空心莲子草响应南方菟丝子寄生的生长-防御权衡

为探讨全寄生植物南方菟丝子(Cuscuta australis)防治入侵植物空心莲子草(Alternanthera philoxeroides)的可行性,以二者野外天然生长的种群为研究对象,分析南方菟丝子寄生对空心莲子草生长及防御的影响,阐明空心莲子草在受到寄生胁迫时如何权衡自身生长与防御的关系,进而发展出一套应对南方菟丝子寄生的生长-防御策略。结果显示:(1)南方菟丝子寄生显著改变空心莲子草茎的形态,茎直径和平均节间长均增加,茎直径变化极显著(P0.01);(2)南方菟丝子寄生显著减少空心莲子草叶片数,但同时显著增加后者茎的分枝数,而茎上的节是潜在的无性繁殖体,故有利于空心莲子草的克隆繁殖;此外,南方菟丝子寄生显著降低了空心莲子草的根、茎、叶生物量和总生物量,抑制空心莲子草的生长;(3)南方菟丝子寄生显著增加空心莲子草茎的单宁、总酚、三萜皂苷含量,增强其防御能力;(4)南方菟丝子寄生的空心莲子草的生物量与茎部木质素、三萜皂苷、单宁和总酚含量均呈现显著负相关性(P0.01),对照组则不存在相关性;且寄生组较对照组相比,生物量的相对百分比显著低于对照组(P0.01),而用于防御的次生代谢产物总含量的相对百分比显著高于对照组(P0.01)。以上结果表明,受到南方菟丝子寄生胁迫后,空心莲子草改变自身的生长-防御策略,减少营养生长投入而将更多的资源投向克隆繁殖,同时增强对"防御"物质的投入,增强其防御能力,以利于后代生存和繁衍。     

福寿螺取食对空心莲子草生长和繁殖的影响

福寿螺(Pomacea canaliculata)和空心莲子草(Alternanthera philoxeroides)是我国南方淡水生态系统中常见的两种入侵生物, 空心莲子草是福寿螺的植物性食物之一。以福寿螺和空心莲子草为研究对象, 研究了不同福寿螺取食强度对空心莲子草生长和繁殖的影响, 探讨了两者之间的相互关系。结果表明: 与对照相比, 福寿螺取食抑制了空心莲子草的生物量积累, 但不同取食强度的影响存在差异。在每盆1、3 只取食强度下, 空心莲子草鲜重先下降然后上升, 而在每盆5、7 只取食强度下, 其鲜重一直保持下降的趋势。与处理前相比, 福寿螺取食下空心莲子草的节数和分枝数均增加(每盆7 只除外), 而叶片数一直保持下降的趋势。每盆7 只福寿螺的取食强度下, 空心莲子草的花数显著高于对照(P<0.05), 为对照的10.5 倍(处理20 天时)。可见, 福寿螺取食在一定程度上抑制了空心莲子草的生长, 但空心莲子草对不同的取食强度产生不同的生长响应。低取食强度可能促进了空心莲子草的营养生长, 高取食强度抑制了空心莲子草的营养生长, 却促进了其有性繁殖。同时, 福寿螺对空心莲子草叶片的取食偏好性优于其茎秆。     

地上-地下植食性天敌对入侵植物空心莲子草与本地种莲子草种间关系的影响

生物入侵是全球生物多样性的主要威胁,外来种与本地种的种间竞争能力会影响其能否成功入侵。本研究选用入侵植物空心莲子草和其本地同属种莲子草为对象,探究其专食性天敌莲草直胸跳甲与南方根结线虫对空心莲子草与莲子草的生长及种间关系的影响。结果表明: 与无天敌胁迫相比,线虫处理显著降低了莲子草的株高(28.1%),但显著增加了空心莲子草的株高(52.8%)和莲子草的地上生物量(63.7%);跳甲处理显著降低了莲子草的株高(40.7%),对空心莲子草无显著影响;而跳甲与线虫的共同胁迫显著降低了莲子草的株高(35.3%)和空心莲子草的地下生物量(62.2%),显著增加了莲子草的地上生物量(69.1%);天敌胁迫对两种植物的茎粗、分枝数和根长均无显著影响。无天敌作用下,两种植物的相对邻体效应指数(RNE)均为正值,且空心莲子草的RNE比莲子草高21.3%;天敌胁迫下,空心莲子草的RNE均为负值,而莲子草的RNE在线虫或跳甲单独胁迫下为正值,在线虫和跳甲共同胁迫下为负值。表明地上-地下天敌互作可以使两种植物的种间关系发生改变,并可能促进空心莲子草的入侵。     

