简介:Settingmonitoringtransectinthemiddleandshallowwaterarea(altitude156-172m)inThreeGorgesreservoirhydro-fluctuationbelttoresearchthechangingcharacteristicsofthecontentsofN,P,K,pHandorganicmatterofthesoilwhichexperiencedtheinfluenceoffluctuationthefirsttime.Theresultsshowedthatbytheinfluenceofwaterlevelfluctuating,contentsofsoilN,P,K,pHandorganicmatterhadreducedindifferentsoillayersinhydro-fluctuationbelt.TheavailableNdecreasedby41.53%-59.87%,availablePdecreasedby5.26%-36.76%,availableKdecreasedby3.55%-45.56%,totalNdecreasedby9.52%-40.00%,totalPhadnochangegenerally,totalKhaddecreasedalittle,contentoforganicmaterialdecreasedby7.62%-37.83%%,pHvalueturnedtoneutral,changedby1.73%-9.58%.
简介:采用封闭罩-气相色谱法观测研究了干旱胁迫对长白山阔叶红松林的几种优势树种-红松(Pinuskoraiensis)、水曲柳(Fraxinusmandshurica)、胡桃楸(Juglansmandshurica)、椴树(Tiliaamurensis)和蒙古栎(Quercusmongolica)叶片N2O排放,并同步测定5种树木叶片净光合速率、呼吸速率和气孔导度.结果表明:土壤水分胁迫明显降低树木叶片气孔导度、净光合速率和N2O排放速率,叶片气孔是树木N2O排放的主要通道.树木N2O排放以白天为主,在相同的水分条件下,不同的苗木有不同的N2O排放速率,同种苗木的N2O排放随干旱胁迫的加重而减少,在受到不同干旱胁迫时,针叶树红松N2O的排放速率降至正常水分条件下的34.43%和100.6%、阔叶树种N2O排放平均降至31.93%和86.35%.不同干旱胁迫的红松、水曲柳、胡逃楸、椴树和蒙古栎幼树叶片N2O排放速率为34.43、14.44、33.02、16.48和32.33ngN2O.g-1DW.h-1.图1表1参12.
简介:最近,许多农民朋友来信,询问现在的农民建房用地审批程序,农房就地拆建、改造、加层房屋是否要办理用地审批手续,交纳什么费用,开具什么票据,现答复如下:一、根据《中华人民共和国土地管理法》第六十二条、《江西省实施〈中华人民共和国土地管理法〉办法》第四十条和四十一条规定,农村村民一户只能拥有一处宅基地;农村村民因建住宅需要使用本集体经济组织土地的,由本人提出申请,经村民会议同意,村委会审查,乡(镇)人民政府审核,报县级人民政府批准。其中,涉及农用地转用的,由县级人民政府审核后整理汇总,每年分批次上报有农用地转用批准权的人民政府批准。二、农房拆建、改造、加层必须符合土
简介:EctomycorrhizalfungusLaccariabicolorS238N,isolatedfromaforestsoilincentralFrancein1990s,hasdemonstratedunequivocallyandabilitytopromotepinegrowth.Inthepresentnurserybedexperiment,theabilityofthisectomycorrhizalfungustoincreasegrowthandPandKuptakeofDouglasFirseedlings(Zone22)wasexamined.Growthofinoculatedseedlingswasovertwice(plantheight)andthreetimes(biomass)thatofnon-inoculatedones.Similarly,boththeconcentrationsandtheamountsofPandKuptakebyseedlingsweresignificantlyincreasedbyfungalinoculation,indicatingtheimprovementofPandKnutritioninmycorrhizalseedlings.Incontrast,Al-Pinthesoilswasdecreasedobviouslybyplants,especiallybymycorrhizas,suggestingutilizationofthissoilPpoolbyplantsandmoreefficientAl-Pmobilizationbymycorrhizasthanbynomycorrhizas.Moreover,Kextractedby1mol/LHClfollowingconsecutiveextractionofH2OandCH3COONH4,whichmaynotbeplantavailable,couldbeutilizedbyfunguscoloniedroots.ThiscouldbeexplainedbythereleaseofprotonsandoxalatebyhypaewhichleadstoreplacementofinterlayerKinnonexpanded2:1claymineralsandbio-weatheringofphyllosilicates.
