丛枝菌根真菌对枳根系形态和蔗糖、葡萄糖含量的影响

研究丛枝菌根真菌接种(摩西球囊霉、地表球囊霉和摩西球囊霉+地表球囊霉)对盆栽枳的生长、根系形态以及蔗糖、葡萄糖含量的影响.结果表明: 3个接种处理都显著提高枳的株高、茎粗、叶片数,以及地上部和地下部生物量,诱导1级、2级和3级侧根的发生,同时增加了根系投影面积、表面积、体积和总长度(主要是0～1 cm根长),但降低根系平均直径,其中以地表球囊霉效果最明显.丛枝菌根真菌接种显著提高枳的叶片蔗糖和根系葡萄糖含量,但降低叶片葡萄糖和根系蔗糖含量.由于根系“菌根碳库”的存在,丛枝菌根真菌接种导致根系维持较高的葡萄糖和较低的蔗糖含量,从而有利于宿主根系的生长和发育,建立更优的根系形态.     

AM真菌和镰刀菌对西瓜根系几种酶活性的影响

在温室盆栽条件下研究了丛枝菌根（Arbuscular Mycorrhiza,AM)真菌Glomus versiforme和西瓜枯萎镰刀菌Fusarium oxysporum f.sp.niveum对西瓜根系中过氧化物酶（POD）,苯丙氨酸解氨酶（PAL）,β－1,2－葡聚糖酶和几丁质酶活性的影响。结果表明,接种AM真菌的西瓜根系中4种酶的活性均高于对照,先接种G.versiforme,后接种F.oxysporum f.sp.niveum处理的4种酶的活性均高于只接种F.oxysporum f.sp.niveum的处理,且酶的活性峰值出现较早,表明接种G.versiforme能预先诱导这4种酶的产生,提高其活性,从而提高西瓜对F.oxysporum f.sp.niveum侵染的抗性,接种G.versiforme的感枯萎病西瓜品种“郑杂5号”酶的增加幅度大于抗病品种“京欣1号”的接种处理,说明G.versiforme对提高感病西瓜品种酶活性的作用更大。     

接种丛植菌根真菌对湿生植物氮磷吸收能力的影响

丛枝菌根(Arbuscular mycorrhizal,AM)真菌是一类能够与大多数陆生植物共生,并改善植物生长和氮磷吸收的微生物.湿生植物在湿地污染净化过程中起着决定性的作用,但利用AM真菌改良湿生植物氮磷吸收能力的研究鲜有报道.本研究选取了3种湿生植物千屈菜、旱伞草和黄花鸢尾,在盆栽培养的基础上,分别接种根内球囊霉(RE)、摩西球囊霉(GM)、幼套球囊霉(CE)三种AM真菌,并和空白对照比较接种AM真菌对不同植物地上、地下及整株的生物量和氮磷吸收的影响.结果表明,接种AM真菌对植物生长和氮磷吸收的影响呈现出植物间和植物内的差异,促进与抑制效应表现不一.综合AM真菌对植物生物量和氮磷吸收的促进效应,最佳AM真菌-植物的组合为:千屈菜-RE,旱伞草-RE,黄花鸢尾接种-GM.三种植物接种最佳的AM真菌后植物生物量、TN量和TP量分别提高了17.7%~29.8%、15.7%~39.0%和22.3%~62.6%.本研究为今后强化湿生植物的氮磷吸收能力提供了一种新的可选择的途径.     

丛枝菌根（AM）真菌对翅果油树幼苗根系的影响

采用接种和不接种(对照)丛枝菌根的方法对翅果油树幼苗在不同生长时期的形态、生物量、矿质元素含量及抗逆性等指标进行比较分析,以探讨丛枝菌根(AM)改善翅果油树在生态系统中的退化及濒危现状的机理.结果显示:(1)摩西球囊霉(Glomus mosseae)和脆无梗囊霉(Acaulospora delicata)与盆栽翅果油树苗木可形成菌根;菌根化苗木的形态及生物量等指标均与对照差异极显著,且与菌根侵染率呈显著正相关(P<0.05).(2)菌根使苗木根系体积增大、总吸收面积增加、根系的活跃吸收面积显著增加,且根系中活跃吸收面积比与磷、钾元素含量呈显著正相关(P<0.05).(3)苗木生长的盛期和末期,菌根化苗木根系过氧化物酶活性显著高于对照,而在生长后期却显著低于对照呈负相关(P<0.05);菌根化苗木根系多酚氧化酶活性显著高于对照(P<0.05),在苗木生长盛期酶活性最强,但接种不同菌种的苗木间差异不显著.研究表明,与不接种相比,接种菌根增加了翅果油树的根系吸收能力,提高了根系酶体系,有利于植物抵抗各种胁迫,对扩大翅果油树植物的分布区有重要意义.     

