马铃薯内生固氮菌的分离及其促生特性研究

内生固氮菌是一类重要的植物促生菌,占据着植物组织内有利于营养供应和微环境适宜的生态位,能更好的发挥促生功能,促生机制包括固氮、解磷、产植物生长素、产ACC脱氨酶、产铁载体及拮抗病害等。本文从连作3年马铃薯根筛选获得8株内生固氮菌,其中短芽孢杆菌属(Brevibacterium)3株,芽孢杆菌属(Bacillus)3株和泛菌属(Pantoea)2株。促生特性研究发现:菌株Brevibacterium sp.GWR4具有较高固氮酶活性[16.206nmol C2H4/(mg蛋白质·h)],与圆褐固氮菌的固氮酶活性具有极显著性差异(P0.01);菌株Pantoea spp.GWR2、GWR3具有极高的产IAA能力,分别为186.07、162.21μg/m L,GWR2兼具产ACC脱氨酶活性[3.74μmol/(mg蛋白质·h)],GWR3兼具溶解无机磷的能力;菌株Brevibacterium sp.GWR5可以拮抗尖孢镰刀菌MLSOF(Fusarium xysporum)和茄病镰刀菌MLS-QB(Fusarium solani),兼具溶解有机磷和产IAA能力;Bacillus spp.GWR7、GWR8兼具固氮和产IAA能力。盆栽试验显示,分别接种Pantoea sp.GWR3,Brevibacterium spp.GWR4、GWR5和Bacillus spp.GWR7、GWR8后小白菜鲜重显著高于未接菌对照处理。可见,这5株菌兼具多种促生特性且对小白菜具有较好的促生效果,有望进一步研究开发成为微生物肥料生产菌种。     

甘肃地区道地药材根际固氮微生物分离鉴定

为调研甘肃中药材种植区的固氮微生物资源,从党参、黄芪和当归3种药材种植地的根际土壤中分离具有固氮酶活性的微生物,单菌株纯化并进行分子生物学鉴定,最后通过乙炔还原法检测各菌株的固氮酶活性。结果表明:这3种作物的根际土壤中固氮微生物资源丰富,共分离得到28株具有固氮酶活性的菌株,经鉴定主要为根瘤菌属、芽孢菌属、单孢菌属、无色杆菌属和粘着箭菌属等,固氮酶活性为53.5 C_2H_2nmol·(h·ml)-1~295.3 C_2H_2nmol·(h·ml)~(-1),无色杆菌属的固氮酶活性较高。此研究为下一步筛选适合中药材生长的微生物固氮菌肥的菌种提供一定的理论依据。     

固氮芽孢杆菌N3的筛选鉴定及其对二月兰的促生效果

从山东泰安农田土壤中筛选获得1株固氮能力强的菌株N3,通过形态观察、生理生化特征以及16S rDNA基因序列分析,确定为巨大芽孢杆菌属(Bacillus megaterium),该菌株固氮酶活性达C2H428.33 nmol/(h·ml).温室条件下进行二月兰盆栽试验,设置不接菌对照(CK)、接种巨大芽孢杆菌N3、接种...     

玉米根际高效固氮菌Sphingomonas sp. GD542的分离鉴定及接种效果初步研究

固氮微生物菌种选育是固氮微生物肥料生产应用的基础。本研究从玉米根际土壤分离到1株高效固氮菌株GD542,菌体短杆状,0.4μm×1.0～1.5μm,革兰氏阴性;固氮酶活性为5.046nmol(C2H4)·h-1·mg-1(蛋白);利用碳源较广泛,抗逆性较强,既可在4℃低温生长,也可以在37℃下生长,耐盐性高达10%。16SrDNA序列分析结果表明,该菌株与鞘氨醇单孢菌Sphingomonas azotifigens的16SrDNA序列有高达96%的同源性,结合形态特征和生理生化特征等,将其初步鉴定为鞘氨醇单孢菌Sphingomonas sp.。接种小白菜的温室盆栽试验表明,菌株GD542具有很好的固氮效能,与无氮对照相比,接种GD542处理植株干重增加206%,含氮量增加230%,达到统计学显著差异水平,开发应用前景较好。     