简介:Nitrogen(N)useefficiencyisusuallylessthan50%,anditremainsamajorprobleminricecultivation.Controlledreleasefertilizer(CRF)technologyisoneofthewell-knowneffortstoovercomethisproblem.TheefficiencyofCRF,however,isverymuchdependentonthetimingofnutrientrelease.ThisstudywasconductedtodeterminetheprecisetimeofNuptakebyriceasaguidelinetodevelopefficientCRF.FertilizerNuptakebyriceatdifferentgrowthstageswasinvestigatedbyusing15Nisotopictechnique.Ricewasplantedinpots,with15NureaasNsourceattherateof120kg/hm2.Potassiumandphosphoruswereappliedatthesamerateof50kg/hm2.Standardagronomicpracticeswereemployedthroughoutthegrowingperiods.Riceplantswereharvestedeverytwoweeksuntilmaturationatthe14thweekandanalyzedfortotalNand15Ncontent.Nitrogenderivedfromfertilizerwascalculated.TotalNuptakeinplantsconsistentlyincreaseduntilthe11thweek.Afterthat,itstartedtoplateauandfinallydeclined.Moreover,Nutilizationbyriceplantspeakedat50%,whichoccurredduringthe11thweekaftertransplanting.Nderivedfromfertilizerinriceplantswereintherangeof18.7%to40.0%inallplanttissues.TheremainingNwasderivedfromsoil.Basedonthisstudy,NreleasefromCRFshouldcompletebythe11thweekafterplantingtoensurethemaximumfertilizerNuptakebyriceplants.EfficientCRFshouldcontributetohigherNderivedfromfertilizerwhichalsoresultedinahighertotalNuptakebyriceplants,increasingthepotentialofricetoproducehigheryieldwhileatthesametimeofreducingloss.
简介:为探寻温带地区山地植物N素保存策略,找出影响植物N素回收率的环境因子,以便了解植物保持所吸收养分的机制,以小浪底库区山地为例,研究该区域3种生活型21种典型植物成熟绿叶中的N素含量、枯叶中N素含量以及N素回收效率(NRE)。结果表明:植物成熟绿叶中的N素含量和枯叶中N素含量有显著的正相关关系;所测定的21种植物NRE在17,4%~50.1%之间,平均值为28-8%,多数种的回收效率低于40%。测定的21种植物都属于N素回收不完全植物。不同生活型的植物其回收效率有显著的差异,一般表现为草本〉灌木〉乔木。植物叶片N素含量与土壤有机质,上壤N素含量和土壤含水量呈显著正相关;而NRE与土壤有机质、土壤N素含量和土壤含水量呈显著负相关关系。说明在研究区不利的土壤条件,可以导致植物NRE的提高,植物在不利的环境条件下。可以通过提高NRE等途径来应对环境的胁迫。
简介:为了解园林植物冠层内外的光合有效辐射(PAR)的空间分布特征,以钻石海棠为例,利用光合有效辐射测定系统,对钻石海棠冠层上部、下部以及交叉重叠三种情况下的PAR强度进行了测定分析。结果表明:1)PAR值随着太阳高度角的增加而增大,观测期间,最高值可达1500μmolm-2s-1;2)随着冠层的加厚和叶片的阻挡,从冠顶到冠下,树冠截取到的PAR呈递减趋势;3)8月-10月间,交叉重叠下的PAR透光率日平均为21%,而遮蔽条件下的PAR透光率可达32%。另外,在条件允许情况下,有必要进一步增加观测仪器数量进行长期观测,从而消除或减弱短期枝叶摆动、云层变化、冠层内透光空隙差异等因素的影响,并进一步反映冠内PAR透光率随叶面积生长的动态变化。