9种植物水浸提液对空心莲子草的化感作用

【背景】空心莲子草是难以防除的恶性入侵杂草,因此,探索高效无毒的化感防治方法具有重要意义。【方法】利用水浸提法研究了博落回、苦瓜、樟树、柳杉、凤尾蕨、柑橘、夹竹桃、洋葱及大蒜9种植物不同器官对空心莲子草的化感作用。【结果】与对照相比,博落回叶、苦瓜果肉与种子、凤尾蕨、樟树叶和柳杉叶的水浸提液对空心莲子草具有较强的化感作用,主要表现为空心莲子草叶片数和茎节数减少,株高与生物量的增长受到抑制。【结论与意义】不同植物水浸提液对空心莲子草的化感作用有所差异。本研究为利用植物的化感作用控制空心莲子草提供了依据。     

空心莲子草叶甲对空心莲子草控制效果的定量评价

为了解空心莲子草叶甲Agasicles hygrophila被引入中国20多年后其取食行为与取食能力是否发生改变, 我们通过采集叶甲自然种群的成虫, 在室内用空心莲子草Alternanthera philoxeroides饲养获得检测用叶甲各虫态与虫量进行室内定量检测, 研究了空心莲子草叶甲自然种群各龄幼虫与成虫在不同密度下对空心莲子草的控害效果。结果显示： 1龄幼虫喜食顶芽嫩叶, 在每株接0.2和1头1龄幼虫密度下, 空心莲子草仍有新叶和侧芽生成, 生物量、 株高与茎节数仍在增加; 在5头/株的密度下, 空心莲子草的生物量、 叶片数和侧芽数均出现负增长; 在10头/株的密度下, 草的生物量、 株高、 叶片数、 侧芽数和茎节数均表现为负增长。2龄幼虫优先取食顶芽嫩叶, 也取食老叶与茎杆, 在每株10头2龄幼虫的密度下, 接虫7 d后, 40%的植株死亡。3龄幼虫取食叶片与茎秆, 后期钻入茎秆中化蛹,在10头/株密度下,7 d后, 已引起52%的植株死亡, 存活株的茎节数显著减少。成虫可24 h连续取食植株的任何组织, 0.2头/株的密度下,空心莲子草叶片与侧芽数量已呈现负增长; 5头/株的密度下,空心莲子草的生物量、 株高、 叶片数、 侧芽数与茎节数均呈现较大的负增长; 10头/株的控草效果更加显著。     

Effects of elevated temperature on chemistry of an invasive plant,its native congener and their herbivores

