香榧营养苗端的结构及淀粉动态的研究

香榧（Torreya grandis Fort ex Lindl)成熟植株营养芽的季节生长可分四个时期,休眠期,叶扩展期,芽鳞形成期和新的顶芽形成期,在整个生长周期中,苗端始终保持一定的分区形式,但各区繁简在不同发育阶段不尽相同,淀粉在苗端的分布及消长也具有分区特性,与细胞组织学分区完全一致。     

中国水仙花芽分化观察及储藏条件对花芽数的影响研究

以三年生中国水仙‘金盏银台’为材料,采用石蜡切片法观察其花芽形态分化过程。结果表明：中国水仙的花芽分化从7月上旬开始,到9月中旬形成雌蕊结束。其过程可分为叶芽时期、花序原基形成期、佛焰状总苞形成期、花原基形成期、花冠形成期、雄蕊形成期、雌蕊形成期7个时期。其中花冠形成期较长,20 d左右。花芽的外部形态变化上,分化后期芽的生长速度明显快于前期。对鳞茎球内花序数量的统计结果显示,高温储藏及烟熏法共同使用对中国水仙花序的形成具有很好的促进作用。     

菹草的生活史、生物量和断枝的无性繁殖

菹草是一种比较典型的秋季发芽、越冬生长的沉水植物。在夏季,多数植株衰败死亡,殖芽则落入水底进入夏季休眠期。春季是菹草群落生物量和生产力的高峰期。植株生物量的垂直分布属表层分布型。植株含水量从根部向枝顶逐渐减少,全株干物质含量的周年测定值平均为风干重=湿重×0.625。水温和植物发育阶段是影响断枝的生根、生长速度和殖芽形成的重要因素。在营养生长阶段,水温3—25℃范围内,断枝均能生根,断枝的相对生长速度为5.49—30.25毫克/克/天。断枝在殖芽形成期均能生长殖芽,但个体较小。       

气候变化背景下中国南方地区季节性干旱特征与适应Ⅴ.南方地区季节性干旱特征分区和评述

在干旱特征研究的基础上开展季节性干旱分类分区,可为不同干旱区域应对全球气候变化、制定抗旱减灾对策和防控技术提供理论依据.以国家标准中的气象干旱、农业干旱指标为主要依据,利用南方地区268个气象台站1959-2008年的气候资料,在分析南方地区季节性干旱的气候背景和分布特征的基础上,采用综合因子与主导因子相结合方法、逐级指标筛选法,综合灾害分析和聚类分析方法,对季节性干旱进行3级分区.一级分区以年干燥度和季干燥度为主要指标,以年尺度和主要作物生长季的降水量为辅助指标,将南方区域分为半干旱区、半湿润区、湿润区和极湿润区4个一级区;在此基础上再划分为川滇高原山地温凉半干旱区,江北温暖半湿润区、华南暖热半湿润区和西南高原温凉半湿润区3个半湿润区,长江流域温热湿润区、华南暖热湿润区和西南山地温暖湿润区3个湿润区,以及华南暖热极湿润区和江南西南山区温凉极湿润区2个极湿润区,共9个二级干旱分区.最后基于多个干旱指标的干旱频率和干旱强度,将南方区域分成29个三级干旱区.在分区基础上对不同季节性干旱特征分区分布情况、干旱特点及对农业生产影响进行评述,并提出了防旱避灾措施.     

中美生态分区及其分级体系比较研究

生态分区及其分级体系越来越多地用于环境保护政策的制定和管理决策,尤其是在自然资源管理、保护和评价方面。目前世界上有许多生态分区及其分级体系,不同的生态分区与分级体系使用不同的生态分区方法和各种指标。如何正确评价和选择这些生态分区及其分级体系进行自然资源管理和环境决策,已经成为管理者和研究者的一个难题。概述了近20a来生态分区分级研究现状与国际进展,重点比较、分析了美国主要生态分区及其分级体系与中国生态功能分区之间的差异。结果表明,在生态分区的分区单元内涵、侧重点以及分区角度3个方面,中美之间有显著的不同。美国的生态分区及其分级体系多注重自然生态系统,尤其在其评价指标中,人类在生态系统中的地位与生态系统内其他生物相平等。而中国的生态功能分区,则更加突出人类在生态系统中的地位以及生态系统为人类社会提供的生态服务功能。这些体系各有优点和缺陷。通过这些体系的比较研究,可为中国后续水生态分区研究和改进中国生态功能分区提供参考和建议。     

水生态功能分区的研究进展

水生态功能分区是基于对流域水生态系统的区域差异的研究而提出的一种分区方法.它阐明了水生环境系统在区域和地带等不同尺度上的空间分异特征,并揭示出水生态系统空间分布规律.本文系统阐述了水功能区划、水环境功能区划、生态地理分区、生态分区以及水生态功能分区等几个重要分区概念的区划方法、目标及局限性,并综述了国内外水生态功能分区的研究进展,比较了国内外分区框架体系的差异,指出了我国水生态功能区划的缺陷,并对其发展趋势进行了展望.     

