氮素营养水平对小麦根际微生物及土壤酶活性的影响

在大田高产栽培条件下．研究了不同施氮水平对豫麦49-198根际微生物和土壤酶活性的影响。结果表明：豫麦49-198根系土壤蛋白酶活性和脲酶活性随生育时期推进均呈先上升后下降的变化趋势．蛋白酶活性、脲酶活性分别在拔节期和返青期达到最大值。在同一生育时期内,随着施氮水平的提高,蛋白酶活性呈先增加后降低的变化趋势．其中以N2（180kg／hm^2）处理的蛋白酶活性最高,但N4（360kg／hm^2）处理的蛋白酶活性仍大于对照N1（0kg／hm^2）;脲酶活性随施氮水平的提高呈上升趋势．以N4（360kg／hm^2）处理的脲酶活性最大。根际微生物总量随生育时期推进呈先增加后下降的趋势,在孕穗期达到最大值．开花期略有降低;在同一生育时期．随着施氨水平的提高,根际微生物数量呈先增加后下降的趋势,以N3（270kg／hm^2）处理的根际微生物总量最高．且各处理之间的差异都达到了显著水平。     

八达岭山地次生林土壤养分与磷酸酶活性研究

 为探讨北京八达岭山地土壤肥力状况,以黑桦、糠椴、核桃楸3种次生林为对象,对其土壤养分和磷酸酶活性进行研究。结果表明:土壤养分有明显的表聚效应;土壤全磷含量仅为0.39～0.66g.kg-1之间,有可能出现缺磷现象;土壤磷酸酶的活性以酸性磷酸酶为主,呈垂直递减分布规律;各种土壤养分和磷酸酶活性均有明显的根际效应,根系/本土比值在1.02～5.25之间。用SPSS软件进行分析表明,土壤磷酸酶活性与土壤pH、有机质、全氮、有效氮、有效磷和速效钾显著正相关,可以作为土壤肥力评价的一个指标。     

Soil Acidity Changes in Bulk Soil and Maize Rhizosphere in Response to Nitrogen Fertilization

The capacity of nitrogen (N) fertilizers to acidify the soil is regulated principally by the rate and N source. Nitrogen fertilizers undergo hydrolysis and nitrification in soil, resulting in the release of free hydrogen (H⁺) ions. Simultaneously, ammonium (NH₄ ⁺) absorption by roots strongly acidifies the rhizosphere, whereas absorption of nitrate (NO₃ ^?) slightly alkalinizes it. The rhizosphere effects on soil acidity and plant growth in conjunction with N rate are not clearly known. To assess the impact of these multiple factors, changes in the acidity of a Typic Argiudol soil, fertilized with two N sources (urea and UAN) at two rates (equivalent to 100 and 200 kg N ha^?1), were studied in a greenhouse experiment using maize as the experimental plant. Soil pH (measured in a soil–water slurry), total acidity, exchangeable acidity, and exchangeable aluminum (Al) were measured in rhizospheric and bulk soil. Plant biomass and foliar area (FA) were also measured at the V₆ stage. Nitrogen fertilization significantly reduce the pH in the bulk soil by 0.3 and 0.5 units for low and high rates respectively. Changes in the rhizosphere (the “rhizospheric effect”) resulted in a significant increase in soil pH, from 5.9 to 6.2. The rhizospheric effect × N source interaction significantly increased exchangeable acidity in the rhizosphere relative to bulk soil, particularly when UAN was added at a low rate. Only total acidity was significantly increased by the fertilizer application rate. In spite of the bulk soil acidification, no significant differences in exchangeable aluminum were detected. Aerial biomass and FA were significantly increased by the higher N rate, but N source had no effect on them. Although changes in acidity were observed, root biomass was not significantly affected.     

