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1.
为探究凋落物对森林土壤氮的影响及氮沉降的调节,本研究以亚热带天然阔叶林(罗浮栲林)和人工针叶林(杉木林)2种林型土壤和凋落物为对象,分别设置土壤(对照)、土壤+凋落物(3倍添加)、土壤+氮(120 mg/kg)、土壤+凋落物(3倍添加)+氮(120 mg/kg) 4种处理,每种处理设置3个重复,进行为期一年的室内模拟淋溶试验,分析土壤可溶性氮和物理分级后各粒径土壤水解氨基酸变化。结果表明：与对照比较,阔叶林土壤添加凋落物处理增加土壤铵态氮和游离氨基酸,而降低硝态氮含量;氮添加降低针叶林土壤氨态氮,增加硝态氮含量,但是增加阔叶林土壤铵态氮和游离氨基酸;凋落物添加的情况下,氮添加显著增加阔叶林土壤硝态氮含量。土壤的各粒径组分分布比例差异显著,氮添加倾向于降低针叶林土壤大粒径、增加小粒径分配比例,而阔叶林相反。针叶林土壤添加凋落物显著增加土壤粒径组分2 000～250μm、20～2μm、<2μm水解氨基酸含量;氮添加增加针叶林全土、2 000～250μm和20～2μm粒径水解氨基酸含量;在凋落物添加或氮添加情况下,氮添加或凋落物显著降低全土、250～53μm、53～20μm粒径水解氨基... 相似文献
2.
封育对蒿类荒漠草地土壤氮素含量及其组分特征的影响 总被引：1，自引：1，他引：0
为探讨蒿类荒漠草地土壤氮素含量及其组分特征,采用成对试验设计,研究封育对天山北坡不同区域蒿类荒漠草地土壤全氮、碱解氮、硝态氮和铵态氮含量的影响。结果表明:(1)封育后蒿类荒漠草地0—50 cm土层土壤氮密度(0.59~0.79 kg/m2)、土壤全氮含量(0.81~1.50 g/kg)、土壤碱解氮含量(19.44~67.49 mg/kg)变化不显著(p＞0.05)。(2)封育对蒿类荒漠草地土壤硝态氮含量(6.41~21.26 mg/kg)、铵态氮含量(0.26~2.53 mg/kg)的影响因区域差异而有所不同。封育后巩留、呼图壁样地0—50 cm土层硝态氮含量依次显著降低24.61%,47.25%(p＜0.01),而奇台样地则显著增加20.95%(p＜0.05);封育后玛纳斯样地0—50 cm土层铵态氮含量显著增加27.98%(p＜0.05),而巩留、博乐、呼图壁样地则降低不显著(p＞0.05)。(3)蒿类荒漠草地土壤硝态氮、铵态氮含量依次占全氮量的0.27%~3.01%,0.02%~0.42%,且随土壤全氮的增加,有机氮占比增加,而无机氮、硝态氮和铵态氮占比降低。(4)相关分析表明,土壤全氮、碱解氮、硝态氮、铵态氮与有机碳、全磷呈正相关,与土壤容重、pH、电导率呈负相关,铵态氮与土壤含水量呈正相关,与速效磷呈负相关。偏冗余分析表明,土壤理化因子对土壤氮素影响的主要因子为土壤有机碳和土壤含水量,解释率依次为32.60%,17.90%。研究结果为揭示封育过程中蒿类荒漠草地土壤恢复及养分管理提供科学数据支撑。 相似文献
3.
