不同填闲模式对黄瓜根际土壤酶活性及细菌群落的影响

以温室连作3年黄瓜土壤为研究对象,以黄瓜为主栽作物,以青葱、小麦、油菜为不同季节填闲作物设置盆栽试验,采用常规化学方法、PCR-DGGE及qPCR技术,研究不同填闲模式对黄瓜土壤酶活性及细菌群落的影响.结果表明: 随着种植茬次的增加,填闲小麦处理的土壤脲酶、中性磷酸酶及转化酶活性均显著高于填闲青葱和油菜处理,同时油菜处理显著高于青葱处理;不同填闲模式间黄瓜根际土壤细菌群落结构不同,冬季填闲青葱和夏季填闲小麦处理维持了相对较高的多样性指数.qPCR检测结果表明: 随着种植茬次的增加,小麦处理的土壤细菌数量显著高于青葱和油菜处理.综上,不同填闲模式对土壤酶活性和细菌群落均产生一定影响,改变了土壤环境,其中夏季填闲小麦能保持相对较高的土壤酶活性、土壤细菌群落结构多样性及细菌数量.
     

Influence of intercropping and intercropping plus rhizobial inoculation on microbial activity and community composition in rhizosphere of alfalfa (Medicago sativa L.) and Siberian wild rye (Elymus sibiricus L.)

Alfalfa–Siberian wild rye intercropping is the predominant cropping system used to produce forage in China. In this study, the effects of intercropping and intercropping-rhizobial inoculation on soil enzyme activities, microbial biomass and bacterial community composition in the rhizosphere were examined. In both treatments, the yield of alfalfa, microbial biomass and activities of soil urease, invertase and alkaline phosphatase in the alfalfa rhizosphere were markedly increased, whereas there was a slight increase in the yield of Siberian wild rye, few impacts on soil microbial biomass, and decreased enzyme activities (except for urease) in the Siberian wild rye rhizosphere. Terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes indicated that Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were the major bacterial groups in the rhizosphere of both plants. However, intercropping and rhizobial inoculation induced some shifts in the relative abundance of them. Nitrosomonas and Nitrosospira groups were detected in all treatments by the T-RFLP patterns of ammonia monooxygenase subunit A ( amoA ) gene, but the relative abundance of Nitrosomonas increased and that of Nitrosospira decreased in the intercropping-rhizobial inoculation treatment. Both treatments tended to increase the diversity of amoA . Conclusively, the two treatments clearly affected soil microbial composition and soil enzyme activities, which might be reflected in changes in yield.     

Impact of transgenic cotton varieties on activity of enzymes in their rhizosphere

The impact of five Bacillus thuringiensis (Bt) cotton varieties and their respective isogenic non-Bt(NBt) isolines (ANKUR-2534, MECH-6304, RCH-317, ANKUR-651 and MECH-6301) was assessed on the key soil enzymes i.e., dehydrogenase, alkaline phosphatase and urease in their rhizosphere at four growth stages of the crop, namely vegetative, flowering, bolling and harvesting. These varieties were grown on farmer's field in villages 22 miles and 24 miles of Ganganagar District of Rajasthan State in India. Results showed that dehydrogenase, alkaline phosphatase and urease activities were higher in rhizosphere of Bt isolines as compared to NBt isolines of all the varieties. Except phosphatase, differences in dehydrogenase and urease activities in rhizosphere of Bt and NBt isolines of all five varieties were significant (P < 0.05). Maximum enhancement in the three enzymes activities was observed in MECH-6304 Bt isoline rhizosphere. Maximum and minimum activities of dehydrogenase and urease were observed in MECH-6304 and RCH-317 Bt isolines, respectively, whereas phosphatase activity was maximum and minimum in MECH-6304 and ANKUR-651 Bt isolines, respectively. Maximum dehydrogenase and urease activities were observed at boll formation and minimum at flowering and harvesting stage, respectively, while maximum phosphatase activity was observed at vegetative stage and minimum at harvesting stage. In conclusion, all the studied Bt isolines of cotton varieties showed no adverse effect on dehydrogenase, alkaline phosphatase and urease activities in the rhizosphere.     