环境因子对AM真菌多样性的影响

土壤,气候和地理因子等环境因子对丝枝菌根（AM）真菌多样性有重要影响,本文系统地综述了最近10年来AM真菌生态学在该方面的最新研究成果,分析当前研究中所存在的问题和动向。     

生物因子对AM真菌多样性的影响

丛枝菌根真菌(Arbuscular Mycorrhizas,AM）真菌分布于自然界各生态系统中,生态因子对AM真菌多样性个有举足轻重的影响,其中动物,植物,微生物,人为因素等生物因子的作用,亦日益受到人们的关注,通过介绍该领域最近10年来的研究成果,探讨和分析当前研究中所存在的问题和动向。     

外源养分和激素对AM真菌侵染和产孢的影响

在温室30%强度Hoagland营养液半水培条件下,对寄主植物玉米Zea mays接种丛枝菌根(Arbuscular myeorrhizae,AM)真菌Glomus mosseae后施加不同浓度的葡萄糖、蔗糖、脯氨酸(Pro)、吲哚-3-乙酸(IAA)、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)。结果表明:除低浓度GA3处理外,其他处理尤其是高浓度处理抑制了玉米植株的生长。中浓度蔗糖、脯氨酸(Pro)和吲哚-3-乙酸(IAA)处理显著提高玉米菌根侵染率,其中以中浓度蔗糖的处理最高,达92.3%。葡萄糖、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)处理则降低菌根侵染率。施加不同有机养分和植物生长物质并未提高AM真菌产孢数量,相反,却减少了孢子的形成。高浓度氨基乙酸(Gly)和低浓度6-BA处理的产孢量分别为50和48个/管,高于其他处理,但低于对照(78个/管);可溶性糖处理的产孢数量最少,平均仅18个/管。本试验条件下菌根侵染率与产孢数量不具有相关性,而产孢数与根外菌丝量具相关性。认为通过外界不同的化学调控,对植物生长、菌根侵染、根外菌丝量和孢子发育产生了一定的影响,具有一定的调节作用。     

AM 真菌影响三叶草根系抗氧化酶活性的系统效应

本文对三叶草接种AM 真菌根内球囊霉, 用盆栽试验和分根试验测定根系的菌根侵染率和抗氧化酶活性, 研究AM 真菌对根系抗氧化酶活性的影响以及该影响的系统性。结果表明, 盆栽试验中接种根内球囊霉显著提高了根系中SOD、POD、CAT 的活性, 表明AM 真菌可以促进根系的抗氧化酶活性; 分根试验中一半根系接种了根内球囊霉的植株, 其另一半未接种的根系SOD、POD 活性也增加, 表明AM 真菌对根系抗氧化酶系统的促进具有系统效应。由于抗氧化酶系统是植物产生抗逆性的生理生化基础, 可以推测, AM 真菌对根系抗氧化酶活性的系统性提高有助于保护根系整体, 而非仅仅保护受侵染根段。     

