Bt maize pollen exposure and impact on the garden spider, Araneus diadematus

Concerns have been raised that Bt maize pollen may have adverse effects on non‐target organisms; consequently, there is a general call for Bt maize risk assessment evaluating lethal and sublethal side effects. Spiders play an important economic and ecological role as pest predators in various crops, including maize. Web‐building spiders, especially, may be exposed to the Cry1Ab toxin of Bt maize by the ingestion of pollen via ‘recycling’ of pollen‐dusted webs and intentional pollen feeding. In this study, the potential Bt maize pollen exposure of orb‐web spiders was quantified in maize fields and adjacent field margins, and laboratory experiments were conducted to evaluate the possible effects of Bt maize pollen consumption on juvenile garden spiders, Araneus diadematus (Clerck) (Araneae: Araneidae). In maize fields and neighbouring field margins, web‐building spiders were exposed to high amounts of Bt maize pollen. However, a laboratory bioassay showed no effects of Bt maize pollen on weight increase, survival, moult frequency, reaction time, and various web variables of A. diadematus. A pyrethroid insecticide (Baythroid) application affected weight increase, survival, and reaction time of spiders negatively. In conclusion, the insecticide tested showed adverse effects on the garden spider, whereas the consumption of Bt maize pollen did not. This study is the first one on Bt maize effects on orb‐web spiders, and additional research is recommended in order to account for further spider species, relative fitness parameters, prey‐mediated effects, and possible long‐term chronic consequences of Bt exposure.     

Purification of the Cry1Ac protein of Bacillus thuringiensis and assessment against the Plutella xylostella and soil microbial community

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is the most commonly used to develop insect‐resistant living modified organisms (LMOs). Insecticidal proteins produced in transgenic plants are released into the soil from the roots. In this study, possible effects of crystal 1Ac (Cry1Ac) protein on the soil microbial community in Korea were studied. To purify the insoluble Cry1Ac protein expressing Escherichia coli cells, we performed repeated sonication and PBS washing of the insoluble part and Cry1Ac protein was isolated in soluble form from the insoluble form using 100 mM Na₂CO₃ buffer (pH 9.6) without affinity bead. Also, size‐exclusion chromatography (SEC) was performed to increase the purity of the isolated Cry1Ac protein. The final protein product was identified as Cry1Ac protein through MALDI‐TOF. Insecticidal activity of Cry1Ac protein was demonstrated through the death of Plutella xylostella treated with Cry1Ac protein. Purely isolated Cry1Ac protein showed the same insecticidal activity as Cry1Ac expressed in LM crops. To investigate the change of soil microbial distribution using maize field soils treated with Cry1Ac protein, we isolated high quality metagenomic DNAs from buffer‐ and Cry1Ac protein‐treated soil groups, and analyzed the distribution of soil microorganisms through next‐generation sequencing (NGS) analysis. NGS results showed a similar microbial distribution in both buffer‐ and Cry1Ac protein‐treated samples. These results suggest a useful risk assessment method for domestic targeted insect and soil microorganisms using the Cry1Ac protein.     

转Bt基因玉米对根际土壤细菌群落结构的影响

利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术及扩增产物序列分析方法研究了转Bt基因玉米对根际土壤细菌群落结构及系统发育的影响.结果表明:转基因玉米与其非转基因亲本根际共有的土壤细菌分别隶属于变形菌门、疣微菌门、放线菌门、拟杆菌门、厚壁菌门、芽单胞菌门和酸杆菌门.其中,变形菌门为主要优势类群,占43.5%...     

Effects of Bt maize on Frankliniella tenuicornis and exposure of thrips predators to prey-mediated Bt toxin

