简介：Twenty-threeprogressiveextractionswereperformedtostudyindividualhumicacids(Has)andhuminfractionsfromatypicalblacksoil(Mollisol)inHeilongjiangProvince,Chinausingelementalanalysisandspectroscopictechniques.After23HAextractionstheresiduewasseparatedintohighandloworganiccarbonhuminfractions.HAyieldwasthehighestforthefirstextractionandthengraduallydecreasedwithfurtherextractions.Organiccarbon(OC)ofthehuminfractionsaccountedfor58％oftotalOCevenafter23successiveHAextractions.Inaddition,theatomicC/HratiodecreasedduringthecourseofextractionwhileC/Oincreased;theE4/E6ratiofromtheUVanalysisdecreasedwithfurtherextractionwhileE2/Eaincreased;thebandassignedtoaliphaticcarbon(2930cm-1)inthediffusereflectanceinfraredFouriertransformspectroscopy(DRIFTS)spectragraduallyincreasedwithprogressiveextraction;thecalculatedratioofthesumofaromaticcarbonpeakheightstothatofaliphaticcarbonpeakheightsfromDRIFTSspectradeclinedwithextractions;andnuclearmagneticresonance(NMR)datasuggestedthatHAaliphaticcarbonsincreasedwithextractionswhilearomaticcarbonsdecreased.Thus,hydrophobicityandaliphaticityofHasincreasedwithextractionswhilepolarityandaromaticitydecreased.Thesedatashowedsubstantialchemical,structural,andmoleculardifferencesamongthe23Hasandtwohuminfractions.Therefore,theseresultsmayhelpexplainwhysoilandsedimenthuminfractionshavehighsorptioncapacityfororganiccontaminants.

简介：为了确定黄土高原地区现有刺槐林改造的最佳间伐强度，１９９５年秋季对密度为２２２０株／公顷的９年生刺槐林进行了三种不同强度的间伐．通过间伐，降低了群落密度，减少了林冠截留率，增加了植树带内的汇流量，根系层内的土壤水分条件得到明显的改善．当间伐后的林分密度为１１１０株／公顷时，生长季内植树带土壤水分提高约４０％．随着间伐强度的增大，林木的水分生产函数曲线由直线上升变为以对数曲线上升；当间伐强度达到某一值时（保留密度为１１１０株／公顷），林木水分生产力随蒸腾量的变化曲线为抛物线．这表明此时水分已不再是林木生产的限制因子，在这种间伐强度条件下，单株林木和整个林分的水分生产力分别达到６０１７１ｇ·ｋｇ－１·ｍｍ－１和１４９７７７ｋｇ·ｈｍ－２·ｍｍ－１，因此将这一强度定为黄土高原地区刺槐林间伐的最佳强度．

简介：Availablewaterandfertilizerhavebeenthemainlimitingfactorsforyieldsofspringwheat,whichoccupiesalargeareaoftheblacksoilzoneinnortheastChina;thus,theneedtosetupappropriatemodelsforscenarioanalysisofcroppingsystemmodelshasbeenincreasing.ThecapabilityofCropSyst,acroppingsystemsimulationmodel,tosimulatespringwheatgrowthofawidelygrownspringcultivar,'Longmai19',intheblacksoilzoneinnortheastChinaunderdifferentwaterandnitrogenregimeswasevaluated.Fielddatacollectedfromarotationexperimentofthreegrowingseasons(1992-1994)wereusedtocalibrateandvalidatethemodel.Themodelwasrunfor3yearsbyprovidinginitialconditionsatthebeginningoftherotationwithoutreinitializingthemodelinlateryearsintherotationsequence.CropinputparametersweresetbasedonmeasureddataortakenfromCropSystmanual.Afewcultivar-specificparameterswereadjustedwithinareasonablerangeoffluctuation.TheresultsdemonstratedtherobustnessofCropSystforsimulatingevapotranspiration,abovegroundbiomass,andgrainyieldof'Longmai19'springwheatwiththerootmeansquareerrorsbeing7%,13%and13%oftheobservedmeansforevapotranspiration(ET),grainyieldandabovegroundbiomass,respectively.AlthoughCropSystwasabletosimulatespringproductionreasonablywell,furtherevaluationandimprovementofthemodelwithamoredetailedfielddatabasewasdesirableforagriculturalsystemsinnortheastChina.