药用植物款冬花芽分化过程观察

实验以不同生长发育阶段的款冬花序芽突起为材料,通过制作石蜡切片,在显微镜下观察款冬花序芽分化各阶段的形态特征。结果表明:款冬花序芽从7月上旬开始花序(盘)分化至十月初小花胚珠分化完成,分化时期可分为分化前期、花盘形成期、花原基分化期、中央花(筒状)花瓣原基分化期、中央花雄蕊原基分化期、中央花雌蕊原基分化期、边缘花(舌状)花瓣原基分化期、边缘花雌蕊原基分化期、中央花花粉分化形成期、子房胚珠分化期共10个时期,阐明了款冬花序芽分化各时期与生长时间的关系。     

基于生态地理分区的大兴安岭植被物候时空变化

植被与气候的关系十分密切,植被物候可作为全球气候变化的指示器.大兴安岭位于我国最北部,对气候变化较为敏感,研究该区植被物候的时空变化对评估全球变化对陆地生态系统的影响具有重要意义.依据中国生态地理区划图,将大兴安岭划分为4个生态研究区域,本文利用GIMMS NDVI 3g遥感数据集分析1982—2012年大兴安岭整体及各生态地理分区植被物候变化.结果表明: 研究期间,所有分区植被生长季开始日期均表现为提前趋势,生长季结束日期均表现为推迟趋势.植被物候对气候因子变化敏感,尤其是对气温的敏感程度高于降水,其中,北段山地落叶针叶林区植被生长季开始日期与春季温度呈显著负相关;除南段草原区外,其他3个分区植被生长季结束日期均与秋季降水呈显著负相关.从整体来看,植被物候随海拔、纬度的变化趋势明显.     

基于遥感和地统计学方法的小麦生长管理分区

以江苏省如皋市和海安县冬小麦种植区域为研究对象,将基于小麦不同生育时期30m分辨率的HJ-1A/B CCD影像提取的归一化植被指数(NDVI)与土壤养分指标(全氮、有机质、有效磷、速效钾)分布状况有机结合,在空间变异性分析和主成分提取的基础上进行聚类分区.结果表明,基于抽穗期NDVI与土壤养分指标耦合的分区方法效果最佳,分区后各子区域内部NDVI值和土壤养分指标的变异系数分别在4.5%～6.1%和3.3%～87.9%,低于单纯基于土壤养分指标或NDVI进行分区的子区域内部的变异系数,大大缩小了区域管理单元内部的变异性.分区结果能提高按区管理作业的精度,可为区域性小麦生长管理和过程模拟奠定基础.     

生态分区的原则、方法与应用—内蒙古自治区生态分区图说明

 区域分异原则是生态学中的重要原理之一。任何陆地生态系统都具严格的区域特点,因此对土地资源的利用必须因地制宜。而生态分区就是正确认识草地资源区域特征的重要手段。本文以内蒙古自治区生态分区图说明为例,提出3个分区等级(生态区、生态亚区和生态小区)及其概念,并结合分区对内蒙古土地资源的管理和利用提出建议,以建立稳定的粮油糖生产基地。     

Structural and Histochemical Studies of Vegetative Apex in Torreya grandis

This article is dealing with the structure and the histochemical changes in the shoot apex of Torreya grandis in the growing seasons. The results of observation are summerized as follows: The vegetative bud in mature plant can be devided into four periods: the resting period, the period of bud expansion, the period of bud scale formation and the period of development of new terminal bud. In tile whole growing cycle, the vegetative apex always maintains a certain kind of zonation: the apical initials, the subapical group, the peripheral tissue zone and the rib meristem. In various periods of development, the composition of different zones is nom all the same. Meanwhile, the distribution and fluctuation of starch in the apex change from zone to zone, and parallel to the change of structure.     

