不同土壤厚度、水分和种植方式对喀斯特两种草本凋落物分解质量损失和化学计量特征的影响

为了探究生长期间不同土壤厚度、水分及种植方式处理对草本植物凋落物分解质量损失和化学计量特征的的影响,采用分解袋法,在露天分解床上分解经过生长期间2种土壤厚度(对照土壤厚度和浅土处理)、2种水分(正常灌水处理和干旱处理)和2种种植方式(单种和混种)处理的苇状羊茅(Festuca arundinacea Schreb.)和黑麦草(Lolium perenne L.)凋落物,研究生长期间土壤厚度和水分减少及不同的种植方式是否通过改变两物种初始凋落物质量、产量和组分来影响自身凋落物分解。结果发现:(1)与对照组(CK)相比,在干旱组(D)和浅土+干旱组(SD),两物种地上、根系和总的凋落物质量损失率、初始N和P含量均显著增加,凋落物产量、C/N和C/P显著降低,凋落物地上组分比大体上无显著变化;而不同的种植方式处理对各组分质量损失率、元素含量、计量比、凋落物产量和组分比大体上无显著影响;(2)两物种地上、根系和总凋落物的质量损失率分别与地上、根系和总N含量呈显著正相关,与C/N呈显著负相关,与凋落量呈显著负相关,而总凋落物质量损失率与地上凋落物组分比呈显著正相关。结果表明,生长期间干旱和浅土+干旱处理能够通过影响苇状羊茅和黑麦草的初始凋落物质量、产量和组分比来加快地上、根系和总凋落物分解,其中凋落物N含量和C/N是影响两物种凋落物分解快慢的主要原因。     

多年生黑麦草对干旱胁迫下喀斯特异质生境的生长响应策略

在喀斯特地区异质性生境中,土壤水分含量、植物生存空间和养分状况等的综合作用共同影响植物的生理功能和生长发育。以多年生黑麦草(Lolium perenne L.)为研究材料,通过模拟同质(S-S:浅土-浅土)和异质(S-D:浅土-深土)两种小生境,探究3种施水量(对照:W_0、中度干旱:W_1、重度干旱:W_2)条件下植物对异质生境的适应,主要解决以下问题:异质生境下植物是否会主动寻求高水分、厚土壤、或者更宽阔的生长空间来提高其对异质性生境的适应?降雨量的改变是否会导致植物的适应策略发生改变?主要结果如下:(1)只有在重度干旱(W_2)条件下,异质性生境中黑麦草的株高、分蘖数以及地上、地下生物量和地上、根质量分数显著高于同质生境,而在对照(W_0)和中度干旱(W_1)条件下两种生境均无明显差异。(2)在对照降水(W_0)条件下,异质生境中黑麦草浅土区根系生物量、根组织密度较深土区少,比根长、比根面积较深土区大;随着施水量的减少,浅土区根系生物量占整个植株根系生物量的比例呈现先减小、后增大的趋势,深土区的比根长、比根面积逐渐增大,根组织密度逐渐减小。以上结果表明,在异质性生境中黑麦草表现出更强的抵御干旱胁迫能力,且随着干旱程度的加重这种优势更加明显:异质性生境中黑麦草通过将有限的生物量更多的分配在深土区,同时增大深土区根系的根组织密度,使得根系在生长环境好的斑块中大量增生和下扎,使植株获得大量的水分和养分,而浅土区则充分利用较少的资源,通过增大比根长和比根面积、减小根组织密度的方式发展根系,尽可能多地利用浅土区的水分和养分。随着干旱程度的加重,植物在维持浅土区正常生理活动的基础上有限度地增大深土区的生物量;当浅土区比根长、比根面积增大到一定限度时,植物会通过逐渐增大深土区的比根长和比根面积、减小根组织密度的策略来应对干旱胁迫。     

