量指数、总的植株生物量均显著下降,连作逆境抑制咖啡生物量积累,使苗木质量变差;非根际土培养后,异源双根咖啡、同源双根咖啡的苗木质量指数和总的植株生物量差异均不显著;而根际土培养后,异源双根咖啡较同源双根咖啡的苗木质量指数、大粒种根系生物量、中粒种根系生物量及总的植株生物量均显著提高。因此,连作逆境虽抑制咖啡生长,但对同源双根咖啡影响更大,异源双根通过其大粒种根系缓解连作逆境咖啡生长障碍。为进一步明确异源双根尤其是大粒种根系缓解咖啡连作障碍的可能机制,以不同分根方式培养异源双根咖啡,发现较无分隔、双盆分隔处理,连作逆境下双根尼龙网分隔后植株苗木质量佳,并且尼龙网分隔后植株的中粒种根系长势最好,说明大粒种根系化感物质促进中粒种根系生长。双根无分隔、双盆分隔后植株的苗木质量差异不显著,无分隔较双盆分隔后植株的大粒种根系长势差,即双根系在能够彼此接触的自然生长状态下,中粒种根系抑制大粒种根系生长,但这种抑制作用与中粒种根际化感物质无关,尼龙网分隔、双盆分隔后大粒种根系长势差异不显著,说明大粒种根际有无中粒种根际化感物质,对大粒种根系生长均无影响。综上所述,异源双根通过其大粒种根系减少自身在连作逆境中的化感抑制,利用其根际化感物质促进中粒种根系生长,实现根壮苗壮,达到缓解咖啡连作障碍的目的。研究结论为异源双根靠接在大田的推广应用提供理论依据。

生物质炭和有机肥配施对苹果重茬育苗地土壤理化性质和微生物群落特征的影响

为研究生物质炭和有机肥配施对连作苹果育苗地的改良效果,以连作5年的苹果育苗地为研究对象,采用高通量测序技术结合土壤理化性质分析,探究不同配比生物质炭和有机肥配施对苹果根际土壤理化性质和微生物群落结构的影响。结果表明,生物质炭和有机肥配施处理后土壤中养分含量显著增加,土壤pH和电导率显著上升。其中以600kg·hm^(-2)生物质炭配施有机肥处理土壤的速效养分含量显著增加,其土壤全氮、碱解氮、速效磷、速效钾和有机碳含量分别显著增加15.06%、27.03%、61.32%、51.55%和20.18%。此外,生物质炭和有机肥处理提高了土壤中细菌群落的多样性和丰度,降低了真菌群落的多样性和丰度,使土壤中有益菌属的丰度显著增加。相关性分析表明,土壤有机碳、速效钾和碱解氮含量对土壤中细菌群落特征影响显著;而真菌群落特征主要受土壤全氮、有机碳和速效钾含量的影响。综上,生物质炭和有机肥配施对苹果育苗地连作障碍具有一定的缓解作用,可改善土壤的微环境,提高土壤质量。

基于土壤微生物群落结构的参地土壤改良研究进展

改良参地土壤是缓解参地资源紧缺、促进人参种植业健康持续发展的有效途径。综述土壤微生物群落结构改变与连作障碍关系,参地土壤化学消毒、农业改良和微生物防治对土壤微生物的影响。结果显示:微生物制剂可以通过调整土壤微生物群落结构、拮抗病原菌、激活养分等有效防治人参病害及改良参地土壤;开发高效、具有广谱抑菌活性的微生物混合菌剂,辅以化学消毒、农业改良等土壤改良技术是改良参地土壤及防治人参病害的关键。