农村混合污水灌溉对小麦生长及其根际微环境的影响

以土柱模拟试验为基础,利用不同稀释倍数的农村混合污水(污水∶清水为1∶0,1∶1,0∶1)灌溉小麦,进而研究农村混合污水灌溉(WG)对小麦生长、根际土壤养分、酶活性和微生物多样性的影响。结果表明,污水含量的高低对小麦生长及根际土壤养分、酶活性和微生物多样性有一定的影响。与清水灌溉(CK)相比,WG处理后:(1)小麦株高、径粗、鲜重和干重均显著高于CK(P0.05),小麦叶片叶绿素a、叶绿素b和总叶绿素含量显著增加(P0.05);(2)小麦根际土壤除有机质含量增加16.42%外,pH、土壤全氮、全钾、全磷、速效磷、速效钾和碱解氮含量及综合肥力均降低(0.95%～16.79%),且速效钾含量降低较为显著(P0.05);(3)小麦根际土壤酸性磷酸酶、脲酶和转化酶活性均显著高于CK(P0.05),过氧化氢酶活性显著降低(P0.05);(4)由Shannon、Ace、Chao、Coverage、Simpson指数及细菌和真菌在genus水平上的微生物群落结构分布可知,小麦根际土壤细菌多样性降低,真菌多样性增加。同时,改变了小麦根际土壤细菌和真菌在genus水平上优势种的相对丰度,但细菌优势种的种类没有发生改变,真菌优势种的种类发生改变。研究结果可为示范区农村混合污水灌溉模式的研究提供有力的理论依据。     

氮及相关的酶活性对小麦根际施肥的反应

In the present experiment,wheat seedlings(Trticucum aestivum L.)were grown on a purple soil with various fertilizer treatments in order to investigate the responses of nitrogen and related enzyme activities in the rhizosphere,The results revealed the increments of both organic matter and total N in the soil with the proximity to the growing roots,especially in treatment of supplying pig manure in combination with chemical fertilizer,suggesting that they could ome from root and microorganism exudation which could be intensified by inorganic-organic fertiliztion,being of benefit to improving the physical and bilogical envi-ronment in the rhizosphere of wheat.Much more inorganic N was observed in the fertilized soils surrounding wheat roots than in the CK treatment ,indicating ,the improvement of crop N supply in the rhizosphere of wheat by fertilization. The activities of invertase,urease and protease in the root zone were greatly enhanced as compared to those in the other parts of soil except that the urease activities were similar in the rhizospher and nonrhi-zosphere of the CK and pig manure treatments,indicating that invertase and protese could be produced by growing roots and rhizosphere microorganisms,in contrast to urease which could be stimulated by urea,Also,significant increment of chemical fertilizer combined with pig manure,suggested that fertilization not only accelerated the renewal of organic matter bu also enhanced bioavailability of organic N in that soil zone .This could be the reason why the total amount of inorganic N available for plants was increased more obviously in the rhizosphere of wheat of the fertilizaton treatments than in taht of the CK treatment.     

落叶松人工林根际与非根际土壤养分特征及酸度研究

采用对比分析方法,揭示了不同发育阶段落叶松人工林根际与非根际土壤有机氮、水解氮、全磷、有效磷、有效钾和酸度的变化规律。结果表明:不同发育阶段落叶松人工林根际与非根际土壤酸性氨基酸、碱性氨基酸、游离氨基酸总量和水解氮,以及根际土壤中性氨基酸、速效钾、全磷和有效磷从幼龄林到中龄林增加,中龄林以后降低。根际活性酸、非根际土壤速效钾随林龄增加呈显著下降趋势,根际与非根际土壤交换性酸、交换性铝、非根际活性酸则相反,随林龄的增大呈明显增加趋势。     