Quantitative evaluation of the role of organic acid exudation in the mobilization of rock phosphate by rape

Phosphorus-deficient rape plants appear to acidify part of their rhizosphere by exuding malic and citric acid. A simulation model was used to evaluate the effect of measured exudation rates on phosphate uptake from Mali rock phosphate. The model used was one on nutrient uptake, extended to include both the effect of ion uptake and exudation on rhizosphere pH and the effect of rhizosphere pH on the solubilization of rock phosphate. Only the youngest zones of the root system were assumed to exude organic acids. The transport of protons released by organic acids was described by mass flow and diffusion. An experimentally determined relation was used describing pH and phosphate concentration in the soil solution as a function of total soil acid concentration. Model parameters were determined in experiments on organic acid exudation and on the uptake of phosphate by rape from a mixture of quartz sand and rock phosphate. Results based on simulation calculations indicated that the exudation rates measured in rape plants deficient in phosphorus can provide the roots with more phosphate than is actually taken up. Presence of root hairs enhanced the effect of organic acid exudation on calculated phosphate uptake. However, increase of root hair length without exudation as an alternative strategy to increase phosphate uptake from rock phosphate appeared to be less effective than exudation of organic acids. It was concluded that organic acid exudation is a highly effective strategy to increase phosphate uptake from rock phosphate, and that it unlikely that other rhizosphere processes play an important role in rock phosphate mobilization by rape.     

甘肃典型高寒草原退化植物瑞香狼毒对根际土壤微生物群落的影响研究

[目的] 瑞香狼毒（Stellera chamaejasme L.）为瑞香科狼毒属（Stellera）多年生草本植物,是我国草地退化的标志性植物之一。本研究旨在探究甘肃高寒草原主要毒草瑞香狼毒根际微生物群落结构及其与土壤环境因子和酶活性之间关系,为治理因瑞香狼毒入侵引起的草地退化提供理论依据。[方法] 采用Illumina MiSeq高通量测序技术对甘肃不同地区高寒草原的瑞香狼毒根际土壤微生物组成及多样性进行分析,并进一步分析土壤理化性质和酶活性与微生物群落的相关性。[结果] 不同地区瑞香狼毒根际土壤pH随海拔升高呈现上升趋势,土壤中大量和微量营养元素含量以及土壤酶活性的变化各异。在门水平上,子囊菌门（Ascomycota）、接合菌门（Zygomycota）和担子菌门（Basidiomycota）在根际土壤真菌中占优势地位;放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）在根际土壤细菌中属于优势类群。海拔2964 m样地的真菌和细菌OTU（operational taxonomic unit）数量和Shannon多样性指数均高于其他4个采样点（海拔2373、2608、2733、3280 m）。RDA（redundancy analysis）分析结果显示,瑞香狼毒根际土壤微生物不同,受土壤环境因子的影响不同;相关系数表明,土壤真菌多样性与土壤钾、磷、铁、钙、钼、海拔、土壤水分、过氧化物酶呈正相关,与土壤温度、多酚氧化酶、脱氢酶、蔗糖酶、碱性磷酸酶呈负相关;土壤细菌与土壤pH、钾、磷、镁、钙、土壤水分呈负相关,与多酚氧化酶、过氧化物酶、脲酶、脱氢酶、蔗糖酶、酸性磷酸酶、碱性磷酸酶呈正相关。[结论] 甘肃省不同地区高寒草原瑞香狼毒根际微生物群落组成和多样性差异明显,土壤理化性质与土壤真菌具有较强的正相关关系,而土壤酶则更多地影响着土壤细菌群落的组成和多样性。     

铜陵铜矿区凤丹根际和非根际土壤酶活性

对铜陵铜矿区凤丹根际和非根际土壤酶活性特征进行了研究.结果表明,凤丹根际土壤各种酶活性显著大于非根际土壤.凤丹非根际土壤过氧化氢酶、磷酸酶和脲酶活性能敏感地反映土壤重金属复合污染状况;根际环境对土壤酶活性的影响表现为: 磷酸酶＞脲酶＞过氧化氢酶＞蔗糖酶＞多酚氧化酶,影响率分别为131.562%、92.492%、87.557%、59.673%34.076%;土壤各种酶活性与重金属复合污染程度呈显著负相关,相关系数均-0.868以上,表现出重金属复合污染对土壤酶活性的抑制效应.凤丹可有效地改善土壤环境,提高土壤各种酶的活性.     