As a part of a risk assessment procedure, the impact of Bt maize expressing Cry1Ab toxin on the thrips Frankliniella tenuicornis (Uzel) (Thysanoptera: Thripidae) was investigated, and the potential risks for predators feeding on thrips on Bt maize were evaluated. The effects of Bt maize on F. tenuicornis were assessed by measuring life‐table parameters when reared on Bt and non‐Bt maize. The content of Cry1Ab toxin in different stages of F. tenuicornis reared on Bt maize and the persistence of the toxin in adults where determined in order to evaluate the possible exposure of predators when feeding on thrips. In addition, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) was used as a model predator to assess how the behaviour of prey and predator may influence the exposure of a natural enemy to the Bt toxin. Life‐table parameter results showed that F. tenuicornis was not affected when it was reared on Bt maize. This indicates that the potential for prey quality‐mediated effects on predators is low. Bt content was highest in thrips larvae and adults, and negligible in the non‐feeding prepupal and pupal stages. The persistence of the Cry1Ab toxin in adult F. tenuicornis was short, resulting in a decrease of 97% within the first 24 h. Predation success by young C. carnea larvae varied among the thrips stages, indicating that exposure of predators to Bt toxin can additionally depend on the prey stage. When combining the current knowledge of the susceptibility of major thrips predators with our findings showing no potential for prey quality‐mediated effects, relatively low toxin content in thrips as well as short persistence, it can be concluded that the risks for predators when feeding on thrips in or next to Bt maize fields are negligible.     

A synthesis of laboratory and field studies on the effects of transgenic Bacillus thuringiensis (Bt) maize on non‐target Lepidoptera

One of the major applications of transgenic crops in agriculture are the so‐called Bacillus thuringiensis Berliner (Bt) plants, in particular Bt maizes, which produce insecticidal Cry proteins that target specific orders, such as the Lepidoptera or Coleoptera. We reviewed publications that reported on the direct toxic effects of Bt‐maize and/or Cry proteins of current Bt‐maize events on larvae of non‐target butterflies and moths (Lepidoptera). In total, 20 peer‐reviewed publications were identified, of which 16 papers contributed laboratory‐based data and seven field‐based data. An adverse effect on caterpillars was recorded in 52% of all laboratory‐based and in 21% of all field‐based observations. The variables most often studied and having the highest occurrence of effects were larval survival, body mass, and developmental time. Parameters of the adult stage were under‐represented in the studies. Overall, 11 lepidopteran species were tested. The majority of the studies originated from the USA, with the Monarch butterfly being the most studied, whereas other species and other parts of the world were widely neglected. Laboratory experiments were often run under unrealistic conditions from an ecological point of view. Although the papers we reviewed indicated a potential hazard for Lepidoptera that are exposed to and feed on lepidopteran‐specific Bt‐maize pollen, a general conclusion on the level of risk for butterflies and moths cannot as yet be drawn. A comprehensive risk characterization would require thorough hazard identification, exposure assessment, and impact assessment. However, our review showed that even the basic level of hazard characterization is as yet incomplete. Reasons for this are the still‐limited numbers of publications and concurrent lack of knowledge, the restriction of data to only a few species, the over‐representation of North American species, and the identified limitations of both laboratory and field experiments. The findings of this review suggest that more realistic, ecologically meaningful, and detailed experiments and analyses are crucial to improve the present assessment of Bt‐maize cultivation effects on Lepidoptera.     

The effects of pollen consumption of transgenic Bt maize on the common swallowtail, Papilio machaon L. (Lepidoptera, Papilionidae)

Effects of exposure to maize pollen of event Bt176 (cultivar “Navares”) on the larvae of the European common swallowtail (Papilio machaon L.) were studied in the laboratory. First instar larvae were exposed to different pollen densities applied to leaf disks of Pastinaca sativa L. for 48 h. Pollen densities applied in this study were in the range recorded from the field. Larvae which were exposed to higher Bt maize pollen densities consumed more pollen and had a lower survival rate. The LD₅₀ with regard to larvae surviving to adulthood was 13.72 pollen grains consumed by first-instar larva. Uptake of Bt maize pollen led to a reduced plant consumption, to a lower body weight, and to a longer development time of larvae. Effects on pupal weight and duration of the pupal period were present but less pronounced and smaller than effects on larvae. Larvae having consumed Bt-maize pollen as first instars had a lower body weight as adult females and smaller forewings as adult males. We conclude that possible effects of Bt maize on European butterflies and moths must be evaluated more rigorously before Bt maize should be cultivated over large areas.     

