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1.
本研究用GnRH并列体二聚物(GnRH-TDK)主动免疫SD雄性大鼠观察其对大鼠垂体-睾丸轴功能的影响,以探讨GnRH主动免疫去势的分子机理.24只性成熟SD雄鼠随机分为免疫组和对照组,免疫组雄鼠于12周龄时初免,8周后加免,对照组雄鼠不做任何注射.每两周采集血液放免法检测血清抗体滴度及激素含量变化.加免后4周脱颈处死所有雄鼠,收集垂体、睾丸实时荧光定量PCR分析相关生殖基因mRNA的变化.结果显示,GnRH主动免疫后12只免疫雄鼠中11只血清GnRH抗体滴度显著上升,血清LH、FSH及睾酮(T)均极显著下降到检测限附近或以下(p＜0.01),同时睾丸严重萎缩,其重量及体积下降到对照组睾丸的20％(p＜0.01),组织切片显示,曲细精管上皮组织严重受损,管内仅有少数退化的精原细胞.与对照组相比,GnRH主动免疫极显著下调雄鼠垂体GnRH受体、LH-β、FSH-β和睾丸LH受体及FSH受体mRNA表达水平(p＜0.01).由此可见,GnRH主动免疫可通过下调垂体GnRH受体、促性腺激素亚基及睾丸LH、FSH受体基因表达,影响垂体-睾丸轴的功能. 相似文献
2.
用蛋白结构修饰后的促性腺激素释放激素并列体二聚物(G6k-GnRH-Tandem-Dimer,GnRH-TDK)2次免疫公兔,研究了该疫苗对公兔生殖性能和生长情况的影响。12只公兔随机分为免疫组和对照组,免疫组于3月龄初免,4周后加免1次。每周采用放射免疫分析法测定公兔血清睾酮水平,发现免疫组睾酮浓度从82.74±16.03ng/ml降至59.24±16.18ng/ml;观察其体重和性行为,免疫组无明显性行为,体重与对照组接近。免疫后9周屠宰公兔比较睾丸重量、体积和精液质量,进行睾丸组织学分析,发现免疫组睾丸大小、精子密度极显著(P<0.01)低于对照组,其睾丸组织结构病变明显。这些现象表明,用新蛋白构型GnRH多肽免疫后,公兔睾酮分泌减少,睾丸发育受阻,精子密度和活力降低,去势效果好,且不影响动物的生长。 相似文献
3.
本研究采用GnRH并列体二聚物(GnRH-Tandem-Dimer,GTD)为免疫原主动免疫SD雌鼠,检测下丘脑-垂体-卵巢轴生殖相关基因表达变化,分析主动免疫GTD对SD雌鼠生殖功能的影响。选取48只性成熟SD雌鼠随机分为GTD免疫去势组和空白组。免疫组雌鼠于12周龄时初免GTD免疫去势疫苗,4周后加免。每两周采集血液检测血清激素含量变化。分别于加免后4、8、12周处死大鼠,每组处死8只,收集血液;并采集下丘脑、垂体、卵巢,分析生殖相关基因mRNA表达变化。结果显示,GTD主动免疫后大鼠卵巢严重萎缩,重量下降到对照组的23.12%(p0.05);血清FSH、LH、P4及E2含量均显著下降(p0.05);除下丘脑GnRH mRNA先上升后下降外,下丘脑ER、垂体GnRH-R、LH-β、FSH-β和卵巢LH-R、FSH-R和ER mRNA表达水平显著下调(p0.05)。结果表明,GTD主动免疫可通过对生殖内分泌激素分泌的调节和对生殖相关基因mRNA表达水平的调控,影响下丘脑-垂体-卵巢轴的功能。 相似文献
4.
为比较不同剂量非甲基化寡聚脱氧核苷酸(CpG-ODN)免疫佐剂与J亚群禽白血病病毒(Subgroup J Avian leukosis virus,ALV-J)gp85重组蛋白联合免疫后诱导母鸡血清抗体和母源抗体的效果,利用原核表达系统制备包含gp85基因的重组蛋白作为免疫原,与不同剂量CpG免疫佐剂联合接种成年海兰褐父母代种母鸡(Gallus domesticus),首免后2周加强免疫一次,于接种前和接种后每周动态检测血清抗体,接种后部分鸡只每周收集种蛋,检测卵黄抗体。结果显示,利用原核表达系统制备的gp85重组蛋白能与ALV-J单克隆抗体JE9特异性结合;与3个不同剂量CpG联合免疫成年种母鸡后均诱导鸡只产生一定效价的血清抗体,首免后28 d效价最高;所诱导的卵黄抗体效价首免后第4周最高。其中以50μg/羽剂量的CpG联合重组蛋白接种鸡只诱导的血清抗体和卵黄抗体效价和阳性比例最佳,100μg/羽剂量的CpG次之。3个不同剂量的CpG与ALV-J gp85重组蛋白联合免疫均能诱导母鸡产生一定的血清抗体和卵黄抗体,50μg/羽剂量的CpG联合免疫的效果明显优于较高剂量的免疫效果。本研究为使用CpG联合ALV-J gp85重组蛋白诱导母鸡产生母源抗体,阻断ALV-J早期感染提供科学依据。 相似文献
5.