基于高通量测序分析大豆和油菜根际微生物群落结构的差异

根肿病是由芸薹根肿菌侵染引起的专性寄生性土传病害,严重制约着油菜等十字花科作物的可持续生产.前期研究发现,大豆作为前茬作物可以显著降低后茬油菜根肿病的发生和危害,"豆-油轮作"模式是一种值得探索和应用的根肿病防治新途径.为了解开大豆作为前茬防治根肿病发生的机理,本研究基于扩增子测序技术探究大豆与油菜根际土壤微生物的群落结构差异.结果表明:大豆和油菜根际土壤微生物类群在门水平的优势类群相同,包括变形菌门、拟杆菌门、酸杆菌门、放线菌门、子囊菌门、接合菌门、担子菌门和壶菌门等丰度都较高.但相比于油菜根际土壤,大豆根际土壤富含具有生防作用和促进植物生长的微生物,如黄杆菌属、鞘脂单胞菌属、芽孢杆菌属、链霉菌属、假单胞菌属、木霉属和盾壳霉属等;而一些植物病原细菌(如肠杆菌、黄单胞菌)和真菌(炭疽菌和尾孢菌)含量则低于油菜根际土壤;另外,大豆根际土壤中还富含具有固氮功能的根瘤菌属、慢生根瘤菌属和丛枝菌根真菌(如球囊霉属).可见,大豆根际土壤利于有益微生物生长并可抑制病原菌繁殖.大豆和油菜根际微生物组差异为大豆-油菜轮作防治根肿病提供了理论依据,并为根肿病的防治提供了一些潜在的生物防治资源.     

Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

The Farm Scale Evaluations of genetically modified herbicide-tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide-application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.     

水稻和稗草共生土壤微生物生物量碳及酶活性的变化

以稻田稗草、化感水稻PI312777和普通水稻辽粳9为试材,研究了田间稗草和水稻1∶1共生条件下,土壤微生物生物量碳及脱氢酶、脲酶和转化酶活性的变化.结果表明：在稗草 的干扰下,化感水稻PI312777根区土壤微生物生物量碳含量比单作减少了 50.52％（P<0.01）,而行间土壤微生物生物量碳含量增加;普通水稻辽粳9根区土壤 微生物生物量碳含量比单作减少了38.99％（P<0.01）,但其行间土壤微生物生物量碳含量无明显变化.两个水稻品种根区土壤脱氢酶活性均被显著抑制（P<0.05）,下降率都在20％以上;PI312777根区土壤脲酶和转化酶活性均被显著促进（P<0.01）;而辽粳9根区土壤转化酶活性也被显著抑制（P<0.01）,但脲酶活性无明显变化.化感水稻根区土壤微生物生物量碳含量的显著减少及脲酶、转化酶活性的增加是其化感特性的表现,表明土壤微生物和酶均参与了水稻和稗草的种间作用,化感水稻具有抗稗草干扰的明显优势.     

呋喃丹对土壤酶活性的影响

通过模拟方法,研究了呋喃丹与土壤中3种重要水解酶类—土壤脲酶、转化酶和碱性磷酸酶的关系及其影响因素.结果表明:呋喃丹加入土壤后,土壤脲酶活性最初受到抑制,随培养时间的延长,呋喃丹的生态毒性逐渐降低,并最终激活脲酶;在0.3%呋喃丹浓度范围内,土壤脲酶、碱性磷酸酶和转化酶均被激活,且部分样品的转化酶活性与呋喃丹浓度呈显著或极显著正相关,说明转化酶活性可在一定程度上表征土壤受呋喃丹污染的程度,且0.3%浓度呋喃丹的生态毒性较弱,对土壤质量及生态环境比较安全.     

施用胶质芽胞杆菌菌剂对黑麦草根际土壤脲酶、磷酸酶及过氧化氢酶活性的影响

土壤酶活性是反映土壤肥力最为重要的生物学指标之一。采用稀释涂布平板法研究了从玉米（K02）、草地早熟禾（K05）、披碱草（K09）、多年生黑麦草（K11）、匍匐翦股颖（K12）根际土壤中分离到的5株胶质芽胞杆菌菌株对黑麦草根际土壤脲酶、磷酸酶及过氧化氢酶活性的影响。结果表明：在苗期、中期、收获期各处理黑麦草根际土壤脲酶、磷酸酶和过氧化氢酶活性均高于对照（P〈0.05）。总体来看,各处理黑麦草根际土壤脲酶和过氧化氢酶活性呈先增加后降低的变化趋势;土壤磷酸酶活性与对照（CK）相比除苗期处理K12外,其他处理均呈上升趋势,以处理K05磷酸酶活性最大。研究表明,施入胶质芽胞杆菌菌剂对黑麦草根际土壤脲酶、磷酸酶及过氧化氢酶活性有一定的积极作用,其结果可为生物钾肥的研制提供必要的数据。     