增温对莲子草属入侵植物与本地同属植物化学物质组成和天敌昆虫的影响 气候变暖影响植物生长和生理活动,然而气候变暖如何改变入侵植物化学物质组成并间接影响其与植食性昆虫互作还少有报道。本研究以入侵植物空心莲子草(Alternanthera philoxeroides)及其本地同属 植物莲子草(A. sessilis)为对象,探究增温对其叶片化学物质组成的影响并进一步检验这些变化如何影响两 种植食性昆虫虾钳菜披龟甲(Cassida piperata)和斜纹夜蛾(Spodoptera litura)的生长发育。通过模拟增温实验,探究增温对空心莲子草和莲子草13个叶片化学物质的影响,并用其饲养两种植食性昆虫,测量它们的生长和发育时间。研究结果显示,增温显著改变了空心莲子草和莲子草叶化学物质组成;增温降低了空心莲子草叶片氮浓度,增加了莲子草叶片总黄酮和总酚浓度;增温对其它营养物质(果糖、蔗糖、总可溶性糖和淀粉)随物种和具体物质发生改变;采用增温处理的莲子草饲养的虾钳菜披龟甲蛹重和斜纹夜蛾幼虫重量,以及增温处理的空心莲子草饲养的斜纹夜蛾幼虫重量,显著低于对照不增温处理;此外,采用增温处理的莲子草饲养的斜纹夜蛾幼虫发育时间显著延长。这些结果表明,增温对植物化学物质组成的影响随物种发生变化,增温对入侵植物和本地植物化学物质组成的影响间接改变了其与植食性昆虫的互作关系。     

Opposing effects of plant growth regulators via clonal integration on apical and basal performance in alligator weed

植物生长调节剂通过克隆整合对空心莲子草顶端和基部生长的不同作用 入侵植物不仅对全球生物多样性造成了巨大的威胁,同时也严重影响了农业生产与粮食安全。克隆整合使得相连植株进行资源共享,能促进入侵植物的生长从而获得优势。然而,入侵杂草 在植物调节剂(plant growth regulators, PGRs)影响下的克隆整合作用则很少有报道。PGRs被广泛应用于 农作物生产上,并能通过土壤淋溶、侵蚀和径流作用,影响分布在作物附近的农田杂草的生长。本 研究采用两种PGRs赤霉素(gibberellins, GA)和多效唑(paclobutrazol,PAC)处理恶性入侵杂草空心莲子草 (Alternanthera philoxeroides)基端,并保持或者通过剪切达到控制基端与顶端的连通,从而探究克隆整合作用在空心莲子草响应两种农业常用PGRs中的作用。研究结果表明,GA和PAC对空心莲子草生长的作用相反。GA通过克隆整合作用显著促进顶端植株的地上生长。相反地,PAC显著抑制基端和顶端的地 上生长,但是能够通过克隆整合作用显著促进基端和顶端的地下生长。这些研究结果解释了克隆整合作用能促进PGRs对空心莲子草生长的促进作用,这很可能是外来杂草能够成功入侵人为干扰较多的农业生态系统的重要原因之一。     

不同生境下空心莲子草响应模拟昆虫采食的生长和化学防御策略

外来植物往往可以入侵多种生境并受到多种昆虫的采食,而不同生境条件将可能会影响这些入侵植物对昆虫采食的防御策略。以入侵我国的克隆植物——空心莲子草为研究对象,分别选择生长在水生生境、水陆两栖生境和陆生生境中的无性个体(分株),通过50%去叶处理模拟昆虫采食,分析不同生境下空心莲子草对模拟昆虫采食处理的生长及化学防御响应的差异。模拟昆虫采食处理显著抑制了陆生生境、水陆两栖生境以及水生生境下空心莲子草的根、茎、叶和总生物量,但对3种生境下空心莲子草的生物量分配(根冠比、根生物量分配、茎生物量分配和叶生物量分配)均无显著影响。陆生生境下空心莲子草根、茎和总生物量显著高于水陆两栖生境和水生生境,根冠比显著低于水陆两栖生境和水生生境。模拟昆虫采食处理显著降低了空心莲子草的木质素含量,而对单宁和总酚含量影响不显著。生境对木质素含量无显著影响,但陆生生境下空心莲子草单宁含量显著高于水陆两栖生境和水生生境,且总酚含量显著高于水陆两栖生境,表明陆生生境中空心莲子草具有更强的防御能力。空心莲子草木质素含量与总生物量无显著相关性,但在模拟采食情况下,其总酚含量与总生物量呈显著负相关,而无论模拟昆虫采食处理存在与否,空心莲子草单宁含量与总生物量均呈显著正相关。因此,空心莲子草存在昆虫介导的生长和化学防御之间的权衡,在昆虫采食的情况下可通过减少生长来增加对化学防御物质的投入,但生境对空心莲子草这种生长-防御权衡的影响十分有限。     

