木本植物的构型及其在植物生态学研究的进展

一般认为,木本植物的植株结构由枝系和根系两个亚系统构成[5,38].其地上部分的枝或茎的顶端分生组织和侧生分生组织通过不断重复的、持续的活动产生新的分枝,构成了复杂的枝系结构和多样的形态特征.     

单子叶植物和双子叶植物的叶发育方式

叶侧生于茎上并与茎共同构成植物的枝条;叶是植物进行光合作用的主要器官,是植物体最富有特征的结构部分之一。单子叶植物和双子叶植物是被子植物的两大类群,人们观察它们的叶,发现其外部形态和内部构造都存在着很大的不同。这种差异,又是与这两类植物的叶发育方式相关联的。     

根茎克隆植物羊草体内可溶性碳水化合物的时间变异及其对去叶干扰的响应

该研究针对根茎型克隆植物羊草(Leymus chinensis)考察了以下内容:1)地上枝条和根茎中可溶性碳水化合物含量的时间动态及其对去叶干扰的响应;2)特定阶段植物体内一定部位的可溶性碳水化合物浓度差异;3)植物体各部分(地上部分、直立茎地下部分及根茎)间可溶性碳水化合物浓度变化之间的关联。基于上述研究结果,作者试图弄清碳水化合物对于羊草克隆分株和整个基株生长和存活的意义。实验共有4个处理:1个对照和3个不同频度(在整个实验进行期间分别去叶1次、3次和5次)的去叶处理。所有去叶处理都采取一个统一的强度,即留茬15 cm。地上枝条和根茎的取样频次为每10 d 1次。植物体各部分可溶性碳水化合物浓度以高效液相色谱法(HPLC)测定。对不同去叶频度处理间的碳水化合物含量差异显著性进行ANOVA分析。结果表明:不去叶对照处理在生长季盛期可溶性碳水化合物浓度的显著下降归因于植物体快速的生长而引起植物叶片旺盛的呼吸消耗,而去叶处理中植物的可溶性碳水化合物浓度并没有大的降低甚至在最频繁的去叶处理下还有所上升,主要是由于去叶处理减少叶片而造成地上部分总呼吸量下降所致。一次性去叶处理并没有影响植物地上部分最终的可溶性碳水化合物浓度,但是连续数次的去叶处理对地上部分可溶性碳水化合物浓度产生了一定的影响。在秋季气温下降时,碳水化合物自地上向地下的转移在去叶频度越大的处理下表现越为迅速。这表明当植物体接受到气温降低的信号后,去叶干扰加速碳水化合物自地上向地下的转移。可能由于地下枝条存在一定的贮藏功能,在实验过程中地下枝条中可溶性碳水化合物浓度比地上枝条中表现的更加稳定。根茎中的可溶性碳水化合物必要时会转移到地上以供应地上枝条的生长,而旺盛的生长会消耗可溶性碳水化合物,然而自未接受去叶处理的分株向接受去叶处理的分株的克隆整合(常常在较高频次的去叶处理中发生)可能会在一定程度上缓解这种消耗所造成的影响。     

细胞壁

细胞壁是植物形态结构的突出特征之一。一般认为细胞壁是植物细胞的惰性外壳,实际上细胞壁像植物细胞的其它部分一样,也经历着生长、分化和衰亡的过程,而且植物细胞的分化在相当大的程度上取决于细胞壁的分化。细胞壁在植物生活中占有相当重要的位置,它能使植物体挺立,以利于获得更多的光能和营养物质。各细胞的壁相互连理,构成植物体的非共质体连续相。非共质体连续相是植物     

小麦和油菜中Cu和Zn的化学结合形态初步研究

1　引　　言微量元素在植物体中的化学结合形态的研究 ,对于充分了解其在植物体内的迁移转化机理 ,以及阐明其生理作用特征等都具有重要意义 .但是 ,至今为止 ,由于植物体内微量元素的化学结合形态比较复杂 ,而且差异很大 ,加上研究方法的限制 ,人们对于微量元素在植物体中存在的化学形态知之甚少 .参照国内外报道的一些资料[1～ 4 ] ,采用连续浸提的方法 ,初步探讨了Ｃｕ和Ｚｎ在小麦和油菜植株中的各种化学形态的含量和分异特征 ,试图阐明其在植物体内各种化学结合形态的差异性规律 ,为明确其在植物体内的转运机理和合理施用微量元素肥料…     

