石榴果实发育期果皮褐变及相关酶活性变化

为探明石榴果实发育期果皮褐变及其相关酶活性、总酚和抗氧化能力的变化规律及相互关系,以泰山红和泰山三白甜石榴为试材,研究各发育期果皮褐变度、多酚氧化酶(PPO)活性、过氧化物酶(POD)活性、苯丙氨酸解氨酶(PAL)活性、总酚含量和DPPH自由基清除率的变化。结果表明,2个品种果皮褐变度、PPO活性、POD活性、总酚含量和DPPH自由基清除率随着发育天数的增加逐渐降低,均在7月15日达到最高。2个品种果实发育期果皮PAL活性呈先降低后升高再降低的变化趋势,分别在7月15日和9月13日出现峰值。泰山红抗褐变能力高于泰山三白甜,二者分别在9月23日和9月13日采收能减轻褐变的发生。相关性分析表明,PAL、PPO、POD、总酚和DPPH自由基清除率均与石榴果实酶促褐变密切相关,石榴果实酚类物质含量高低与其抗氧化能力极显著正相关。本研究结果为深入揭示石榴果实褐变机理提供了理论依据。     

日喀则市青稞全籽粒抗氧化品质研究

为揭示日喀则青稞全籽粒所含酚类物质与抗氧化能力间的关系,遴选出抗氧化品质优异的品种,对13份青稞材料的酚类物质含量和抗氧化能力进行了品种间的多重比较分析、酚类物质含量和抗氧化能力的相关分析、抗氧化品质的主成分分析以及品种间的聚类分析。结果表明,按籽粒颜色可将13份青稞品种划分为棕、紫、黑三色,深色(紫色和黑色)品种中花色苷、原花青素、总黄酮和总酚含量较高,且氧化自由基吸收能力(ORAC)、铁离子还原能力(FRAP)、1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力也高于浅色(棕色)品种。ORAC、FRAP、DPPH自由基清除能力与酚类物质含量之间存在显著或极显著相关性,而金属离子螯合能力(MCC)与酚类物质无显著相关性。主成分分析和聚类分析结果表明,可通过籽粒颜色来进行青稞抗氧化品质初筛,深色青稞品种尤其是黑色青稞品种籽粒抗氧化品质最高。研究青稞籽粒酚类物质抗氧化有助于完善青稞抗氧化品质评价体系,为开发青稞抗氧化功能食品筛选出抗氧化能力优异的品种。     

枣果皮中酚类物质提取工艺优化及抗氧化活性分析

为提高枣果皮中的酚类物质的提取效率,该文以马牙枣为试验材料,对枣果皮中酚类物质提取条件进行了优化,同时通过测定酚类物质清除2,2’-二苯基-1-间三硝苯基联肼(DPPH),2,2'-连氮基双(3-乙基苯并噻唑啉)-6-磺酸(ABTS)自由基和铁还原能力,分析了枣果皮提取物中酚类物质的抗氧化活性。结果显示,枣果皮中酚类物质提取的最优条件是采用70%(V/V)的甲醇、在40℃下,以1∶60的料液比浸提4h,重复浸提2次。枣果皮中酚类物质具有很强的抗氧化能力,与合成抗氧化剂2,6-二叔丁基对甲酚(BHT)相比,虽然果皮中酚类物质清除ABTS·+自由基能力略低于BHT,但其清除DPPH自由基和铁还原能力与之相当。研究结果表明枣果皮中酚类物质具有很强的抗氧化能力,在一定程度上可以取代合成抗氧化剂BHT,应用于食品加工业。     

果实采前套袋对龙眼果实品质和耐贮性的影响

以福建省主栽龙眼品种“福眼”果实为材料，研究果实采前套袋对龙眼果实品质和采后耐贮性的影响。结果表明：果实采前套袋可明显改善龙眼果实的外观品质；但降低了果肉可溶性固形物、可滴定酸、维生素C和总糖等营养物质含量，导致龙眼果实甜度下降、风味变淡。果实采前套袋降低了与龙眼果皮褐变密切相关的酚类物质(包括花色素苷、类黄酮和总酚)含量和多酚氧化酶、过氧化物酶的活性，减少了龙眼果实在贮藏期间果皮褐变的发生；同时，果实采前套袋明显减轻由采前病原菌潜伏侵染所致的采后龙眼果实病害，提高果实耐贮性，延长果实贮藏期。     