香榧营养苗端细胞组织分区的超微结构观察

本文研究了榧树(Torreya grandis)成熟植株在季节生长中营养苗端的超微结构变化。各区域细胞的主要区别特征为:顶端原始细胞与亚顶端细胞相接的细胞壁较厚,液泡多分布于细胞游离面,质体中淀粉粒较小;亚顶端细胞壁较厚,液泡较大,质体中淀粉粒较大而多;周缘区细胞质体多不具淀粉粒,液泡也较小,胞间连丝丰富;肋状区细胞被大量的含淀粉质体及液泡占据了大部分空间,胞间连丝丰富。在季节变化的四个时期中,各区域细胞的亚显微结构特征亦不相同。休眠期各区细胞淀粉质体较发达,细胞壁较厚,液泡大;叶扩展期淀粉质体减少或消失;芽鳞形成期出现大量小液泡;新的顶芽形成期液泡增加,核糖体含量较高。讨论了各区域细胞核形态与其细胞活跃性的关系。     

Floral transition as a sequence of growth changes in different components of the shoot apical meristem ofChenopodium rubrum

The changes in cell division rate were studied in different components of the shoot apex ofChenopodium rubrum during short-day photoperiodic induction and after the inductive treatments. Induced and vegetative apices were compared. Accumulation of metaphases by colchicine treatment was used to compare the mean cell cycle duration in different components of the apex. A direct method of evaluating the increase in cell number obtained by anticlinal or periclinal divisions was applied if the corresponding components of induced and non-induced apices had to be compared. The short-day treatment prolonged the cell cycle more in the peripheral zone than in the central zone and still more in the leaf primordia. The importance of changing growth relations for floral transition was shown particularly if the induced plants were compared with the vegetative control with interrupted dark periods. Induced plants transferred to continuous light showed further changes in the rates of cell division. The cell cycle was shortened more in the central zone than in the peripheral zone,i.e. there was a further shift in growth relations within the apical dome. The cell cycle in the leaf and bud primordia was also shortened if compared with the vegetative control, the acceleration being stronger in the bud primordia. There was a subsequent retardation in cell division in the leaf primordia formed during and after the inductive treatment if the plants were fully induced. An inhibition of the oldest bud primordia was observed in fully induced apices, as well.     

The Structure of the Plumule of Nelumbo Nucifera Gaertn. and the Nature of its Scale

The structure of the plumule of Nelumbo nucifera Gaertn. and its feature covered with scale are seldom seen in dicotyledon. The fact that the plumule possesses scale is even more uncommon. This particular phenomenon is investigated by observing the differentiation of the plumule apex and the development of the leaf organs. After the seed is formed, the embryo has two young leaves and a terminal bud covered with scale. In the bud it has already differentiated the 3rd and the 4th leaf primordium and a shoot apex, the differentiation of which is very complex. So the structure of the plumule passes through 4 plastochrons altogether. It is made clear through observation and analysis that, before the 4th leaf primordium is formed, the transforma- tions of the shoot apex of the embryo in each plastochron are fundamentally alike. After the 4th leaf primordium is developed, the shoot apex becomes complex and there appear 3 different active cell regions which become the bases of vegetative bud of the seeding apex. The development of these 3 active cell regions will be stated in “The Structure of the Vegetative Bud of Nelumbo nucifera Gaertn. and the Nature of its Scales.” The apices of the plumule are almost slightly domed in structure. As a rule, their width is from 95 to 107 μ. Their height is from 17 to 20 μ during one plastochron. Before the 3rd leaf initiation, the anatomical structure of apices is examined and the fol- lowing zones may be delimited: zone of tunica initials, zone of corpus initials, peripheral zone, and zone of rib meristems. It is frequently observed that the cell of corpus in subapical peripheral zone develops periclinal division, which is the initial cell of leaf primordium; Procambium will appear before the stage of the appearance of leaf buttress. The apex of the plumule is in an apical position, but when the seedling is formed, as the developing leaves are alternate, the directions of the shoot apex are changed, simultaneously the base part of the leaf encloses the axis, and the adaxial meristem also differentiates the scale which encloses the terminal bud, thus placing the bud in axillary of the leaf and forming a zigzag phenomenon of the axis of the seedling. Above the basal adaxial side of the leaf primordium develops the scale of the plumule with meristem periclinal division of closely attached protoderm as its base. So the scale of the plumule of Nelumbo nucifera Gaertn. and the axillary stipule are of the same origin. To sum up, the scale of the embryo of Nelumbo nucifera Gaertn. is differentiated from the adaxial meristem of the basal part of the leaf primordium, and is the derivative part of the leaf. It has the same function as the coleoptile of the monocotyledon. Whether they are homologous organs or not is still to be investigated.     

