Optimising diquat use for submerged aquatic weed management

An experimentally derived prediction tool is under development which aims to assess potential deactivation of diquat caused by water and deposits on plant leaf surfaces in New Zealand water bodies, where aquatic weeds are targeted for diquat treatment. Optimising the use and success of diquat is important not only in managing public confidence in the use of aquatic herbicides, but also in minimising financial risk from failed treatments. Our approach focuses on characterising lake water quality and plant condition factors in these lakes to identify parameters that might be useful indicators of diquat deactivation potential. Water samples have been collected at 3-month intervals from lakes receiving large scale treatment for weed control. Samples have been analysed for turbidity, suspended solids, chlorophyll a, conductivity and dissolved anions. Samples have also been spiked with 1 mg l⁻¹ diquat to measure loss from adsorption and/or absorption. Shoot samples were also collected from targeted weed species at each sampling site and the amount of organic and inorganic deposits on plants has been measured and then added to a second diquat spiked sample to assess potential additional diquat loss from these deposits. Our results have shown deactivation from deposits on plant surfaces which is highly correlated with turbidity, including inorganic suspended solids and total suspended solids. A plant “dirtiness” scale has been devised to help predict the likely success or risk of diquat failure prior to any decision to proceed with treatment. Deactivation in water was only weakly linked to total suspended solids. Our failure to find significant correlation with the water quality factors measured may reflect the need for more detailed analysis of the particle size and composition of suspended solids and future research will address these issues.     

Quantifying the deposition of particulate matter on climber vegetation on living walls

The beneficial effect of vegetation on particle deposition is often stated in arboricultural literature but has rarely been researched in detail. To quantify these filtering effects of façade greening, it is necessary to study the accumulation properties of leaf surfaces on particle adsorption. In this paper attention will be given to a measure technique for particle adsorption on vegetation. The presented preliminary study aims to classify the total amount of particles by counting of particles on ESEM photographs. In the PhD research more attention will be given on the relation between particle reduction and the effect of vegetation on air quality improvements. Two locations were investigated, namely: leaves from near a traffic road and from a woodland. A difference in the particle amount was found at the underside and upper side of the leaves. For example, in a sampling at early autumn for the road location roughly 7000 particles (per 1275 × 950 μm) were counted for the upper side, and, roughly 3200 particles for the underside. Also a difference in particle amount was found between the two different locations, respectively roughly 7000 particles for the upper side of the leaf at the road location and roughly 3300 for the woodland location. The comparison must give more insight into the sink capacity of vegetation, but also between the environments. In the paper, results of counting particles on leaves from both locations are provided via a factorial design approach with four independent factors at two levels (height, leaf, time and environment). The outcome of the factorial design shows that there is a difference between the collecting capacity of the leaf (upper side/underside) and between the environments (road/woodland). Fine and ultra-fine particles (i.e., the fractions that are potentially the most harmful to human health) were more abundantly found on the leaves than coarser particles. Also some energy dispersive X-ray analysis (EDS) of the adhered particles is provided. As the main conclusion of this research, it can be said that counting particles instead of weighing particles on a specific leaf area seems to be a proper way to classify aerosol deposition on vegetation.     

叶片结构的水力学特性对植物生理功能影响的研究进展

叶片是植物进行光合、呼吸、蒸腾作用的主要器官, 早期的研究主要集中于水分在叶片中的运输路径, 而对叶脉结构及其生态学意义研究甚少。近年来关于叶片叶脉结构、气孔结构的功能及叶片水力学特性的意义研究已经成为植物生理生态的研究热点。该文综述了叶脉的结构性状的指标(叶脉密度、直径、间距等), 叶片水力学结构特性对植物生长、水分运输、气体交换、光合作用等生理功能的影响, 及其与植物对干旱适应性之间的关系。叶脉结构是决定叶片生理功能的基础, 因此在未来的工作中应分析比较不同种类植物叶脉结构形态与导水、光合、呼吸、同化作用之间的关系, 建立植物茎干-枝-叶系统水力传导的机理性模型, 用以探索不同植物功能结构和高效用水生理生态学机制, 据此评估不同种类植物在未来气候情景下的地位。     