黄土高原苹果园地深层土壤氮素含量与分布特征 总被引：3，自引：1，他引：2
在黄土高原的凤翔、 白水、 长武、 西峰、 延安和静宁等6个苹果产区,测定了628龄苹果园地0300 cm土层土壤的全氮、 铵态氮和硝态氮含量,分析和比较了不同地区和不同树龄果园土壤全氮、 铵态氮和硝态氮含量及其剖面分布特征。结果表明: 1）不同地区和不同树龄果园土壤全氮含量为0.19 g/kg（延安）1.28 g/kg（白水）,土壤铵态氮含量为5.19 mg/kg（静宁）39.46 mg/kg（长武）,土壤硝态氮含量为3.97 mg/kg（延安）352.86 mg/kg（白水）,除延安点土壤明显较低外其它试点果园土壤全氮含量差异不大,各类果园土壤硝态氮含量差异较大,而铵态氮含量差异较小; 2）不同地区和不同树龄果园60 cm以上土层土壤全氮含量明显高于深层土壤,高龄果园土壤硝态氮含量明显高于低龄果园,并在100 cm以下土层出现不同程度的土壤硝态氮累积现象; 3）延安果园土壤全氮、 铵态氮和硝态氮含量均低于其它试点,需要增施氮肥以提高苹果产量,而凤翔、 白水、 长武、 静宁和西峰苹果园深层土壤硝态氮积累量较高,应维持或适当减少氮肥施用量。 相似文献
4.
祁连山东段青海云杉林区土壤氮矿化与土壤因子的相关性 总被引：4，自引：0，他引：4
以祁连山东段青海云杉(Picea crassifolia)林分布带土壤为研究对象,采用顶盖埋管的野外取样法和室内分析法,对海拔梯度上土壤铵态氮(NH+4-N)、硝态氮(NO-3-N)净矿化速率、氮净矿化量和净矿化速率进行测定分析,旨在探讨土壤净氮矿化量与气温降水和土壤理化性质的相关关系,以期建立环境变量与土壤氮矿化量和矿化速率模型,进而提高祁连山青海云杉林生产力及水源涵养能力。其结果表明:(1)土壤硝态氮、铵态氮净矿化速率、土壤净氮矿化量和矿化速率随海拔的升高差异性均极显著;土壤氮净矿化量和矿化速率随海拔梯度的升高呈"W"形变化,与硝态氮净矿化速率随海拔升高的变化规律一致,与铵态氮净矿化速率变化规律相反;在海拔2 800m处,硝态氮净矿化速率、土壤净氮矿化量和矿化速率均达到最大值,为0.372,160.3,0.44 mg/(kg·d),铵态氮净矿化速率出现最低值0.067 mg/(kg·d);在海拔2 900m处出现最低值,为0.155,94.7,0.26mg/(kg·d),在海拔3 100m处,铵态氮的净矿化速率出现最大值0.13mg/(kg·d);(2)回归分析表明,土壤净氮矿化量与年均气温呈极显著负相关(P0.01),R2=0.717 3;与年降水量呈极显著正相关(P0.01),R2=0.383 5;得出气候变化对土壤净氮矿化量的影响程度为:年均气温年降水量;(3)回归分析表明,土壤氮净矿化量与土壤全氮、有机质、含水量、pH值呈极显著正相关(P0.01),其R2依次为0.910 1,0.906 0,0.842 8,0.797 9;与土壤容重呈极显著负相关(P0.01),其R2为0.222 4;由R2值大小可知土壤养分对土壤净氮矿化量的影响程度为:土壤全氮土壤有机质土壤含水量土壤pH土壤容重。 相似文献
5.
于2008年10月、2009年5月和8月对黄河口湿地进行了3次野外调查和室内及野外模拟实验,研究了湿地土壤中各形态氮素的季节变化及转化过程,结果表明:农业种植区表层土壤氮素含量明显高于自然湿地,自然湿地全氮的含量低于1 000 mg/kg,铵态氮含量小于10 mg/kg,硝态氮含量小于3 mg/kg,研究区土壤氮素含量处于低营养水平。土壤中氮素的含量8月份最低,其中无机氮的季节变化较有机氮明显;0-10 cm表层土壤氮素含量明显高于下层土壤,10 cm以下氮含量无显著垂直变化。在氮素的转化过程中,氮的反硝化能力最强,硝态氮的最大损失量达到23.44 g/(m3.d),这与研究区域土壤中硝态氮含量较低相吻合;矿化能力较弱,有机氮的最大转化量仅为0.91 g/(m3.d);氮的硝化过程中铵态氮的最大转化量为12.77 g/(m3.d)。芦苇枯落物在分解过程中发生了氮素的净释放,夏季淹水环境芦苇枯落物氮素的日均归还量最高,达到0.039 g/(m2.d),冬季最低,芦苇枯落物分解对土壤氮库的储量有一定影响。 相似文献
6.