简介：Thedynamicsofrhizospheremicrobialcommunitiesisimportantforplanthealthandproductivity,andcanbeinfluencedbysoiltype,plantspeciesorgenotype,andplantgrowthstage.ApotexperimentwascarriedouttoexaminethedynamicsofmicrobialcommunitiesintherhizosphereoftwosoybeangenotypesgrowninablacksoilinNortheastChinawithalonghistoryofsoybeancultivation.Thetwosoybeangenotypes,Beifeng11andHai9731,differinginproductivityweregrowninamixtureofblacksoilandsiliceoussand.Thebacterialcommunitieswerecomparedatthreezonelocationsincludingrhizoplane,rhizosphere,andbulksoilatthethirdnode(V3),earlyflowering(R1),andearlypod(R3)stagesusingpolymerasechainreaction-denaturinggradientgelelectrophoresis(PCR-DGGE)of16SrDNA.Theresultsofprincipalcomponentanalyses(PCA)showedthatthebacterialcommunitystructurechangedwithgrowthstage.Spatially,thebacterialcommunitiesintherhizoplaneandrhizosphereweresignificantlydifferentfromthoseinthebulksoil.Nevertheless,thebacterialcommunitiesintherhizoplaneweredistinctfromthoseintherhizosphereattheV3stage,whilenoobviousdifferenceswerefoundattheR1andR3stages.Forthetwogenotypes,thebacterialcommunitystructurewassimilarattheV3stage,butdifferedattheR1andR3stages.Inotherwords,somebacterialpopulationsbecamedominantandsomeothersrecessiveatthetwolaterstages,whichcontributedtothevariationofthebacterialcommunitybetweenthetwogenotypes.Theseresultssuggestthatsoybeanplantscanmodifytherhizospherebacterialcommunitiesintheblacksoil,andthereexistedgenotype-specificbacterialpopulationsintherhizosphere,whichmayberelatedtosoybeanproductivity.

简介：Soilaggregatestability,animportantindexofthephysicalcharacteristicsofasoil,canprovideagoodindicationofasoil’serodibility,anddeservesspecialconsiderationinregionswithcoldclimate.Theobjectiveofthisstudywastostudytheeffectoffreeze-thawonsoilwater-stableaggregatesintheblacksoilregionofNortheastChina.Samplesofatypicalblacksoilintheregionwerecollectedtomeasurewater-stableaggregatesafterfreeze-thawunderdifferentconditions(i.e.,initialmoisturecontents,freezethawcyclesandfreezingtemperatures)bywet-sievingintoeightparticlesizegroups(>10,10–6,6–5,5–3,3–2,2–1,1–0.5,and0.5–0.25mm).Freeze-thawhadthemosteffectonaggregatestabilitywhenthesampleshadaninitialmoisturecontentof400gkg-1.Thewater-stableaggregatesofthefourlargerparticlesizegroups(>5,5–3,3–2,and2–1mm)reachedapeakstabilityvalue,butthoseofthetwosmallerparticlesizegroups(1–0.5and0.5–0.25mm)reachedaminimumvaluewhenthesoilmoisturecontentwas400gkg-1.Water-stableaggregatesofthefourlargerparticlesizegroupsdecreasedwhilethoseofthetwosmallerparticlesizegroupsincreasedwiththeincreaseoffreeze-thawcycles.Astemperaturesfell,thewater-stableaggregatesofthefourlargerparticlesizegroupsdecreasedwhilethoseofthetwosmallerparticlesizegroupsincreased.

简介：在中国的黄土高原上，干燥土壤层可以由于过量蒸发形成，导致蝗虫(Robiniapseudoacacia)承受的黑色的降级。为了更好设法，预测包含黑蝗虫，这研究被打算调查黑蝗虫蒸发率的反应玷污在黄土高原上用二代表性的土壤(卢拇的泥土和沙的沃土)由气象学的因素影响了的水可获得性。四个土壤水内容为在开始户外的壶然后在一个控制气候的房间种的黑蝗虫幼苗被维持，由弄干或灌溉壶。在两环境，每日的蒸发率被力量功能与空气温度并且由逻辑功能有关引用土壤水分蒸发蒸腾损失总量(et0)。蒸发率比在卢拇的黏土更产生处于在沙的沃土的气象学的条件的变化。在浇得好的处理的蒸发率为比在卢拇的黏土在沙的沃土种的黑蝗虫是更大的。规范的蒸发率由et0是未受影响的直到土壤水内容的批评价值(c)被达到；c价值为卢拇的黏土显著地减少了，但是当et0增加了时，为沙的沃土土壤显著地增加了。这些建议黑蝗虫的蒸发特征上的气象学的条件的效果依赖于土壤质地。