石榴PAL基因的克隆与表达分析

为探究石榴PAL基因的功能及表达特性,解析石榴呈色和褐变机理,以石榴品种泰山红和泰山三白甜为试材,利用RT-PCR和RACE技术克隆PAL基因全长,分析其在不同发育期的表达情况。结果表明,从泰山红果皮c DNA中克隆得到石榴PAL基因(Gen Bank登录号为KY094504)。PAL基因ORF序列长2 205 bp,编码734个氨基酸,含有典型的苯丙氨酸和组氨酸解氨酶保守结构域、PLN02457结合位点和PLN02457超家族保守结构域;石榴PAL编码蛋白的预测分子质量为79 693.87 Da,为稳定蛋白和亲水性蛋白,存在丝氨酸、苏氨酸和酪氨酸3个磷酸化位点,二级结构中含有丰富的α-螺旋(47.55%)和无规则卷曲(30.52%);实时荧光定量PCR分析表明,泰山红和泰山三白甜果实发育过程中,PAL表达水平呈先降低后升高的变化趋势,泰山红果实发育各时期果皮中PAL表达水平均高于泰山三白甜;2个品种发育期果皮褐变度逐渐降低,且泰山三白甜褐变度明显高于泰山红;泰山红果实发育期果皮花青苷含量逐渐升高,泰山三白甜变化较平缓,且泰山红花青苷含量明显高于泰山三白甜。2个品种PAL基因表达量与褐变度呈显著正相关,泰山红PAL基因表达量与花青苷含量呈极显著负相关。本研究结果为揭示石榴果实呈色和褐变机理提供了理论依据。     

氮营养对青花菜花球酚类物质及抗氧化能力的影响

采用无机基质盆栽,研究不同氮营养水平（5、10、15和20 mmol/L）对两品种青花菜花球生长、总酚、类黄酮含量及抗氧化能力的影响。结果表明,提高氮浓度水平,有利于青花菜株高、花球直径、花球鲜重和干重的增加;两品种花球的总酚含量随着氮浓度的增加呈降低的变化趋势,当供氮浓度高于10 mmol/L,总酚含量显著降低。花球中主要含有槲皮素和山萘黄素两种黄酮醇物质,而且山萘黄素含量是槲皮素的1.48倍;在低氮 （5 mmol/L）处理下,两品种花球的槲皮素含量和绿优2号的山萘黄素含量显著高于其他处理。增加供氮浓度,花球的二苯代苦味酰基（DPPH, 1,1-diphenyl-2-picrylhydrazyl）自由基清除率和铁还原抗氧化能力(FRAP, Ferric reducing /antioxidant power assay) 值呈下降趋势,限制了其抗氧化能力。相关性分析表明,两品种花球的FRAP值与酚类物质的正相关性显著高于DPPH自由基清除率。两品种相比较,中晚熟品种马拉松的花球直径、鲜重和干重显著高于中早熟品种绿优2号,而其总酚含量和抗氧化能力明显低于绿优2号。以上结果说明,通过氮营养水平能够调控青花菜酚类物质合成和抗氧化能力,从而为生产高营养品质的青花菜产品提供了可能的途径。     