不同水分处理下喀斯特土层厚度异质性对两种草本叶片解剖结构和光合特性的影响

为了探究不同水分处理下草本植物对喀斯特土层厚度变化的叶片形态建成和光合生理响应,以黑麦草(Lolium perenne L.)和苇状羊茅(Festuca arundinacea Schreb.)为研究对象,通过盆栽水分受控试验,研究了3种水分处理[正常供水(W_(ck)),减水1组(D1)和减水2组(D2)]下3种土层厚度[浅土组(S_S)、对照组(S_(CK))和深土组(S_D)]对两种草本叶片解剖结构和光合特性的影响。结果表明:(1)正常供水下(W_(ck)),黑麦草和苇状羊茅在浅土组(S_S)的气孔密度和气孔限制值(Ls)均显著高于对照组(S_(CK)),净光合速率(Pn)、胞间CO_2浓度(Ci)和蒸腾速率(Tr)降低;在深土组(S_D),两种植物的气孔密度都有所下降,黑麦草的叶脉密度、Pn和Tr均低于对照组,而苇状羊茅的叶脉密度和Pn表现出增加;(2)D1水分条件下,黑麦草在浅土组的气孔密度较对照组增加,叶脉密度、Pn和Tr均降低,而苇状羊茅的气孔密度有所降低,叶脉密度、Pn和Tr未受到显著影响;在深土组中,黑麦草的气孔密度不变,叶脉密度增加,而Pn和Tr均降低;苇状羊茅的气孔密度降低,但叶脉密度、Pn和Tr均升高;(3)D2水分条件下,两种植物在浅土组的叶脉密度较对照组均增加,气孔密度、Pn和Tr均受到抑制;在深土组,黑麦草的远轴面气孔密度较对照组下降,两种植物的其他指标未受到明显影响。可见,在不同水分条件下,植物的叶片解剖结构和光合特性对不同土层厚度的响应不一,且不同物种间也有差异。总体上随着水分减少,土层厚度降低对植物的光合抑制作用增强,而厚度增加对深根植物的光合促进作用和对浅根植物的光合抑制作用先增强后减弱。植物气孔和叶脉性状特征随水分条件的变化在一定程度上与叶面积和叶片宽度的变化有关。     

基于容器分区处理探究黑麦草生长对喀斯特不同土壤生境和水分的响应

为了探究不同水分条件下喀斯特地区分布不均、厚薄不一土壤小生境对禾本科草本植物生长的影响,用3种不同深度的容器(对照深度CK,深土D和浅土S)两两组合为6种复合容器(CK-CK、CK-S、CK-D、D-D、S-D和S-S)以实现容器分区,研究了黑麦草的根系生长、生物量积累及其分配特征。结果表明:1)在水分充足(W_0)条件下,组合了浅土容器和深土容器的处理中,黑麦草的根系生长(根长、根直径、根表面积和根生物量)均低于对照容器(CK-CK),且有浅土容器的组合处理(S-S,S-D,CK-S)受抑制程度大于有深土容器的组合处理(CK-D,D-D);当水分含量降低后,即中水(W_1)和低水(W_2)条件下,有深土容器的组合[D-D和(或)CK-D]根系生长与对照相比显著增加,而有浅土容器的组合[S-S和(或)CK-S]根系生长与对照相比显著降低。2)对比同一处理不同容器分区中黑麦草生长指标发现,在水分充足情况下,深土容器和浅土容器均会抑制植物生长,而当水分减少,S区根系生长被严重抑制,但D区根系增长优势明显。3)水分充足条件下,根冠比未受到显著影响;当水分降低时,组合了深土容器的处理根冠比均有升高的趋势,组合了浅土容器的处理根冠比有降低趋势。由此可见,不同土壤生境带来的物理空间限制会影响植物根系生长和生物量积累与分配,但水分的减少会改变根系生长及生物量积累对不同土壤生境的响应:在水分充足时,土壤物理空间是影响根系生长和生物量积累与分配的主要因子,黑麦草主要发展浅层根系。而当水分减少时,黑麦草根系在浅层土壤中无法获取供给生长代谢活动的足量水分,更倾向于将有限的有机物分配给根,通过根系伸长、表面积和体积增大、直径增粗等策略加强水分吸收,从而增强对干旱的抗逆性,提高对土壤和水分异质性的适应。     