胶州湾典型河口湿地土壤活性有机碳和酶活性对互花米草入侵的响应

以胶州湾洋河口湿地为研究对象,按照互花米草入侵年份(0、1、5、8年)分层采集土壤样品(0—10、10—20、20—40 cm和40—60 cm),研究土壤活性有机碳(LOC)和酶(脲酶、过氧化氢酶、碱性磷酸酶、蔗糖酶)活性的变化,分析土壤活性有机碳和酶活性及两者相关性对互花米草入侵的响应。结果表明:与光滩相比,互花米草入侵增加了表层土壤LOC含量,且随着入侵时间的延长显著增加(P0.05)。同时也改变了土壤LOC垂直分布规律,除光滩和入侵1年样地表现出沿剖面逐渐上升之外,其他样地表现为沿剖面先上升后下降趋势;互花米草入侵提高了河口湿地土壤酶活性,但并未改变酶活性随深度增加而逐渐降低的分布规律。随着入侵时间的延长4种酶活性变化趋势有所差异,过氧化氢酶和蔗糖酶活性变化趋势一致,表现为随入侵时间延长先急剧增加后逐渐减少,而碱性磷酸酶和脲酶活性随着入侵时间的延长逐渐增加。Pearson相关性分析结果显示,土壤LOC和酶活性呈显著负相关且互花米草入侵时间越长两者间相关性越低,8年后无显著相关性。     

Oilseed Rape Transformation and the Establishment of a Bromoxynil Resistant Transgenic Oilseed Rape

Using hypocotyls and cotyledons as transformed materials, an efficient transformation system of oilseed rape (Brassica napus L.) was established. Bxn gene (bromoxynil-resistant gene)was introduced into these plants, and bromoxynil-resistant transgenic oilseed rape was obtained. Themolecular monitoring experiments showed that these transgenic plants contained bxn gene. The herbicide experiments showed that these transgenic plants had resistance to 10-3 moL/Lbromoxynil.     

荒漠草原区土壤粒径组成对柠条根际土壤微生物数量及酶活性的影响

柠条(Caragana korshinskii)是荒漠草原区主要的造林绿化树种,研究其根际土壤微生物和酶活性与不同土壤类型土壤粒径组成的关系有重要意义,然而土壤粒径对荒漠草原柠条根际土壤微生物数量和酶活性的影响知之甚少,探讨土壤颗粒组分与微生物数量、土壤酶活性之间的关系,以及土壤颗粒组成对荒漠草原区固沙灌木植物柠条根际土壤微生物数量及酶活性的影响,可为揭示荒漠草原土壤退化及生态修复提供参考。以宁夏荒漠草原区土壤粒径组成差异显著的灰钙土、红黏土、风沙土环境下栽植的柠条为研究对象,研究不同土壤颗粒组成对根际土壤微生物数量及酶活性的相互关系与影响。结果表明:土壤微生物的数量表现为细菌放线菌真菌。根际土壤中的细菌、真菌数量显著高于非根际,且在3种不同类型的土壤中随着细砂粒的增多,真菌和放线菌数量逐渐降低,而细菌数量呈先增大后减小的趋势;根际与非根际土壤的蔗糖酶、碱性磷酸酶及过氧化氢酶活性均呈现出灰钙土红黏土风沙土的趋势,红黏土根际土壤中的脲酶活性显著高于灰钙土与风沙土;除过氧化氢酶外,土壤酶活性表现为根际高于非根际,在3种不同类型的土壤中随着细砂含量的增加,土壤酶活性均呈递减趋势。土壤颗粒组成与微生物数量之间没有明显的相关性,而与土壤酶活性之间显著相关,土壤酶活性与黏粒、粉粒呈正相关,与细砂、中砂呈负相关关系,根际土壤中酶活性更高,能够为植物及微生物提供更多的营养。     