根茎类药用植物连作障碍研究进展

在根茎类药用植物集约化种植中,长期连作引起的植株生长不良、产量下降和品质降低等连作障碍问题,已成为制约我国中药材产业发展的重要因素。为缓解根茎类药用植物的连作障碍,促进根茎类药用作物的产业发展,本文综述了根茎类药用植物连作障碍的成因,并概括总结了消除连作障碍的措施。根茎类药用植物连作障碍成因十分复杂,包括植物的化感作用、土壤理化性质恶化、土壤酶活性改变和土壤中致病菌增加等,这些因素单独作用或共同作用。目前常用的消减技术措施包括:筛选耐重茬抗病新品种、合理轮作间作、土壤强还原处理、土壤蒸汽消毒和施加生物炭等物理措施、使用氯化苦、威百亩、棉隆和噻唑膦等化学农药,以及利用微生物菌剂如芽孢杆菌、哈茨木霉和淡紫拟青霉等调节土壤微生物群落并抑制有害微生物等。其中,利用微生物菌剂消减连作障碍是近年来的研究热点之一,但由于连作障碍涉及根系、土壤和微生物等诸多因素,采取综合防控措施才能有效消减连作障碍。最后从选育抗病性强、耐连作的优质新品种、进一步探索适宜的轮作间作模式和提高病原菌拮抗微生物稳定性等方面,对我国根茎类药用植物连作障碍的研究方向进行了展望。

温度对厌氧土壤消毒处理效果的影响

为探讨温度对厌氧土壤消毒处理消除连作障碍因子的影响,以番茄连作土壤为研究对象,设置5个处理:对照、10℃、20℃、30℃和40℃处理,置于生化恒温培养箱内,密封处理3周。结果表明,不同温度ASD处理均可使土壤pH显著升高、EC显著降低,土壤有机碳(TOC)、速效钾含量显著增加,低温(小于10℃)ASD处理不能完全消除土壤累积的NO_(3)^(-),高温(40℃)ASD处理中NH_(4)^(+)含量显著升高;不同温度ASD处理中细菌数量显著增加,高温(40℃)ASD处理中真菌、尖孢镰刀菌数量均显著降低。可见,高温(40℃)ASD处理效果最好,不同温度ASD处理均显著提高土壤TOC、速效钾含量。

紫花苜蓿连作障碍研究进展

作物连作障碍会造成土壤营养匮乏、含水量下降、自毒物质积累、有益微生物减少以及病虫害加剧等问题,严重影响作物产量。紫花苜蓿作为多年生优质牧草,在我国广泛种植,长期连作紫花苜蓿会出现土壤质量逐年下降、有害微生物比例升高、病虫害暴发、自毒作用等连作障碍。本文收集和梳理相关文献,提出紫花苜蓿连作障碍问题,分析其成因,并借鉴解决其他作物,提出轮作、间作套种、合理施肥、植物生长调节剂等可缓解紫花苜蓿人工草地连作障碍的措施,指出使用功能微生物改变土壤微生态环境是防控紫花苜蓿连作障碍的有效途径,以期为后期研究解决紫花苜蓿连作障碍提供理论基础。

木醋液的抑菌活性及其对连作番茄根际土壤微环境生态的影响

为探索木醋液对番茄根际土壤微生态的作用,以番茄为供试材料,连续3 a常规种植于相同田块,设置木醋液稀释300倍(A)、稀释600倍(B)、稀释900倍(C)处理,以无菌去离子水为对照(CK),探究不同稀释度木醋液的抑菌活性及其对连作番茄植株根系生长、根际土壤细菌和真菌群落结构的影响。结果显示:不同稀释度木醋液对青枯病菌和枯萎病菌均具有显著的抑制作用;3种稀释度的木醋液中,稀释600倍的木醋液浇灌不仅有利于连作番茄根系的生长,而且有助于提高番茄连作根际土壤细菌和真菌的多样性;与对照(CK)相比,不同稀释度木醋液处理均不同程度地降低了放线菌门(Actinobacteriota)细菌的相对丰度,提高了酸杆菌门(Acidobacteriota)细菌以及子囊菌门(Ascomycota)、新赤壳属(Neocosmospora)、曲霉属(Aspergillus)、青霉属(Penicilli⁃um)、木霉属(Trichoderma)、毛壳菌属(Chaetomium)和镰刀菌属(Fusarium)真菌等有益微生物的相对丰度。结果表明,木醋液具有显著抑制番茄青枯病及枯萎病病原微生物的作用,浇灌稀释木醋液有利于连作番茄根系生长,改善连作番茄根际土壤微环境生态的作用;其中,以稀释600倍(B)木醋液的改良效果最佳。