盐碱胁迫对染内生菌和不染菌苇状羊茅根系丛枝菌根真菌群落多样性和组成的影响

香柱菌属Epichloë内生真菌存在于宿主植物地上部组织,不仅能提高宿主植物对生物与非生物逆境的抗性,而且能对周围环境中的微生物产生影响。该研究以染内生菌(endophyte-infected,EI)和不染菌(endophyte-free,EF)苇状羊茅Festuca arundinacea为实验材料,探究内生真菌和不同水平盐碱胁迫处理对宿主根系丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性和组成的影响。结果表明,内生真菌和盐碱胁迫处理对苇状羊茅根系AMF多样性影响存在交互作用。EF苇状羊茅根系AMF多样性随盐碱胁迫处理水平的增加而降低,内生真菌的存在缓解了这一效应,在200和400 mmol/L盐碱胁迫处理下,内生真菌感染增加了苇状羊茅根系AMF多样性;此外,内生真菌感染改变了苇状羊茅根系AMF群落组成,降低了优势属Funneliformis相对多度,增加了Claroideoglomus、Glomus和unclassified AMF相对多度。结构方程模型结果表明,内生真菌通过间接增加土壤总磷浓度对苇状羊茅根系AMF多样性产生影响。本研究为筛选盐碱污染区生态修复的植物-微生物共生体提供基础。     

Variability of water supply affected shoot biomass and root depth distribution of four temperate grassland species in monocultures and mixtures

极端降雨事件对生态系统功能影响的研究主要集中在干旱或洪水事件，通常包括全年或某个季度的平均或总降雨量的变化。然而，在不改变平均量或总量的情况下，增加降雨变异性的影响还很少被研究。本研究调查了增加水分供应变异性对单一栽培和混合栽培下4种草原植物的地上和根系生物量以及根系生物量分布的影响。将多年生黑麦草(Lolium perenne L., 浅根)，菊苣(Cichorium intybus L., 深根)，白车轴草(Trifolium repens L., 浅根)和红车轴草(Trifolium pratense L., 深根)种植在中型实验生态系统中。单一栽培条件下种植4株同种植物，混合栽 培条件下每种植物各1株。水分供应变异性处理设置低中高3种水平：与低变异水分供应处理相比，另设置一个中度变异处理(±40%)和高度变 异处理(±80%)，测定了地上和根的生物量，拟合了根系垂直分布模型。研究结果表明，与低变异处理相比，白车轴草，红车轴草和4种植物 混种群落的茎生物量在高变异处理下显著减少。在所有处理中，4种植物混种群落产生的茎和根生物量比单一栽培(超产)中物种表现所预测的要多。在水分变异增加的情况下，菊苣在单一栽培下根系分配了更多的生物量到更深的土层，而白车轴草在单一栽培下根系总生物量显著降 低。这些结果表明，水分供应变异的增加会对单一栽培和混合栽培草地的地上和根的生物量产生负面影响。在野外尺度上，水分变异对多物种 草地系统功能的影响需要进一步研究。     