陕北石油污染对土壤理化性质的影响 总被引：7，自引：1，他引：7
为了研究石油污染对土壤理化性质的影响,对安塞县8个类型油井井场周围土壤中的石油烃含量和理化性质进行分析测定。结果表明,井场周围土壤石油烃含量变化范围为0.08~71.49 g/kg,其中井场外0~5 m区域和5~20 m区域内土壤污染严重。石油污染导致土壤含水率、pH值、硝态氮、速效磷、全钾和速效钾含量显著降低,容重、有机质和铵态氮含量显著升高,全氮和全磷含量无显著变化;石油污染土壤中的石油烃含量与含水率、容重、有机质、铵态氮、速效磷和速效钾均呈极显著相关,与pH值和全钾呈显著相关,与全氮、硝态氮和全磷无显著相关关系。 相似文献
7.
祁连山青海云杉林土壤氮的含量特征 总被引：3，自引：0，他引：3
通过野外取样和实验室分析,研究了祁连山东、西段青海云杉林土壤全氮和有效氮(铵态氮和硝态氮)含量的特征.结果表明:①祁连山东、西段土壤全氮、铵态氮和硝态氮含量变化范围分别为1.78 ～ 7.89 g/kg和1.50～4.39 g/kg,6.33 ～ 24.96 mg/kg和0.37～23.60 mg/kg,5.23～ 20.74 mg/kg和0.20 ～ 10.19 mg/kg,各氮素形态含量均是祁连山东段大于祁连山西段;在祁连山青海云杉林中土壤铵态氮为土壤有效氮的主要存在形式,其所占比例在祁连山东、西段分别为70.58％和87.58％.②在祁连山东、西段0～ 10、10～ 20、20 ～ 40 cm土层中,土壤全氮和铵态氮含量均随土层深度的增加呈减小趋势;不同土层土壤全氮平均含量均是祁连山东段显著高于祁连山西段(P＜0.05);祁连山东、西段土壤铵态氮含量在0～10 cm和10～20 cm土层中差异均不显著(P＞0.05),仅在20～40 cm土层中差异显著(P＜0.05);硝态氮含量在祁连山东段随土层的加深并没有明显的变化规律,在西段随土层深度的增加呈减小趋势,东、西段土壤硝态氮含量在0～ 10cm土层差异不显著(P＞0.05),在10 ～ 20 cm和20 ～ 40 cm差异显著(P＜0.05).③祁连山东、西段土壤全氮、铵态氮和硝态氮含量在不同土层深度的变异系数均没有明显的变化规律,除土壤硝态氮在祁连山西段不同土层深度的变异为强变异性外,土壤全氮、铵态氮和硝态氮含量在祁连山东、西段不同土层深度的变异均为中等变异.④祁连山东、西段土壤全氮和铵态氮含量之间均呈显著相关性,但全氮和硝态氮含量及铵态氮和硝态氮含量之间均无显著相关性. 相似文献
8.