两个水稻基因型根际磷素组分、pH以及磷酸酶活性的动态变化

A rhizobox experiment with two phosphorus （P） treatments, zero-P （0 mg P kg^-1） and plus-P （100 mg P kg^-1） as Ca（H2PO4）2.H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of two rice genotypes （cv. Zhongbu 51 and Pembe） different in P uptake ability and their relationship with the depletion of soil P fractions. Plant P uptake, pH, phosphatase activity, and soil P fractions in the rhizosphere were measured. Both total dry weight and total P uptake of Pembe were significantly （P 〈 0.05） higher than those of Zhongbu 51 in the zero-P and plus-P treatments. Significant depletions of resin-Pi, NaHCO3-Pi, NaHCO3-Po, and NaOH-Pi, where Pi stands for inorganic P and Po for organic P, were observed in the rhizosphere of both Zhongbu 51 and Pembe under both P treatments. Pembe showed a greater ability than Zhongbu 51 in depleting resin-Pi, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, and NaOH- Po in the rhizosphere. HCl-Pi and residual-P were not depleted in the rhizosphere of both genotypes, regardless of P treatments despite significant acidification in the rhizosphere of Pembe under zero-P treatment. Higher acid phosphatase （AcPME） activity and alkaline phosphatase （AlPME） activity were observed in the rhizosphere of both Zhongbu 51 and Pembe compared to the corresponding controls without plant. AcPME activity was negatively （P 〈 0.01） correlated to NaHCO3-Po concentration in the rhizosphere of both Zhongbu 51 and Pembe, suggesting that AcPME was associated with the mineralization of soil organic P.     

不同磷肥对石灰性土壤磷效率小麦基因型生长发育的影响

田间试验和测试结果表明 ,磷酸二铵、普钙和沉淀磷肥分别比对照增产 2 1 .8%、1 7.9%和 1 1 .3 %.对枸溶性磷肥 ,磷高效基因型冀 87-4 61 7小麦比对照增产 1 3 .9%,而磷低效基因型的秦麦 1号仅增产 2 .9%.对各种磷肥的利用率亦以冀 87-4 61 7最高 ,秦麦 1号最低     

不同年龄木麻黄林地根际土壤养分含量和酶活性动态

在福建省东山县滨海沙地,开展了不同年龄木麻黄林地根际和非根际土壤养分和酶活性的测定,研究结果表明：（1）不同年龄木麻黄林地根际pH小于非根际土壤,随林龄增长根际土壤和非根际土壤pH值均表现为下降趋势;根际土壤有机质、全氮和水解氮含量高于非根际土壤,各土层有机质含量在中龄林时最大;从中龄林阶段至过熟林,水解氮含量下降;全磷和速效磷含量从幼林发育至中龄林、近熟林逐渐减少,至过熟林略有恢复;根际土壤全钾、速效钾含量呈增加趋势。（2）不同年龄木麻黄林地根际CEC值、水解性总酸度、交换性盐基总量、交换性Mg^2＋均大于非根际土壤;幼林龄根际交换性Ca^2＋低于非根际;土壤CEC值在中龄林时最高。（3）不同年龄木麻黄林地根际土壤磷酸酶、过氧化物酶和多酚氧化酶活性均大于非根际土壤;随着林木的生长,根际和非根际土壤磷酸酶活性逐渐升高,并且根际与非根际间的差异也呈增大趋势;根际过氧化物酶活性从幼龄林到中龄林下降,随着林木生长至过熟林有所升高;根际多酚氧化酶活性在过熟林阶段高于其它发育阶段。     

长期定位施肥对丛枝菌根真菌多样性的影响

Diversity of arbuscular mycorrhizal fungi (AMF) was investigated in a field that had received long-term fixed ferti-lization (LFF) for 26 years.There were a total of 12 treatments in triplicates with different amounts of manure,urea,calcium phosphate,and potassium chloride.Rhizosphere soil samples of maize and wheat grown in the experimental field in Shandong Province,China,were collected in September 2003 and May 2004,respectively.Arbuscular mycorrhizal fungal spores were isolated and identified using morphological characters.Mycorrhizal colonization percentage,spore density (SD),species richness (SR),relative abundance (RA),and Shannon-Weiner index (SWI) were determined.Nineteen recognized species of AMF belonging to 5 genera were identified.Long-term fixed fertilization significantly influenced colonization percentage,SR,SD,and species diversity of AMF.The adaptability of AMF to soil fertility was different among species.Species richness and SD of AMF in maize and wheat rhizosphere soils were the highest in the nonferti-lization treatment (control) and lowest in the high manure + high nitrogen treatment (M₂N₂).The SWI decreased as the fertilization level increased except in the low manure treatment (M₁) on maize.Compared with the other treatments,Treatment M₂N₂ significantly reduced SD of Glomus,and the high manure + low nitrogen treatment (M₂N₁) significantly retarded sporulation of Scutellospora.Manure treatments stimulated sporulation of Glomus mosseae.Spore density of G.mosseae was higher in the high nitrogen + phosphorus + potassium treatment (N₂PK) than in the high nitrogen + phosphorus treatment (N₂P) and the high nitrogen + potassium treatment (N₂K).The SD of S.pellucida was higher in Treatment N₂K than Treatments N₂PK and N₂P.In conclusion,long-term fixed fertilization,especially with high levels of manure and N,decreased SR,SD,and colonization and changed the species composition of AMF.     