外源施N对干旱河谷白刺花（Sophora davidii）幼苗生长，生物量及C、N、P积累与分配的影响

干旱气候条件下改善土壤养分能否提高植物抗旱能力,促进植物生长一直是一个争论性的问题.为了解外源施N是否可提高岷江上游干旱河谷优势灌木白刺花(Sophora davidii)幼苗适应干旱贫瘠环境的能力,研究了不同施N(0、92 mg N · kg-1土和184 mg N · kg-1土)处理下一个生长季节内白刺花幼苗生长、生物生产量、C、N和P的积累与分配特性,以及N和P利用效率.研究结果表明:轻度施N(92 mg N ·kg-1土)处理促进了植物生长,增加了生物生产量,强化了C的固定和N、P等资源的吸收和积累,提高了其它受限资源的利用效率(如P),降低了N利用效率;但并不显著改变幼苗生物生产量及C、N和P等资源的分配格局,从而维持了资源的吸收、分配与利用的相对平衡,可能改善白刺花幼苗适应干旱贫瘠环境能力.而重度施N(184 mg N · kg-1土)处理虽然也相对于对照增加了叶片数目、生物生产量和C、N、P的积累量,但显著降低了幼苗根系的长度,抑制了根系的生长,并导致生物量及资源(生物量、C、N、P)较多地分配给地上部分(主要是叶片),不利于干旱环境下水分的吸收和利用,因而可能会加重幼苗受胁迫伤害的程度.综合分析表明,适当施加N肥可以促进白刺花幼苗的生长,一定程度上提高幼苗抗旱能力,改善幼苗定居,但也应避免过度施N.     

水分胁迫对大果沙枣光合特性及生物量分配的影响

选取大果沙枣1年生幼苗,盆栽于相对含水量分别为70%~75%(CK)、50%~55%(T1)、35%~40%(T2)和15%~20%(T3)的土壤中培养25 d,研究大果沙枣在水分胁迫下的光合特性变化和生物产量积累及其分配规律。结果显示:水分胁迫抑制了大果沙枣的光合作用,与对照相比,T2和T3处理导致净光合速率、叶片蒸腾速率和水分利用效率显著降低,气孔阻力、胞间二氧化碳浓度和叶绿素含量升高,而且光合午休明显,非气孔因素是干旱时大果沙枣净光合速率下降的主要原因;水分胁迫下,大果沙枣的生长受到抑制,地上部分和地下部分的干生物量积累同时降低,但地下干生物量降低的程度低于地上部分;干旱处理中,T3处理显著抑制大果沙枣的生长,但仍保持一定的生物量增加。结果表明:大果沙枣具有一定的自我调节与保护能力,在水分胁迫下大果沙枣趋于将更多的资源分配给根系,以提高根冠比而适应干旱的环境。     

松土对干旱胁迫下油橄榄抗性生理及土壤环境因子的影响

以田间树龄6~7年的油橄榄树为对象,设置充分灌溉(W_(CK))、2/3灌溉量(W_1)、1/3灌溉量(W_2)3个土壤水分环境条件,考察松土对干旱胁迫下油橄榄根际土壤理化指标、土壤酶活性、油橄榄叶片抗性生理及根系活力的影响,探究松土提高油橄榄抗旱性的生理机制,为油橄榄的抗旱生产提供理论和技术支持。结果表明:(1)随着灌溉量的减少,油橄榄叶片O~-·_2产生速率、MDA含量和H_2O_2含量都有所增加,油橄榄叶片受到了干旱造成的氧化胁迫,但松土处理均抑制了O~-·_2产生速率、MDA含量和H_2O_2含量的增长,同时也缓解了细胞膜稳定指数的下降;(2)经松土处理后,除SOD活性和还原型谷胱甘肽含量增加不明显外,油橄榄叶片POD活性、CAT活性均比不松土处理显著增加,增强了其抵御氧化胁迫的能力;(3)松土处理使油橄榄根际土壤相关酶活性、根际土壤含水量有所增加,但土壤pH值有所降低,这些根际土壤环境因子的变化对于油橄榄的矿质营养和水分状况的改善都具有积极的作用,尤其在因灌溉不足引起干旱胁迫的情形下更为重要。(4)松土处理提高了油橄榄叶片叶绿素含量和根系活力。研究认为,松土处理通过改善干旱胁迫下油橄榄的根际微环境条件,强化油橄榄叶片的酶促和非酶促抗氧化系统活性,提高自身渗透调节能力,增强根系活力,从而有效提高油橄榄对干旱的整体抗性。     