PRRSV GP5和M蛋白重组腺病毒对猪的安全性和免疫效力 总被引：3，自引：0，他引：3
将猪繁殖与呼吸综合征病毒(PRRSV) GP5 重组腺病毒(recombinant Adenovirus-GP5,rAd-GP5)和M蛋白重组腺病毒(rAd‐M)分别接种4只30日龄PRRSV阴性断奶健康仔猪，结果为仔猪接种后2周内体温和食欲正常，猪血液、鼻塞、粪便和猪舍环境中重组腺病毒及其野生型腺病毒检测均为阴性。同时，将rAd‐GP5、rAd-M、rAd-GP5+M (rAd-GP5和rAd-M,V/V=1)和PRRSV-Resp弱毒株分别接种4只30日龄PRRSV阴性仔猪，不同时间检测PRRSV抗体，结果为免疫后14和45 d可检出PRRSV ELISA抗体和中和抗体；免疫后60～90 d，rAd-GP5和rAd-M免疫组ELISA抗体滴度均达1∶2400以上，与PRRSV‐Resp弱毒免疫组相似，而中和抗体滴度达1∶6以上，低于PRRSV-Resp弱毒免疫组；rAd-M免疫组ELISA抗体和中和抗体滴度则低于rAd‐GP5免疫组。rAd-GP5和rAd-M混合免疫组ELISA抗体达1∶4800,其中和抗体滴度与其单独免疫组相似。15只仔猪免疫后28 d进行攻毒保护试验，结果为重组腺病毒免疫猪攻毒后3 d平均体温为39.5℃,病毒血症和排毒时间仅为2周，与PRRSV-Resp弱毒免疫组相似，而空白对照组病毒血症和排毒时间至少60 d。攻毒后7～14 d，rAd-GP5和rAd‐M免疫组ELISA抗体和中和抗体水平明显升高。研究表明rAd-GP5和rAd-M重组腺病毒具有较好的安全性，均可诱导猪体产生较好的免疫反应，两者具有明显的协同免疫作用。 相似文献
6.
鸡主要组织相容性复合体(MHC)由一组紧密连锁的、高度多态的基因座位所组成,在机体的免疫应答和调控等方面具有极其重要的作用.本研究旨在研究3个地方鸡(Gallus domestic us)品种(鲁禽鸡、琅琊鸡、石岐杂鸡)Major histocompatibility complex (MHC) B-F基因遗传变异与Sheep red blood cell (SRBC)、Avian influenza (AI)和Newcastle disease(ND)免疫抗体滴度等免疫性状的关系,揭示不同品种间基因变异与免疫性状的相关性.研究结果表明:3个品种SRBC免疫抗体滴度石歧杂鸡最高,与另外两个品种差异极显著(P＜0.01); ND、H9抗体滴度趋势与SRBC一致,石歧杂另外两个品种差异极显著(P＜0.01); H5抗体滴度石歧杂鸡最低,与另外两个品种差异极显著(P＜0.01)；亲缘关系较近的琅琊鸡和鲁禽鸡在4个抗体间结果基本一致,2个品种间差异均不显著(P＞0.05).通过PCR-SSCP方法分析了包括MHC B-F基因外显子2在内长度为396 bp的片段.在这3个品种中分别发现了49、45和41个核苷酸变异位点,其中分别有40、37和32个引起了氨基酸突变,关联分析结果表明:3个品种中分别有6、9、4个SNPs位点与所检测的免疫性状显著相关(P＜0.05).亲缘关系最近的鲁禽和琅琊鸡其基因变异与免疫性状相关性基本一致,二者共有5个变异位点与免疫性状相关性一致,其中位点A192C、A217G均与新城疫抗体滴度显著相关(P＜0.05),位点A217G与禽流感H5抗体滴度显著相关(P＜0.05),位点A211G与禽流感H9抗体滴度显著相关(P＜0.05),位点G232A与绵羊红细胞抗体滴度显著相关(P＜0.05).在石歧杂鸡中位点C183G与新城疫、禽流感H9抗体滴度显著相关(P＜0.05).研究结果对于临床疫苗的使用具有重要的指导作用. 相似文献
7.