重金属胁迫条件下空心莲子草的生长和营养特征分析

空心莲子草是一种常见的水生植物,并能在重金属污染的水体或附近土壤中生长.本研究发现,空心莲子草能富集6种常见的重金属元素,其富集能力为:Zn2+>Mn2+>Pb2+>Cu2+>Cd2+>Cr3+.高浓度(1 mmol/L) Cu2+、Mn2+、Zn2+和Cr3+ 等重金属胁迫处理条件下,空心莲子草的根冠比增加,生物干重、总根长和总根表面积都相应降低.此外,高浓度(1 mmol/L) Pb2+、Cd2+、Cu2+或Zn2+分别胁迫处理条件下,空心莲子草的K+、Ca+和Mg+等元素的含量变化差异显著(P＜0.05).以上研究表明,空心莲子草通过改变体内钾钙镁等重要生长元素营养情况来适应重金属污染的胁迫,有很强的富集重金属元素的能力,进而降低污染、净化水体.空心莲子草对重金属污染的生长响应及体内重要矿物元素营养特性之间的相互关系,可能为重金属污染的水土生物修复提供理论依据.     

酸雨和采食模拟胁迫下克隆整合对空心莲子草生长的影响

研究表明克隆整合可以显著提升异质环境中克隆植物的生长,然而当克隆植物遭受均质环境压力时,整合对植物生长影响的研究相对较少。本文以典型入侵克隆植物空心莲子草（Alternanthera philoxeroides）为例,研究均质环境压力酸雨和采食模拟胁迫对空心莲子草生长的影响,以及克隆整合在空心莲子草适应不利环境过程中所起的作用。酸雨设3种浓度梯度：pH值3.5 、pH值4.5和 pH值6.5（对照）;采食设3种水平：不去叶、去叶50%和去叶90%;整合水平：匍匐茎切断和连接。结果表明：无论保持或切断匍匐茎的连接,酸雨处理都不影响空心莲子草生物量。当保持匍匐茎连接时,pH值4.5酸雨处理增加了空心莲子草匍匐茎长度和分株数目,因此,低度酸雨可能对空心莲子草生长有一定的促进作用。同样,无论匍匐茎是否被切断,采食处理都显著降低了空心莲子草克隆片段生物量,而显著增加了叶片数目。当切断匍匐茎连接时,采食处理使空心莲子草分株数目显著增加。本文得出的结论是：空心莲子草能较好地适应酸雨和采食的环境压力,当空心莲子草全部克隆分株遭受均质环境胁迫时,克隆整合并不能显著改善它的生长。     

根茎型植物扁秆荆三棱对光照强度和养分水平的生长响应及资源分配策略

自然界中光照和养分因子常存在时空变化,对植物造成选择压力。克隆植物可通过克隆生长和生物量分配的可塑性来适应环境变化。尽管一些研究关注了克隆植物对光照和养分因子的生长响应,但尚未深入全面了解克隆植物对光照和养分资源投资的分配策略。以根茎型草本克隆植物扁秆荆三棱(Bolboschoenus planiculmis)为研究对象,在温室实验中,将其独立分株种植于由2种光照强度(光照和遮阴)和4种养分水平(对照、低养分、中养分和高养分)交叉组成的8种处理组合中,研究了光照和养分对其生长繁殖及资源贮存策略的影响。结果表明,扁秆荆三棱的生长、无性繁殖及资源贮存性状均受到光照强度的显著影响,在遮阴条件下各生长繁殖性状指标被抑制。且构件的数目、长度等特征对养分差异的可塑性响应先于其生物量积累特征。在光照条件下,高养分处理的总生物量、叶片数、总根茎分株数、长根茎分株数、总根茎长、芽长度、芽数量等指标大于其他养分处理,而在遮阴条件下,其在不同养分处理间无显著差异,表明光照条件可影响养分对扁秆荆三棱可塑性的作用,且高营养水平不能补偿由于光照不足而导致的生长能力下降。光照强度显著影响了总根茎、总球茎及大、中、小球茎的生物量分配,遮阴条件下,总生物量减少了对地下部分根茎和球茎的分配,并将有限的生物量优先分配给小球茎。总根茎的生物量分配未对养分发生可塑性反应,而随着养分增加,总球茎分配下降,说明在养分受限的环境中球茎的贮存功能可缓冲资源缺乏对植物生长的影响。在相同条件下,根茎生物量对长根茎的分配显著大于短根茎,以保持较高的繁殖能力;而总球茎对有分株球茎的生物量分配小于无分株球茎,表明扁秆荆三棱总球茎对贮存功能的分配优先于繁殖功能。研究为进一步理解根茎型克隆植物对光强及基质养分环境变化的生态适应提供了依据。     