水肥管理对春小麦产量和根际土壤肥力特征的影响

为确定灌漠土带田春小麦高产的水肥管理模式,本研究采用裂-裂区的试验方法研究了灌溉定额(4 500 m³·hm^-2、6 000 m³·hm^-2和7 500 m³·hm^-2)、绿肥(不种绿肥和种植绿肥)、化肥(不施化肥和施用化肥)及其交互作用对春小麦产量和根际土壤肥力的影响。结果表明,增加灌溉定额能显著增加春小麦产量,与4 500 m³·hm^-2的灌溉定额相比,6 000 m³·hm^-2和7 500 m³·hm^-2的灌溉定额对春小麦产量的增加幅度为7.73%和9.99%。与不施化肥相比,施用化肥对春小麦的增产幅度为132%。绿肥和化肥之间的交互作用对春小麦产量的影响极显著,种植绿肥和施用化肥条件下春小麦产量最高,为2 639 kg·hm^-2;种植绿肥和不施化肥条件下春小麦产量最低,为987 kg·hm^-2;两者相差167%。随灌溉定额的增加,春小麦根际土壤速效氮和速效钾含量呈极显著降低的趋势,含水量和pH值呈极显著增加的趋势。种植绿肥能显著提高土壤的速效氮、有机质和含水量,能极显著降低土壤的pH值。施用化肥能极显著提高土壤的速效氮、速效磷和含盐量,能极显著降低土壤的速效钾、含水量和pH值。灌溉定额与化肥之间的交互作用对土壤速效氮含量的影响表现显著,4 500 m³·hm^-2的灌溉定额和施用化肥条件下土壤速效氮含量最高,7 500 m³·hm^-2的灌溉定额和不施化肥条件下土壤速效氮含量最低,两者相差80.6%。依据本研究得出的灌漠土带田春小麦高产的最佳水肥管理模式为:6 000 m³·hm^-2的灌溉定额、种植绿肥和施用化肥相结合。此管理模式下的带田春小麦产量为2 667 kg·hm^-2,根际土壤速效氮、速效磷、速效钾、有机质、含水量和pH值分别为106 mg·kg^-1、34.7 mg·kg^-1、93.6 mg·kg^-1、23.3 g·kg^-1、11.5%和8.29。     

外源硒肥对黄精生长及其根际土壤养分和酶活性的影响

硒是人类必需的微量营养元素,食用富硒农产品具有预防疾病、增强免疫力和抗衰老等功效。黄精对硒有较强的生物富集能力,通过硒肥生物强化黄精是安全有效获得富硒农产品的途径之一,因此,研究硒肥对黄精生长及其根际土壤养分和酶活性的影响具有重要意义。以多花黄精为材料,通过盆栽试验,研究3种不同种类肥料(普通蚯蚓肥、蚯蚓无机硒肥、蚯蚓有机硒肥)对黄精幼苗生物量、叶片生长、茎粗、株高、生根数、多糖、硒含量、硒形态、根际土壤养分和酶活性的影响。结果表明,土壤施用普通蚯蚓肥和蚯蚓无机硒肥较不施肥对黄精幼苗的生长无显著促进作用,施加蚯蚓有机硒肥能显著提升黄精生物量、叶片、株高、生根数和多糖等生长指标。施用外源硒肥显著增加了黄精硒含量,蚯蚓有机硒肥处理中黄精总硒和有机硒含量分别是无机硒肥处理的1.38和1.56倍,施用蚯蚓有机硒肥更利于黄精总硒和有机硒的积累。蚯蚓有机硒肥促进了黄精根际土壤中碱解氮和速效钾的释放,相关性分析表明,土壤碱解氮和速效钾的增加可能是蚯蚓有机硒肥促进黄精生长和品质提升的原因之一。黄精根际土壤酶活性对不同硒肥表现出不同的动态响应,外源硒肥显著提升了土壤脲酶和蔗糖酶的活性,有机硒肥与无机硒肥相比更有利于促进土壤微生物的生长繁殖,提高土壤酶活性。综上所述,蚯蚓有机硒肥是黄精幼苗阶段较为理想的促生肥和硒强化肥,蚯蚓有机硒肥替代普通蚯蚓肥和蚯蚓无机硒肥有望成为未来培育富硒农产品的主要途径。     