披碱草根际促生菌筛选及其接种剂的促生作用

【目的】体外促生能力是衡量微生物菌株作用的一个重要指标,测定获取的植物根际促生菌并明确其对披碱草的促生效果,可为其在生产中的应用提供依据。【方法】2014年9月从西藏阿里地区采集披碱草根系及根际土壤,以常规方法分离出其中的溶磷菌、 固氮菌和分泌3-吲哚乙酸(IAA)细菌的10株菌株。测定其溶磷量、 固氮酶活性及分泌生长素能力,并将其制成植物根际接种剂,测定接种剂对披碱草生长的影响及其在根际的定殖能力。【结果】菌株PWXZ10溶磷能力较好,达40.89 mg/L; 菌株003PWXZ6固氮酶活性较强,达421.21 nmol/(mL·h); 菌株NXP17分泌生长素能力较强,达31.33 μg/mL。与对照菌株(Pseudomonas sp. Jm92)相比,菌株003PWXZ6和NXP17制备的接种剂可显著增加披碱草株高、 地上生物量和地下生物量(P0.05),但两者之间差异不显著(P0.05); 接种剂003PWXZ6对披碱草根总长、 根表面积、 根体积、 根直径、 含磷量、 含氮量和粗蛋白含量增加显著(P0.05),分别较对照菌株(Pseudomonas sp. Jm92)增加了330%、 199%、 118%、 187%、 70%、 15%和19%,并且该菌株在根际定殖能力很强。 【结论】植物根际促生菌003PWXZ6和NXP17对披碱草具有良好促生效果,可为开发经济环保的生物肥料提供了菌种资源。     

几株高效溶磷解钾药用稻内生固氮菌的筛选与鉴定

从药用稻(Oryza officinalis)中筛选具有高效溶磷解钾的内生固氮菌,在农业生产上具有很大的潜在应用价值.本研究以药用稻为材料,采用两种选择性无氮培养基结合乙炔还原法进行内生固氮菌的分离,利用平板筛选法从所分离的内生固氮菌中筛选出高效溶磷解钾菌,应用全细胞蛋白SDS-聚丙烯酰氨凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)对所筛选到的菌株进行快速聚类.选取每个类群的代表菌株进行16S rRNA基因序列测定及生理生化鉴定.通过钼锑抗比色法和四苯硼钠法测定其溶磷解钾量,同时通过接种水稻对其促生作用进行分析.结果表明,从药用稻中筛选到了4株具有高效溶磷解钾能力的内生固氮菌,其固氮酶活性在8.78～8.88 μmol C2H4/(mL·h)之间.SDS-PAGE全细胞蛋白电泳将4株菌聚为1个类群.16S rRNA基因序列相似性分析及理化鉴定表明,代表菌株yy01为久留里伯克霍尔德菌(Burkholderia kururiensis,菌株yy01发酵培养5d后,溶无机磷量达116.28mg/L,是参比菌株变栖克雷伯氏菌(Klebsiella variicola)的2.73倍;解钾量达268.31 mg/L,是参比菌株变栖克雷伯氏菌的4.67倍.此外,yy01还具有分泌生长素等特性,接种水稻之后能明显的促进水稻的生长,其中水稻叶长增加了25.90％,根增长了42.30％,分蘖数增加了79.64％,鲜重增加了166.90％,氮、磷、钾的含量分别增加了61.54％、41.18％和54.05％.因此,从药用稻中筛选到的4株具有高效溶磷解钾能力的内生固氮菌是一类对农业生产有着重要意义的菌株.     