两种常见绿化树种对大气颗粒物的滞留与再悬浮

植物叶片对大气颗粒物的作用机制可分为吸附、再悬浮、雨水淋洗、吸收等过程,但却少有研究探讨大气颗粒物沉降于叶片表面后的再悬浮过程,并对叶片表面吸附的颗粒物含量与叶片内部元素含量之间的相关性进行探讨.本研究选择二球悬铃木和广玉兰两种常见绿化树种,分析其叶表大气颗粒物和叶内元素成分与含量及再悬浮比例.结果表明: 二球悬铃木叶片的单位面积滞尘量(4.98 g·m^-2)明显高于广玉兰(2.65 g·m^-2),这可能与二球悬铃木叶片上下表面均粗糙、有绒毛有关.电感耦合等离子体发射光谱(ICP)分析表明,15种不同的元素均可在二球悬铃木和广玉兰叶表和叶内监测出来,在整体上两树种叶表与叶内元素含量间存在明显的相关性.但仅有Cr、Fe、V等 3种元素在二球悬铃木叶表与叶内间存在显著的相关性,而广玉兰中仅有K、Mn、Si、Ti和Zn 等5种元素没有显著的相关性,说明两树种叶片对不同元素的吸收具有较强的选择性.再悬浮分析表明,无论是随着风速的增加还是随着风力作用时间的延长,大气颗粒物的再悬浮比例均随之显著增加.在研究植物对大气颗粒物滞留效果时,必须考虑到颗粒物的再悬浮,才能准确评估植被与大气颗粒物的沉降关系.     

Effects of colchicine on polyploidy induction of Buddleja lindleyana seeds

Buddleja lindleyana Fort. is a garden ornamental plant with great potential for development and also a commonly used medicinal plant. To enrich its germplasm resources, the seeds of B. lindleyana were treated with colchicine solution with concentration gradients of 0.5%, 1.0%, 1.5%, 2.0% and 3.0% for 12-, 24- and 48-h respectively, and the water treatment was set as the control group. The purpose was to explore the effects of colchicine on the germination and mutagenic effect of B. lindleyana seeds at different concentrations and different times, to screen the appropriate combination of mutagenic concentration and time, to provide guidance for the construction of B. lindleyana mutation population in future research. The results were as follows: (1) Colchicine had an inhibitory effect on seed germination and seedling height of B. lindleyana seeds, and the higher the concentration, the more obvious the inhibitory effect. (2) After colchicine treatment, 30 mutant plants showed morphological variations such as leaf malformation, leaf color macular, early leaf bud germination, uneven leaf surface and leaf hyperplasia, among which 3.0%?+?48-h treatment group had great potential to produce yellow-leaf plants. (3) Detection and analysis by flow cytometry revealed that among the 30 morphologically variant plants, there were 22 diploid plants, 3 tetraploid plants, and 5 chimera plants. Among them, tetraploids were mainly from colchicine concentration of 3.0% (2 plants) and 1.5% (1 plant), chimeras were mainly from colchicine concentration of 1.0% (2 plants), 1.5% (1 plant) and 3.0% (2 plants), and the seed soaking time was 48-h. (4) The length and width of guard cells and stomata were significantly different between diploid and tetraploid, and there were significant differences in leaf width and leaf shape index between tetraploid and diploid, but there were no significant differences in leaf length among diploid, tetraploid and chimera. In short, we got tetraploids and chimeras materials which were potentially useful cultivars of B. lindleyana and provided an effective identification method for polyploids of B. lindleyana.

     

彩叶植物叶片呈色分子机制研究进展

彩叶植物叶片呈现不同的颜色主要是受遗传因素和外部环境的共同作用,揭示彩叶植物叶片呈色机制对选育彩叶植物新品种和彩叶植物的应用推广具有重要理论和实践意义。目前对彩叶植物呈色机制的研究主要集中于叶片中色素变化、光合特性、叶片结构和环境条件等方面。该文主要対近年来有关彩叶植物叶片中叶绿素代谢途径、类胡萝卜素代谢途径、次生代谢途径、光合作用和叶绿体发育相关结构基因和转录因子调控机制的研究进展进行综述,并对以后的研究方向进行了展望,为培育彩叶植物新品种提供了理论基础,也为人工调控叶色以及叶色的定向遗传改良提供了参考。     

Nitrogen Uptake and Plant Growth II. An Empirical Model of Vegetative Growth and Partitioning

An empirical model of vegetative plant growth is presented.The model is based on experimental data on Polygonum cuspidatum,which showed (1) that the partitioning of dry matter and nitrogenamong organs was linearly related to the nitrogen concentrationof the whole plant and (2) that leaf thickness was negativelycorrelated with leaf nitrogen concentration. The model properlydescribes the behaviour of plants. Steady-state solutions ofthe model give the relative growth rate, specific leaf weight,and partitioning of dry matter and nitrogen among organs withthe net assimilation rate and the specific absorption rate asenvironmental variables. The effect of nitrogen removal on drymatter and nitrogen partitioning was examined as non-steady-statedynamic solutions of the model. The model predicted not onlyreduced leaf growth and enhanced root growth but also a fluxof nitrogen from the leaf to the root, which agreed with theexperimental results. Mathematical model, partitioning of dry matter and nitrogen, plant nitrogen, relative growth rate, shoot: root ratio, specific leaf weight     

