埃及白睡莲的胚胎学研究

对埃及白睡莲的大、小孢子的发生,雌、雄配子体的发育,以及胚和胚乳的发育进行了观察研究.结果表明埃及白睡莲的花药壁由5层细胞组成,绒毡层细胞具双核,属于分泌型.小孢子母细胞减数分裂时,胞质分裂属于同时型,小孢子四分体呈四面体型.成熟花粉为三细胞类型,花粉粒表面具有环沟.胚珠为倒生型、双珠被、厚珠心,珠孔仅由内珠被形成.大胞子母细胞减数分裂形成三分体,合点端2个细胞退化,珠孔端1个细胞发育为功能性大胞子.成熟雌配子体由4细胞组成,即2助细胞,1卵细胞和1中央细胞.合子的第一次分裂是横向的,形成的基细胞不再分裂,体积增大后成为一个大的胚柄细胞.而顶细胞进行一系列分裂形成胚.在此基础上,还比较了睡莲目不同属的胚胎学特征.     

睡莲无性繁殖栽培技术初探

本文介绍了睡莲属(Nymphaea L.)3个种(延药睡莲N.stellata,黄睡莲N.mexicana,白睡莲N.alba[1])的无性繁殖栽培试验结果,探讨了睡莲无性繁殖栽培技术,为睡莲属植物的快速繁殖奠定了良好的基础。     

Two very unusual macrocyclic flavonoids from the water lily Nymphaea lotus

Three novel flavonols, myricetin-3'-O-(6"-p-coumaroyl)glucoside and two epimeric macrocyclic derivatives, as well as the known myricetin-3-O-rhamnoside and pentagalloyl glucose, have been isolated from the wild water lily Nymphaea lotus L. and identified using 2D NMR. This is the first report of such a macrocycle from any source.     

Long-distance transport of gases in plants: a perspective on internal aeration and radial oxygen loss from roots

Internal transport of gases is crucial for vascular plants inhabiting aquatic, wetland or flood‐prone environments. Diffusivity of gases in water is approximately 10 000 times slower than in air; thus direct exchange of gases between submerged tissues and the environment is strongly impeded. Aerenchyma provides a low‐resistance internal pathway for gas transport between shoot and root extremities. By this pathway, O₂ is supplied to the roots and rhizosphere, while CO₂, ethylene, and methane move from the soil to the shoots and atmosphere. Diffusion is the mechanism by which gases move within roots of all plant species, but significant pressurized through‐flow occurs in stems and rhizomes of several emergent and floating‐leaved wetland plants. Through‐flows can raise O₂ concentrations in the rhizomes close to ambient levels. In general, rates of flow are determined by plant characteristics such as capacity to generate positive pressures in shoot tissues, and resistance to flow in the aerenchyma, as well as environmental conditions affecting leaf‐to‐air gradients in humidity and temperature. O₂ diffusion in roots is influenced by anatomical, morphological and physiological characteristics, and environmental conditions. Roots of many (but not all) wetland species contain large volumes of aerenchyma (e.g. root porosity can reach 55%), while a barrier impermeable to radial O₂ loss (ROL) often occurs in basal zones. These traits act synergistically to enhance the amount of O₂ diffusing to the root apex and enable the development of an aerobic rhizosphere around the root tip, which enhances root penetration into anaerobic substrates. The barrier to ROL in roots of some species is induced by growth in stagnant conditions, whereas it is constitutive in others. An inducible change in the resistance to O₂ across the hypodermis/exodermis is hypothesized to be of adaptive significance to plants inhabiting transiently waterlogged soils. Knowledge on the anatomical basis of the barrier to ROL in various species is scant. Nevertheless, it has been suggested that the barrier may also impede influx of: (i) soil‐derived gases, such as CO₂, methane, and ethylene; (ii) potentially toxic substances (e.g. reduced metal ions) often present in waterlogged soils; and (iii) nutrients and water. Lateral roots, that remain permeable to O₂, may be the main surface for exchange of substances between the roots and rhizosphere in wetland species. Further work is required to determine whether diversity in structure and function in roots of wetland species can be related to various niche habitats.     

