京海黄鸡繁殖性状与29个多态位点的关联性

为了寻找影响鸡(Gallus gallus)繁殖性状的候选基因,本研究利用单核苷酸多态(single nucleotide polymorphism,SNP)芯片分型技术,利用已报道的影响鸡繁殖性状的29个位点对396只京海黄鸡母鸡的29个位点直接进行SNP分型,并对11个繁殖性状进行关联分析。结果发现,29个SNP中,有12个SNP与至少1个繁殖性状关联显著(P0.05),其中有7个SNP同时与2个繁殖性状关联显著(P0.05)。所有繁殖性状中,与京海黄鸡开产体重关联显著的SNP有1个,与京海黄鸡462 d产蛋数关联显著的SNP有2个,与蛋重关联显著的SNP有6个,与开产体重关联显著的SNP有6个,与综合选择指数关联显著的SNP有2个,与后代健雏率关联显著的SNP有1个,没有发现与300 d产蛋数、300~462 d产蛋数和后代孵化率关联显著的SNP。同时,根据这些位点的群体遗传参数发现,12个SNP的平均多态信息含量偏低,说明京海黄鸡有持续选育提高的可能性和必要性。大部分有利基因型为纯合基因型,但有部分基因型为杂合基因型。对与12个SNP最近的功能基因犰狳(Priodontes maximus)重复基因(armadillo repeat gene deleted in velocardiofacial syndrome,ARVCF)、集落刺激因子3受体基因(colony stimulating factor 3receptor,CSF3R)和ODZ同源物2基因(odz,odd Oz/ten-m homolog 2,ODZ2)的功能探讨发现,这些基因可以通过不同的途径影响鸡的繁殖性状。本研究为鸡繁殖性状候选基因的进一步研究提供了基础资料。     

鸡CEBPA和Six1基因的多态性及其与屠体和体尺性状的相关分析

CCAAT/增强子结合蛋白α基因(CCAAT/enhancer binding protein alpha gene,CEBPA)在脂肪生成、生长发育过程中发挥重要作用,同源异型基因Six1(sine oculis homeobox homolog 1 gene)在骨骼肌的发育和肌纤维类型的转化中起调控作用,且两者均与骨骼的发育密切相关。本研究以CEBPA和Six1基因为候选基因,采用直接测序法检测2个基因外显子的单核苷酸多态性(single nucleotide polymorphisms,SNPs),并分析其对无量山乌骨鸡(Gallus gallus)屠体和体尺性状的影响。研究结果表明,在CEBPA基因外显子上共检测到74 CG、552 GA、936 CT 3个突变位点,在Six1基因外显子上共检测到375 GA和564 GA 2个突变位点,其中只有CEBPA基因74 CG位点的突变引起了氨基酸的变化,且为中性突变。连锁不平衡(linkage disequilibrium,LD)分析发现,CEBPA基因的各突变位点间、Six1基因的各突变位点间均不存在强连锁不平衡。在无量山乌骨鸡群体中,CEBPA基因的3个SNPs位点形成了5种单倍型和7种双倍型,Six1基因的2个SNPs位点形成了4种单倍型和5种双倍型。关联分析表明,CEBPA基因的74 CG突变位点对半净膛率、全净膛率、体斜长、胸宽、胸深和龙骨长有显著或极显著影响(P0.05或P0.01),936 CT突变位点对活重、屠体重、半净膛重、全净膛重、胸肌重、体斜长、骨盆宽和胫长有显著或极显著影响(P0.05或P0.01)。双倍型H1H1、H4H4的半净膛率、全净膛率,H1H2的胸肌重、骨盆宽、胫长,H1H4和H4H4的体斜长,H4H4的胸宽、胸深、龙骨长分别显著高于其他部分双倍型(P0.05或P0.01);Six1基因的375 GA和564 GA突变位点对部分屠体和体尺性状有显著性影响(P0.05或P0.01),双倍型H6H6、H6H7、H6H8的胸肌重、胸肌率,H6H7的屠宰率,H6H8的全净膛重、胸深、骨盆宽,H7H7的胸角、胫长、胫围,分别显著高于其他部分双倍型(P0.05或P0.01)。本研究结果表明,CEBPA基因和Six1基因的多态性对无量山乌骨鸡的屠体和体尺性状有显著影响,可作为无量山乌骨鸡及其他鸡种屠体和体尺性状分子标记辅助性选择的候选基因。     

郏县红牛跨膜蛋白18基因(TMEM18)SNPs检测及其与生长性状的关联分析

跨膜蛋白18基因(Transmembrane protein 18,TMEM18)在神经系统表达.全基因组关联分析(GWAS)表明,该基因的突变会影响人类肥胖和Body Mass Index(BMI)值变化.本研究采用DNA池测序技术检测了郏县红牛(Bos taurus) TMEM18基因5个外显子和部分内含子区单核苷酸多态(single nucleotide polymorphism,SNP)位点,通过PCR-RFLP技术对所发现的SNP位点进行分型验证,然后分析不同基因型与郏县红牛生长性状的关联性.结果表明,在郏县红牛TMEM18基因上共发现了3处新的SNPs:NW_003099175.1∶g.2303G＞A、g.3835 G＞A和g.3865 A＞G(aa.Gly＞Ser).关联分析结果表明,郏县红牛TMEM18基因g.2303G＞A位点AA型个体体高、体长、胸围和体重显著大于GG型(P＜0.05),郏县红牛TMEM18基因g.3835 G＞A位点AG型个体胸围和体重显著大于AA型(P＜0.05).研究结果提示,这两个位点可作为郏县红牛品种体尺和体重生长性状选择的分子育种候选标记.     

