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1.
钙和NO对NaCl胁迫下黄瓜幼苗生长和活性氧代谢的影响   总被引：1，自引：0，他引：1  
采用营养液培养的方法,研究了Ca2+对外源一氧化氮(Nitric oxide,NO)所诱导的NaCl胁迫下黄瓜幼苗生长、活性氧代谢的影响。结果表明,添加外源NO或Ca2+显著缓解了NaCl胁迫对黄瓜幼苗生长的抑制,叶片和根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性较单独NaCl胁迫处理显著提高,丙二醛(MDA)和过氧化氢(H2O2)的含量、超氧阴离子(O.-2)产生速率明显下降;添加NO的同时添加Ca2+通道抑制剂La3+抑制了NO的这些调节作用。结果表明Ca2+对NO诱导的NaCl胁迫下黄瓜幼苗植株活性氧清除能力的提高起重要作用,NO的作用可能依赖于胞浆Ca2+。  相似文献   

2.
【目的】设施栽培中土壤次生盐渍化严重,导致植株出现缺镁失绿症状。通过研究硝酸盐胁迫下外源NO供体(硝普钠,SNP)对缺镁黄瓜幼苗生长的影响,探究硝酸盐胁迫下外源NO对缺镁黄瓜幼苗的胁迫缓解效应,为解决设施生产中黄瓜幼苗的缺镁失绿症状提供理论指导。【方法】采用水培的方式培养黄瓜幼苗,幼苗长至三叶一心时进行处理。营养液采用山崎配方,镁离子浓度设两个水平为2 mmol/L(正常浓度)和1 mmol/L(缺镁胁迫);硝酸盐浓度设两个水平为14 mmol/L(正常浓度)和140 mmol/L(硝酸盐胁迫);硝酸盐和镁正常浓度为对照。用0.1mmol/L SNP分别缓解缺镁胁迫、硝酸盐胁迫以及缺镁和硝酸盐双重胁迫,用0.1 mmol/L SF(铁氰化钠)处理,观察SNP反应产物的影响;NO-3由Ca(NO3)2·4H2O和KNO3提供,各占1/2,p H由H2SO4调节,保持在5.5 6.5。【结果】1)缺镁胁迫下,黄瓜幼苗株高和叶面积增加值、干物质增长量较正常处理的黄瓜幼苗显著降低;电解质渗漏率、丙二醛含量和可溶性蛋白含量较正常处理的黄瓜幼苗显著升高。缺镁处理的黄瓜幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光及抗氧化酶活性与正常处理的黄瓜幼苗相比明显降低。2)硝酸盐胁迫下,黄瓜幼苗株高和叶面积增加值、干物质增长量、黄瓜幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光及抗氧化酶活性较正常处理的黄瓜幼苗显著降低;电解质渗漏率、丙二醛含量和可溶性蛋白含量较正常处理的黄瓜幼苗显著升高。3)缺镁和硝酸盐双重胁迫下,黄瓜幼苗的相关生长指标和抗逆指标较正常处理的黄瓜幼苗降低或增大更为显著。4)缺镁胁迫,硝酸盐胁迫以及缺镁和硝酸盐双重胁迫下,外施0.1 mmol/L SNP处理的黄瓜幼苗,株高和叶面积增加值、干物质增长量、幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光、可溶性蛋白含量及抗氧化酶活性较未添加SNP处理的黄瓜幼苗显著提高,电解质渗漏率和丙二醛含量则明显降低。外施0.1 mmol/L SF则没有表现出明显的作用。【结论】硝酸盐胁迫下缺镁黄瓜幼苗生长受到明显抑制,出现失绿症状,通过添加0.1 mmol/L SNP,黄瓜幼苗的生长抑制得到明显缓解,说明在硝酸盐胁迫下外源NO对缺镁黄瓜幼苗的胁迫有显著缓解作用,增强黄瓜幼苗的耐盐性和对镁的吸收能力。  相似文献   

