^60Co在小麦,油菜,玉米中的吸收积累和转移规律

＾６０Ｃｏ可从土壤通过作物根系吸收，转移到地上部各个器官。试验表明，在土壤污染量为１．３×１０＾５Ｂｑ／ｋｇ土时，春小麦各器官单位重量的放射性在度为根〉老叶〉叶鞘〉茎〉颖壳〉上部叶〉籽粒；污染量２．６×１０＾５Ｂｑ／ｋｇ土时，则为根〉老叶〉颖壳〉籽粒〉茎〉叶鞘〉上部叶；污染量１．３×１０＾５Ｂｑ／ｋｇ土时，为根〉老叶〉籽粒〉颖壳〉茎〉叶鞘〉上部叶。     

冬小麦抽穗始期标记14C-同化物分配与运转的研究

采用＾１４Ｃ－示踪法研究小麦表明,始穗期标记＾１４Ｃ－同化物的分配与运转在两个冬小麦品种之间存在着显著差异,西农１３７６的＾１４Ｃ－同化物开花前在茎、穗中的分配率较高,开花后茎中＾１４Ｃ－同化物输出时间长、输出量大,因而＾１４Ｃ－同化物在籽粒中分配率较高,籽粒灌浆较好。试验还表明,＾１４Ｃ－同化物分配率和运转能力还表现出上部节位器官大于下部节位器官,且西农１３７６上下部器官分配率和运转能力的差异大     

水稻对^137Cs的叶面吸收

水稻不同生态期污染主茎单个叶片结果表明，＾１３７Ｃｓ向植株未污染部位的转移与污染叶的叶位有关，植株中的＾１３７Ｃｓ主要分布在茎叶中。受污染的水稻各部位＾１３７Ｃｓ积累量与污染量呈线性正相关，植株各未污染部位＾１３７Ｃｓ比活度大小顺序为叶－茎－根－穗。     

旱地冬小麦籽粒充实期间光合产物的分配与运转

＾１４示踪试验表明，在大田自然干旱、浇水和浇水＋追踪Ｎ肥３种处理条件下，冬小麦植株＾１４Ｃ光合产物对籽粒的比率分别为８５．９％，７８．０％和７３．４％；旗叶节以上器官－－旗叶、旗叶鞘、旗叶节间、芒及颖壳５种光合器官的＾１４Ｃ产的运至籽粒的比率分别为５９．９％，５４．２％和４４．９％。     

^14C—PP333在不同土壤中的降解动态

利用＾１４Ｃ－ＰＰ３３３研究了它在不同土壤７０％田间最大持水量及淹水情况下的降解动态。结果为两种处理的＾１４Ｃ－ＰＰ３３３均按指数衰减，半衰期分别为１２８－１６１ｄ和１４４－２２４ｄ。降解半衰期与土壤ｐＨ值呈负相关，在淹水情况下与土壤物理粘粒含量呈显著正相关。     

PP333浸种促进小麦壮苗的研究

用２０～５０ｍｇ／Ｌ的ＰＰ３３３浸种，能抑制小麦萌发种子的α－淀粉酶活性与呼吸速率，减慢萌发速度。但不影响最终的发芽率，反而使发芽更整齐。ＰＰ３３３浸种明显促进小麦壮苗的培育，表现在：第一，植株矮化，叶片短小、肥厚；第二，叶片叶绿素和可溶性蛋白质含量增加；第三，根系粗壮，支根多，根重增加，根的干物质累积提高；第四，叶片与根中的抗坏血酸氧化酶及叶中的过氧化物酶活性显著增强；第五，分蘖率提高。但不同浓度ＰＰ３３３对小麦幼苗根中过氧化物酶活性的影响表现出两重性。     

烯效唑对小麦成熟期间叶片光合同化能力及产物分配的影响

小麦齐穗期喷施烯效唑１０～４０ｐｐｍ显提高麦株叶片对＾１４ＣＯ２的同化能力，并增加＾１４ＣＯ２同化物向穗部及根系转移。研究还表明，烯效唑处理，增加了麦株主茎叶片同化的＾１４Ｃ－物质向分蘖株的运移，烯效唑处理延缓了叶片衰老，使穗粒灌浆进程延缓，灌浆时间延长，千粒重增加。     

水稻秧苗对14C－S07的吸收与运转

用浸种、土施或叶饲等方法施入＾１４Ｃ－Ｓ０７，水稻种子、根系和叶片均能吸收＾１４Ｃ－Ｓ０７。经种子吸收的＾１４Ｃ－Ｓ０７，出苗后植株各部位均有＾１４Ｃ放射性；经根系吸收的＾１４Ｃ－Ｓ０７，主要运转到地上部各器官；经叶片吸收的＾１４Ｃ－Ｓ０７，大部分滞留于原吸收部位。水稻秧苗内的＾１４Ｃ－Ｓ０７均有向顶部运输的特性。     

苯并（α）芘在土壤和水稻中降解和存在形态

土壤薄板层析测定苯并（α）芘（ＢａＰ）的Ｒｆ值小于０．１，在土壤中ＢａＰ属于不迁移性有机化合物，土壤中ＢａＰ被降解成极性化合物（占总＾１４Ｃ－ＢａＰ２３．５％）水溶形式（占１．７％）和非极性形式（占３８．４％）。土壤＾１４－Ｂａｐ组合态占３６．４％。土壤表层（０～１ｃｍ）＾１４Ｃ－ＢａＰ为０．１％，水稻苗期对ＢａＰ吸收速度快，且数量大，拔节期间吸收转缓，分蘖期后吸收达平衡。水稻体内＾１４Ｃ－ＢａＰ     

盐胁迫下大白菜吸收转运45Ca2＋的变化

在５ｍＳｃｍ＾－１和１０ｍＳｃｍ＾－１ＮａＣｌ胁迫过程中，大白菜幼苗根系膜透性、ＴＴＣ还原能力和丙二醛含量的变化显示根受到不同程度伤害。盐腔迫处理下，根系对钙的吸收速率在〔Ｃａ＾２＋〕〉０．７５ｍｍｏｌ／Ｌ时明显受到抑制。根系对＾４５Ｃａ＾２＋的积累能力分别在５ｍＳｃｍ＾－１ＮａＣｌ胁迫５ｈ生１０ｍＳｃｍ＾－１ＮａＣｌ胁迫３ｈ后受到抑制，而且大白菜各器官（根、茎、叶）对＾４５Ｃａ＾２＋的吸收、转运     

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.