西藏卓巴百合组织培养技术研究

对西藏野生卓巴百合（Lilium wardlii stapf)进行组织培养结果表明，选用球茎内层、基部的鳞片作为外殖体，转绿率最高；在参试的培养基中MS＋BA0.5mg/kg NAA0.5-1.0mg/kg的培养基对诱导愈伤组织（EC）和不定芽的效果较好，MS＋IBA1.0mg/kg对促进小鳞茎生根效果最佳；茎盘切块在MS＋BA0.2-0.5mg/kg＋NAA0.5-1.0mg/kg的培养基上能正常转录，形成愈伤组织和不定芽；活性碳有助于小鳞茎生根；组培苗移栽到松锯末中其成活率可达到95％。     

金线莲组培快繁技术研究

以金线莲植株茎段为外植体,MS为基本培养基,附加不同浓度的植物生长调节剂组合进行组织培养与快繁研究,结果表明不定芽诱导与继代增殖的较适宜的培养基分别为MS＋6-BA1.0mg/L＋KT1.0mg/L,MS＋6-BA1.0mg/L＋NAA0.5mg/L;生根培养基以MS＋IBA0.5mg/L＋活性炭0.5g/L＋香蕉泥20g/L为宜。     

牛角瓜的组织培养

以牛角瓜的叶片为外植体,进行牛角瓜的组织培养。结果表明,培养基MS 2,4-D 2 mg/L利于愈伤组织的诱导;培养基MS 6-BA 0.5 mg/L NAA 0.1 mg/L有利于芽的分化和增殖;生根壮苗的培养基为1/2 MS NAA 0.5 mg/L,其生根率100%;试管苗生根培养30 d后移栽,成活率可达85%以上。     

滇黄芩器官发生与不同继代次数遗传稳定性的RAPD分析

本研究以滇黄芩不带腋芽茎段为外植体,采用不同配比激素的MS培养基建立了滇黄芩器官发生,植株再生体系。结果表明,茎段在MS＋6-BA 2mg／L＋NAA 0.5mg／L培养基上培养时,愈伤组织诱导率达到100％;以相同培养基进行分化,并在MS＋6-BA 2mg／L＋NAA 0.2mg／L培养基上扩繁丛生芽。在1／2MS＋IBA 0.2mg／L培养基诱导生根,扦插继代。利用RAPD分析不同继代次数再生植株,所用的39条随机引物中只有1条引物带型发生变化。说明经组织培养获得的再生植株遗传稳定,可多次继代培养,为滇黄芩进一步遗传操作和扩大药材资源奠定基础。     

绣球绣线菊组培快繁体系的建立

本研究采取绣球绣线菊幼嫩茎段作为外植体,进行离体组织培养,获得了正常健康的再生植株.研究中通过对外植体灭菌时间的筛选,以及对绣球绣线菊初代、继代和壮苗生根培养基的筛选进行研究,建立了较为适宜的绣球绣线菊组织培养快繁体系.以0.1%HgCl2灭菌8 min可以达到较好的外植体灭菌效果.初代培养的最佳培养基为MS BA0.5 mg/L NAA0.5 mg/L;适宜的增殖培养基为MS BA 1.0mg/L NAA0.1 mg/L;适宜的壮苗生根组合培养基是1/2MS BA0.3 mg/L IBA0.5 mg/L,生根状况表现良好.     

箭根薯的试管繁殖

本实验用箭根薯成熟种子为材料，培育出无菌幼苗，再用幼叶、叶柄进行试管繁殖。经实验得出各阶段适宜的培养基分别为：（1）种子萌了：MS＋6－BA 1mg/L(单位下同）＋NAA 0．1；（2）诱导愈伤组织：MS＋6－BA 1＋2，4－D 1．5＋KT0．2；（3）丛芽诱导：MS＋6－BA0．5＋NAA0．5；（4）生根培养：1／2MS＋NAA0．5。     

红掌的离体组织培养与快速繁殖

本研究从红掌组培的实用化生产出发,在不同激素成份及浓度水平下,以MS为基本培养基,红掌的叶片或叶柄为外植体进行组培快繁试验。实验结果表明：MS＋6-BA1mg/L＋2.4-D0.1mg/L为最佳诱导培养基,诱导率可达89%以上,红掌的叶片诱导效果比叶柄较为理想。最适分化培养基为：MS＋BA1.5mg/L＋NAA0.1mg/L,其分化率为93%;继代增殖培养基为MS＋6-BA2mg/L＋NAA0.2mg/L,增殖系数达7.1;适合生根诱导培养基为l/2MS＋NAA0.2mg/L,生根率达96.5%以上。生根苗田间移栽后成活率可达95%以上。     

枣幼胚子叶再生植株的研究

本试验研究了影响金丝小枣幼胚子叶再生植株的相关因素,获得了金丝小枣幼胚子叶的再生植株。正交试验结果表明:金丝小枣幼胚子叶在附加TDZ0.6mg/L、IAA0.5mg/L、NAA0.3mg/L的1/2MS培养基中,暗培养20d,愈伤组织诱导率和再生频率均最高,分别达到100%和41.86%。再生获得的不定芽在MS培养基上,添加6-BA1.0mg/L和IBA0.1mg/L,增殖效果最好;在1/2MS+IBA1.0mg/L培养基上,生根率达到100%。     

大花卷丹百合组培快繁技术研究

为获得大花卷丹百合的优质种苗，促进其规模化生产，以大花卷丹百合的鳞片为外植体，采用MS、N6、B5培养基，添加激素NAA、6-BA、GA3，进行了大花卷丹百合的快繁技术研究。结果表明，外植体在N6培养基中产生愈伤组织最快、效果最好。愈伤组织及不定芽诱导最佳培养基配方为N6+1.0 mg/L 6-BA+0.1 mg/L NAA；不定芽增殖最佳培养基为N6+0.5 mg/L 6-BA+0.1 mg/L NAA+1.0 mg/L GA3。NAA诱导小鳞茎效果最佳，最适培养基为 N6+1.0 mg/L NAA；促进小鳞茎膨大生根要在诱导鳞茎的基础上加入IBA，即最适培养基为N6+0.1 mg/L NAA+2.0 mg/L IBA。     

食用仙人掌的离体快速繁殖

仙人掌茎段的腋芽 (刺座芽 )在 MS 6-BA0 .5 mg/L NAA0 .1 mg/L培养基上培养 30 d,可诱导产生 1～ 2个小芽 ,将小芽分切继代培养 ( 2 5 d为 1周期转移培养 1次 ) ,繁殖系数达 3～ 4。芽长2～ 3cm时再切分成单芽 ,在 1 /2 MS NAA0 .1～ 0 .5 mg/L或 IBA1～ 3mg/L 活性炭 0 .2 %培养基上进行生根培养 ,培养 2 5 d,生根率达 85 %以上。移栽成活率 90 %以上     

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,     

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.     

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.     

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.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

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.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.