汉江小流域土壤氮素空间分布特征及影响因素 总被引：2，自引：0，他引：2
氮素是土壤中不可或缺的营养元素之一,对植物生长具有至关重要的作用。利用网格采样法(30m×30m)和典型样地取样法在汉江余姐河小流域进行土样采集,每个样点分为3层A1(0—20cm),A2(20—40cm),A3(40—60cm),分别测定其土壤全氮、土壤铵态氮和土壤硝态氮含量。研究了土壤氮素的空间异质性、氮素的组成比例以及不同土地利用类型下土壤全氮、铵态氮和硝态氮与环境因子间的相关关系,并且分析了不同形态氮素间的相互关系。结果表明:土壤氮素的空间变异性为土壤硝态氮土壤铵态氮土壤全氮;土壤全氮与硝态氮在A1土层为强空间相关性,在A2,A3层为中等程度的空间相关性,土壤铵态氮在各土层均表现为中等空间相关性;农地、林地、草地对全氮储量的贡献依次增大;相较于林地草地,农地对铵态氮储量的贡献最大;而草地对硝态氮储量的贡献在三种土地利用中最大;不同土地利用类型中,农地的氮素空间分布主要与土壤粒径具有相关性,而与地形因子(坡度、坡向等)相关性较小;林地的氮素空间分布主要与地形因子相关性较高,草地介于两者之间;在流域内增加草地林地面积,在流域出口处布设林草地等措施可以减少流域土壤氮素的流失。 相似文献
9.
《土壤通报》2010,(4)
试验以2个大豆品种,3种施氮肥水平(N0:0 kg hm-2、N75:75 kg hm-2、N150:150 kg hm-2),对大豆生育期间土壤无机态氮(铵态氮、硝态氮)与植株硝态氮含量及变化规律加以研究,结果表明,土壤中无机态氮与大豆植株中硝态氮含量均呈下降趋势,三种施氮肥水平相比,除土壤铵态氮含量表现为N150N75N0,土壤硝态氮与植株硝态氮含量在各氮肥水平处理间未表现出明显的差异,并且大豆茎、叶柄中硝态氮含量与土壤中硝态氮含量呈极显著正相关(r=0.9316**;r=0.9355**),土壤铵态氮与土壤硝态氮含量呈极显著正相关(r=0.8746**,)可以用茎、叶柄中硝态氮含量来表征土壤无机态氮营养状况。 相似文献
10.
降雨对不同土地利用类型土壤水氮变化特征的影响 总被引：1，自引：0，他引：1
以2018年6—10月降雨条件下园地、林地、荒草地、坡耕地和裸地的标准径流小区为研究对象,裸地为对照,通过研究降雨对园地、林地、荒草地、坡耕地和裸地的土壤含水率、总氮、硝态氮和铵态氮含量与土层深度和时间的变化特征,经野外试验数据统计分析,提出降雨对园地、林地、荒草地、坡耕地和裸地土壤含水率、总氮、硝态氮和铵态氮含量与土层深度和时间变化特征的影响。结果表明:降雨增加园地、林地、荒草地、坡耕地和裸地土壤含水率,加速土壤总氮、硝态氮和铵态氮水解转化硝化和反硝化速度,影响土壤含水率、总氮、硝态氮和铵态氮含量,降雨与土壤含水率、总氮、硝态氮、铵态氮呈显著相关性(P0.05)。降雨条件下园地、林地、荒草地、坡耕地和裸地的土壤含水率随土层深度增大而增大,土层深度100 cm处土壤含水率最大,分别为30.34%,27.67%,24.98%,24.03%和21.95%,总氮随土层深度增大呈先增大后减小,在土层深度为60 cm土壤总氮含量最大,分别为1.02,0.99,0.90,0.86,0.75 g/kg,硝态氮和铵态氮含量随土层深度增大而减小,在土层深度为100 cm硝态氮和铵态氮含量均最小,其中硝态氮含量分别为9.01,7.89,7.25,6.10,5.22 mg/kg,铵态氮含量分别为9.41,9.14,6.40,5.38,4.37 mg/kg。土壤含水率随时间的延长先减小后增大又减小,呈正余弦变化趋势,8月土壤含水率最大,分别为22.97%,22.01%,19.87%,19.03%和17.98%,总氮随时间的延长先增大后减小,8月总氮最大,分别为1.09,1.01,0.94,0.84,0.76 g/kg,硝态氮和铵态氮含量随时间的延长而逐渐减少,6月硝态氮和铵态氮含量均最大,其中硝态氮含量分别为13.40,12.37,11.20,10.39,8.67 mg/kg,铵态氮含量分别为18.89,17.02,14.54,12.02,8.36 mg/kg。不同土地利用类型土壤含水率、总氮、硝态氮和铵态氮平均值与土层深度和时间关系由大到小依次为园地、林地、荒草地、坡耕地和裸地,研究结果为农田土壤水肥流失控制和养分利用提供理论技术支持。 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.