Untested Assumptions: The Role of Canals in the Dispersal of Sea Lamprey, Alewife, and other Fishes in the Eastern United States

Canals provide aquatic organisms with an excellent thoroughfare to disperse, expand their range, and gain access to new drainages. The evidence used to support this contention is vast and dates to at least the early nineteenth century. In most cases however, the evidence used to defend the contention is not a direct observation of fish dispersing through a canal. Instead, the transfer is generally inferred after the new species is observed in a new watershed, one connected by a canal to the watershed in which the fish was already established. Often, these inferences are developed without considering aspects of the life history and behavior of the fishes involved, or the structure of the canal. I explore the historic transfer of sea lamprey, alewife and other fishes from one watershed to another in the inland waters of eastern North America, primarily New York. New York is an ideal area for examining this phenomenon as a canal has connected each of the five major drainages in the state during part of the previous 200 years. These twelve major canals, and the Welland Canal that connects lakes Ontario and Erie, bypassed major obstructions and created a continuous water route among drainages. Also, many of the 167 freshwater and diadromous fishes of New York exhibited distribution patterns historically limited to a watershed or set of neighboring watersheds. When several important cases are re-examined, dispersal through a canal is not the most parsimonious explanation for the presence of the species in a new drainage. To argue fish dispersal through navigation canals, researchers must consider the natural history and ecological requirements of the species, the characteristics and environmental conditions of the canal, and alternative explanations. The mere presence of a canal does not demonstrate that fish used the canal for dispersal.     

Effects of <Emphasis Type="Italic">Carex rostrata</Emphasis> on soil oxygen in relation to soil moisture

Many wetland plants are faced with severe edaphic problems. Long term flooding effects a sequence of chemical processes that result in soil anoxia and production of several phytotoxic compounds. In order to maintain an aerobic root respiration wetland plants produce aerenchyms that enable oxygen conduction through the plant body to underground organs. Moreover wetland plants are able to release oxygen into the soil. This aeration effect of wetland plants in turn can influence soil chemistry considerably and protects roots by an aerobic rhizosphere. Oxygen release by underground organs of aerenchymous plants has been well documented in laboratory investigations but not under field conditions. In this study, dynamics of oxygen saturation were measured together with soil water content and microclimatic parameters. Measurements were carried out on some lowland peat covered by Carex rostrata Stokes from July to October 2001. Oxygen saturation was quantified using novel optical sensors (microoptrodes). The presence of C. rostrata significantly increased oxygen content in the soil. Mean oxygen saturation under Carex rostrata (56.0%) was significantly higher than in a control plot without vegetation (26.6%). Due to fluctuating water content, oxygen saturation in both plots was characterized by pronounced time variation. Increasing soil water content caused an extreme decline of oxygen saturation in both plots and led to anoxia in the control plot. In the presence of C.rostrata, the decline in soil oxygen took place at significantly higher water content (68.5% compared to 67.5% in the control plot) which is substantial as the mean water contents varied between 67 and 69% during the measurement period.     

基因组学技术大发展助力园艺植物研究取得新进展

园艺植物包括花卉、蔬菜、果树、部分瓜类(如西瓜(Citrullus lanatus)和甜瓜(Cucumis melo))和茶树(Camellia sinensis),在植物分类上涉及大量物种。园艺植物的基因组学和遗传学研究具有重要的理论价值和经济意义。基因组测序技术及相关生物信息学工具的发展为园艺植物基因组和分子生物学研究注入了新的活力。睡莲是一种重要的花卉植物,除了具有观赏价值,其进化地位也非常特殊,属于一种早期被子植物类群。最近,蓝星睡莲(N.colorata)的高质量基因组图谱绘制完成。通过系统分析和比较睡莲基因组与其它被子植物的基因组,研究者阐明了睡莲的进化位置及相关进化事件。所获得的高质量基因组序列将有助于园艺植物研究者开展深入的分子遗传学研究,鉴定到控制和调控花器官、花色花香及品质等众多性状的功能基因,从而推动基础研究的快速发展和加快新品种创制。     

Effects of stormwater sewer discharges on the aquatic community in urban canals in Lelystad

In urban areas with a separate sewerage system, the stormwater runoff is discharged into surface waters. A study on the effects of stormwater sewer discharges on the composition of the aquatic community in urban waters was carried out in two areas with a primarily residential use in the new town of Lelystad. The aquatic organisms considered included hydrophytes, epiphytic diatoms, filamentous algae and macroinvertebrates.The results indicate that the stormwater sewer discharges cause a slight change in the composition of the aquatic community. The water in the urban surface waters can be characterized as eutrophic and - toa-mesosaprobic. Near stormwater sewer outfalls the water tends to the more polluteda-mesosaprobic state. The shifts in the composition of the aquatic community could be traced primarily on the basis of a number of epiphytic diatoms and macroinvertebrates (in particular some Diptera and Trichoptera). Most hydrophytes, filamentous algae and the remaining epiphytic diatoms and macroinvertebrates (in particular water beetles and water mites) turned out to be of little or no use in this respect.Because the investigation was carried out in an unusually dry summer, the results probably underestimate the effects of stormwater discharges on the aquatic community.     