转Bt基因玉米根际土壤及秸秆残体中Cry1Ab蛋白含量动态

采用ELISA法研究了田间种植条件下转Bt基因玉米MON810生育期根际土壤及还田秸秆中Cry1Ab蛋白的田间残留降解动态,并分别用移动对数模型、指数模型和双指数模型对秸秆分解释放Cry1Ab蛋白的田间降解动态进行拟合,估算了DT5o和DT90值.结果表明:Bt玉米不同生育期根际土壤中Cry1 Ab蛋白含量差异较大,但总体随生育期的延长而显著降低.收获后地表覆盖和埋入土壤两种秸秆还田方式下,秸秆中Cry1Ab蛋白在土壤中的降解规律基本一致,均呈现前期大量快速降解,中后期极少量稳定降解两个阶段.秸秆还田7d内,地表覆盖处理的Cry1Ab蛋白降解率均极显著高于埋入土壤处理;10 d时两处理的降解率基本一致,分别为88.8％和88.6％;20 d后,两处理秸秆中Cry1Ab蛋白的降解日趋缓慢;至180 d时仍能检测到少量的Cry1Ab蛋白.3种模型均能较好地反映秸秆中Cry1Ab蛋白的田间降解规律,从相关系数(R)及DTgo值与实测值的吻合程度来看,双指数模型最优.     

种植转Bt基因抗虫棉对土壤生物学活性的影响

采用温室盆栽实验,研究了种植转Bt基因棉（苏抗103）和同源常规棉（苏棉12）对根际土壤生物学活性的影响。结果表明：与对照常规棉相比,种植转Bt基因棉对根际土壤脱氢酶、碱性磷酸酶、蔗糖酶和土壤呼吸的影响因生育期而异,土壤脲酶、蛋白酶和微生物量C在各生育期均没有显著差异;土壤蔗糖酶、土壤脱氢酶和土壤呼吸分别只在苗期（苏抗103〉苏棉12,增幅为25．5％）、花铃期（苏抗103〉苏棉12,增幅为21．6％）、花铃期（苏抗103〉苏棉12,增幅为36．1％）存在显著差异;土壤磷酸酶在花铃期和吐絮期活性显著下降（降幅分别为22．1％和32．9％）。     

Resistance monitoring of field populations of the corn borers Sesamia nonagrioides and Ostrinia nubilalis after 5 years of Bt maize cultivation in Spain

Approximately 22 000 hectares (5% of the total maize growing area) of transgenic maize expressing the Cry1Ab toxin from Bacillus thuringiensis (Bt maize) have been planted annually in Spain since 1998. Changes in the susceptibility to Cry1Ab of Spanish populations of the Mediterranean corn borer (MCB), Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae), and the European corn borer (ECB), Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), were assessed by annual monitoring on Bt maize fields. No increase in resistance was detected in the MCB populations from Ebro, Albacete, and Badajoz, nor in the ECB populations from Ebro and Badajoz during the period 1999–2002. The susceptibility of the MCB population from Madrid fluctuated from year to year, but a gradual trend towards higher levels of tolerance was not observed. Laboratory selection assays for eight generations yielded selected strains of MCB and ECB that were 21‐ and 10‐fold significantly more tolerant to Cry1Ab than the corresponding unselected strains, respectively. Nevertheless, none of the field‐collected or laboratory‐selected larvae were able to survive on Bt maize. Considering these data, no consistent shifts in susceptibility were found for Spanish populations of MCB nor ECB after 5 years of Bt maize cultivation, but systematic field monitoring needs to be continued.     

A 3-year field-scale monitoring of foliage-dwelling spiders (Araneae) in transgenic Bt maize fields and adjacent field margins

Concerns have been raised that genetically modified Bt maize may harm non-target organisms, and there is a general call and need for a risk assessment of Bt maize. Spiders are important pest predators in agroecosystems and in maize, and can be exposed to the Bt toxin by herbivorous or pollen-collecting prey, by active Bt maize pollen feeding, and by ingesting their pollen-dusted webs. The foliage-dwelling spider fauna of Bt maize fields and adjacent margins was monitored and compared to non-transgenic maize fields. The study took place during the vegetation seasons of 2001–2003 in Bavaria, South Germany. Maize fields and adjacent nettle field margins were colonized by a typical spider assemblage, dominated by space-web spiders (Theridiidae and Linyphiidae). Abundance and species richness of spiders was higher in nettle margins than in maize fields. The proportion of hunting spiders tended to be higher in nettle margins, whereas space-web spiders tended to be more frequent in maize fields. Bt maize showed no consistent effect on individual numbers, species richness and guild structure of spiders in maize fields and adjacent nettle field margin strips. The spider abundance was higher in Bt treatments in 2003, whereas in 2001 and 2002 no significant differences were found. The results provide an important contribution for the implementation of case-specific and general surveillance of transgenic plants to be employed due to the regulations of the European Community.     