3.
外源NO对盐胁迫下甜高粱种子萌发和幼苗生长的影响   总被引：2，自引：0，他引：2  
为探究外源NO对盐胁迫下甜高粱种子萌发和幼苗生长的影响,以国能4号甜高粱为试验材料,采用不同浓度(0.05、0.1和0.2 mmol·L-1)硝普钠(SNP,NO供体)处理1.6%NaCl胁迫下的种子和幼苗,统计种子发芽数,测定幼苗叶片叶绿素、脯氨酸、可溶性糖、可溶性蛋白、丙二醛(MDA)含量及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性等生理生化指标。结果表明,盐胁迫抑制了甜高粱种子的萌发,种子发芽指标(种子发芽率、发芽势和发芽指数)显著降低,1.6%NaCl是甜高粱种子萌发的敏感盐浓度;喷施不同浓度SNP可显著提高盐胁迫下甜高粱种子的发芽率及幼苗叶片叶绿素、可溶性糖、可溶性蛋白和脯氨酸含量,降低叶片MDA含量,增强抗氧化酶活性,其中0.1 mmol·L-1SNP处理效果最佳。0.1 mmol·L-1SNP处理下,与单独盐浓度处理相比,甜高粱种子发芽率、发芽势和发芽指数分别增加了29.51%、39.21%和38.91%;幼苗叶片叶绿素a、叶绿素b、总叶绿素、可溶性糖、可溶性蛋白和脯氨酸含量分别提高了230.00%、184.38%、214.13%、17.00%、8.78%和40.63%;MDA含量降低了34.01%;SOD、POD、CAT和APX活性分别增强了33.38%、55.75%、23.17%和116.46%。综上,盐胁迫下适宜浓度的SNP处理,可提高甜高粱幼苗叶片渗透调节物质含量,增强抗氧化酶活性,清除体内活性氧,从而促进幼苗生长,增强植株抗盐性。本研究结果为提高甜高粱耐盐性及揭示其耐盐机制提供了理论依据。  相似文献   

4.
低温下NO对黄瓜光合荧光及抗氧化特性的影响   总被引：3，自引：1，他引：2  
为了探讨低温前NO处理对低温(10℃/6℃)过程中黄瓜幼苗叶绿素荧光和抗氧化酶活性的调控作用,以津研4号黄瓜幼苗为试材,叶面喷施一氧化氮(NO)供体SNP及一氧化氮合酶(NOS)抑制剂LNAME、NO清除剂PTIO,研究低温胁迫过程中黄瓜幼苗叶绿素荧光参数及抗氧化酶活性的变化。结果显示:低温处理前喷施NO供体SNP仅显著提高了ΦPSⅡ、POD和APX活性,但低温后24h,SNP处理提高了ΦPSⅡ、Fv/Fm、qP、NPQ及光化学反应P部分的份额,提高光能利用率,减少了非光化学耗散Ex的部分,改善光能分配不平衡,这种趋势一直延续到48h,而NOS抑制剂L-NAME和NO清除剂PTIO却能够阻断SNP的作用效果。与低温前相比,各处理(即处理1.喷施蒸馏水;2.喷施蒸馏水+SNP;3.喷施L-NAME+SNP;4.喷施PTIO+SNP)在低温后24和48h,丙二醛(MDA)的积累相比于对照减少了12.82%、16.69%,电导率值降低了13.33%,15.54%,SOD活性上升,CAT酶活性迅速下降,POD先上升后下降,NOS抑制剂L-NAME和NO清除剂PTIO阻碍了SNP在低温前和低温过程中显著诱导抗氧化酶的活性,说明NOS路径产生的NO在调节叶绿素荧光及抗氧化酶活性提高黄瓜耐冷性中发挥着重要作用,同时在低温过程中APX和POD对H2O2调节发挥主要作用。  相似文献   

5.
以“影武者”为砧木,“宝大903”为接穗,在营养液栽培条件下,对80 mmol/L Ca(NO3)2胁迫下番茄嫁接苗和自根苗的生长、叶片抗氧化酶活性、活性氧代谢以及渗透调节物质含量进行了比较。结果表明,Ca(NO3)2胁迫明显抑制植株生长,显著提高植株抗氧化酶活性,显著增加植株O2.-生成速率以及H2O2、MDA、脯氨酸和可溶性蛋白含量,但胁迫后嫁接苗的生物量显著高于自根苗,抗氧化酶活性、脯氨酸和可溶性蛋白含量均显著高于自根苗,而O2.-生成速率、H2O2和MDA含量则显著低于自根苗。以上结果表明,Ca(NO3)2胁迫下较高的抗氧化酶活性和渗透调节物质含量以及较低的氧化损伤与番茄嫁接苗耐盐性增强有关。  相似文献   