Trade-offs among growth, clonal, and sexual reproduction in an invasive plant Spartina alterniflora responding to inundation and clonal integration

The purpose of this article was to study the trade-offs among vegetative growth, clonal, and sexual reproduction in an aquatic invasive weed Spartina alterniflora that experienced different inundation depths and clonal integration. Here, the rhizome connections between mother and daughter ramets were either severed or left intact. Subsequently, these clones were flooded with water levels of 0, 9, and 18 cm above the soil surface. Severing rhizomes decreased growth and clonal reproduction of daughter ramets, and increased those of mother ramets grown in shallow and deep water. The daughter ramets disconnected from mother ramets did not flower, while sexual reproduction of mother ramets was not affected by severing. Clonal integration only benefited the total rhizome length, rhizome biomass, and number of rhizomes of the whole clones in non-inundation conditions. Furthermore, growth and clonal reproduction of mother, daughter ramets, and the whole clone decreased with inundation depth, whereas sexual reproduction of mother ramets and the whole clones increased. We concluded that the trade-offs among growth, clonal, and sexual reproduction of S. alterniflora would be affected by inundation depth, but not by clonal integration.     

克隆整合对无芒雀麦在异质性盐分环境中存活和生长的影响

无芒雀麦是浑善达克沙地植物群落中占优势的多年生根茎禾草.研究了克隆整合特性对无芒雀麦在异质性盐分环境中存活和生长的影响.结果表明,克隆整合显著提高了无芒雀麦分株在高盐环境中的存活能力,耗-益分析表明无芒雀麦在高盐斑块中分株的生物量、分株数、根茎节数和根茎总长显著受益于克隆整合,而与之相连的非盐分斑块中的分株却没有产生显著的损耗.因而,克隆整合特性是无芒雀麦对异质性环境形成的重要适应对策,它使无芒雀麦能够扩展到不适合植物生长的高盐分斑块中,从而增加了无芒雀麦在浑善达克沙地中的存活和生长,提高了其在半干旱沙化地区的适合度.     

Clonal integration supports the expansion from terrestrial to aquatic environments of the amphibious stoloniferous herb Alternanthera philoxeroides

Effects of clonal integration on land plants have been extensively studied, but little is known about the role in amphibious plants that expand from terrestrial to aquatic conditions. We simulated expansion from terrestrial to aquatic habitats in the amphibious stoloniferous alien invasive alligator weed ( Alternanthera philoxeroides ) by growing basal ramets of clonal fragments in soils connected (allowing integration) or disconnected (preventing integration) to the apical ramets of the same fragments submerged in water to a depth of 0, 5, 10 or 15 cm. Clonal integration significantly increased growth and clonal reproduction of the apical ramets, but decreased both of these characteristics in basal ramets. Consequently, integration did not affect the performance of whole clonal fragments. We propose that alligator weed possesses a double-edged mechanism during population expansion: apical ramets in aquatic habitats can increase growth through connected basal parts in terrestrial habitats; however, once stolon connections with apical ramets are lost by external disturbance, the basal ramets in terrestrial habitats increase stolon and ramet production for rapid spreading. This may contribute greatly to the invasiveness of alligator weed and also make it very adaptable to habitats with heavy disturbance and/or highly heterogeneous resource supply.     