基于不同浓度变量的温带落叶阔叶林CO2储存通量的误差分析

利用帽儿山温带落叶阔叶林通量塔8层CO₂/H₂O浓度廓线的测定数据,比较分析了基于不同浓度变量\[密度(ρ_c)、摩尔分数(c_c)和混合比(χ_c)\]计算CO₂储存通量(F_s)的误差.结果表明： 通量观测的控制体积内部干空气储存量不为常数,其波动可引起CO₂分子进出控制体积,即干空气储存通量调整项(F_sd)的变化.在夜间以及昼夜转换期,F_sd相对于涡动通量而言较大,忽略F_sd将为森林与大气之间净CO₂交换量的计算带来误差.大气水热过程对F_s计算引起的误差包括3方面：空气温度变化引起的误差最大,比大气压强(P)的影响高1个数量级;水蒸气的影响在温暖湿润的夏季大于P的影响,但在寒冷干燥的冬季则相反; P的效应在全年均较低.基于ρ_c、c_c和χ_c计算F_s分别平均高估CO₂有效储存通量(F_{s_E})8.5%、0.6%和0.1%.在通量计算过程中,建议选择对大气水热过程守恒的χ_c计算F_s.     

杉木人工林土壤质量演变过程中土壤微生物群落结构变化

以中国科学院会同森林生态站自然林、杉木连栽林和杉木阔叶树混交林地土壤为研究对象,采用PCR-DGGE、DNA-sequencing和主成分分析(PCA)等方法分析土壤微生物群落结构变化及其与土壤质量变化之间的关系.结果表明,该地区杉木人工林土壤中细菌优势种群为α-、β-、γ-proteobacteria和Cytophaga-Flexibacter-Bacterioides (CFB)类群;真菌优势种群为子囊菌(Ascomycetes)和担子菌(Basidiomycetes)亚门的种属.杉木人工林替代自然林后,土壤细菌多样性指数显著降低,且随连栽代数增加呈持续降低趋势;杉木人工林土壤中与Pedobacter cryoconitis亲缘关系密切的细菌种群消失,出现与Xanthomonas sp.和Rhodanobacter sp.亲缘关系密切的细菌种群.土壤真菌群落结构的变化与细菌相反,杉木人工林替代自然林后并不断连栽时,土壤真菌多样性指数呈现上升的趋势,自然林土壤中优势真菌种群在杉木三代林中消失.杉木与火力楠或桤木混交后土壤细菌和真菌种群结构与自然林类似.土壤细菌多样性指数与土壤总有机碳、全氮、可溶性有机碳、铵态氮、速效磷、速效钾含量以及土壤pH值呈显著正相关关系(P＜0.05).土壤真菌多样性指数仅与土壤碳氮比呈显著正相关关系,而与土壤pH值呈显著负相关关系.杉木林土壤质量变化对土壤细菌和真菌优势种群有较大影响,细菌Burkholderia sp.、Pedobactersp.、Xanthomonas sp.和真菌Sclerotinia sclerotiorum、Mycosphaerella cannabis可能是引起土壤质量变化的关键种群.     

大田环境下转Bt基因玉米对土壤酶活性的影响

在大田自然条件下,比较研究了转Bt基因玉米和非转基因亲本玉米在种植和秸秆分解时对土壤酶活性影响的差异。结果表明,与亲本非转基因玉米相比,在各生育期内种植转Bt玉米对土壤蛋白酶和土壤脲酶活性均没有显著影响;在喇叭口期和抽雄期,土壤蔗糖酶和土壤酸性磷酸酶活性显著提高。在秸秆还田后,两种玉米秸秆对土壤酸性磷酸酶活性的影响没有显著差异,但使用转Bt玉米秸秆的土壤蔗糖酶、土壤脲酶和土壤蛋白酶的活性则有显著提高。与亲本玉米相比,在所有观测期内,种植Bt玉米及秸秆还田对土壤酶活性的影响,在影响的幅度及趋势上随玉米生育期和土壤酶种类的不同而产生差异,但没有观测到显著不利影响;商业化Bt玉米的环境释放仍有待长期定位观测和评价。     

外源微生物对木麻黄幼苗生长和土壤微生物群落的影响

将解淀粉芽孢杆菌(YB706)和伯克氏菌(BK8)外源添加至木麻黄盆栽苗中,运用Biolog生态板和磷脂脂肪酸(PLFA)技术,探究外施细菌能否改善连栽木麻黄土壤养分和微生物群落及植株生长.结果 表明:与空白处理(CK)相比,YB706和BK8处理的木麻黄盆栽苗土壤碱解氮、速效磷显著增加,土壤全氮、全磷、全钾和速效钾无...     