简介：Invarioustemperatures,theeffectsofinorganicacidsonthefreephenollevelinliquefactionproductswereinvestigated.Inthispaper,thefreephenollevelwasusedasanindicatortoevaluateliquefactionefficiency.Resultsshowedthatsulfuricacidwasthebestamongthe4acids.Undertheconditionofreactiontemperature150oC,reactiontime1.5h,liquefactionratio(liquid/particleboard)4andcontentofsulfuricacid6%,thefreephenollevelintheliquefactionproductsofwasteparticleboardis36.95%,andthatoforiginalparticleboardis24.27%.

简介：应用根系喷雾箱（ＲｏｏｔＭｉｓｔｉｎｇＣｈａｍｂｅｒ，ＲＭＣ）形成的５次干旱循环，通过ＰＶ曲线的水分参数研究了多重复干旱循环对１年生北美短叶松ＰｉｎｕｓｂａｎｋｓｉａｎａＬａｍｂ．和黑云杉Ｐｉｃｅａｍａｒｉａｎａ［Ｍｉｌ］Ｂ．Ｓ．Ｄ．苗木耐旱特性的影响．结果表明，生长在干旱沙地的深根性树种北美短叶松，其丧失膨压的相对含水量（８０７６％～８１４１％）和水势（（－１７４±０１０）ＭＰａ）都比较低，细胞弹性模量（５７３～６５２ＭＰａ）比较小，而束缚水含量（５２７２％～５４２６％）比较高，显示出它固有的强有力的忍耐脱水能力；但是在多重复干旱循环下它却不能进一步调节其渗透势和细胞弹性，而且其束缚水含量和吸水能力也有所下降．生长在湿润地区的浅根性树种黑云杉，虽然其丧失膨压的相对含水量（８３５３％～８５５０％）和水势（（－１６８±００３）ＭＰａ）比较高，细胞弹性模量（８６２～９６４ＭＰａ）比较大，束缚水含量（３６４４％～４６０５％）比较低，显示出较弱的耐旱能力，但是它在多重复干旱循环下却能提高其束缚水含量以改善原生质耐旱程度，降低细胞弹性以提高其吸水能力，调节其渗透势以保持较高的膨压．这表?

简介：Riceblack-streakeddwarfvirus(RBSDV)isarecognizedmemberofthegenusFijivirus,familyReoviridae.Itsgenomehastendouble-strandedRNA(dsRNA)segments(S1-S10),inwhichthefifthgenomesegment(S5)containstwoopenreadingframes(ORFs)withapartiallyoverlappingregion.ThesecondORFofRBSDVS5encodesaviralnonstructuralproteinnamedp5bwithunknownfunction.Torevealthefunctionofp5b,itsgenewasligatedintothebaitplasmidpGBKT7andanexpressionlibrarycontainingricecDNAswasconstructedusingplasmidpGADT7foryeasttwo-hybridassay.Thebaitproteinp5bwasdetectedinyeastbywesternblot,andtheresultofanauto-activationtestshowedthatp5bcouldnotautonomouslyactivatetheexpressionofreportergenesinyeast.Thenthebaitproteinp5bwasusedforscreeningthecDNAexpressionlibrariesofrice.Genefragmentsofsomepivotalenzymesinvolvedinphotosynthesis,respirationandotherimportantmetabolicprocesses,wereidentifiedtointeractwithp5binyeast,suggestingthattheseinteractionsmayplayrolesinsymptomdevelopmentininfectedplants.