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
15.
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
16.
《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
17.
Y. Bashan J. J. Bustillos L. A. Leyva J.-P. Hernandez M. Bacilio 《Biology and Fertility of Soils》2006,42(4):279-285
Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several
photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene.
This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments
for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference
in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless
of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots.
Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production
or the positive response of the plants towards A. brasilense Cd inoculation. 相似文献
18.
Dhritiman Ghosh Velusamy Srinivasan Olli H. Tuovinen Aaron Peacock Mark Radosevich 《Soil biology & biochemistry》2009,41(6):1331-1334
We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg−1 buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg−1 in conditioned and control soil, respectively. The results demonstrate that BioSep® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation. 相似文献
19.
Pilar García Juan-Vicente Monte Carlos Casanova Consuelo Soler 《Genetic Resources and Crop Evolution》2002,49(1):103-109
Arbitrary oligonucleotides were used as primers to amplifygenomic DNA of 48 wild Spanish populations of Agropyroncristatum, Elymus hispanicus,E. caninus,E. repens,Thinopyrum curvifolium, Th.junceum and Th.intermedium. Genetic diversity was analysedusing nineteen primers. The number of amplified products ranged from8 to 18 per primer and a total of 240 markers were scored. Differentlevels of intraspecific genetic diversity were found, the allogamousspecies E. repens andTh. intermedium being themost variable. Jaccard's similarity coefficients for internalmeasure within and between populations were used to produce a clusterdiagram. The results demonstrate differences in the degree ofsimilarity between taxonomic units. Interpopulational variability andinterspecific genomic relationships of these species arediscussed. 相似文献
20.
The effects of three commonly used fungicides on the colonization and sporulation by a mixture of three arbuscular mycorrhizal (AM) fungi consisting of Glomus etunicatum (Becker & Gerd.), Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and Gigaspora rosea (Nicol. & Schenck) in symbiosis with pea plants and the resulting response of the host-plant were examined. Benomyl, PCNB, and captan were applied as soil drenches at a rate of 20 mg active ingredient kg-1 soil 2 weeks after transplanting pea seedlings in a silty clay-loam soil containing the mixed inocula of AM fungi (AM plants). Effects of fungicides were compared to untreated plants that were inoculated with fungi (AM control). The effect of mycorrhizal inoculation on plant growth was also examined by including nonmycorrhizal, non-fungicide-treated plants (non-AM control). Fungicides or inoculation with AM fungi had only a small effect on the final shoot weights of pea plants, but had greater effects on root length and seed yield. AM control plants had higher seed yields and lower root lengths than the corresponding non-AM plants, and the fungicide-treated AM plants had intermediate yields and root lengths. Seed N and P contents were likewise highest in AM control plants, lowest in non-AM plants, and intermediate in fungicide-treated AM plants. All three fungicides depressed the proportion (%) of root length colonized by AM fungi, but these differences did not translate to reductions in the total root length that was colonized, since roots were longer in the fungicide-treated AM plants. Pea plants apparently compensated for the reduction in AM-fungal metabolism due to fungicides by increasing root growth. Fungicides affected the population of the three fungi as determined by sporulation at the final harvest. Captan significantly reduced the number, relative abundance, and relative volume of G. rosea spores in the final population relative to the controls. The relative volume of G. etunicatum spores was greater in all the fungicide-treated soils, while G. mosseae relative volumes were only greater in the captan-treated soil. These findings show that fungicides can alter the species composition of an AM-fungal community. The results also show that AM fungi can increase seed yield without enhancing the vegetative shoot growth of host plants. 相似文献