黑素皮质素受体3基因(MC3R)多态性及其单倍型组合与京海黄鸡屠体性状的关联分析

本研究旨在探讨黑素皮质素受体3基因(melanocortin 3 receptor,MC3R)对鸡(Gallus gallus)屠体性状的影响。采用聚合酶链式反应-单链构象多态性(polymerase chain reaction-single strand conformation polymorphism,PCR-SSCP)检测及测序的方法,检测MC3R在京海黄鸡群体中的单核苷酸多态性(single nucleotide polymorphisms,SNPs),并对这些多态位点进行连锁不平衡和单倍型分析。结果表明,在MC3R编码区序列(coding sequence,CDS)共检测到6个SNPs位点,各位点间均不存在强连锁不平衡;6个SNPs位点在379只京海黄鸡的群体中形成了5种单倍型和11种单倍型组合。最小二乘法分析结果表明,不同单倍型组合间京海黄鸡屠体性状(包括活体重、屠体重、胸肌重、腿肌重、全净膛重、半净膛重和腹脂重)存在显著或极显著差异(P<0.05或P<0.01),其中单倍型组合H3H4和H3H3的各种屠体性状均极显著高于单倍型组合H4H5(P<0.01),也显著高于其他部分单倍型组合(P<0.05),为屠体性状优势组合;单倍型组合H4H5各屠体性状均为最低,均显著或极显著低于其他大部分单倍型组合(P<0.05或P<0.01),为屠体性状劣势组合。因此,MC3R可能是影响鸡屠体性状的主效基因或与主效基因连锁,本研究为京海黄鸡屠体性状分子标记辅助选择提供了参考依据。     

基于DNA池重测序技术研究细毛羊LAMB1基因的SNPs分析

层粘连蛋白β1 (laminin-beta-1,LAMB1)作为层粘连蛋白家族成员之一,在生物过程中发挥极为重要的作用.为了分析细毛羊(Ovis aries)毛性状相关候选基因LAMB1的遗传效应,本研究通过DNA池重测序技术筛选了LAMB1基因外显子区的5个单核苷酸多态性(single nucleotide polymorphisms,SNPs),对其使用聚合酶链反应-单链构象多态性(single strand conformation polymorphism analysis of polymerase chain reaction products,PCR-SSCP)技术分型,在此基础上,利用SAS 8.1的GLM程序分析其对新疆巩乃斯种羊场418只细毛羊毛性状的遗传效应,利用HaploView 4.2软件进行连锁不平衡(linkagedisequilibrium,LD)分析.结果显示,该细毛羊群体遗传变异处于中等水平,LAMB1的5个SNPs发生错义突变.SNP2中AA和GA基因型个体鉴定时体重、剪毛后体重极显著高于GG基因型个体(P＜0.O1);SNP4中CC、TT和TC基因型个体间的自然长度差异极显著(P＜0.01),CC基因型个体的剪毛后体重极显著高于TT和TC基因型的个体(P＜0.01);而其他SNPs各基因型个体间的部分毛性状有显著差异(P＜0.05).SNP1和SNP3、SNP2和SNP3处于连锁不平衡状态,LAMB1基因可作为具有潜在应用价值的细毛羊毛性状分子标记之一.本研究揭示了L4MB1基因的分子遗传特征及其与细毛羊群体的遗传关系,为高效选育细毛羊经济性状及对其种质资源的保护与利用提供了分子学基础.     