简介：Blacklocust(RobiniapseudoacaciaL.)wasthefirstNorth-AmericantreespeciesimportedtoEuropeatthebeginningoftheseventeenthcentury.Itiscommonlyplantedworldwidebecauseofitsadaptabilitytoenvironmentalstresses,itsvaluablewood,easypropagation,frequentandabundantseedproduction,excellentcoppicing,highseedlingsurvival,andrelativelyhighwoodyield.InEurope,RomaniaandHungaryhavethemosthighly-developedblacklocustgrowingtechniquesandexperiences.Asaresultofincreasinginterestinblacklocustinmanycountries,thisreviewaimstoprovideacomprehensiveoverviewofstate-of-the-artsiterequirements,propagation,improvementandmanagement(includinggrowthandyieldaswellasuseinenergyplantations).

简介：TheinteractionbetweenricehostanditspathogenXanthomonasoryzaepv.oryzae(Xoo)atcellularlevelwasstudiedbyusingaresistantsomaclonalmutantHX-3anditssusceptabledonorMinghui63.AfterinoculationwithXoostrainZhe173(Chinesepathotype|\).theactivityofsuperoxidedismutase(SOD)andperoxidase(POD)inthecallusofMinghui63wasincreaseddramatically,andtheactiveoxygen(O2^-)wasproducedatahigherrate;Meanwhile,thecallusgrewslowlywiththereductionofproteincontent.ComparedtotheactivityofSODandPOD.theproductionrateofO2^-andthefreshweightinHX-3callusvariedlittleaftertheinoculation.ItcouldbeproposedthatthereweregreatdifferencesbetweentheresistanceofHX-3andMighui63atcellularlevel.TherewasnodifferencedetectedconcerningresistancetobacterialleafblightinHX-3betweentheplantandthecallus.

简介：Canada'sborealforestrepresentsanimportantcontributoroftheworld'swoodsupplyindustry.However,maintainingorincreasingproductivityoftheborealforestmaybechallenginginareasdominatedbyforestedpeatlands.Moreover,sustainablemanagementoftheseforestsmustalsoconsiderotherimportantaspectsoftheforestecosystemsuchasbiodiversityandcarbonsequestration.Toaddresstheseconcerns,ecosystem-basedmanagementhasbeenimplementedinsomeCanadianjurisdictions,suchasinregionswherealargeportionoftheborealforestisdominatedbyforestedpeatlands.Theobjectivesofthispaperare(1)tosummarizeourcurrentunderstandingofhownaturaldisturbancesinfluencestanddynamicsandbiodiversityinforestedpeatlands,and(2)toreviewthemaindifferencesbetweennaturalandmanagedforeststandswithrespecttosoil.properties,standproductivity,understoryplantcommunities.Wealsodiscusshoweven-agemanagementregimesucceedsorfailstopreserveoldforestsandhowthislossaffectsbothforeststructureandhabitatdiversityatthelandscapelevel.Weconcludebyshowinghow,inborealforestedpeatlands,forestmanagementcouldcontributetocarbonsequestrationandmitigateprojectedclimatechange.

简介：Ｓｅｌｆ－ＨｅｌｐＤｅｖｅｌｏｐｍｅｎｔ，ＳｕｓｔａｉｎａｂｌｅＭａｎａｇｅｍｅｎｔａｎｄＵｓｅｏｆＦｏｒｅｓｔｓａｎｄＴｒｅｅｓａｔｔｈｅＬｏｃａｌＣｏｍｍｕｎｉｔｙＬｅｖｅｌＴｈｅＦｏｒｅｓｔｓ，ＴｒｅｅｓａｎｄＰｅｏｐｌｅＰｒｏｇｒａｍｍｅＰｈ...

简介：Nonlinearmixedeffectsmodel(NLMEM)isbuiltontherelationshipofthefixedandrandomeffectsintheregressionfunction.TheNLMEMhasanobviouscomparativeadvantageinanalyzingthelongitudinaldata,repeatedmeasuresdataandmultileveldata.Two-levelNLMEMisusedtoanalyzethedominantheightforChinesefir(Cunninghamialanceolata).Theauthorsoutlinethetwo-levelNLMEMandintroducetheparametersestimationmethodofthemodel.BasedonfivecommonRichardandLogisticmodels,themixedmodelisbuilt.Themodelingdataareusedtocalculateandcomparewith19modelsderivedfromeachbasedmodel,and5optimalmixedmodelsarebuilt.Comparedthe5optimalmixedmodelswithtraditionalregressionmodels,itisshowedthatthetwo-levelNLMEMhasabetterfittingeffectthantheregressionmodel.