辽东栎芽库统计:芽的命运

植物体是一个构件集合体,植物的枝系伸展可由芽库出生率、死亡率的统计学过程来分析。在东灵山地区,应用随机枝取样法调查了辽东栎芽的命运,并对其与枝长、叶数、果数等的关系进行了统计分析。结果表明：（1）辽东栎的芽或保持休眠状态,或死亡后脱落,或分化为营养枝、生殖枝（包括雄花枝、雄花序、雌花枝和两花枝）等;（2）不同生境中芽的命运不同,生活在林窗中的幼树上的芽分化为具有生殖功能的枝条的比例显著高于郁闭林中的幼树,而与成熟个体接近;（3）芽的命运还受其它因子的影响,如上层枝条上、或叶数多的长枝上的芽分化为生殖枝的可能性大于其它的芽,另外还发现结实枝的枝长、枝上叶数都明显高于非结实枝。     

抱囊蕨属—四川早泥盆世一新属

本文描述了四川早泥盆世陆地植物的一个新属种——江油抱囊蕨(Amplectosporangiumjiangyouense)。植物体茎轴裸露,等或不等二歧式分枝多次,在其远端区密集的二歧式分枝构成了一个椭圆状或梨状轮廓的能育顶枝系。孢子囊椭圆形,具短柄,呈单列侧生于能育枝的内侧。根据新植物显示的形态特征,除与一些早期陆地维管植物作了比较外,还初步探讨了它与种子植物珠被演化间的关系。     

川西北高寒沙区切断根茎对赖草和沙生苔草克隆生长的影响

为了研究高原亚寒带沙化生境中切断根茎对克隆植物基株扩展能力和分株定居能力的影响,在川西北若尔盖高原沙化区内,对根茎禾草赖草和沙生苔草进行了以切断根茎为处理的野外实验。结果表明,赖草和沙生苔草基株的幼小部分(观测单元)地上枝总长度增量、主根茎长度增量和根茎总长度增量显著减少,而对根茎数增量、主根茎节增量和根茎节总数增量影响不显著;赖草观测单元地上枝数增量显著减少,而对沙生苔草地上枝数增量无影响;赖草地上枝与根茎的相关性质发生逆转。这表明．在高原亚寒带半湿润沙化生境中．克隆整合效应显著促进基株幼小部分地上枝和根茎的伸长生长,但对新生根茎的产生和根茎节分化没有影响;切断根茎处理导致赖草、沙生苔草生殖生长与营养生长间竞争加剧,同时使赖草地上部分与地下部分间竞争加剧;观测单元在缺少与基株(或上级株系)的克隆整合作用时,赖草受到的影响大于沙生苔草。     

切断根茎对根茎禾草沙鞭的赖草克隆生长的影响

为了研究半干旱内陆沙化生境中植物克隆整合对克隆植物基株扩展能力和对克隆植物株定居逆境能力的贡献,在内蒙古鄂尔多斯高原毛乌素沙地对根茎禾草沙鞭和赖草,进行了以切断根茎为处理的野外实验。实验结果表明,切断根茎处理使根茎禾草沙鞭基株的幼小部分（观测单元）在实验期间根茎数量增量,地上枝数量增量,地上枝总长度增量,主根茎节数增量,根茎节总数增量,主根茎长度增量和根茎总长度增量显著地减少。然而,切断根茎处理对     