6.
为探究Ca~(2+)在一氧化氮(NO)增强黄瓜抗氧化能力和耐冷性中的作用,本研究以津研四号黄瓜幼苗为试验材料,通过叶面喷施NO供体亚硝基铁氰化钠(SNP),游离Ca~(2+)螯合剂乙二醇-双-(2-氨基乙基)四乙酸(EGTA),质膜Ca~(2+)通道阻断剂三氯化镧(La Cl3),钙调素(Ca M)活性抑制剂三氟啦嗪(TFP)和钙调素激酶(Ca M-PK)阻断剂N-(6-氨基己基)-5-氯-1-萘磺胺(W-7),研究低温(10℃/6℃)胁迫下黄瓜幼苗叶片相对电导率、丙二醛(MDA)含量、抗氧化酶活性及其相关基因表达量、H_2O_2含量和O_2~(-·)含量的变化。结果表明,与CK相比,水+SNP处理在低温24 h和48 h提高了黄瓜幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性及其相关基因表达,降低了电导率以及MDA和H_2O_2含量,而EGTA+SNP、LaCl_3+SNP、TFP+SNP和W-7+SNP处理抑制了SNP作用效果,表明Ca~(2+)参与NO对低温胁迫下黄瓜幼苗叶片抗氧化过程的调节。此外,在低温0、3和6 h,H_2O_2组织染色显示水+SNP处理的黄瓜幼苗叶片H_2O_2积累量显著高于其他处理;在低温6 h,水+SNP处理黄瓜幼苗叶片O-·2积累量显著高于其他处理,表明活性氧(ROS)可能也作为一种信号分子,位于Ca~(2+)的下游参与NO增强黄瓜幼苗的抗氧化能力。本研究为阐明Ca~(2+)和NO信号系统在提高植物耐冷性中的作用机理提供了理论依据。  相似文献   

7.
以4℃模拟低温胁迫状况,研究了外源一氧化氮（NO）供体硝普钠（SNP）对低温胁迫下玉米种子萌发、幼苗生长和生理特性的影响。结果表明,低温胁迫下,玉米种子萌发和幼苗生长受到抑制,叶片丙二醛（MDA）含量和相对电导率显著上升,叶片相对含水量、脯氨酸含量和叶绿素含量显著降低。不同浓度的SNP均能显著提高低温胁迫下玉米种子的发芽率、发芽势、发芽指数和活力指数;促进低温胁迫下玉米幼苗的生长;抑制低温胁迫下玉米幼苗叶片MDA含量的上升,降低叶片质膜相对透性,增加相对含水量、脯氨酸含量和叶绿素含量。表明外源NO可缓解低温胁迫对玉米种子萌发及幼苗生长的抑制作用,缓解低温胁迫引起的膜脂过氧化,保护细胞膜免受或减少损伤,提高植物抗低温胁迫的能力。在SNP不同的使用浓度中,以100μmol·L-1SNP对低温胁迫的缓解效果最佳,当SNP浓度过低和过高时均达不到理想的效果。  相似文献   

8.
外源NO对Ca(NO_3)_2胁迫下番茄叶片活性氧损伤的缓解效应   总被引：1，自引：0，他引：1  
为探讨外源一氧化氮(NO)对次生盐渍胁迫下植物抗氧化系统的调节作用,以番茄品种‘秦丰保冠’为试材,在营养液栽培条件下研究叶面喷施外源NO供体硝普钠(SNP)对80mmol·L~(-1)Ca(NO_3)_2胁迫下番茄幼苗生长、叶片光合、活性氧物质、抗氧化酶活性和抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果表明,Ca(NO_3)_2胁迫下喷施SNP处理的番茄幼苗叶片超氧阴离子(O_2~(·-))的产生速率以及过氧化氢(H_2O_2)、丙二醛(MDA)、脱氢抗坏血酸(DHA)、氧化型谷胱甘肽(GSSG)的含量和电解质渗漏率显著降低,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDHAR)的活性显著升高或得以维持,同时叶片抗坏血酸(AsA)、谷胱甘肽(GSH)含量及其还原力(AsA/DHA、GSH/GSSG值)显著升高,叶片活性氧损伤得到有效缓解,叶绿素降解和光合速率的下降得到有效抑制,进而促进了植株的生长发育,提高了番茄幼苗的耐盐能力。  相似文献   