自生固氮菌的固氮能力及其对春小麦生长发育的影响

为挑选具有高固氮能力的自生固氮菌菌株, 用乙炔还原法对甘肃省春小麦和玉米等非豆科作物根际土壤中分离所得的13株菌进行固氮酶活性测定, 并通过盆栽试验对其进行春小麦肥效试验.结果表明:供试13株自生固氮菌对春小麦籽粒、生物产量及其构成因素均有一定促进作用, N6、N10、N13、N14、N27和N42 6株菌对春小麦产量的促进作用相对较高, 具有一定的应用前景, 有望成为微生物肥料研制的菌种.其中N13对春小麦的增产效果最为明显, 与施同量肥料(1/3N)的对照相比, 籽粒增产66.04%, 生物产量增产54.19%, 穗重增加47.65%, 穗粒数增多37.91%, 千粒重增加20.42%, 株高增加5.16%, 穗长增加21.89%, 且具有较强的固氮能力, 每盆固氮量为212.55 mg, 固氮酶活性也显著高于其他菌株, 达到139.79 nmol(C2H4)·h-1·mL-1.     

兰州地区盐碱地小麦根际联合固氮菌分离及部分特性研究

结合气相色谱仪和高效液相色谱仪 ,利用乙炔还原等方法对兰州地区盐碱地小麦根际联合固氮菌进行分离和固氮酶活性、溶磷性、分泌植物激素特性研究。结果表明 :从小麦根际分离获得的 12株联合固氮菌株固氮酶活性差异较大 (C2 H4,12 4 6～ 6 5 1 6nmolh-1ml-1) ,具有较高固氮酶活性的菌株较少 (C2 H4大于 5 0 0nmolh-1ml-1的菌株只有 4株 ) ;固氮菌株中有 2株具有溶磷性 ,其溶磷强度 (P)分别为 16 30 μgml-1和 9 82 μgml-1;9株固氮菌株可分泌IAA ,但分泌IAA浓度相对较低 (1 4 0～ 15 13μgml-1) ,大于 10 μgml-1的菌株只有 2株。从菌株固氮酶活性、溶磷性和分泌植物生长素特性看 ,Pseudomonassp ChW1、Azotobactersp ChW5、Zoogloeasp ChW6、AzotobacterchroococcumChW11和Azospirillussp ChW15等在研制小麦菌肥方面具有较大的开发潜力。     

广东省刺竹内生固氮菌多样性

采用好氧和厌氧培养方法对广东省刺竹(Bambusa blumeana)的根、茎和叶的内生细菌进行了分离和纯化,利用乙炔还原法检测了各菌株固氮酶活性,共获得40株具有较高固氮酶活性的刺竹内生固氮菌。对所获得的菌株进行SDS-PAGE全细胞蛋白电泳聚类分析,在80%相似性水平上,选取不同类群的代表菌株进行16S rRNA基因全序列测定。结果表明广东省刺竹内生固氮菌具有一定的多样性,它们分属Azospirillum(α-亚纲)、Escherichias和Pseudomonas(γ-亚纲)、Aquaspirillum(β-亚纲)。     

一株具有ACC脱氨酶活性固氮菌的筛选与鉴定

ACC（1-aminocyclopropane-1-carboxylate, 1-氨基环丙烷-1-羧酸）脱氨酶是近年来发现的许多植物促生细菌（Plant growth promoting bacteria, PGPB）共有的一个特征性酶,很多具有ACC脱氨酶活性的细菌能够增强植物抗逆性,缓解干旱、淹水、盐碱、高温、病虫害等对植物的危害。因此,ACC脱氨酶阳性细菌的筛选和研究对促进农业生产具有重要意义。本文从大量样品中分离、筛选到1株ACC脱氨酶阳性固氮菌,编号为7037,该菌株ACC脱氨酶活性为-丁酮酸2.530 mol /(hmg),protein,固氮酶活性为C2H410.068 nmol /(hmg), protein;具有较为广泛的碳源利用能力和很强的环境适应能力,被鉴定为节杆菌属（Arthrobacter sp.）的一个种。盆栽试验显示,小白菜接种7037菌株比对照组鲜重增加了139%,差异极显著。该菌株可望进一步研究开发成为微生物肥料的生产菌种。     

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。     

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.     

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,     

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.     

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.     

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.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

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,     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.