3种不同腌渍方式对腌渍黄瓜品质的影响

为改善低盐腌渍蔬菜品质下降的问题,本研究通过分析测定腌渍黄瓜的微观结构、质构性质、风味物质,研究低盐腌渍、复合腌制剂腌渍、高盐腌渍3种不同腌渍方式对腌渍黄瓜品质的影响。结果表明,高盐腌渍黄瓜和复合腌制剂腌渍黄瓜的质构及风味品质均优于低盐腌渍黄瓜。其中,高盐腌渍黄瓜的硬度略高于复合腌制剂腌渍黄瓜,氨基酸总量和有机酸总量差别不大;复合腌制剂腌渍黄瓜的硬度比低盐腌渍黄瓜高271 g;氨基酸、有机酸总量分别比低盐腌渍黄瓜样品高35.3和55.1 mg·100g^-1。 复合腌制剂腌渍黄瓜的质构、风味和感官等品质接近传统高盐腌渍黄瓜,优于低盐腌渍黄瓜。本研究结果为有效解决低盐腌渍使得黄瓜品质下降提供了一定的数据支持。     

汽爆玉米秸秆同步糖化发酵产乙醇的工艺优化

该文对同步糖化发酵玉米秸秆生产纤维乙醇的工艺条件进行了研究,分别利用单因素试验和正交试验考察了影响发酵的工艺条件。结果显示：温度37℃、pH值4.8、底物15%（质量分数）、表面活性剂Tween-20 0.15%（质量分数）、纤维素酶用量30 U/g、酵母用2%的葡萄糖溶液活化,接种量5‰（相对底物干质量）、培养基的组成：KH2PO4 2.5 g/L,(NH4)2SO4 2.0 g/L,MgSO4·7H2O 0.15 g/L,CaCl2 0.35 g/L、发酵时间60 h为同步糖化发酵（SSF）生产乙醇的最优工艺条件,该条件下乙醇的体积分数为2.85%,乙醇得率达理论值的88.12%。     

猪粪秸秆不同物料比对固体产酸发酵效果的影响

在沼液回流的条件下,研究猪粪和秸秆固体产酸发酵过程中,不同原料配比（猪粪与秸秆质量比分别为4︰1、2︰1、1︰1、1︰3和0︰1即纯秸秆）对产酸发酵效果的影响。试验结果表明：增加发酵原料猪粪比例有利于调节发酵体系pH值,但酸化液中氨氮质量浓度较高;沼液回流能有效避免体系过酸现象;上述不同原料质量配比产酸发酵产物以乙酸为主,试验周期内,累积产乙酸质量分别占各反应器挥发性脂肪酸（VFAs）总质量的80.8%、81.8%、77.1%、78.3%和73.8%,酸化液中丙酸质量浓度均低于1.6 g/L,累积产生质量分别占各反应器VFAs总质量的4.8%、2.8%、7.2%、6.5%和8.4%。综合分析表明,猪粪与秸秆比为2︰1时,发酵过程中产酸效果优于其他配比试验。     

堆肥隧道式后发酵技术及效果

该文采用发酵隧道对堆肥进行后发酵处理,并测定发酵过程中的温度、pH值、含氮量、微生物的变化,旨在为集约化生产双孢蘑菇培养料提供理论依据。该技术可以对堆肥进行10 h以上的巴氏灭菌（温度在57～62℃之间）处理和5 d的腐熟处理（温度在45～53℃之间）。处理后发酵堆肥中氮质量分数从1.58%增加至1.85%;pH值从8.7下降到7.5。嗜热细菌的菌落数从5.2×108 cfu/g上升到7.3×108 cfu/g（第3天）,发酵结束时降低为2.88×108 cfu/g;放线菌和嗜热真菌菌落数发酵开始时分别为2.4×105 cfu/g 和3.2×104 cfu/g,发酵结束时分别为19.6×105 cfu/g和10.1×104 cfu/g。试验结果表明,经过隧道式后发酵的堆肥适合于双孢蘑菇生长需要,隧道式后发酵技术可以用于规模化生产优质双孢蘑菇培养料。     

磁场及流速场条件下盐渍液快速腌渍芥菜

为了实现对芥菜的快速腌渍,采用磁场和流动盐液相结合的方式对样品进行处理,并与静置条件下的腌渍进行了对比。利用不同磁感应强度的磁场(200、1 000、2 000 Gs)和流速场(0.03、0.06、0.22 m/s)完成对芥菜的腌渍处理,同时考察了传质动力学方程。结果表明:当腌渍条件于磁感应强度2 000 Gs和流速0.06 m/s时,可在180 min时间内使样品表层盐分达到饱和,盐分扩散系数为k=2.35×10-2 min-1,而当腌渍液处于湍流(0.22 m/s,雷诺数Re=4 132)的情况下则不利于盐分扩散,只施加磁场的静置腌渍对传质无显著提高(P0.05),而当腌渍液在层流状态下(雷诺数Re=563和1 127)则有利于盐分向多孔状原料的渗透,最佳工艺参数为磁感应强度B=2 000 Gs和流速v=0.06 m/s且该条件下的传质动力学模型可采用Logistic方程进行描述,预测方程决定系数为R2=0.976,该研究为农产品快速浸渍加工提供了参考。     