9.
采用营养液栽培,以白籽南瓜（Cucurbita maximaCucurbita moschata）为砧木,津优3号黄瓜为接穗,研究了白籽南瓜嫁接对等渗Ca(NO3)2和NaCl胁迫下黄瓜幼苗生长、氮代谢、渗透调节物质和蛋白表达的影响。结果表明:白籽南瓜嫁接黄瓜可明显促进Ca(NO3)2和NaCl胁迫下黄瓜嫁接苗生长,提高叶片和根系中硝酸还原酶（NR）活性及NO3--N、可溶性糖、脯氨酸和可溶性蛋白含量,抑制NH4+-N升高;叶片中可溶性蛋白表达量增强,其相对分子质量（103）分别约为188.4、156.1、120.4、54.0、37.3、32.1、30.6、18.9、17.8和17.1,并出现相对分子质量为64.3103的一种新蛋白,而81.0103的蛋白表达量减弱,这12种蛋白可能与白籽南瓜嫁接提高黄瓜耐盐性密切相关。研究还发现:NaCl胁迫下黄瓜自根嫁接和砧木嫁接植株叶片中相对分子质量（103）约为86.1、23.4、18.9和17.8的蛋白表达量大于等渗的Ca(NO3)2,相对分子质量（103）约为188.4、156.1、54.0和17.1 的蛋白表达量小于等渗的Ca(NO3)2;NaCl胁迫9 d后39.1103、35.4103和21.2103三种蛋白在自根嫁接株中消失,这11种蛋白可能与白籽南瓜嫁接株耐Ca(NO3)2胁迫能力强有关。综上,Ca(NO3)2胁迫对黄瓜幼苗造成的伤害程度显著低于等渗的NaCl 胁迫,白籽南瓜砧木嫁接可调节黄瓜植株体内氮素代谢,提高渗调能力,有效地缓解Ca(NO3)2和NaCl胁迫对黄瓜植株的伤害,尤其对Ca(NO3)2胁迫伤害的缓解效果明显,可以作为黄瓜耐盐砧木在生产上应用。  相似文献   

10.
外源NO对盐胁迫下小麦幼苗生长及生理特性的影响   总被引：5，自引：0，他引：5  
在盆栽试验条件下,以冬小麦(山农22)为供试材料,以硝普钠(SNP)为外源一氧化氮(NO)供体,研究了3种施用方式的外源NO对盐胁迫下小麦幼苗生长及生理特性的影响。试验共设5个处理:对照(CK)、氮磷钾(NPK)肥(T1)、NPK肥+SNP浸种(T2)、NPK肥+SNP粉末施入土壤(T3)和NPK肥+SNP缓释颗粒施入土壤(T4)。结果表明:盐胁迫条件下,小麦植株体内会积累大量的活性氧,抑制了小麦幼苗的生长;T1-T4处理的小麦幼苗长势均优于CK。与T1处理相比,添加外源NO的T2-T4处理均可显著提高小麦出苗率,其中以T4效果最为显著,可显著促进小麦幼苗的生长,提高叶片鲜重、叶片干重、叶绿素含量及抗氧化酶活性,降低叶片中超氧阴离子产生速率及过氧化氢含量,减少小麦幼苗对Na+的吸收,增加K+的吸收,维持小麦体内Na+、K+平衡,并促进根系对N、P元素的吸收,从而保证小麦植株养分吸收平衡。因此,添加外源NO既能通过促进幼苗生长、提高抗氧化酶活性、调节离子平衡等途径来提高小麦幼苗的抗盐性,缓解盐胁迫对小麦幼苗的伤害,又能通过调节根系对营养元素的吸收来促进小麦幼苗的生长。且在3种不同的SNP施用方式中,以SNP制成缓释颗粒施入土壤的施用方式对小麦盐胁迫的缓解效果最优。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引：2，自引：2，他引：0  
【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.
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.
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.
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   

15.
“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.  相似文献   

16.
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.  相似文献   

17.
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   

18.
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   

19.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

20.
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.  相似文献   

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