覆膜与接种AM真菌对半干旱区玉米根际土壤理化性质的影响

本研究采用裂区试验设计,主区设置了3种覆膜方式:露地平播(即常规播种方法,无覆膜)、半覆膜平作(即常规播种方法,覆膜占小区面积一半)、全膜垄上穴播(即起垄后小区全覆膜,垄上播种),副区设置了2个丛枝菌根(AM)真菌接种水平:接种AM真菌(AM)和不接种对照(CK),研究了大田条件3种覆膜方式下接种AM真菌对半干旱区春播玉米根际土壤养分、有机碳含量及AM真菌特性(侵染率、根外菌丝密度与土壤球囊霉素)的影响。结果表明:3种覆膜方式下,与不接种对照相比,接种AM真菌显著提高了根系侵染率、根外菌丝密度、土壤中球囊霉素和有机碳含量、植株干重、碳氮比和土壤含水量,同时显著促进了土壤养分吸收(个别例外),其中土壤根外菌丝密度、易提取球囊霉素、有机碳、速效磷和速效钾含量、碳氮比随着覆膜方式由无覆膜-半覆膜-全覆膜的变化呈降低趋势,而植株干重、土壤中总球囊霉素、全氮和含水量随着覆膜方式由无覆膜-半覆膜-全覆膜的变化呈升高的趋势。全覆膜结合接种AM真菌在促进西北半干旱地区田间作物生长、提高土壤含水量、以及改善菌根侵染率、菌丝密度与土壤中球囊霉素含量的作用最大,但降低了土壤养分,后期还可能需要通过合理施肥措施加以维持土壤肥力水平。相关分析表明,土壤根外菌丝密度和球囊霉素含量与土壤矿质养分和水分存在一定程度的协同效应,接种AM真菌有助于根际土壤养分转化,促进植物生长。     

AM真菌和镰刀菌对西瓜根系几种酶活性的影响

在温室盆栽条件下研究了丛枝菌根(Arbuscular Mycorrhiza, AM)真菌Glomus versiforme和西瓜枯萎镰刀菌Fusarium oxysporum f.sp. niveum对西瓜根系中过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3-葡聚糖酶和几丁质酶活性的影响。结果表明,接种AM真菌的西瓜根系中4种酶的活性均高于对照,先接种G. versiforme,后接种F. oxysporum f.sp. niveum处理的4种酶的活性均高于只接种F. oxysporum f.sp. niveum 的处理,且酶的活性峰值出现较早。表明接种G. versiforme 能预先诱导这4种酶的产生,提高其活性,从而提高西瓜对F. oxysporum f.sp. niveum侵染的抗性。接种G. versiforme的感枯萎病西瓜品种“郑杂5号”酶的增加幅度大于抗病品种“京欣1号”的接种处理,说明G. versiforme对提高感病西瓜品种酶活性的作用更大。     

环境因子对西藏高原草地植物丛枝菌根真菌的影响

对西藏高原不同草地类型建群种植物的研究结果表明,寄主植物根围土壤AM真菌孢子密度与菌根侵染率之间无相关性;不同海拔条件下温度、降水量等的显著变化对草地植物AM真菌的发育和侵染具有重要影响,不同草地类型、土壤质地对AM真菌的影响亦较明显;在一定范围内,孢子密度随土壤pH、有机质含量的提高分别呈显著增加(r=0.5319^*,n=20)和下降趋势(r=-0.1973,n=20),菌根侵染率与土壤pH、有机质含量间则分别呈一定程度的负相关和正相关;高磷土壤环境对AM真菌的产孢和侵染均具有不同程度的抑制作用;最适AM真菌发育和产孢的土壤pH、有机质和有效磷含量范围分别为8.0～8.7、3.8～4.8g·kg和7.8～10.1mg·kg^-1;中度特别是重度退化草地对AM真菌的繁殖和侵染均具有不利影响,适度放牧对AM真菌关键种的保持具有重要意义;AM真菌对沙生苔草、矮生嵩草和扁穗莎草根系均具有良好的侵染效应.     

Effects of temperature on the development and growth of winter wheat roots

Winter wheat was sown on 2 dates with 3 levels of nitrogen fiertiliser (0, 50 and 200 kg N ha⁻¹) in one year and on 2 sites in a followign season. Shoot and root development and growth were measured between emergence and anthesis in the first season and emergence and 7 mainstem leaves in the second. Differences in temperature and light regime led to significant differences in shoot and root development and growth between sowing dates. A thermal time-scale, based on soil surface or air temperatures, with a base of 0°C, adequately described the production of mainstem leaves and nodal root axes over all treatments. Autumn applied nitrogen had little effect on development. Shoot growth and green area index increased exponentially with thermal time prior to spring nitrogen application and the completion of canopy development. Early-sown crops had larger root systems than late-sown crops prior to winter and this divergence was retained until anthesis. The relationship between root growth and thermal time was little better than with days after sowing and was not improved by either varying the site of temperature measurement or the base temperature used for calculation. Differences in soil texture and drainage, between sites, led to significant changes in root length distribution. Although spring applied nitrogen generally increased root length, its effects were inconsistent. There was a curvilinear relation between root length and the amount of photosynthetically active radiation (PAR) intercepted; this relation was unaffected by sowing date or nitrogen treatment. The amount of root produced per unit PAR decreased as the season progressed, reflecting the decrease in the proportion of total dry matter partitioned to the root system.     