浙江天童木本植物水力结构与树高的关联性

垂直分层是森林群落的基本结构,但有关群落不同垂直层次植物水力结构策略的研究仍然比较缺乏。以浙江天童木荷林内25株高度不同的9种木本植物为对象,通过测量其枝条直径、边材面积、干材密度、导管直径、内腔面积以及枝条水分比导率,旨在检验植物水力结构与树高的关联性。结果显示：除干材密度外,枝条直径、导管直径、枝条和导管内腔面积、边材面积、水分比导率均随树高增加而显著增大。作为重要的水力结构特征,比导率与导管直径和内腔面积、枝直径和内腔面积、边材面积显著正关联。该结果强调了局域群落内不同垂直层次植物水力结构特征的显著差异,以及植物水分生态位在不同垂直层次的分化过程。     

Research Progress and Application of Plant Branching

Plant branching development plays an important role in plant morphogenesis (aboveground plant type), the number and angle of branches are important agronomic characters that determine crop plant type. Effective branches determine the number of panicles or pods of crops and then control the yield of crops. With the rapid development of plant genomics and molecular genetics, great progress has been made in the study of branching development. In recent years, a series of important branching-related genes have been validated from Arabidopsis thaliana, rice, pea, tomato and maize mutants. It is reviewed that plant branching development is controlled by genetic elements and plant hormones, such as auxin, cytokinin and lactones (or lactone derivatives), as well as by environment and genetic elements. Meanwhile, shoot architecture in crop breeding was discussed in order to provide theoretical basis for the study of crop branching regulation.     

生长素调控植物株型形成的研究进展

高等植物通过调节顶端分生组织和侧生分生组织的活性建立地上株型系统,分生组织的活性受环境信号、发育阶段和遗传因素的综合调控,植物激素参与这些信号的整合。顶端优势是植物分枝调控的核心问题,而生长素对顶端优势的形成和维持发挥关键作用。本文综述了近几年与植物地上部分株型形成相关的生长素合成代谢、极性运输及信号转导领域的研究进展,并提出了展望。     

生长素调控植物株型形成的研究进展

高等植物通过调节顶端分生组织和侧生分生组织的活性建立地上株型系统, 分生组织的活性受环境信号、发育阶段和遗传因素的综合调控, 植物激素参与这些信号的整合。顶端优势是植物分枝调控的核心问题, 而生长素对顶端优势的形成和维持发挥关键作用。本文综述了近几年与植物地上部分株型形成相关的生长素合成代谢、极性运输及信号转导领域的研究进展, 并提出了展望。     

The Natural Philosophy of Plant Form: Cellular Autoreproduction as a Component of a Structural Explanation of Plant Form

A map-L-system is described which simulates the developmentof the two-dimensional patterns of cell walls displayed at thesurfaces of shoot apices of Psilotum nudum. The simulation ofthese cellular patterns commences with the division of a triangularcell and continues until a complete set of ten different cells,including new triangular cells, is formed amongst the descendantsof each merophyte. The triangular cells generated by means ofthis division pathway, P1, are, in their three-dimensional aspect,four-sided apical cells. In the plant, they have the potentialityto support the development of a shoot apex. The generation ofnew triangular cells by pathway P1 therefore seems to be a preconditionfor the branching of the shoot. Observed variations upon thecellular pattern developed by pathway P1 have also been analysed.Two of these variant pathways, P2 and P3, suggest the typesof controls which are required to bring about all three (P1–P3)patterns of cells. These controls may involve the participationof the plant cytoskeleton and may also require an influencefrom the apical cell itself. The triangular shoot apical cellsof Psilotum are autoreproductive cells: that is, at each division,one of the daughters is a new triangular cell, the other daughterhas some other shape. This example of triangular cell autoreproductionand self-maintenance and its relation to organogenesis is discussedin light of the views on reproduction and self-maintenance expressedby Agnes Arber (1950) in her book The natural philosophy ofplant form(Cambridge: Cambridge University Press). Copyright2001 Annals of Botany Company Agnes Arber, apical cell, cell division patterns, computer simulation, cytoskeleton, L-systems, Living Systems Theory, meristems, Psilotum, shoot apex, stem cell     

Analysis of the plant architecture via tree-structured statistical models: the hidden Markov tree models