Microsatellite identification of ramet genotypes in a clonal plant with phalanx growth: The case of Cirsium rivulare (Asteraceae)

Cirsium rivulare is a perennial plant that forms patches consisting of ramets resulting from sexual reproduction by seeds and asexual propagation by rhizome fragmentation. We examined the relationship between the size of patches and genetic differentiation of ramets within and between patches. Ramet genotypes were identified using microsatellites. From among 216 ramets examined in the studied population, 123 had a unique genotype, while 93 were clonal, i.e., their genotype was present in at least two ramets. The frequency of ramets with clonal genotypes was 43% and the frequency of unique genotypes was 57%. Ramets with identical genotypes were dominant in small patches. Large patches consisted of ramets with both unique and clonal genotypes, usually with the predominance of the latter. A molecular variance analysis showed the highest level of variance between ramets and the lowest between patches. Additionally, 21.02% of the total variance was recorded between ramets and within patches. The size of patches was correlated with the number of clonal ramets and the number of unique ramets, but it was not correlated with the clonality index. This population of C. rivulare is currently in a phase of decline from 30 years of vegetation transformation, and there appears to have been an increase in sexual propagation based growth over clonal propagation based growth. Hence, a predominance of ramets with unique genotypes was observed. This can happen as a result of disintegration of large patches and formation of gaps between them. These gaps become convenient places for seed germination and the subsequent development of seedlings.     

Functional specialization of ramets in Scirpus maritimus – Splitting the tasks of sexual reproduction, vegetative growth, and resource storage

Clonal plant species can be considered as populations of interconnected ramets which are basically identical in form and function, and potentially independent from each other. Experimental studies and field observations suggest that an intra-clonal specialization of ramets with different roles (division of labour) can increase the performance of clonal systems under heterogeneous conditions. This paper explores structural and functional variation in the emergent macrophyte Scirpus maritimus, which forms ramets that specialize in three main activities: sexual reproduction, photosynthetic assimilation and vegetative growth, and reserve storage. The main question asked in this study is whether such specialization is a developmentally programmed syndrome in this species, and whether environmental conditions can alter the pattern of ramet differentiation along rhizome systems.We analyzed clonal fragments collected from a population in the field, and grew clones individually in pots of two sizes to simulate different degrees of crowding and shoot density. Specialization of ramets was largely predictable from their position along the rhizome system, indicating that specialization is an inherent feature (developmentally programmed) of clone ontogeny in S. maritimus. In the field, sexual ramets were always situated at the base of rhizome systems, vegetative ramets were in first and intermediate positions, and shoot-less storage ramets were almost always formed distally on rhizomes (terminal ramets). In the pot experiment flowering ramets were observed in all positions along rhizome systems, suggesting that specialization for sexual reproduction shows a plastic response to environmental conditions.S. maritimus can adjust the relative numbers of ramets with and without above-ground shoots when grown in different shoot densities, i.e. the frequency of individual ramets responsible for a certain functional or developmental process can be adjusted to environmental conditions and internal needs. In S. maritimus, the density-dependant regulation of storage versus vegetative growth and sexual reproduction may represent a mechanism to limit shoot competition in crowded populations.     

Position of tillers in a clone determines their ontogeny: example of the clonal grass <Emphasis Type="Italic">Phalaris arundinacea</Emphasis>

For practical reasons, all ramets of a clonal plant are considered to be independent individuals in demographical studies, but there are reports that ramet ontogeny is affected by their position in a clone. This means that ramets growing from buds located in certain parts of the rhizome system differ in size and probability of flowering from ramets emerging from buds at various positions. We studied the growth characteristics and ontogeny of tillers (ramets) of a rhizomatous grass in relation to their position in a clone and examined whether it is affected by the disturbance regime. We assessed the position of tillers in a clone, the developmental stage of their apical meristem and growth characteristics in mown and unmown stands of the rhizomatous grass Phalaris arundinacea at two sites, one representing optimal (lowland) and the other suboptimal (highland) environmental conditions. We found that tiller characteristics and the probability of a tiller to start flowering are related to the tiller position in a clone. Tiller differences were preserved even in suboptimal environmental conditions but disappeared after mowing, which equalized size and ontogeny. Our results imply that ramets of clonal plants are not independent demographical units, thus their position in a clone should be taken into account.     