Effects of temperature on the development and growth of winter wheat roots

Wheat plants were grown in columns of soil until early stem elongation at a wide range of constant root temperatures. Two light environments were imposed and three levels of nitrogen fertilizer added at sowing. Shoot and root development and growth were measured by destructive sampling to investigate the combined effects of temperature and changing nutrient and assimilate supply. Both mainstem leaf and root axis production were linearly related to thermal time above a base temperature of 0°C. Low irradiance affected the appearance of mainstem tillers and associated nodal root axes. Nitrogen had little effect on shoot or root development but increased shoot area between 6 and 8 mainstem leaves. Higher temperatures and supplementary light resulted in larger root systems when compared at equivalent times after sowing. Total root length and root dry weight increased exponentially with thermal time, based on the mean of 4 cm soil and 2 cm air temperatures, but no single relation existed for all temperature and light treatments. Total plant dry matter, root length and root dry weight increased linearly with accumulated, intercepted, photosynthetically active radiation. Root growth responded less than the shoot to supplementary light. Increasing temperature reduced the proportion of root weight to total plant weight.     

Effects of low-molecular-weight organic acids on uptake of lanthanum by wheat roots

Effects of low-molecular-weight organic acids (LMWOAs) on the uptake of lanthanum by wheat (Triticum aestivum L.) roots were studied under hydroponic conditions. Acetic and malic acids were chosen as the representatives of LMWOAs. Uptake kinetics of lanthanum indicated that when lanthanum concentrations in the uptake solutions were high or uptake time was long lanthanum uptake by roots was enhanced by LMWAOs. After wheat was cultured in the uptake solution of lanthanum containing acetic or malic acids for 48 h the uptake of lanthanum by roots increased by 57 and 44%, respectively, compared with that in the absence of acetic and malic acids. The increase in uptake of lanthanum was determined by the ratio of the concentrations of organic acids to lanthanum in the uptake solutions. The highest uptake of lanthanum was obtained at the ratio of 5:1.     

Development of wheat roots under zinc deficiency

Summary Wheat seedlings were cultured in nutrient solutions with and without zinc supply. Shoot: root ratio was reduced in plants without zinc and the greater biomass of –Zn roots was a result of enhanced 1st order lateral root numbers and length. The implications of morphological changes under zinc stress are discussed in relation to knowledge of ion absorption pathways across roots.     

冬小麦根系各种参数垂直分布实验研究

本文根据田间实测资料研究了冬小麦根系各种参数(长度、重量、活性表面和根径)的垂直分布。结果表明,在所观测地区的土壤条件下,冬小麦根系的长度、重量、表面积和体积随深度呈指数分布,而累积根系的长度、重量和表面积随深度呈双曲线型分布。根据作者的观测资料和国内外其它观测资料分析研究表明,对于不同土壤,根区各层土壤中累计根重及根长的百分比随相对深度的变化都符合下列双曲线函数形式:这一研究结果可为根系生态研究和作物对水分吸收的模拟工作提供参考。     

Effects of decenylsuccinic Acid on p uptake and translocation by barley and winter wheat

After 3 days of exposure to 10⁻³ and 10⁻⁴ M decenylsuccinic acid, winter wheat plants wilted and died. Decenylsuccinate at 10⁻³ M inhibited ³²P uptake by barley roots and wheat roots and resulted in significant (P ≤ 0.05) leakage of previously absorbed ³²P and total phosphorus (barley roots). Decenylsuccinate effects on ³²P uptake and retention were attributed to increased permeability resulting from injury. Decenylsuccinate at 10⁻⁴ M did not inhibit root uptake of ³²P but decreased movement into the shoot. This could be interpreted as an indication of reduced transpiration or inhibition of ³²P loading into the transpiration stream. Decenylsuccinate did not increase cold hardiness in winter wheat in a nonhardening environment.