转菜豆几丁质酶基因和烟草葡聚糖酶基因抗病棉花的种植对棉花根际土壤酶活性的影响

本研究探讨了转菜豆几丁质酶基因和烟草葡聚糖酶基因的抗病棉花株系７p、２８p（双价载体）以及受体高代材料９７１８５、７９７０１的种植对根际土壤过氧化氢酶活性、蛋白酶活性、纤维素酶活性、脲酶活性、蔗糖酶活性的影响。结果表明：整个生育时期抗病转基因棉花根际土壤的过氧化氢酶活性与其受体之间差异不显著（Ｐ＞０．０５）。另外,根际土壤的蛋白酶活性、纤维素酶活性、脲酶活性、蔗糖酶活性在同一生育期内差异不显著（Ｐ＞０．０５）,而在不同的生育时期差异显著（Ｐ＜０．０５）。说明抗病转基因棉花的种植对根际土壤过氧化氢酶和蛋白酶几乎无影响,而根际土壤纤维素酶、脲酶、蔗糖酶活性的变化转基因抗病棉花与受体种植之间几乎没有影响,而在不同棉花株系和生育期之间产生一定的影响,这可能与不同基因类型以及生育期植株根部分泌物有关。研究初步表明转基因抗病棉花的种植对土壤微生态的影响不大。     

黑垆土和红壤上两种磷效率小麦根际特征差异

以磷高效型小麦洛夫林和磷低效型小麦中国春为试材设计三室根箱试验,通过测定两品种小麦生物量、吸磷量、pH值和酸性磷酸酶活性,对比它们在两种磷水平(P 0 mg/kg、P 100 mg/kg)及两种土壤(石灰性黑垆土、酸性红壤)上的根际特征差异。结果表明,黑垆土上增施磷肥,洛夫林和中国春的总生物量分别增加了30.14%和17.75%,总吸磷量分别增加了139.24%和71.72%;红壤上增施磷肥,两小麦总生物量并没有显著增加。根际pH方面,黑垆土上,不施磷条件下,洛夫林和中国春的根际pH值分别降低0.30和0.12个单位,但在红壤上两小麦根际pH值变化不大。酸性磷酸酶方面,PO条件下,黑垆土上两小麦根际酸性磷酸酶活性差异不显著,但红壤上洛夫林酸性磷酸酶活性显著高于中国春。P100条件下,黑垆土上洛夫林酸性磷酸酶活性显著高于中国春,而红壤上两小麦酸性磷酸酶活性差异不大。试验结果表明,在黑垆土和红壤上,两种磷效率小麦根际特征存在差异。     

小麦生长期内土壤养分与土壤酶活性变化及其相关性研究

研究了小麦生长期内土壤氮、钾与土壤过氧化氢酶(CAT)、脲酶(URE)、多酚氧化酶(PPO)活性变化及其相关性。结果表明,土壤速效氮(AN)、土壤速效钾(AK)和非交换性钾(NEK)含量随小麦生育进程呈现有规律的变化;土壤CAT、URE、PPO活性呈现先上升,但在拔节期到孕穗期出现峰值后逐渐下降,并渐趋平缓的变化规律。除小麦生长期内土壤AN、NEK与土壤PPO活性,小麦生长前、后期土壤NEK与URE活性,小麦生长后期AK与URE、PPO活性相关性不显著外,土壤AN、AK、NEK与土壤CAT、URE、PPO活性在小麦其它生长时期均显著或极显著相关。