羌塘高原降水梯度植物叶片、根系性状变异和生态适应对策

叶片和根系是植物获取资源的最重要的器官,其性状随环境梯度的变化反映了植物光合碳获取和水分与养分的吸收能力及其对环境变化适应的生态对策。羌塘高原降水梯度带高寒草地群落叶片和根系成对性状关系研究不仅能揭示环境梯度对植物性状的塑造作用,也可为理解寒、旱和贫瘠等极端环境下植物的适应策略提供依据。为此,选择3组具有代表性的叶片和根系成对性状:比叶面积(SLA)和比根长(SRL);单位质量叶氮含量(LN_(mass))和单位质量根氮含量(RN_(mass));单位面积叶氮含量(LN_(area))和单位长度根氮含量(RN_(length)),分析不同优势植物地上、地下成对性状变异特征及其与环境因子的关系,探讨植物性状对高寒生态系统水分和养分限制因素的适应策略。研究表明,区域气候和土壤环境导致的叶片性状变异大于根系性状的变异,干旱端的植物既具有高的SRL,又具有高的叶片和根系的养分含量(LN_(mass),LN_(area)和RN_(mass))。SLA-SRL、LN_(mass)-RN_(mass)、LN_(area)-RN_(length)均表现为权衡关系,在干旱端(年降雨量MAP 400 mm)的高寒草原、荒漠草原和极湿润端(MAP 600 mm)的高寒草甸这种权衡关系更为明显,而中间区域(400 MAP 600 mm)的高寒草甸养分和水分限制不是很强烈,叶片和根系性状更多地表现出协同关系。从植物功能类群来看,苔草和禾草类植物叶片和根系成对性状之间具有更强烈的权衡关系。干旱端植物通过增加SRL和叶片、根系养分含量来提高水分和养分的吸收能力,同时通过叶片高的氮含量提高光合碳获取能力,保障了根系生长的物质来源,表现出地上和地下同时投入的策略。干旱端植物保持较高的养分含量是抵御和适应严酷的寒、旱和贫瘠的环境胁迫的重要策略。而在湿润端植物则采取增加SLA,维持地上光合生产力的生态策略。     

Host selectivity and the mediation of competition by the root hemiparasite Rhinanthus minor

Summary Rhinanthus minor (Yellow-rattle) was grown in replacement series mixtures with Lolium perenne and Trifolium repens. The hemiparasitic interaction resulted in Relative Yield Totals (the sum of the yields in mixture relative to those in monoculture) considerably above 2. The hemiparasite caused a greater decrease in the yield of the legume and also performed better on the legume, indicating that T. repens was a better host for R. minor than L. perenne under the experimental conditions. When L. perenne and T. repens were grown in binary mixture with or without R. minor the hemiparasite affected considerably the competitive relationship between the two species by selectively parasitizing the legume. The effect of R. minor on competition between the two species was, however, dependent upon the nutrient status of the soil: the higher the level of soil nitrogen the fewer haustorial connections were made with T. repens and the less was the depression in its yield. In another series of experiments in which Festuca rubra, Holcus lanatus and L. perenne were grown in various binary mixtures with or without R. minor it was also shown that the yield of a preferred host was depressed to the advantage of a non-preferred host. It is suggested that the mediation of competition by the hemiparasite provides a mechanism by which it might affect the structure and diversity of plant communities.     