转基因水稻对土壤微生物群落结构及功能的影响

以非转基因水稻为对照,以变性梯度凝胶电泳(DGGE)和Biolog技术为手段,研究了2种转基因水稻对土壤微生物群落结构及功能的影响。结果显示:转基因水稻仅在生长发育旺盛期对土壤细菌数量有显著影响;且不同品种转基因水稻土壤微生物间的遗传距离大于转基因水稻与对照间土壤微生物的距离,即2个转基因水稻品种对土壤微生物群落遗传多样性的影响均不显著;在水稻抽穗期,2种转基因水稻与其对照的土壤微生物群落在72h时的平均光密度呈现显著差异,而到了成熟期则差异不显著。土壤微生物群落多样性指数和均匀度指数也表现出类似趋势。本试验证明,在水稻生长发育旺盛时期,Mclntosh指数(u)是一个有效区分转基因水稻和非转基因水稻土壤微生物群落多样性的指标。     

土壤耕作及秸秆还田对夏玉米田杂草生物多样性的影响

于2008年夏玉米(Zea mays)生长期间,在连续5a秸秆全量还田的免耕、旋耕、耙耕、深松和常规耕作试验地中,研究了杂草总密度、优势杂草种类、生物多样性指数、杂草生物量和夏玉米产量。调查共记录杂草种类13种,秸秆全量还田时,免耕显著提高杂草的总密度;无秸秆还田时,常规耕作的杂草密度高于免耕、旋耕、耙耕和深松。秸秆全量还田后,免耕和深松条件下,杂草优势种为马唐和旱稗,旋耕和耙耕条件下为马唐、旱稗和牛筋草;常规耕作条件下,优势杂草为马唐、苘麻、旱稗和香附子。无秸秆还田条件下,免耕和常规耕作增加了杂草优势种的数量。秸秆全量还田后,免耕、耙耕和深松等耕作措施导致杂草群落的物种丰富度及均匀度均较高。无论哪种耕作条件,5a连续秸秆还田能够显著提高夏玉米籽粒产量和生物学产量,其中尤以常规耕作秸秆全量还田处理产量最高,且田间杂草的生物学产量与夏玉米的生物学产量呈显著负相关关系。     

Host-plant mediated effects of transgenic maize on the insect parasitoid Campoletis sonorensis (Hymenoptera: Ichneumonidae)

Determining the impact of genetically modified (GM) crops on beneficial organisms is an important aspect of the environmental risk assessment of GM crops. In the present study, the impact of Bt maize expressing Cry1Ab on the development and behaviour of the parasitoid Campoletis sonorensis was compared to individuals reared on hosts fed conventionally bred plants partially resistant to the European corn borer (Ostrinia nubilalis Hübner) and on susceptible maize hybrids. Adult parasitoids reared on Bt maize-fed Spodoptera frugiperda larvae were significantly smaller (15–30%) than those reared in hosts fed either of the conventional maize hybrids. The magnitude of this effect was dependent on the size of the host at oviposition and its subsequent growth rate. The development time of C. sonorensis was not affected by the maize treatment. In choice tests, female parasitoids displayed no preference for hosts fed a specific maize hybrid. No Cry1Ab was detected within adult parasitoids.     

