不同虫态谷蠹侵害对小麦淀粉组分及微观形态结构的影响

为了探讨不同生长发育阶段的谷蠹侵害对小麦淀粉组分及形态结构的影响。通过控制谷蠹侵害小麦的温度(30℃±1℃)、相对湿度(75%±5%)及虫口密度(1 000头/100 g),保证其完成一个生长发育周期,以谷蠹感染后的小麦为研究对象,对谷蠹不同发育阶段(卵期、幼虫期、蛹期、成虫期)侵害后小麦中粗淀粉、破损淀粉含量、还原糖含量及淀粉颗粒形貌及结构、淀粉粒度和淀粉结晶度进行测定与分析。结果表明:不同生长发育阶段的谷蠹对小麦侵害后,与谷蠹未侵害的小麦对照样相比,粗淀粉含量除在卵期略有增加外其余各期均低于对照样,在4个发育阶段谷蠹侵害后均呈现显著差异性(P0.05),还原糖含量、破损淀粉含量在各发育期均高于原始样,中位径变化则呈现波动性,且均明显低于原始样;还原糖含量从卵期到成虫期时均与原始样品差异性明显(P0.05),破损淀粉含量从卵期的2.42%上升至成虫期的5.58%,其中从卵期到幼虫期破损淀粉含量增幅最大;与原始样相比,小麦淀粉的X射线衍射曲线变化差异不明显,结晶度值各虫期间变化不显著(P0.05);淀粉的扫描电镜图显示:随着谷蠹由卵期发育至成虫期,其小麦籽粒中淀粉颗粒表面逐渐变得粗糙不完整,形状变得无规则,且小粒径颗粒增多,破损淀粉含量增加,大粒径淀粉颗粒表面出现较大凹坑和破损。因此,在实际的小麦储藏过程,应关注谷蠹在发育过程中的幼虫期对小麦品质的影响。     

大米淀粉纯化工艺及其性质的研究

该文采用碱性蛋白酶对碱法制备得到的大米淀粉进行纯化,酶解条件为 pH 9,温度45℃,酶与底物比48 AU/kg,时间60 min。大米淀粉中的蛋白质含量从2.87%降低到0.40%。扫描电镜分析大米淀粉的超微结构显示,碱性蛋白酶纯化处理后的大米淀粉中未见明显的蛋白质颗粒存在。比较纯化前后的大米淀粉发现,大米淀粉经过碱性蛋白酶纯化后,其溶解度和膨润力都明显增加。     

水稻胚乳糖质突变体Sug-11的淀粉粒结构和粒径分布及相关理化特性

本试验以水稻胚乳糖质突变体Sug-11与其野生型对照中花11为材料,利用扫描电镜、激光散射粒度分析仪、差示扫描量热分析仪和X-射线衍射图谱等方法,对两者稻米淀粉粒的形态结构、粒径分布、晶体结构和酶解抗性及其糊化过程中的热力学参数变化进行比较分析,揭示胚乳糖质稻米淀粉的理化特征,为稻米品质改良和功能稻米的开发提供理论依据.结果表明,胚乳糖质突变体Sug-11的稻米淀粉粒径分布呈单峰状正态分布,与野生型对照相比其稻米淀粉平均粒径值(6.48 μm)显著降低,大型淀粉粒(粒径大于8μm)比例(21.63％)显著减少,而小型和中型淀粉粒比例则明显增多,扫描电镜下Sug-11的淀粉粒结构更接近于籽粒灌浆过程胚乳尚未完全充实时的淀粉粒形态结构特点;突变体Sug-11的淀粉粒酶解抗性与野生对照相比显著下降,其抗性淀粉含量的下降幅度接近50％,同时,Sug-11除具有相对较低的淀粉糊化温度外,其淀粉粒糊化过程的热焓值(△H)也显著降低.Sug-11糖质突变体的淀粉晶体类型与野生对照相同(A型淀粉晶体),其淀粉粒的相对结晶度(35.3％)略低于对照,两者间的差异主要表现在诸尖峰的相对强度比值和相对结晶度上,而20°2θ/18°2θ的尖峰相对强度比值则高于其野生对照;糖质突变对稻米淀粉的化学组分(成)、膨胀势和溶解度也产生了十分显著的影响,突变体Sug-11的淀粉溶解度显著高于野生对照,而淀粉膨胀势和表观直链淀粉含量则显著低于野生对照材料.     

胚乳突变体在水稻淀粉合成调控研究中的作用

淀粉作为稻米最主要的储藏物质,其含量、结构及其特性影响水稻的产量和品质。随着分子生物学的不断发展,通过筛选胚乳突变体,克隆了大量调控水稻淀粉合成相关的基因,使淀粉生物合成的机理也逐渐清晰。本文综述了水稻淀粉结构、淀粉生物合成,以及淀粉突变体,包括糯性、高直链淀粉、垩白、粉质、暗色、糖质、皱缩等突变体的突变基因克隆及功能研究最新进展,以期为进一步阐明水稻淀粉生物合成的途径,以及优质水稻新品种的培育提供参考。     