柠檬酸和EDTA-Na2对黑麦草吸收Pb及营养元素特性的影响

为探究柠檬酸或EDTA-Na_2对Pb污染下黑麦草(Lolium perenne L.)吸收Pb和营养元素特性的影响,对水培黑麦草进行不同处理,研究黑麦草一些生理生化指标的变化。结果表明,与对照相比,Pb处理降低黑麦草干重,增加质膜透性和根系脱氢酶活性,且在叶和根中积累Pb,而叶和根中6种营养元素含量的变化不尽相同。与Pb处理同时加入低浓度的柠檬酸或EDTA-Na_2对其生长影响较小,且叶片的Pb积累量较低;而同时加入高浓度的柠檬酸或EDTA-Na_2,虽然强化Pb在叶片中的积累,但是加重了生长的抑制作用和营养元素的稳态失衡;1 mmol L~(–1)的柠檬酸强化叶片积累Pb的效应强于同浓度的EDTA-Na_2,而5和10 mmol L~(–1)柠檬酸的强化作用则弱于同浓度的EDTA-Na_2。因此,适当浓度的柠檬酸或EDTA-Na_2在治理Pb污染环境中具有一定作用。     

Biomass responses to elevated CO<Subscript>2</Subscript>, soil heterogeneity and diversity: an experimental assessment with grassland assemblages

While it is well-established that the spatial distribution of soil nutrients (soil heterogeneity) influences the competitive ability and survival of individual plants, as well as the productivity of plant communities, there is a paucity of data on how soil heterogeneity and global change drivers interact to affect plant performance and ecosystem functioning. To evaluate the effects of elevated CO₂, soil heterogeneity and diversity (species richness and composition) on productivity, patterns of biomass allocation and root foraging precision, we conducted an experiment with grassland assemblages formed by monocultures, two- and three-species mixtures of Lolium perenne, Plantago lanceolata and Holcus lanatus. The experiment lasted for 90 days, and was conducted on microcosms built out of PVC pipe (length 38 cm, internal diameter 10 cm). When nutrients were heterogeneously supplied (in discrete patches), assemblages exhibited precise root foraging patterns, and had higher total, above- and belowground biomass. Greater aboveground biomass was observed under elevated CO₂. Species composition affected the below:aboveground biomass ratio and interacted with nutrient heterogeneity to determine belowground and total biomass. Species richness had no significant effects, and did not interact with either CO₂ or nutrient heterogeneity. Under elevated CO₂ conditions, the two- and three-species mixtures showed a clear trend towards underyielding. Our results show that differences among composition levels were dependent on soil heterogeneity, highlighting its potential role in modulating diversity–productivity relationships. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorized users.     

The effect of drought stress on chlorophyll fluorescence in Lolium-Festuca hybrids

The effects of drought on photochemical efficiency of PSII in leaves of 22 hybrids of Festuca pratensis × Lolium multiflorum and Festuca pratensis × Lolium perenne and of Festuca pratensis cv. Skra were investigated. A significant decrease of electron transport efficiency (about 25%) in PSII (Φ_PSII) was not found before 9 days of seedling growth in hydroponics with water potential (Ψ_w) equal to −0.8 MPa (simulated “soil drought”). The decrease of Φ_PSII was similarly related to that of excitation energy capture by open PSII reaction centre (Fv’/Fm’) and also to the decrease of the proportion of oxidized to reduced Q_A (photochemical fluorescence quenching, q_p). According to the drought prolongation, variation of all parameters of fluorescence between genotypes significantly increased. The seedlings of some genotypes were able to recover electron transport efficiency in PSII after increasing water potential in nutrient solution (removing the “soil drought”). When plants grew in containers with soil and 4 genotypes with the highest sensitivity of electron transport to drought (S) as well as 4 genotypes with the highest tolerance (T) were compared 17 days after watering ceased, Ψ_w in leaves considerably decreased, but the differences between S and T genotypes were often not significant in this respect. The differences between S and T genotypes, as values of Fv/Fm were concerned, also appeared small (about 5%), similarly as that of Fv’/Fm’ (5%), q_p (12%) and Φ_PSII (about 15%). Drought stress increased non-photochemical quenching of chlorophyll fluorescence (NPQ) 15 to 47% and this could protect the PSII reaction centres from damages because of energy excess. The increase of NPQ was not closely connected with drought resistance of plants because it was similar in some genotypes tolerant to dehydration as well as in sensitive ones. The results of the experiments suggest that resources of genetic variability in Festulolium may be sufficient for revealing differences between genotypes on the basis of measurement of chlorophyll a fluorescence, as far as their tolerance to soil drought is concerned. As the tolerance of PSII against drought is high, the determinations of fluorescence should be performed rather under severe stress. Such methods seem to be useful for selection of genotypes with high drought tolerance as well as with the ability to at least partial repairing of PSII after drought.     