The enhanced removal and phytodegradation of sodium dodecyl sulfate (SDS) in wastewater using controllable water hyacinth

Abstract

Surfactant is an emerging and popular pollutant in both rural and urban areas and its treatment efficacy by phytoremediation is rarely reported. Water hyacinth was utilized to clean anionic surfactant sodium dodecyl sulfate (SDS) in water and its growth and physiological activities were regulated with Chromolaena odorata L. extract. SDS was effectively removed from the water and then transferred to both root and aerial part of water hyacinth. Part of SDS was converted into low-molecular weight degradation intermediates by the hydrogen abstraction reactions in water hyacinth. The removal efficiency and the degradation of SDS were evidently strengthened accompanying with enhanced root activity and ascorbate peroxidase (APX) activity in the presence of Chromolaena odorata L. extract. Meanwhile, the growth of water hyacinth was effectively controlled, exhibiting low-growth rate (≤0.036?g.day^?1). Furthermore, the root was considered as the major organ to degrade SDS, which was correlated to the remarkable increase in APX activity and a slight increase in root activity under both SDS and extract stress. In conclusion, water hyacinth managed with Chromolaena odorata L. extract should be proposed as an eco-friendly biotechnical treatment for the surfactant.     

The effects of lime addition on aquatic macrophytes in hard water: in situ and microcosm experiments

1. Aquatic macrophytes are abundant in ponds and canals that are constructed in semi‐arid regions for water storage and conveyance, as well as in lakes that are culturally enriched. 2. Addition of Ca(OH)₂ to two hardwater ponds at 250 or 275 mg L^–1 caused an immediate eradication of submersed aquatic plants. Although these ponds are well‐buffered (alkalinity: 2.57–3.94 mequiv L^–1; pH: 8.1–9.0), lime addition caused an immediate increase in pH of 0.2–3 units. 3. Application of 135 mg L^–1 Ca(OH)₂ for 24 h or 210 mg L^–1 Ca(OH)₂ for 65 h to two irrigation canals had no effect on macrophyte biomass at the lower concentration and duration, but resulted in the elimination of aquatic macrophytes 1 month after the higher concentration, longer duration treatment. 4. Unlike the macrophyte control achieved following application of 210–275 mg L^–1 Ca(OH)₂ to ponds or canals, microcosm experiments in which lime formulation [slaked lime (Ca(OH)₂), calcite (CaCO₃), or a 1 : 1 mixture] and concentrations (up to 1500 mg L^–1) were manipulated failed to elicit a consistent change in macrophyte biomass. Macrophytes in microcosms treated for the short‐term (23–33 days) with ≥ 200 mg L^–1 Ca(OH)₂ or a mixed Ca(OH)₂/CaCO₃ formulation always lost pigmentation, but biomass was not consistently reduced. 5. Declines in macrophyte biomass following treatment of ponds and canals may have been triggered by a short‐term rise in pH which, in these relatively warm (22–23 °C) alkaline (2.28–3.94 mequiv L^–1) systems, would have resulted in low concentrations of free CO₂ and bicarbonate for photosynthesis.     

屏障系统动物室单向流与乱流空气净化方式的细菌比较分析

目的探讨屏障系统动物室控制微生物污染,维持洁净的方法。方法将屏障系统动物室的乱流空气净化方式进行改进,在乱流室内增加能改变气流方式的无动力的设施,使室内气流改变为单向流动的方式。结果乱流动物室的沉降菌平均为47个,浮游菌平均为154.5个;单向气流动物室内的沉降菌平均为1.5个,浮游菌平均为7个。结论单向流优于乱流。这将为今后我国制定新的实验动物屏障系统环境标准提供技术数据。     

