陕北黄土高原退耕还林地甘肃鼢鼠数量与植被覆盖度的相关性研究

简述了黄土高原退耕还林地植被恢复的时间序列和该时序中鼢鼠种群的消长规律。通过延安市17个样地的随机抽样调查,结果表明,甘肃鼢鼠的种群密度与退耕还林地的植被覆盖度呈极显著负相关。在黄土高原,针对预防鼢鼠危害,认为幼林成林的生态安全植被覆盖度的阈值为64.15%。     

奈树桑白蚧雌成虫空间分布型及抽样技术的研究

奈树桑白蚧雌成虫空间分布型测定结果表明：频次分布检验为负二项分布;聚集指标和Ｔａｙｌｏｒ幂法则测定为聚集分布;Ｉｗａｏ的直线回归式提示了奈权地桑白蚧雌成虫属于最普通的聚集分布,在此基础上得出田间调查的理论抽样数公式：Ｎ＝ｔ＾２／Ｄ＾２（１．７７６８／ｍ＋０．４０４１）,描述了Ｋｕｎｏ种群序贯抽样的模型：Ｔｎ＝１．７７６８／（Ｄ＾２－０．４０４１／ｎ）。     

外界铜离子浓度对柑桔小苗常量元素吸收特性的影响

以柑桔品种［Ｃｌｅｏｐａｔｒａｍａｎｄａｒｉｎ（ＣＭ）和Ｓｗｉｎｇｌｅｃｉｔｒｕｍｅｌｏ（ＳＣ）］的小苗为试验材料，应用营养液水培法，研究了不同ｐＨ值（ｐＨ４．５～７．５）范围内和不同铜离子浓度（０．１～２０．０μｍｏｌＬ－１）条件下，柑桔小苗的营养吸收特性。试验结果表明：在所有试验ｐＨ值条件下，随着营养液中铜离子浓度的增加，两个品种柑桔体内积累的铜亦呈线性增加（ｒ＝０．８６～０．９６），而小苗对常量元素（磷、钾、钙、镁）的吸收以及小苗的生长量却大大地下降，其相关性达Ｐ＝０．０１的显著水平（ｒ＝０．７７～０．９９）。当营养液中铜离子浓度≥０．１μｍｏｌＬ－１就对柑桔小苗的生长有抑制作用，干扰小苗对营养元素的吸收。     

TDB模拟侵蚀降雨器的研制与应用

最近研制的单喷头变雨强模拟侵蚀降雨器经过２５０余次性能检测,达到了如下技术指标：有效降雨面积２０～４０ｍ２;降雨强度与供水压力的关系为Ｉ＝１３．０１７ｐ１．４５６;降雨均为系数Ｋ≥０．８０;雨滴动能Ｅ、尺度参数α和中数直径ｄ５０％与供水压力之间的关系为Ｅ＝６．３７４ｐ０．４５９;α＝０．９１９ｐ０．２５９,ｄ５０％＝０．８５６ｐ０．２５８。辽宁省柞蚕场模拟土壤侵蚀试验证明：该设备体积小、重量轻、能耗低、安装操作方便、计算简单、性能可靠,是研究山区土壤侵蚀的理想设备     

用均衡试验法测定土壤吸附参数

用均衡试验法测定了５种土壤的吸附量、分布系数，阻滞因子。结果表明，土壤阻滞因子，分布系数受土壤初始浓度，土壤质地影响大。一般来说，分布系数Ｋｄ＝０．０１￣１．５０之间，阻滞因子Ｒ＝１．０￣４．５６之间，均衡试验法物理概念明确，试验简单，易操作，测定结果可靠，是用数学模型研究溶质运移问题所必需的基础实验。     

泥质海岸防护林土壤酶活性特征研究

研究了苏北淤泥质海岸防护林土壤磷酸酶活性的特点以及几种酶活性的分布规律。结果表明：（１）滨海潮土中磷酸酶以碱性磷酸酶为主,占总磷酸酶活性的６２．６％,因而可用碱性磷酸酶活性反映整个磷酸酶活性;总磷酶酶和碱性磷酸酶活性关系式为：ｙ＝－０．０４７６５＋１．６７４２６ｘ１,ｒ＝０．９７３１。（２０土壤酶活性在剖面上存在显著差异。对林地而言取样深度６０ｃｍ即满足精度要求,取样数为３－４个,当取样深度为４０     

连续UV-B胁迫对绿色型豌豆蚜生物学特性的影响

为了明确连续UV-B胁迫对绿色型豌豆蚜生长发育及种群参数的影响,将12 h内所产绿色型豌豆蚜若蚜经40 W UV-B辐射连续处理8代,每代6次,每天1次,每次分别处理20 min、30 min、40 min、50 min和60 min,每次处理后单头饲养,最终采用实验种群生命表方法进行评价,获得多代种群内禀增长率(rm)、净增殖率(R0)、平均世代周期(T)和周限增长率(λ)等生命参数。结果显示,随着辐射时间延长,世代数增加,各处理下若蚜历期最终延长,最长为8.11 d,成蚜寿命先延长后缩短,F8代为对照的6.71%~21.27%;净增殖率先升高后降低,F8代为对照的0.20%~22.32%;内禀增长率在F8代时显著降低,最高为对照的11.05%;周限增长率先升高后缩短,F8代为对照的0.90%~22.14%;F8代平均世代周期显著缩短,相对于对照减短8.54%~21.11%。连续UV-B胁迫试验中,处理时间越长,随着世代数增多,UV-B对绿色型豌豆蚜生长发育和繁殖抑制作用越强,种群数量增长越慢。     

长期施用有机肥料对紫色水稻土有机无机复合性状的影响

连续九年施用有机肥料，紫色水稻土壤及＜０．００２ｍｍ的有机无机复合体中无定形铁，铝和铬合态铁，铝的含量呈不同程度的增加，铬合态铁和铝间具拮抗作用（ｒ＝０．７９９８ｎ＝７）；土壤的有机质含量增加主要是由于轻组有机质含量增加，而有机无机复合度下降，土壤重组腐殖质的含量为０．２５－０．０１ｍｍ＞＜０．００２ｍｍ＞１－０．２５ｍｍ＞０．０１－０．００２ｍｍ；有机无机复合度及重组腐殖质中松结态与紧结态的比值     

同时测定食品中维生素B_1和维生素B_2的高效液相色谱方法

介绍了高效液相色谱法同时测定维生素Ｂ１和维生素Ｂ２的方法，该方法色谱条件为μＢｏｎｄｐａｋＣ（１８）柱；甲醇／水４０／６０（Ｖ／Ｖ）为流动相，流速为０．８ｍＬ／ｍｉｎ；采用荧光检测器（λ（Ｅｘ）＝３６５ｎｍ，λ（Ｅｍ）＝４２５ｎｍ）．维生素Ｂ１和维生素Ｂ２的平均回收率分别为９５．５０％和９５．８２％，变异系数分别为０．３７％和０．４８％．该方法具有简单、省时、干扰小等优点，并有较高的灵敏度、准确度和宽的应用范围。     

长江防护林(四川段)初期水土保持效益研究

该重点研究了新造防护林前５年的防护效益，结果林冠截留系数可达１９％，地表径流系数比荒地减少１０％至１９％，土壤蓄水能力比荒地提高９０％。造林第３年产沙量减少至造林前的０．３至０．９，第５年时仅为造林前的０．１至０．３。同时防护林效益将随林龄增加而增长。     

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.