UCP基因多态性及与黑安格斯牛生长性状的关联分析

解偶联蛋白(uncoupling protein,UCP)在动物机体能量代谢和脂类代谢方面发挥着重要作用。为探讨UCP2和UCP3基因作为黑安格斯牛生长性状候选基因的可能性,及寻找与黑安格斯牛生长性状相关的分子标记,本研究以宁夏地区739头黑安格斯牛(Bos taurus)为研究对象,利用Sequenom SNP分型技术,对UCP2和UCP3基因进行SNP分型,研究其多态性,并分析其多态位点不同基因型与黑安格斯牛生长性状的关联性。通过遗传多态性分析发现,4个SNPs(UCP2-655、UCP3-5465、UCP3-7921和UCP3-8018)均处于Hardy-Weinberg平衡状态(P0.05),除UCP2-655位点属于中度多态外(0.25PIC0.5),其余3个位点均属于低度多态(PIC0.25);利用Popgene32软件对4个位点的等位基因频率和基因型频率进行分析发现,UCP2-655位点优势等位基因A的频率为0.809;UCP3-5465位点优势等位基因G的频率为0.907;UCP3-7921位点优势等位基因G的频率为0.978;UCP3-8018位点优势等位基因C的频率为0.978;关联性分析结果表明,在本实验群体中,UCP3-5465位点对黑安格斯牛管围的效应达到显著水平(P0.05),GG型个体均值在管围方面显著高于AA型和AG型个体均值。UCP3-7921位点和UCP3-8018位点对黑安格斯牛体重的效应均达到显著水平(P0.05),UCP3-7921位点GG型个体均值在体重方面显著高于GC型个体均值,UCP3-8018位点CC型个体均值在体重方面显著高于CT型个体均值。综上,UCP3基因对黑安格斯牛部分体尺性状有显著影响,可以尝试将UCP3基因作为影响黑安格斯牛生长性状的主效基因,为黑安格斯牛选育工作提供理论依据。     

品种和饲养模式对鸡肉风味性状及其候选基因mRNA表达水平的影响

肌苷酸(inosine monophosphate acid,IMP)和肌内脂肪(intramuscular fat,IMF)是重要的肉质性状指标。为探讨品种和饲养模式对鸡(Gallus gallus)肉质风味的影响,本研究以散养和笼养的城口山地鸡、大宁河鸡和青脚麻鸡为研究群体,采用高效液相色谱仪和索氏浸提法测定鸡胸肌IMP和IMF含量,利用荧光定量PCR方法检测5个IMP候选基因和9个IMF候选基因mRNA的表达量情况。结果显示,从总体上看,城口山地鸡IMP含量高于大宁河鸡和青脚麻鸡,散养鸡IMP含量高于笼养鸡;城口山地鸡IMF含量低于大宁河鸡和青脚麻鸡,散养鸡IMF含量低于笼养鸡。IMP候选基因氨基咪唑氨甲酰核苷酸转甲酰基酶(aminoimidazole-4-carboxamide ribonucleotide transformylase/IMPcyclohydrolase,PURH)和腺苷-磷酸脱氨酶(adenosine monophosphate deaminase1,AMPD1)基因,IMF候选基因心脏型脂肪酸结合蛋白基因(heart fatty acid binding protein,H-FABP)、瘦素受体(leptin receptor,LEPR)、脂肪酸转运蛋白1基因(fatty acid transport protein 1,FATP1)和解偶联蛋白3基因(uncoupling protein 3,UCP3)胸肌组织表达量分别与胸肌IMP含量和IMF含量存在相关性。本研究结果表明,品种和饲养模式均显著影响IMP和IMF含量及其候选基因的mRNA表达,且候选基因的表达水平与IMP和IMF含量有着密切的关系。本研究结果为优质肉鸡的选育提供了一定的理论基础。     

玉米主要株型性状与产量的全基因组关联分析

为了深入剖析玉米的株型性状和产量性状的遗传基础及其相关关系,本研究以204份玉米自交系作为关联群体,利用分布于玉米全基因组上的558 529个单核苷酸多态性标记(SNPs)对5个相关性状进行全基因组关联分析。结果表明,供试自交系各性状基本呈正态分布,且各性状间存在丰富的变异,变异系数在9.00%~50.00%之间;通过相关性分析和热图层次聚类分析株型和产量相关性状间彼此紧密关联;且由主成分分析筛选出总体方差累计贡献率达到71.667%的主成分2个;以P≤1×10^-5为显著阙值,利用Q+K模型对供试材料的5个相关性状进行全基因组关联分析,在株高、穗位高和单穗重间共检测到13个显著的SNP位点,分别分布于玉米的第3、第5、第6、第7号染色体上,而在总叶片数和穗上叶数间未检测到显著的SNP位点;在显著SNP上下游各50 kb范围共搜索到39个相关候选基因,其中有注释的基因12个,并对株高与穗位高最佳候选基因进行了预测。本研究通过对玉米株型及产量相关性状进行全基因组关联分析,为后期基因功能的验证与新功能的开发奠定了良好的基础。     

鸡解耦联蛋白基因型与活性氧含量、初生重的相关性分析

为了研究解耦联蛋白基因(uncoupling protein,UCP)对鸡(Gallus gallus)初生重及活性氧含量的影响,本实验通过对3个品种鸡初生重、UCP C353T多态位点基因型以及肌肉组织活性氧(ROS)含量的测定,发现丝羽乌鸡ROS值显著低于白莱航、寿光鸡,UCP TT基因型ROS值显著高于CT和CC基因型,而ROS含量与雏鸡初生重之间存在着正向的相关性(r=0.5011),UCP TT基因型的初生重显著高于CT和CC基因型。实验结果揭示了鸡UCP基因型对初生重性状具有选择效应。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.