MORPHOLOGICAL AND ONTOGENETIC STUDIES ON TORREYA CALIFORNICA. II. DEVELOPMENT OF THE MEGASPORANGIATE SHOOT PRIOR TO POLLINATION

Kemp , Mahgaret . (Smith Coll., Northampton, Mass.) Morphological and ontogenetic studies on Torreya californica. II. Development of the megasporangiate shoot prior to pollination. Amer. Jour. Bot. 46(4): 249–261. Illus. 1959.—The development of the megasporangiate of Torreya californica during the first part of its maturation cycle of 26 months is described in detail. This first developmental period extends from the initiation stage in late July of one year through pollination of the young ovules in April of the following spring. At the end of this period, the reproductive shoot is a loosely organized, compound, determinate structure. It consists of a short primary axis which originated in the axil of one of the last formed bud scales or one of the first formed foliage leaves of the vegetative bud. This primary axis bears only 2 lateral and oppositely placed prophylls which stand at right angles to the subtending structure. In the axil of each prophyll is a short secondary axis which bears 2 successive pseudodecussate pairs of subopposite, sterile, scale-like perianth segments below a solitary, erect, terminal ovule. The integument of the ovule originates as a single lateral primordium, but its margins quickly merge and at pollination time it is a tubular envelope free from the nucellus. The nucellus, which is massive and contains a single deeply imbedded megasporocyte, terminates the secondary axis. Histogenetically, both primary and secondary axis systems of the megasporangiate shoot resemble a vegetative dwarf shoot. They both originate as axillary mounds of uniformly meristematic cells, whose apices soon exhibit a zonal pattern comparable to that of the apex of the vegetative shoot of the same species. The determinate nature of the primary axis is caused by cell senescence in its apex. The prophylls of the primary axis and the perianth segments of the secondary axes are comparable to bud scales of the vegetative bud in their arrangement, their origin from subsurface layers, the presence of apical and subapical initials which produce their first vertical growth, a basal intercalary meristem which completes their elongation, and marginal initials which produce a slender wing to the lamina of each type of cataphyll. At maturity all 3 types of cataphylls are basically similar in their histology. The apex of each secondary axis, at the initiation of the integument, shows an altered cellular pattern which rapidly becomes organized into a conspicuous fanshaped coaxial system as the central portion develops directly into the massive, cauline nucellus. This coaxial apical configuration differs markedly from the zonal pattern of the vegetative shoot apex and also from the similar zonal pattern in the apex of the primary axis of the megasporangiate shoot and its secondary axes during an earlier period of indeterminate growth.     

AXILLARY BUD DEVELOPMENT IN POPULUS DELTOIDES. I. ORIGIN AND EARLY ONTOGENY

Origin and early development of axillary buds on the apical shoot of a young Populus deltoides plant were investigated. The ontogenetic sequence of axillary buds extended from LPI –1 (Leaf Plastochron Index) near the apical bud base to LPI –11, the fifth primordium below the bud apex. Two original bud traces diverged from the central (C) trace of the axillant leaf and developed acropetally. During their acropetal traverse the original bud traces gave rise to three pairs of scale traces. All subsequent scale traces, and later the foliar traces, were derived by divergencies from the first two pairs of scale traces. Just before the bud vascular system separated from that of the main axis, a third pair of traces diverged from the original bud traces to vascularize the adaxial scale. Concomitantly, the original bud traces were inflected toward the main vascular cylinder where they developed acropetally and eventually merged with the left lateral trace of the leaf primordium situated three nodes above the axillant leaf; they did not participate in further vascularization of the bud. During early ontogeny a shell zone formed concurrent with initiation of the original bud traces and lay interjacent to them. The shell zone defined the position of the cleavage plane that formed between the axillary bud and the main axis. The axillary bud apex first appeared in the region bounded laterally by the original bud traces and adaxially by the shell zone. Following divergence of the main prophyll traces from the original bud traces, the apex assumed a new position intermediate to the prophyll traces. Ontogenetic development suggested that the axillary bud apex may have been initiated by the acropetally developing original bud traces under the influence of stimuli arising in more mature vegetative organs below.     

PtABI3 impinges on the growth and differentiation of embryonic leaves during bud set in poplar