松嫩平原野古草种群构件结构动态

野古草是根茎型无性系禾草,在松嫩平原草甸经常形成单优种群落。采用单位面积挖掘取样、分株按营养繁殖世代划分龄级、根茎按实际生活年限划分龄级的方法,对松嫩平原单优群落和混生群落的野古草种群构件结构进行了调查与分析。结果表明,在生长季初期两群落野古草种群均以春性分株和根茎芽占优势,且分株及芽构件结构相对稳定,芽库的输出率单优群落为80.4%,混生群落为62.5%;整个生长季分株由2—3个龄级组成,1a分株数量是2a的2.9—10.2倍,其生物量各月份所占比例平均为93%,随着龄级的增加依次明显减少,呈增长型年龄结构;根茎由3—4个龄级组成,根茎累积长度及生物量均以2a占绝对优势,为稳定型年龄结构;分株生产力1a明显高于2a,对种群贡献最大;根茎贮藏力除个别月份以3a、4a最高外,两群落大部分以2a最高,在生长季后期,1a根茎物质积累的速率最快。     

Clonal Integration Enhances the Performance of a Clonal Plant Species under Soil Alkalinity Stress

Clonal plants have been shown to successfully survive in stressful environments, including salinity stress, drought and depleted nutrients through clonal integration between original and subsequent ramets. However, relatively little is known about whether clonal integration can enhance the performance of clonal plants under alkalinity stress. We investigated the effect of clonal integration on the performance of a typical rhizomatous clonal plant, Leymus chinensis, using a factorial experimental design with four levels of alkalinity and two levels of rhizome connection treatments, connected (allowing integration) and severed (preventing integration). Clonal integration was estimated by comparing physiological and biomass features between the rhizome-connected and rhizome-severed treatments. We found that rhizome-connected treatment increased the biomass, height and leaf water potential of subsequent ramets at highly alkalinity treatments but did not affect them at low alkalinity treatments. However, rhizome-connected treatment decreased the root biomass of subsequent ramets and did not influence the photosynthetic rates of subsequent ramets. The biomass of original ramets was reduced by rhizome-connected treatment at the highest alkalinity level. These results suggest that clonal integration can increase the performance of clonal plants under alkalinity stress. Rhizome-connected plants showed dramatically increased survival of buds with negative effects on root weight, indicating that clonal integration influenced the resource allocation pattern of clonal plants. A cost-benefit analysis based on biomass measures showed that original and subsequent ramets significantly benefited from clonal integration in highly alkalinity stress, indicating that clonal integration is an important adaptive strategy by which clonal plants could survive in local alkalinity soil.     

克隆整合对无芒雀麦(Bromus inermis)忍受沙埋能力的影响

无芒雀麦是浑善达克沙地植物群落中占优势的多年生根茎禾草。研究了克隆整合特性对无芒雀麦忍受沙埋能力的影响。结果表明,克隆整合显著提高了远端完全沙埋分株的存活,耗-益分析表明远端沙埋分株的生物量、分株数、叶片数、根茎节数和根茎总长显著受益于克隆整合,而与之相连的近端非沙埋分株却没有产生显著的损耗,并且随着沙埋程度增加时,远端沙埋分株的收益有增大的趋势。因而,克隆整合特性是无芒雀麦对严酷沙埋环境形成的重要适应对策,它能够缓解沙埋对无芒雀麦存活、生长的胁迫,提高其在半干旱沙化地区的适合度。