超临界CO2静态膨胀-动态循环萃取灵芝孢子油

为了直接从未破壁的灵芝孢子中萃取油脂,在超临界CO2动态循环萃取之前引入静态膨胀工艺,考察了各膨胀因素对灵芝孢子油萃取率的影响。试验结果表明,膨胀压力越高,膨胀时间越短,静态萃取时间越长,越有利于灵芝孢子油的萃取,而膨胀温度过高或过低均不利于灵芝孢子油的萃取。超临界CO2静态膨胀-动态循环萃取灵芝孢子油的优化工艺为:膨胀压力30MPa,膨胀时间30s,膨胀温度70℃,静态萃取时间20min,在此条件下灵芝孢子油的萃取率达94.3%。     

超临界CO2萃取大蒜精油及油树脂的研究

研究了大蒜精油及油树脂的超临界CO₂提取工艺，探讨了粒度，萃取及分离的温度、压力和时间对各萃取率的影响，建立了萃取温度、压力与各萃取率的数学模型。确定了超临界CO₂同时提取大蒜精油及油树脂的优化工艺条件。     

超临界CO2萃取万寿菊花中叶黄素的研究

采用超临界CO₂萃取技术,研究了从万寿菊花中萃取叶黄素的工艺条件。对影响超临界CO₂萃取叶黄素的各种因素,包括分离参数、原料含水率、粉碎粒径，超临界萃取温度、压力、流速、时间等因素进行了考察,得到较佳的萃取工艺条件为:原料含水率10.92％，粒径40目，萃取温度60℃，压力30 MPa，CO₂流速15 L/h，分离釜Ⅰ温度40℃，压力6 MPa，分离釜Ⅱ温度20℃，时间为6 h。     

响应曲面法建立超临界CO2萃取结晶穿心莲内酯工艺模型

以穿心莲内酯含量为30%的穿心莲浸膏为试验原料，采用响应曲面分析法(Response Surface Methodology，RSM)建立了超临界CO₂萃取结晶穿心莲内酯结晶率的二次多项数学模型，验证了数学模型的有效性，并探讨了萃取结晶压力、温度、时间对结晶率的作用规律。根据该模型进行了工艺参数的优选，以结晶率为指标，试验所得穿心莲内酯超临界CO₂萃取结晶优化工艺条件为：压力20.88 MPa，温度50.27℃，时间97.02 min，该条件下结晶率高达74.77%。     

超声强化超临界CO2萃取人参皂苷的研究

为了探讨超声波对超临界CO₂萃取(SCE)的影响，考察了在不同萃取温度、萃取压力、萃取时间和流体流量下，有、无超声时超临界CO₂萃取人参皂苷的萃取率。试验结果发现，超声强化超临界CO₂萃取(USCE)的合适萃取温度比没加超声(SCE)时的低10℃；在各自合适的萃取压力下，USCE的皂苷萃取率是SCE的1.64倍；CO₂流体的流量大更有利于USCE。在SCE中，超声的加入能明显提高产物的萃取率和生产效率，降低生产能耗和节     

超临界CO2流体萃取杏仁油工艺研究

该研究以单因素试验和正交试验相结合的方法对苦杏仁脂肪油的超临界CO₂萃取工艺进行了研究。确定了超临界CO₂萃取杏仁油的最佳工艺为：萃取压力35 MPa、萃取温度50℃、CO₂流量24 L/ｈ、粒径60目、萃取时间2 h。各因素影响杏仁的得率的顺序为：粒径>时间>萃取压力>CO₂流量>萃取温度。最佳工艺验证试验的杏仁油的得率为52.98％。本研究的结果为下一步综合、无毒、高效地开发利用苦杏仁奠定了基础。     

耕作措施对华北农田CO2排放影响及水热关系分析

为探讨不同耕作措施对农田土壤呼吸排放的影响及其与土壤温度、水分之间的关系,该研究利用长期定位试验研究翻耕、旋耕、免耕3种耕作措施下冬小麦、夏玉米生育期农田CO₂的排放通量及其季节变化规律,并通过农田土壤温度、水分对CO₂的排放通量进行回归统计分析。结果表明：不同耕作措施下农田CO₂排放通量具有明显的季节排放规律,冬小麦、夏玉米生育期农田CO₂排放通量：翻耕＞旋耕＞免耕,且处理间差异都达到显著或极显著水平。不同耕作措施对农田土壤温度及土壤含水率具有显著的影响,免耕条件下农田各层土壤温度最低,冬小麦季免耕农田土壤水分含量高于其他两处理。各处理条件下农田CO₂排放通量与土壤温度具有显著的相关性,其中翻耕处理的CO₂排放通量与10 cm土温相关性最高,旋耕和免耕则均与20 cm土温相关性最高。当土壤温度高于10℃时CO₂排放通量与5 cm土壤含水率具有显著的相关性,此时土壤水分成为CO₂排放的主要影响因素。     

超临界CO2萃取小麦胚芽油的试验研究

测定并分析了小麦胚芽的粒度、含水量、萃取温度、压力和CO₂流量对小麦胚芽油的超临界CO₂萃取率及产物品质(包括脂肪酸构成、VE含量、酸价和色泽)的影响。     

柚子花芳香油超临界CO2萃取研究

介绍了新鲜柚子花中芳香性成分超临界CO₂萃取分离工艺和分析检测方法，重点探讨了压力、温度、时间对萃取率的影响。应用正交试验优化得出：影响萃取的主次因素依次为为萃取压力、萃取温度、萃取时间；较佳工艺参数为：压力18 MPa，温度50℃，时间90 min，流量25 L/min，得到超临界柚子花芳香油的萃取率高达2.7‰。应用气相色谱-质谱联用仪共鉴定出39个组分，占总芳香油的91.281%。通过对柚子花的深度加工研究，为开发高附加值的柚子花香精提供科学依据。     

根际CO2浓度对网纹甜瓜根系生长和活力的影响

采用气雾法栽培方式,在开花结果期对网纹甜瓜进行不同浓度的根际CO₂处理,探讨根际CO₂浓度对网纹甜瓜根系生长及伤流中4种内源激素含量的影响。结果表明：随着处理时间的延长,根际CO₂浓度为2500 μL/L处理和5000 μL/L处理与350 μL/L处理相比,根系的生长受到了抑制,根系活力呈先升高后降低的趋势。同时伤流液体积、电导率、pH值以及促进生长类激素IAA（生长素）、ZT（玉米素）、GA3（赤霉素）含量显著降低,而ABA（脱落酸）含量升高。说明根际CO₂浓度超过2500 μL/L就会明显影响网纹甜瓜根系生长和根系合成生长类内源激素的能力,这可能也是土壤栽培和基质无土栽培较汽雾法栽培减产的重要原因之一。     

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.     

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.     

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,     

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.