简介：Tocomparetheeffectsofslow-releasenitrogenfertilizeratsixdifferentlevelsontheflagleafchlorophyllfluorescencecharacteristicsofsuperhybridrice,afieldfertilizationexperimentwasconductedwithsuperhybridriceYLiangyou1asatestmaterial.Thephotosyntheticelectrontransportrate(ETR),effectivequantumyield(EQY),photochemicalquenchingcoefficient(qP),andnon-photochemicalquenchingcoefficient(NPQ)offlagleavesweremeasuredattheinitialheading,fullheading,10dafterfullheadingand20dafterfullheadingstages.ResultsshowedthatthevaluesofETR,EQYandqPincreasedwithricedevelopmentfrominitialheadingto20dafterfullheading,whereastheNPQdecreased.Duringthemeasuredstages,ETR,EQYandqPincreasedinitiallyandthendecreasedasnitrogenapplicationamountincreased,buttheypeakedatdifferentnitrogenfertilizerlevels.ThemaximumETRandEQYvaluesappearedatthetreatmentof135kg/hm2N.Inconclusion,theoptimumnitrogenamountforchlorophyllfluorescencecharacteristicsofsuperhybridricewas135180kg/hm2.

简介：以便为对米饭识别米饭变化的抵抗保存病毒黑条纹的矮子疾病，一个简单、可靠的方法被开发，通过哪个没有病毒的小棕色的planthopper(SBPH)获得了米饭从冻结的感染的叶子的黑条纹的矮子病毒(RBSDV)和病毒被传给健康米饭植物。试验性的结果证明SBPH能从冻结的感染的米饭叶子获得RBSDV，病毒能被传给一个易受影响的米饭变化。能力获得RBSDV并且由SBPH把病毒传给健康植物，冻结的感染的叶子之间并且在vitro没有重要差别感染的叶子。新奇方法能被用于米饭变化抵抗的鉴定到米饭黑条纹的矮子疾病，为米饭便于繁殖过程黑条纹的矮子疾病抵抗。

简介：Basedonamultilevellinearmixedmodelapproach,anindividualdiameterincrementmodelwasdevelopedforfirplantationtreesgrowinginJiangxiProvince.Thedatasetusedinthisstudycamefromlong-termpermanentresearchplots.Thedatabaseconsistsoftotalof82counties,365plots,5416treesand16248observations.Thepaperchosemixedeffectsmodelsinsteadofregressionanalysisapproachbecauseitallowsforpropertreatmentoferrortermsandcorrelationinarepeatedmeasuresanalysisframework.Themodelwasdefinedasamixedlinearmodelwithparameterrandomeffectofplot,areaorplotandareasimultaneous.Inadditiontheheteroscedasticityandcorrelationwastakenintoaccount.Mixedmodelcalibrationofdiameterincrementwascarriedoutwiththeindependentdatausingadifferentsampleofcomplementaryobservations.Theresultshowedthatthetotalstandbasalarea,thediameteroftargettrees,theratioofbasalareaoflargertreestotargettreediameter,andaltitudewerefoundtobesignificantpredictors.Boththefittingmodelandthecalibratedmodelmeanasubstantialimprovementcomparedwiththeclassicalapproachwidelyusedinforestmanagement.Aftertakingintoaccountreasonablevariancefunctionofheteroscedasticityandcorrelation,themodelshowsbetterofgoodnessoffitthanonlytakingintoaccountparameterrandomeffects.Thistypeofmodelingmethodologyshowsflexible,preciseandaccurate.

简介：从一个螺丝钉出版社的米饭糠蛋糕或分泌物的外观对应于在抽取过程生产的油的水平。在操作背景，油抽取水平和蛋糕外观之间的关系被学习。蛋糕特征可靠地显示期望的油恢复抽取水平。这些结论适用于两Chainat1米饭糠和parboiled米饭糠。变量是螺丝钉出版社(在从8.5～19.8r/min的五个层次的集合)和在螺丝钉和桶(在1.0和1.9厘米之间的集合)之间的相应清理距离的速度。结果证明抽取的最大的层次为米饭糠是4.17%并且8.20%为parboiled米饭糠。在最大的抽取水平，仪器连续地解除了难的蛋糕，易碎，片状，在一个方面上晴朗、擦亮却在其它上迟钝、粗糙。