A role for young leaves in vernalization of cauliflower: I. Analysis of leaf development during curd induction

Growth analysis techniques are used to test the hypothesis that chilling induces curd (flower) initiation in the cauliflower ( Brassica oleracea Botrytis L. cv. Perfection) through inhibiting leaf growth, thereby increasing the availability of growth factors to the stem apex and enabling differentiation of the curd. Effects of chilling on leaf growth and curd induction are compared in juvenile and mature, vegetative plants. Chilling at 5°C reduced dry matter accumulation in the total leaf complement by ca 60% in juvenile plants and 40% in mature plants, compared to control plants growth at 20°C. Juvenile plants showed slower rates of leaf initiation than mature plants. Leaf initiation was retarded by chilling in both plant types with the most marked effect seen in the juvenile plants. This was consistent with dry matter availability to the stem apex limiting differentiation more severely in juvenile plants than in mature plants. The rate of dry matter accumulation in existing leaves, however, was faster in juvenile plants than in mature plants at 20°C. Plants that were juvenile during chilling produced an average of 43 leaves below the curd whereas those that were mature produced 25.
Dry matter accumulation in younger leaves was more markedly inhibited by chilling than in older leaves. Chilling also reduced the rate at which enlarging leaves became positionally more remote from the stem apex. Possible roles for such leaves in regulating apical development are considered.     

叶甲科昆虫的定殖机制

在复杂的生态环境中,叶甲科昆虫利用寄主植物的挥发物作为嗅觉信号,并协同视觉信号共同作用以提高其远距离搜寻和定位寄主的效率。叶甲科昆虫也释放信息素来调节同种或者异种个体的行为反应;找到寄主植物后,叶子的形态学特性和化学组分的浓度等接触性因素就会影响叶甲科昆虫对寄主植物的最终选择。叶甲对上述这些信号物质的反应也受叶甲本身状态的影响,如生殖、滞育、饥饿、交配以及取食等。叶甲科昆虫对寄主植物的搜寻、辨识和接受、取食以及繁殖的过程受一种或多种因素协同影响。从嗅觉、视觉和触觉等方面对叶甲科昆虫的定殖机制做一综述。     

Screening a cucumber crop during leaf area development reduces yield

In order to reduce heat energy consumption in greenhouse cucumber production, (transparent) screens may be used also during the day, particularly in the early growth phase when high temperatures are required to achieve rapid leaf area development. However, energy savings must be optimised against light reduction‐induced yield loss. For this reason, two experiments were conducted to quantify the effect on photosynthesis and growth of screening cucumber plants during their early growth phase, and on yield in the following generative phase. Screening with different light transmission coefficients was simulated using shading nets. Shading the plants during the first 5 weeks under Central European winter conditions reduced the leaf area by 0.40% per 1% reduction in photosynthetic active radiation (PAR). Moreover, potential leaf net photosynthesis decreased by 0.46% per 1% PAR reduction. A major impact was that the leaf dry matter content, leaf starch content and leaf sugar content of shaded plants diminished significantly. In the course of the following 2 weeks under full light, the leaf photosynthesis of the plants previously shaded recovered fully and the leaf area index rose to 3.3 m² m^?2, considered sufficient for optimal crop photosynthesis. The yield from plants previously shaded diminished slightly as early as from the first harvest week on. These yield losses increased further over the next few weeks, measuring approximately 0.8 kg m^?2 per 1 mol m^?2 day^?1 PAR reduction in the early growth phase. The effect of PAR on plant growth was proportional when relating the PAR integral over the entire experimental period to the total yield and to the total dry matter production, respectively.     