生物有机肥对连作当归根际土壤细菌群落结构和根腐病的影响

研究生物有机肥料DZF-363对当归生长、根腐病的发病情况及土壤微生物群落结构和功能的影响,可为其对连作当归根际土壤环境的调节和改善提供理论依据.本研究以连作2年的当归及其根际土壤为对象,设置对照(不施农药和微生物肥料,CK)、农药(15%的阿维毒死蜱乳油+50%多菌灵可湿性粉剂,N)和生物有机肥DZF-363(DZF)处理,利用高通量测序和比色的方法,研究施用DZF-363对当归根际土壤微生物群落结构和土壤脲酶、磷酸酶活性的影响.结果表明:施用DZF-363比对照和农药处理分别增产18.8%和6.8%.施用DZF-363使当归根腐病病情指数显著降低,对根腐病防效达52.0%;整个生育期当归根际土壤的脲酶、中性磷酸酶、碱性磷酸酶活性显著提高,苗期、生长中期及收获期脲酶活性分别提高52.4%、13.9%、10.3%,中性磷酸酶活性分别提高15.5%、10.2%、10.3%,碱性磷酸酶活性分别提高10.3%、4.4%、4.0%,酸性磷酸酶活性在当归生长中期及收获期分别提高15.6%、8.2%.放线菌门在CK、N和DZF处理中的占比分别为11.3%、10%和20%,未知的放线菌纲和芽孢杆菌纲在DZF处理中的占比显著高于CK和N处理.施用DZF-363能显著增加当归根际土壤Shannon指数,且Shannon指数和Simpson指数与当归产量呈正相关,与根腐病呈负相关.表明施用DZF-363能显著增加当归根际土壤细菌多样性,改变当归根际土壤细菌群落结构,提高根际土壤脲酶和磷酸酶活性,减轻当归根腐病的发生,显著提高当归产量.     

3种菊科入侵植物不同生长时期的土壤酶活性和养分变化

【目的】黄顶菊、三叶鬼针草和豚草是我国危害较严重的3种菊科入侵植物。了解3种菊科植物生长过程中土壤养分和酶活性的变化,可以为研究其入侵机制提供依据。【方法】在中国农业科学院植物保护研究所廊坊中试基地开展同质园实验,比较分析了黄顶菊、三叶鬼针草和豚草3种菊科入侵植物在幼苗期、旺盛生长期和生殖生长期根际土壤养分和酶活性的变化。【结果】3种外来菊科植物的生长时期对土壤养分和酶活性存在显著影响。3种外来植物入侵域的土壤速效磷、硝态氮含量以及磷酸酶活性随生长时期变化都表现出先升高后降低的趋势,均在旺盛生长期达到最大值。入侵域土壤速效磷和硝态氮含量的变化趋势与狗尾草明显不同。3种外来植物入侵降低了土壤速效钾含量,提高了土壤脲酶、磷酸酶活性。【结论】3种外来菊科植物的入侵改变了土壤养分和酶活性,创造出更有利于自身生长和繁殖的条件,以利于其进一步扩张。     

Biological changes in the rhizosphere of wheat after foliar application of chlorocholinechloride,urea and 4-chloro-2-methylphenoxyacetic acid

In field experiments wheat in the phase of shooting was sprayed with solutions of chlorocholinechloride (CCC) and urea, CCC and ammonium salt MCPA (Aminex) or CCC, urea and Aminex. The effect of the treatment on dry weight of overground parts of wheat, number of bacteria, production of carbon dioxide, urease activity and content of ammonium in the rhizosphere soil was investigated. In all cases evolution of carbon dioxide in the rhizosphere soil was higher than that in the control soil. Highest numbers of bacteria were found in the rhizosphere soil of plants treated with urea, the herbicide and their mixtures. Content of ammonium was higher in the control soil than in the rhizosphere soils, the urease activity was highest in the rhizosphere soil of plants treated with the solution of the herbicide and with the combination of the herbicide with urea.     

宁南山区典型植物根际与非根际土壤微生物功能多样性

选择宁南山区9种典型植物的根际与非根际土壤为研究对象,采用Biolog方法对土壤微生物功能多样性进行了研究。结果表明:9种不同植物根际土壤与非根际土壤的微生物活性(AWCD)、微生物多样性指数和微生物均匀度指数均存在明显差异;除冰草外,其他各种植物的根际土壤的微生物活性AWCD、微生物多样性指数和微生物均匀度指数均比非根际土壤的高;9种典型植物根际土壤微生物主要碳源利用类型是羧酸类和氨基酸类,非根际土壤微生物主要碳源利用类型是羧酸类、胺类、氨基酸类;微生物活性、微生物多样性指数和微生物均匀度指数两两之间均达到了极显著相关,与土壤化学性质各指标之间均未达到显著相关水平。