海拔梯度变化对中亚热带黄山松土壤微生物生物量和群落结构的影响

全球变暖对陆地生态系统造成一系列生态问题,使这些问题将随着全球平均气温的升高而进一步加剧。海拔梯度变化是研究气候变暖对陆地生态系统影响的一种重要手段。目前为止利用海拔梯度对微生物影响的研究尚未定论,其主要原因是忽略了植被类型的影响。因此,以中亚热带戴云山的3个海拔(1300、1450、1600 m)的黄山松(Pinus taiwanensis)林为研究对象,探究沿海拔梯度的变化,森林土壤微生物生物量和微生物群落结构的响应变化。结果表明:土壤碳氮磷养分(SOC、TN、TP)、微生物生物量氮(MBN)、微生物生物量磷(MBP)和丛枝菌根真菌(AMF)、革兰氏阴性菌(GN)、真菌(Fungi)、总磷脂脂肪酸(T_(PLFA)),细菌∶真菌(F∶B)均随海拔升高显著下降,而革兰氏阳性菌∶革兰氏阴性菌(GP∶GN)随海拔升高呈相反的趋势。冗余分析(RDA)表明,温度(T)和可溶性有机氮(DON)是影响微生物群落结构的最重要的环境因子。研究表明:与1600 m海拔相比,1300 m海拔温度较高,土壤有机质矿化作用较强,土壤速效养分及微生物生物量随之增加,从而提高(Fungi)、细菌(Bacteria)等。因此,未来气候变暖将通过改变土壤碳氮磷养分来影响本区域微生物群落组成结构。这对进一步深入了解气候变化对山地生态系统土壤养分循环过程具有重要意义。     

Influence of introducing the genetically modified strain <Emphasis Type="Italic">Sinorhizobium meliloti</Emphasis> ACH-5 on the structure of the soil microbial community

To study the influence of genetically modified microorganisms (GMM) on the number and structure of the soil microbial community, we introduced the genetically modified strain of Sinorhizobium meliloti into soil under controlled laboratory conditions. The analysis of the dynamics of soil microorganisms of all the main groups (archaea, bacteria, fungi) using the PCR with real-time detection and the analysis of the species structure of all the indicated components using T-RFLP were carried out for a month. The results of the quantitative PCR demonstrated that none of the components of the soil microbial community was appreciably influenced by the GMM introduced. The number of GMM decreased over a month more than 300-fold. The analysis of the dynamics of the eubacterial, archaeal, and fungal communities using T-RFLP did not detect fundamental changes in their structure.     

覆盖模式对旱作农田土壤微生物多样性及群落结构的影响

土壤微生物是表征土壤质量的敏感指标,采用Illumina HiSep技术分析不同覆盖方式对半湿润易旱区农田土壤微生物群落结构及多样性的影响,以期从微生物的角度评价农田不同覆盖措施对土壤质量的影响。设3种覆盖模式：平作塑料薄膜覆盖（P）、平作秸秆覆盖（S）和垄膜沟播覆盖（R）,以平作不覆盖为对照（CK）,研究不同覆盖模式下土壤微生物群落变化,分析各土壤理化因子与微生物群落之间的关系。研究结果表明各覆盖处理显著改变了土壤微生物的群落结构和多样性。所有土壤样品中,细菌群落的优势菌门是变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、放线菌门（Actinobacteria）,丰度分别为29.69%、28.28%和20.76%,CK处理下较高的土壤pH和低NO₃-N含量抑制了土壤中酸杆菌门（Acidobacteria）的生长繁殖,而放线菌门（Actinobacteria）相对丰度为所有处理中最高。真菌群落的优势菌门是子囊菌门（Ascomycota）、担子菌门（Basidiomycota）,丰度分别为59.65%和20.96%,S处理下过低的土壤温度抑制了担子菌门（Basidiomycota）生长和繁殖,其相对丰度为所有处理中最低。与CK相比,P和R处理显著提高土壤细菌的多样性和丰富度;S和R处理下土壤真菌多样性和丰富度显著增加,而P处理的土壤真菌多样性和丰富度均无显著差异。斯皮尔曼相关分析表明土壤细菌多样性主要受土壤含水量（SM）和硝态氮含量（NO₃-N）影响,而土壤真菌多样性主要受土壤温度（ST）、全氮（TN）和硝态氮含量（NO₃-N）影响;RDA分析表明微生物群落结构的变化主要受SM、ST、NO₃-N和TN含量的影响。总的来说,R处理下土壤细菌和真菌的多样性和丰富度较CK处理显著提高,该处理下土壤中担子菌门（Basidiomycota）和球囊菌（Glomeromycota）相对丰度为所有处理中最高,两者分别形成的外生菌根和从生菌根不但促进了根部养分的吸收,而且提高了作物的抗逆性,且结果证明该处理的作物产量为最高,因此在半湿润旱作区推荐采用垄膜沟播覆盖种植方式。