鲤鱼酶解发酵制饮料的技术研究

该文对鲤鱼酶解发酵制饮料的加工技术进行了研究。结果表明：枯草杆菌蛋白酶酶解鲤鱼蛋白的最佳酶解条件是酶用量(酶与底物浓度比，E/S)0.12 g/kg，温度45℃，pH值8.0,在此条件下酶解鲤鱼4 h，氨基态氮含量由0.0017 g/L增加到0.0414 g/L，增加了23倍；游离氨基酸由19.943 mg/(100 mL)增加到78.001 mg/(100 mL)，增加了291%。经保加利亚乳杆菌和嗜热链球菌发酵后，酶解液风味得到明显改善，并产生了特殊的乳酸发酵香味。鲤鱼高压水煮液体外·OH清除率为0.97％，经枯草杆菌蛋白酶酶解后酶解液体外·OH清除率为80.21％，酶解发酵液体外·OH清除率为78.74％。鲤鱼蛋白经酶解和发酵后体外·OH清除能力都得到明显的提高。鲤鱼饮料的配方组成是：鲤鱼酶解发酵过滤液80 g/kg，麦芽糖30 g/kg，蔗糖45 g/kg，乳化稳定剂3 g/kg，浓缩苹果汁15 g/kg，酸味剂和香精适量。     

基于间歇非稳态方法的溶氧装置增氧能力检测

针对常用溶氧装置增氧能力试验操作随意性和试验误差较大的缺点,通过试验研究,提出了一种基于间歇非稳态法的试验方法。从所需设施、设备,试验过程和计算方法几个方面进行了具体的说明。使用该方法对DP18-Y型多腔喷淋式溶氧装置进行了验证试验：在气液比（G/L）1︰100和1.5︰100两种条件下,系统稳定运行约130和220 min,池内的平均溶解氧质量浓度达到17 mg/L（接近理论饱和溶解氧浓度）,3个测量点示值误差在±0.78 mg/L范围内;在两种气液比条件下重复进行3次试验,增氧能力计算结果分别为(20     

纳米TiO2对黄瓜叶围细菌群落的影响

利用可培养和变性梯度凝胶电泳(DGGE)方法,对经不同浓度TiO2处理黄瓜(Cucumis sativus)叶围细菌群落结构的变化进行了分析。研究发现,TiO2处理后黄瓜叶围可培养细菌数量较对照显著降低。随着TiO2浓度从0.02 mg/mL提高至20 mg/mL,黄瓜叶围可培养细菌数量从1.8×107 cfu/g降低至3.1×106 cfu/g。DGGE指纹图谱分析表明,当TiO2的喷雾浓度超过0.02 mg/mL时,黄瓜叶围细菌的多样性显著降低。对DGGE条带克隆测序结果显示,在黄瓜叶围至少存在7种不同属的细菌,其中只有一种叶围细菌不受TiO2喷雾浓度影响。     

秸秆生物反应堆对温室葡萄根围土壤微环境及生长的影响

为了探究秸秆生物反应堆对寒冷地区温室葡萄根系周围土壤微环境及生长的影响，在温室内开展了葡萄秸秆生物反应堆栽培试验，共设计了4个处理（秸秆2.4×104 kg/hm2+发酵菌种配比2‰、秸秆3.6×104 kg/hm2+发酵菌种配比2‰、秸秆2.4×104 kg/hm2+发酵菌种配比3‰、秸秆3.6×104 kg/hm2+发酵菌种配比3‰），并以常规栽培作为对照。结果表明：1）在葡萄行间设置秸秆生物反应堆的当年，地温得到了明显提升，且生物反应堆中发酵菌种配比越高，则秸秆在前期发酵越快，地温变幅越大，但秸秆生物反应堆处理对下一年地温的影响微小；2）葡萄行间秸秆生物反应堆处理可以有效提高土壤中细菌和真菌数量，且反应堆中秸秆用量较高的处理（3.6×104 kg/hm2）对应的土壤细菌数量与秸秆用量较低的处理（2.4×104 kg/hm2）之间的差异达到显著水平（P<0.05），但秸秆生物反应堆处理对土壤放线菌的影响相对较小；3)在秸秆生物反应堆处理的当年，土壤脲酶活性大幅升高，增幅在38.5%～68.4%，但在下一年其活性相对稳定，而土壤蔗糖酶的活性却表现出持续升高的趋势，且在反应堆中秸秆用量相同的条件下，生物发酵菌种配比为2‰和3‰处理之间的差异并不显著（P>0.05）；4)在葡萄行间设置秸秆生物反应堆，可以有效提高葡萄根系活力和产量，在处理的当年，葡萄产量增幅为11.5%～17.2%，且还能促进下一年增产，增幅为9.6%～15.7%。综上，在葡萄行间设置秸秆生物反应堆处理后，根系周围土壤微环境得到明显改善，对葡萄生长产生了积极的效应，且生物反应堆中秸秆用量为3.6×104 kg/hm2、发酵菌种配比为2‰时处理效果较佳。该研究结果对寒冷地区温室葡萄生产具有一定的指导意义和参考依据。     

草坪草糖化及发酵生产燃料乙醇

为利用草坪草生产燃料乙醇,通过粉碎和碱性氧化物浸泡预处理草坪草,采用纤维素酶和果胶酶混合糖化纤维素,研究嗜鞣管囊酵母和酿酒酵母发酵水解液生产乙醇,结果表明,碱性氧化物固液比为1:40（质量比）,浸泡48 h预处理后的木质素脱除率为70%（质量分数）;嗜鞣管囊酵母和酿酒酵母发酵30 h后乙醇的质量体积分数最高,分别为9.6 g/L和11.7 g/L,以可发酵糖减少量计算,糖醇转化率分别为25.7%和38.1%（质量分数）,为理论糖醇转化率的61.2%和74.7%。     

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,     

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.     

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.