L-半胱氨酸处理对采后青脆李果实苯丙烷代谢的影响

L-半胱氨酸(L-cysteine)作为生物体中的常见氨基酸,已有研究发现其能有效延缓青脆李果实的衰老和品质的下降。然而,L-半胱氨酸处理对李果实中苯丙烷代谢途径合成酚类物质的影响尚不清楚。因此,该研究以青脆李果实为试材,采用1 g/L L-半胱氨酸浸泡处理后于(20±1)℃贮藏,研究贮藏期间苯丙烷代谢途径中关键酶活性以及总酚、总黄酮等相关代谢产物的变化规律,同时测定果实中糖酸含量和抗氧化活性的变化。结果表明,李果实在贮藏过程中可溶性固形物(Total soluble solids,TSS)含量和可滴定酸(Titratable acid,TA)呈逐渐降低的趋势,L-半胱氨酸处理显著延缓了李果实TSS和TA的下降(P0.05)。在贮藏期间,苯丙烷代谢途径中关键酶活性均呈逐渐上升的趋势,与对照组相比,处理组中苯丙氨酸解氨酶、4-香豆酸辅酶A连接酶活性更高。果实中总酚、总黄酮含量在贮藏期间先降低后上升,在贮藏前三天,处理组中总酚、总黄酮含量显著高于对照组(P0.05)。对酚类物质单体含量的测定发现,处理后的果实中绿原酸、咖啡酸、丁香酸、芦丁等酚类物质单体含量显著高于对照组(P0.05)。抗氧化活性与总酚、总黄酮的变化趋势一致,经L-半胱氨酸处理后的果实保持了较高的抗氧化活性。相关性分析结果表明,果实中苯丙氨酸解氨酶、肉桂酸-4-羟基化酶和4-香豆酸辅酶A连接酶与果实酚类物质含量及抗氧化活性显著相关(P0.05)。总体来说,1 g/L L-半胱氨酸浸泡处理能够延缓青脆李果实贮藏品质下降,同时能够激活苯丙烷代谢途径关键酶,促进果实中酚类物质的积累。     

不同番茄品种中类黄酮和咖啡酰奎尼酸含量测定及与抗氧化能力相关分析

为了研究番茄不同遗传种质资源中类黄酮和咖啡酰奎尼酸的含量差别及其与抗氧化能力的相关性,应用HPLC方法分别测定了23个番茄品种的果皮和果肉中芦丁、山奈酚芸香苷、绿原酸、1,5-二咖啡酰奎尼酸和3,4,5-三咖啡酰奎尼酸的含量,并与其抗氧化能力进行了相关性分析。结果表明,在不同品种的番茄果实中类黄酮和咖啡酰奎尼酸的含量差异显著,在同一番茄品种的果皮和果肉中其含量也有较大差别。此外,相关性分析的结果表明,多数所测物质的含量与抗氧化能力均具有一定的相关性。     

云南红梨色素变化规律及套袋对果实品质的影响

以高接的早熟、中熟、晚熟3个梨树品系为试材,研究在果实发育期间色素(叶绿素、花青苷、胡萝卜素)的动态变化规律以及色素之间的相互关系;同时研究套袋对果实上色及品质的影响。结果表明:①果实发育过程中,果皮随叶绿素的降解,花青苷大量合成。在研究红梨上色时发现,花青苷含量与叶绿素含量呈负相关,相关系数和回归系数分别是:早熟R2=0.9283,回归系数b=-2.6101;中熟R2=0.4781,回归系数b=-1.2509;晚熟R2=0.5588,回归系数b=-1.2340。②胡萝卜素含量的变化与花青苷的基本一致,在果实花青苷大量积累的同时,胡萝卜素也大量积累。③在同时满足外观和内在品质的要求下,以采用单层白色膜袋套袋为最佳选择。     

贵州不同生态区蓝莓果实抗氧化特性研究

为了探讨贵州省不同生态区不同蓝莓品种果实抗氧化能力的差异,对不同生态区蓝莓品种选育及栽种配置做出合理规划。选择贵州省3个不同海拔生态区内种植5年生的4个蓝莓品种,并分别对供试蓝莓果实样品的总抗氧化能力、羟自由基清除能力和DPPH自由基清除能力进行测定,并结合测定蓝莓果实中总酚、类黄酮和原花色素含量,对蓝莓果实的抗氧化能力进行评价,结果表明,在高海拔地区蓝莓果实抗氧化能力强于低海拔地区,4个品种中"园蓝"的综合抗氧化能力最强;兔眼蓝莓中"园蓝"抗氧化能力强于"灿烂",高丛类蓝莓中"蓝雨"的抗氧化能力强于"莱克西"。蓝莓果实中原花青素含量、类黄酮含量、总酚含量与植株抗氧化活性显著相关(p0.01)。     

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,     

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.     

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.