Plant architecture is the result of repetitions that occur through growth and branching processes. During plant ontogeny, changes in the morphological characteristics of plant entities are interpreted as the indirect translation of different physiological states of the meristems. Thus connected entities can exhibit either similar or very contrasted characteristics. We propose a statistical model to reveal and characterize homogeneous zones and transitions between zones within tree-structured data: the hidden Markov tree (HMT) model. This model leads to a clustering of the entities into classes sharing the same 'hidden state'. The application of the HMT model to two plant sets (apple trees and bush willows), measured at annual shoot scale, highlights ordered states defined by different morphological characteristics. The model provides a synthetic overview of state locations, pointing out homogeneous zones or ruptures. It also illustrates where within branching structures, and when during plant ontogeny, morphological changes occur. However, the labelling exhibits some patterns that cannot be described by the model parameters. Some of these limitations are addressed by two alternative HMT families.     

Structural cost of shoot modules and its implications on plant potential fitness in a Mediterranean perennial shrub, Retama sphaerocarpa (L.) Boiss

This paper introduces a methodology to analyse the structural costs on plant potential fitness, empirically exemplified in the hierarchical shoot system of a Mediterranean perennial plant, Retama sphaerocarpa (L.) Boiss. During growing season every year (March-August), the terminal shoot (which is the basic unit of growth) develops inflorescences, flowers and fruits, as well as new shoots (first-, second- and third-order branching shoots) which have the potential to "behave" as terminal shoots in the following year. Different morphological and demographical aspects of the modules within the terminal shoot were measured in 100 terminal shoots selected from different plants of a natural population of R. sphaerocarpa. Complementary samples of 100 shoots of different branching orders were collected to obtain biomass estimations of the terminal shoots. We propose a simple procedure to estimate structural cost (biomass investment) on plant potential fitness (flowering buds) as a methodology for interpreting and comparing the consequences on fitness of different plant growth patterns. The results of this study exemplify how differential allocation patterns among plant structural modules, depending on their position within the shoot system, can be quantified to estimate their influence upon plant potential fitness.     

LAX PANICLE2 of rice encodes a novel nuclear protein and regulates the formation of axillary meristems

Aerial architecture in higher plants is dependent on the activity of the shoot apical meristem (SAM) and axillary meristems (AMs). The SAM produces a main shoot and leaf primordia, while AMs are generated at the axils of leaf primordia and give rise to branches and flowers. Therefore, the formation of AMs is a critical step in the construction of plant architecture. Here, we characterized the rice (Oryza sativa) lax panicle2 (lax2) mutant, which has altered AM formation. LAX2 regulates the branching of the aboveground parts of a rice plant throughout plant development, except for the primary branch in the panicle. The lax2 mutant is similar to lax panicle1 (lax1) in that it lacks an AM in most of the lateral branching of the panicle and has a reduced number of AMs at the vegetative stage. The lax1 lax2 double mutant synergistically enhances the reduced-branching phenotype, indicating the presence of multiple pathways for branching. LAX2 encodes a nuclear protein that contains a plant-specific conserved domain and physically interacts with LAX1. We propose that LAX2 is a novel factor that acts together with LAX1 in rice to regulate the process of AM formation.     

The Hexagonal Branching Pattern of Rhizomes of Alpinia speciosa L. (Zingiberaceae)

Alpinia speciosa L. (Zingiberaceae) is a striking example ofa plant in which an organized architectural structure fulfilsa basic functional requirement - the economical explorationand exploitation of the substrate. This rhizomatous plant spreadslaterally in a predictable manner by vegetative growth to forma clone of separated ramets. A morphological study establishes‘rules of growth’ governing the success and failureof lateral branches (sympodial units), their lengths, and theirrelative angles. The basic branching pattern of this rhizome system approximatesto that of a hexagonal grid - the most economical structuralshape that uniformly ‘samples’ a plane surface.It is shown that the significant deviation of branching anglefound in Alpinia from that required to develop an exact hexagonalnetwork will virtually eliminate aerial shoot ‘clashes’in which the placing of one aerial shoot coincides with thatof another aerial shoot, whilst at the same time enhancing thebenefits of the hexagonal system. The broader implications ofthe organised architecture of plants are emphasised. rhizome, branching pattern, architecture, productivity