基于水分控制的切花百合生长预测模型

光合作用与干物质生产是观赏植物外观品质形成的基础。水分是影响植物光合作用与干物质生产的重要因子。为定量研究水分对切花百合光合作用与干物质生产的影响,以切花百合品种‘索邦’(Lilium‘Sorbonne’)为试验材料,于2009年3月至2010年1月在南京的连栋温室内开展了不同定植期和不同水分处理的栽培试验,以基于光温的温室花卉生长动态预测模型为基础,定量分析了不同定植期和不同水分处理条件下切花百合叶面积指数、光合速率和干物质生产的动态影响,并确定了切花百合正常生长的临界基质水势,建立了基质水势对切花百合光合速率和干物质生产影响的动态预测模型。结果表明,本文所建模型对切花百合叶片最大总光合速率和植株总干质量的预测效果较好,模型对叶面积指数、叶片最大总光合速率和植株干物质量的预测值与实测值之间的决定系数(r2)分别为0.97,0.96,0.94,相对根均方差(rRMSE)分别为7.12%、4.37%、11.14%。该模型能较好地预测水分对切花百合叶片最大总光合速率和植株总干质量的动态影响,可为进一步优化切花百合生产的水分管理提供决策支持。     

Responses to flooding intensity in Leontodon taraxacoides

Natural flooding is one of the major factors affecting vegetation dynamics in many regions of the world. The Flooding Pampa Grasslands (Argentina) are frequently exposed to flooding events of diverse intensity and duration, some of which Leontodon taraxacoides , an exotic dicot. frequent in these grasslands, seems to survive. Its responses to four different water depths (0, 1, 7 and 13 cm) were studied. The results indicate that plants in conditions of total submergence (depth of 13 cm) did not survive. In less severe flood conditions, increases in the leaf insertion angle resulted in the maintenance of a large proportion of the total leaf area above the water. Differences in leaf length and a decrease in the width and the proportion of lobes per leaf were also found under partial submergence conditions (depth of 7 cm). Root and leaf aerenchyma, present in unflooded plants, showed a significant increase in flood conditions. In spite of the anatomical and morphological responses, total biomass and leaf area were severely affected by water depth. Control plants allocated more biomass to reproductive organs, while partly submerged plants allocated more to leaves and less to reproductive organs. Mature L. taraxacoides plants presented a wide range of plastic adjustment as a survival strategy in soil anaerobiosis, and appear to be able to survive short spring floods in a vegetative state; in contrast, they might not tolerate total submergence conditions imposed by more intense and long-lasting floods.     

基质水势对切花百合植株干物质分配影响的预测模型

干物质分配与转移是观赏植物外观品质形成的基础,受水分影响极大.本文以切花百合品种‘索邦’为试验材料,于2009年3月至2010年1月在南京的连栋温室内开展了不同定植期和不同水分处理的栽培试验,定量分析了不同定植期和不同水分处理条件下切花百合干物质分配和转移的变化规律,以及基质水势对百合地上部和地下部各器官(花、茎、叶、鳞茎、茎生根)干物质分配指数的动态影响,并确定了切花百合正常生长的临界基质水势,最终建立了基质水势对切花百合植株干物质分配影响的动态预测模型.结果表明:本文所建模型对百合各器官(花、茎、叶、鳞茎、茎生根)干质量的预测效果较好,模型对花、茎、叶、鳞茎、茎生根干质量的预测值与实测值之间的决定系数分别为0.96、0.95、0.86、0.95、0.85,预测相对标准误分别为19.2％、12.4％、19.4％、12.2％、31.7％.-15 kPa可作为切花百合‘索邦’水分管理的临界水势.     

Comparison of genetic variation and differentiation using microsatellite markers among three rare threatened and one widespread toad lily species of Tricyrtis section Flavae (Convallariaceae) in Japan

Genetic diversities were examined using six microsatellite markers amplifiable in three rare and one widespread species of Tricyrtis section Flavae, which are endemic to Japan. Contrary to a general expectation, the three rare species, Tricyrtis flava, Tricyrtis ohsumiensis and Tricyrtis perfoliata, have comparable genetic variation at the species level to that of the widespread Tricyrtis nana. This is probably because T. nana has not sufficiently recovered genetic diversity from the bottleneck at speciation or because recent range contractions have occurred in the three rare species. Genetic diversity at the population level was smaller in the putative selfing species T. nana than in the other three outcrossing species. Compared with a preceding study using allozyme markers, the genetic diversity in microsatellite loci was considerably larger, probably resulting from higher mutation rates at the microsatellite loci. Owing to the high genetic diversity of the microsatellite markers, genetic differentiation among populations could be estimated even in T. nana with little allozyme polymorphism.