The Arabidopsis ABSCISIC ACID-INSENSITIVE3 (ABI3) protein plays a crucial role during late seed development and has an additional function at the vegetative meristem, particularly during periods of growth-arresting conditions and quiescence. Here, we show that the ABI3 homolog of poplar (PtABI3) is expressed in buds during natural bud set. Expression occurs clearly after perception of the critical daylength that initiates bud set and dormancy in poplar. In short-day conditions mimicking natural bud set, the expression of a chimeric PtABI3::beta-glucuronidase (GUS) gene occurred in those organs and cells of the apex that grow actively but will undergo arrest: the young embryonic leaves, the subapical meristem, and the procambial strands. If PtABI3 is overexpressed or downregulated, bud development in short-day conditions is altered. Constitutive overexpression of PtABI3 resulted in apical buds with large embryonic leaves and small stipules, whereas in antisense lines, bud scales were large and leaves were small. Thus, PtABI3 influences the size and ratio of embryonic leaves and bud scales/stipules that differentiate from the primordia under short-day conditions. These observations, together with the expression of PtABI3::GUS in embryonic leaves but not in bud scales/stipules, support the idea that wild-type PtABI3 is required for the relative growth rate and differentiation of embryonic leaves inside the bud. These experiments reveal that ABI3 plays a role in the cellular differentiation of vegetative tissues, in addition to its function in seeds.     

DEVELOPMENT AND PHYLLOTAXIS OF THE VEGETATIVE AXILLARY BUD OF MICHELIA FUSCATA

Tucker, Shirley C. (Northwestern U., Evanston, III.) Development and phyllotaxis of the vegetative axillary bud of Michelia fuscata . Amer. Jour. Bot. 50(7): 661–668. Illus. 1963.—The vegetative axillary buds of Michelia fuscala are dorsiventrally symmetrical with 2 ranks of alternately produced leaves. The direction of the ontogenetic spiral in each of these buds is related both to the symmetry of the supporting branch and to the position of the bud along the branch. On a radially symmetrical branch, all the axillary buds are alike—all clockwise, for example. But in a dorsiventrally organized branch the symmetry alternates from clockwise in 1 axillary bud to counterclockwise in the next bud along the axis. Leaf initiation and ontogeny of the axillary apical meristem conform with those of the terminal vegetative bud. The axillary bud arises as a shell zone in the second leaf axil from the terminal meristem. During this process the axillary apex develops a zonate appearance. The acropetally developing procambial supply of the axillary bud consists wholly of leaf traces. At the nodal level the bud traces diverge from the same gap as the median bundle trace of the subtending leaf. Only the basal 1–2 axillary buds which form immediately after the flowers elongate each year, while the majority remains dormant with 3 leaves or fewer.     

TENDRILS OF PASSIFLORA FOETIDA: HISTOGENESIS AND MORPHOLOGY

Passiflora foetida bears an unbranched tendril, one or two laterally situated flowers, and one accessory vegetative bud in the axil of each leaf. The vegetative shoot apex has a single-layered tunica and an inner corpus. The degree of stratification in the peripheral meristem, the discreteness of the central meristem, and its centric and acentric position in the shoot apex are important plastochronic features. The procambium of the lateral leaf trace is close to the site of stipule initiation. The main axillary bud differentiates at the second node below the shoot apex. Adaxial to the bud 1–3 layers of cells form a shell-zone delimiting the bud meristem from the surrounding cells. A group of cells of the bud meristem adjacent to the axis later differentiates as an accessory bud. A second accessory bud also develops from the main bud opposite the previous one. A bud complex then consists of two laterally placed accessory bud primordia and a centrally-situated tendril bud primordium. The two accessory bud primordia differentiate into floral branches. During this development the initiation of a third vegetative accessory bud occurs on the axis just above the insertion of the tendril. This accessory bud develops into a vegetative branch and does not arise from the tissue of the tendril and adjacent two floral buds. The trace of the tendril bud consists of two procambial strands. There is a single strand for the floral branch trace. The tendril primordium grows by marked meristematic activity of its apical region and general intercalary growth.     

LEAF-OPPOSED BUDS IN MUSA: THEIR DEVELOPMENT AND A COMPARISON WITH ALLIED MONOCOTYLEDONS

A single, lateral, vegetative bud which is positioned 180° from the axil of a leaf is a generic feature of Musa (Musaceae). Such leaf-opposed buds occur in all ten species and five cultivars examined, representing all four sections of the genus and all groups of cultivated bananas and plantains. The bud arises relatively late and is first visible as a vascular-free “clear zone” in the axis directly below the future bud meristem site. It is first associated with the fifth or sixth leaf primordium from the apex. A defined superficial meristem develops on the stem directly above the insertion of the leaf margins one or more plastochrons later. Normal, basically axillary, vegetative buds occur in the closely related genera: Orchidantha (Lowiaceae), Heliconia (Heliconiaceae), Strelitzia, and Ravenala (Strelitziaceae). These buds arise in the axil of the first to the third leaf primordium in a manner similar to most other monocotyledons. Axillary vegetative buds also occur in the remaining families of the Zingiberales: Cannaceae, Costaceae, Marantaceae, and Zingiberaceae.