将人工合成促性腺激素释放激素(GnRH)六聚体基因片段连接至pMAL-c4x载体,获得的pMAL-c4x-GnRH6重组质粒转化到大肠杆菌TB1中进行表达.采用SDS-PAGE,Western blot进行鉴定,并通过动物实验对表达产物的免疫原性进行检测.获得了分子量大小约为50 kD的麦芽糖结合蛋白-GnRH六聚体(MBP-GnRH6),且融合蛋白与GnRH抗体的反应性较好,并能使睾丸萎缩、变性.表明重组MBP-GnRH6融合蛋白具有较好的反应原性和免疫原性,可用于小鼠的免疫去势. 相似文献
8.
利用基因免疫技术,以成功构建的串联抑制素重组质粒pcDNA-DPPISS-DINH和pcDNA-DPPISS-DINH-sC3d3为免疫原,对60只绵羊(Ovis aries)进行基因免疫试验;应用酶联免疫法(ELISA)检测抗抑制素抗体;放射免疫法(RIA)测定处理后不同时期血清中激素水平.结果表明,重组质粒pcDNA-DPPISS-DINH和pcDNA-DPPISS-DINH-sC3d3免疫绵羊后,各实验组P(血样吸光值)/N(对照吸光值)值均显著高于对照组(P<0.05),且在第3次加强免疫后抗体水平明显上升.首次免疫后,促卵泡素(FSH)平均含量均高于对照组,且在第2次、第3次加强免疫阶段差异显著(P<0.05).第2次免疫后促黄体素(LH)、雌二醇(E2)和孕酮(P)含量均高于对照组(P>0.05),第3次加强免疫后E2和P含量均显著高于对照组(P<0.05).两种重组质粒免疫绵羊后,双羔率分别为22.2%和30.0%,均与对照组差异显著(P<0.05).结果提示,串联抑制素基因免疫绵羊可促进FSH分泌,分子佐剂sC3d能增加绵羊对串联抑制素基因免疫的反应性,进而影响绵羊卵泡发育和诱导绵羊产双羔. 相似文献
9.
猪瘟DNA疫苗的临床免疫实验 总被引：1，自引：0，他引：1
在前期研究工作筛选出2种DNA疫苗质粒的基础上,采用3种免疫策略(DNA疫苗单独免疫法、DNA疫苗初免蛋白免疫加强的prime-boost方法以及沙门氏菌(Salmonella)载体介导法),于某规模化猪场对猪瘟病毒(CSFV)的DNA免疫效果进行了临床应用研究。随机选择未经猪瘟疫苗免疫的断奶仔猪60头,分6组进行免疫接种,检测免疫猪抗体产生情况并对各组免疫猪进行攻毒试验。免疫猪血清抗体ELISA检测结果表明,pcDSW组、pIRE2IL2组、pcDSW E2protein组和pIRE2IL2 E2protein组均产生了较高的抗体水平,而沙门氏菌介导的2种DNA疫苗质粒诱导的抗体水平不显著。攻毒试验结果表明,pcDSW和pIRE2IL2单独免疫组或prime-boost组能够抵抗致死剂量的CSFV石门强毒攻击,保护率87.50%￣90.00%。其中pcDSW效果好于pIRE2IL2。而沙门氏菌介导的DNA疫苗组不能产生有效保护。不同接种途径的免疫效果比较结果表明,颈部肌肉注射免疫后产生的抗体水平较后肢胫前肌注射免疫产生的抗体水平高。 相似文献
10.
应用RT-PCR技术,直接从麻鸭(Tadorna ferruginea)脾淋巴细胞总RNA中扩增出麻鸭IL-18成熟蛋白(mDuIL-18)基因,克隆到pGEM-T Easy载体。测序结果表明获得了mDuIL-18基因,其大小为513bp,并将该基因亚克隆到原核表达载体pQE30。SDS-PAGE可检测到分子质量为19.76kD的重组蛋白,Western blot证实该重组蛋白可与兔抗鸡IL-18血清发生特异性反应。表达产物以包涵体形式存在,经变性和复性处理后明显促进鸭T细胞转化。用mDuIL-18(150或200ng/鸭)和禽流感病毒(AIV)疫苗免疫鸭2周后,血凝抑制(HI)抗体平均滴度达到7.5～7.7log2,而只用AIV疫苗免疫和用mDuIL-18(100ng/鸭)和AIV疫苗免疫的HI抗体平均滴度仅达到6.3～6.6log2,表明mDuIL-18提高AIV灭活油乳苗诱导的免疫应答。 相似文献
11.
【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。 相似文献
12.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
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. 相似文献
13.
《中国生态农业学报》2014,(8)
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, 相似文献
14.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
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. 相似文献
15.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
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. 相似文献
16.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
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. 相似文献
17.
《中国生态农业学报》2014,(7)
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, 相似文献
18.
《中国生态农业学报》2014,(6)
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, 相似文献
19.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
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. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
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. 相似文献