Competitive relationships between two contrasting but coexisting grasses

Leymus chinensis (Trin.) Tzvelev and Phragmites communis Trin. are co-dominant grasses in both nutrient-poor and rich steppes in the Songnen Plains of northeastern China. A replacement series experiment was conducted along a five-level nutrient gradient to test for changes in the competitive relationships of the species with nutrient availability. There were significant effects of nutrient level and species proportion on mean plant height, biomass and rhizome length. Facilitation was found in these plant attributes for both species when grown in mixture compared with monoculture, especially at high nutrient levels. For example, L. chinensis grew taller and intercepted more light when in mixture. The aboveground dominance of P. communis did not decrease in mixture, possibly because it benefited from belowground interactions with L. chinensis. Biomass allocation was apparently influenced by both above and belowground competition. For example, L. chinensis allocated much more biomass to shoots and less to roots when neighbor number was increased, suggesting that aboveground competition occurred. Root: shoot ratios of L. chinensis in monoculture decreased gradually with increasing nutrient availability, whereas the ratio in mixture declined rapidly, implying intense competition for light at high levels. Our results support the hypothesis that nutrient competition is more important than light competition when soil nutrients are scarce. Although the interactions between these species benefit both, P. communis is more likely to displace L. chinensis at high nutrient availability.     

Temporal and spatial patterns of soil water following wildfire-induced changes in plant communities in the Great Basin in Nevada,USA

Infection of tall fescue (Festuca arundinacea Schreb.) with its endemicNeotyphodium coenophialum-endophyte (Morgan-Jones and Gams) Glenn, Bacon and Hanlin appears to reduce copper (Cu) concentrations in forage and serum of grazing animals, contributing to a range of immune-related disorders. A greenhouse experiment was conducted to identify effects of novel endophyte strains on Cu acquisition by tall fescue (Festuca arundinacea Schreb.) varieties Grasslands Flecha and Jesup infected with a novel, non ergot producing endophyte strain AR542, and two perennial ryegrass (Lolium perenne L.) varieties Aries and Quartet infected with a novel, non lolitrem B producing strain AR1, and their noninfected (E−) forms. Individual endophyte/grass associations were cultivated in nutrient solutions at 1.0 (P+) and 0.0 mM (P−) phosphorus concentrations. The Cu²⁺-binding activity of extracellular root exudates, and concentrations of Cu and other heavy metals in roots and shoots were measured. Extracellular root exudates of AR542-infected vs. E− tall fescue had higher Cu²⁺-binding activity only in P− nutrient solution as shown by lower concentration of free Cu²⁺ (0.096 vs. 0.188 mmol Cu²⁺ g⁻¹ root DM, respectively). The Cu²⁺-binding activity by root exudates of perennial ryegrass was not affected by endophyte infection, but was higher (i.e., lower concentration of free Cu²⁺) in P− vs. P+ nutrient solution (0.068 vs. 0.114 mmol Cu²⁺ g⁻¹ root DM). In this hydroponic experiment, Cu concentrations in shoots of both grasses were not a function of Cu²⁺-binding activity and endophyte effects on heavy metal concentrations in shoots and roots were specific for each variety. The Cu²⁺-binding activity of extracellular root exudates may affect Cu accumulation by field-grown, endophyte-infected tall fescue under P-limiting growth conditions and warrants verification by more specific methods.