水稻胚乳淀粉合成及其育种应用

淀粉是稻米胚乳的主要组成成分,具有重要的生物学功能和经济价值。籽粒胚乳淀粉合成和贮藏于一种异质化的质体中,即淀粉体。而籽粒形成期,胚乳中富集大量淀粉以充实淀粉体胞内空间并形成晶体状的淀粉颗粒,因此胚乳淀粉组成和结构会极大地影响稻米产量和食味品质的形成。本文综述了胚乳淀粉合成的分子途径,改良稻米产量和食味品质的分子策略,以期为优质稻米育种实践提供一定的理论依据。     

影响米粉品质的稻米质量指标分析

大米原料的质量是影响米粉加工性能、烹煮性能和感官品质的重要因素。影响米粉品质的大米原料质量指标主要有直链淀粉含量、胶稠度、糊化温度、蛋白质含量和储藏时间等,本文对近年来有关这些指标的研究进行了归纳总结,对各项指标对米粉品质的影响进行了逐一评述。通过总结分析可以得出,直链淀粉含量较高的籼米适宜于生产米粉;胶稠度与稻米其他各项指标有显著的相关性,可以作为选取米粉原料的主要指标;不同种类大米的糊化温度是不同的,可以根据糊化温度来指导米粉生产,避免淀粉过度糊化和米粉品质降低;蛋白质含量不仅决定大米的营养品质,也影响大米制品外观、加工和食用品质;使用陈化一段时间的大米制作米粉能够提升米粉品质。     

纳米级大米淀粉的制备及性质

为了探索纳米淀粉的新型制备方法及可行性,采用超高压均质和超微粉碎制备了纳米级大米淀粉,并研究了其颗粒粒度、吸湿性能、溶解度和膨胀率等理化性质.结果表明,超高压均质和超微粉碎能明显减小大米淀粉的颗粒粒度,成功制得纳米级大米淀粉,且随着大米淀粉粒度的减小,其吸湿性能、溶解度和膨胀率明显增加,说明纳米级大米淀粉的水合能力增强,体现了纳米级大米淀粉的表面效应和小尺寸效应.     

稻谷自然晾晒后显微结构分析研究

通过研究自然晾晒后稻谷内部的显微组织结构，可以分析稻谷应力裂纹的生成扩展机理。通过扫描电子显微镜观察，发现自然晾晒后的稻谷胚乳组织结构遭到轻微破坏，产生应力裂纹，籽实皮与胚乳之间的结合区域也有应力裂纹产生。应力裂纹首先生成在胚乳组织的中心部位，然后向四周扩展。产生应力裂纹时，只是裂纹两侧的胚乳组织遭到破坏，其它部位的胚乳组织状态良好。大多数应力裂纹扩展的路径都是穿越细胞壁，沿着淀粉颗粒的边缘进行扩展。分析研究稻谷自然晾晒后胚乳组织的形态结构以及应力裂纹的显微形态、生成位置和扩展方向，对稻谷应力裂纹检测技术的提高和干燥品质的评价都具有重要的价值。     

缓苏过程中玉米颗粒内部水分分布的数学模拟

在平面直角坐标下,利用有限元方法,对玉米颗粒在缓苏过程中的含水量变化进行了数学模拟。玉米颗粒在75℃的热风温度下干燥2小时,然后进行密闭保温缓苏,结果表明:随着缓苏时间的增加,玉米颗粒中心部位的含水量缓慢下降,表面的含水量增加较快,只有次中间部位的含水量变化较小。在玉米颗粒内部,粉质胚乳的平均含水量呈下降的趋势,而角质胚乳和胚的平均含水量是增加的。     

碾轧时间和频率对玉米淀粉机械力化学效应的影响

为了研究碾轧对玉米淀粉机械力化学效应的影响,该研究以玉米淀粉为原料,采用扫描电镜、偏光显微镜、激光共聚焦显微镜、X-射线衍射、傅立叶变换红外光谱仪、差示扫描量热仪、快速黏度分析仪等手段来研究碾轧处理时间和转速对样品的表面形貌、粒度分布、结晶结构、糊化特性和热特性等结构和性质的影响。结果表明,在频率为20 Hz条件下,碾轧处理3~9 h时,碾轧对淀粉结晶结构破坏作用较弱,主要是对颗粒的无定型区产生了破坏作用,破坏了无定型区的双螺旋结构,中央腔变大,孔道模糊。碾轧处理3~6 h时,淀粉颗粒形状发生不规则变化,粒径也发生了相应的变化,热焓值下降,而结晶度下降不显著。在碾轧处理9 h时,球状凸起变大,水溶指数、膨胀度、透光率、峰值黏度和热焓值都有所减小,而淀粉乳稳定性增强。碾轧处理12~24 h时,淀粉颗粒表面球状凸起变的不明显,淀粉颗粒结晶区内部双螺旋结构破坏,孔道增多变粗,粒径增大,热焓值下降。总之,频率为20 Hz时的碾轧处理对淀粉颗粒的无定形区、结晶区产生不同程度的机械力化学作用,导致玉米淀粉颗粒内部依次发生了受力、聚集和团聚效应。而频率为30 Hz时,由于剪切力更强,碾轧处理对淀粉结构和性质的影响更为显著。     

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.     

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,     

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.