陆地生态系统植物挥发性有机化合物的排放及其生态学功能研究进展

综述了国内外生物源挥发性有机化合物 (Biologicalvolatileorganiccompounds, BVOCs) 研究现状及未来的研究方向, 侧重介绍了陆地生态系统中植物排放BVOCs的种类、生物学功能及其对大气化学过程的影响。BVOCs按其化学结构以及在大气中的滞留时间可以分为 4类 :异戊二烯、单萜、其它活性BVOCs和其它次活性BVOCs。不同的植物类群排放不同的BVOCs种类并具有不同的排放特性, 环境条件对植物不同BVOCs的排放影响也不同。BVOCs作为有机物质被排放到体外, 从植物能量代谢的角度来讲要消耗一部分植物光合作用产物从而降低植物的生产力, 因此推测植物排放BVOCs具有一定的生理学或者生态学的功能。其中比较成熟的假说是抗热胁迫假说, 其次是抗氧化假说, 也有一些其它假说例如促氮同化假说等。但这些假说都还缺乏直接的有力证据, 有待更多的研究来支持。BVOCs被排放到大气中对大气化学过程的影响更是科学家关注的问题, BVOCs对大气的影响一方面是在大气对流层中促进臭氧 (O3 ) 的形成, 造成环境污染, 另一方面BVOCs通过对大气中的OH自由基和臭氧等氧化物浓度的调整而影响到大气中甲烷等温室气体的平衡, 对大气温室效应具有间接的贡献。我国在BVOCs的研究上也做了大量的工作, 包括分析鉴定了一些植物排放的BVOCs, 探讨了环境因子对植物BVOCs排放速率的影响, 从不同尺度估测了BVOCs的排放量等等。今后对BVOCs的研究将会集中在以下几个方面 :1) 进一步研究不同植物类群释放的BVOCs种类及其它们在大气中的理化性质 ;2 ) 继续探讨植物排放BVOCs的合成与代谢途径及其生物学功能 ;3) 研究BVOCs对大气化学过程的作用, 以及区域植被变化对BVOCs排放格局进而对区域乃至全球环境变化的影响 ;4 ) 加强对一些研究比较薄弱的生态系统例如在热带地区所进行的BVOCs研究工作 ;5 ) 进一步建立和完善BVOCs排放的理论模型, 以模拟不同陆地生态系统BVOCs排放的时空动态。     

植物叶片氮分配及其影响因子研究进展

氮是植物生长的基本限制性因子,它的有效利用可以增加植物的适应性。叶片氮分配是指氮在植物叶片细胞各细胞结构以及游离化合物中所分配的比例。叶片氮的分配方式决定了叶片光合作用的强弱,影响叶片的坚韧程度以及化学防御强度,因此研究氮在植物叶片内的分配方式具有重要意义。阐述了叶片氮分配的方式,分析了影响叶片氮分配的生物和非生物因子(CO2,光,土壤养分),介绍了常用的叶片氮分配的研究方法,并对未来的研究进行了展望。     

A study of absorption characteristics of chromophoric dissolved organic matter and particles in Lake Taihu,China

Absorptions by non-phytoplankton particles and phytoplankton, and chromophoric dissolved organic matter (CDOM) were measured at 50 sites in large, shallow, Lake Taihu in winter and summer 2006 to study their seasonal and spatial variations, and their relative contributions to total absorption. The CDOM absorption was significantly higher in winter than in summer, due to degradation and release of fixed carbon in phytoplankton and submerged aquatic vegetation (SAV). The hyperbolic model was used to model the spectral absorption of CDOM, and the mean spectral slope of 6.38 nm⁻¹ was obtained. At most sites, the spectral absorption of non-phytoplankton particles was similar to that of the total particles, demonstrating that the absorption of the total particles is dominated by the absorption of non-phytoplankton particles. In summer, phytoplankton absorption increased markedly, due to frequent algal blooms especially in Meiliang Bay. In winter, the significant increase in non-phytoplankton particle absorption resulted from the increase of inorganic particulate matter caused by sediment resuspension. Strong linear relationships were found between a _d(440) and total suspended matter (TSM), organic suspended matter (OSM), and inorganic suspended matter (ISM). Strong linear relationships were also found between a _ph(440), a _ph(675) and chlorophyll a (Chl-a) concentration. The total relative contributions of non-phytoplankton particles over the range of photosynthetically active radiation (PAR) (400–700 nm) were 48.4 and 79.9% in summer and winter respectively. Non-phytoplankton particle absorption dominated the total absorption, especially in winter, in Lake Taihu, due to frequent sediment resuspension in the large shallow lake as a result of strong windy conditions. The results indicate that strong absorption by CDOM and non-phytoplankton particles at the blue wavelength has an impact on the spectral availability, and acts as a selection factor for the composition of the phytoplankton community, with cyanobacteria being the dominate species in Lake Taihu. Handling editor: L. Naselli-Flores     

The influence of black bean aphid, Aphis fabae Scop., and its honeydew on leaf growth and dry matter production of sugar beet

A. fabae populations, started at the 3–4 leaf-stage of sugar beet in the glasshouse and peaking at 3000 individuals per plant, reduced leaf area by 64% at the 14 leaf-stage. The size of the heavily-infested leaves number 5 to 10 was reduced by 80% or more. The rate of leaf growth regained normal values after the aphid populations collapsed, but the infested plants did not make up for the decrease in leaf area production that had been incurred during the infestation. Total dry matter production over a period of 15 weeks was reduced by 47%. Honeydew had no effect on leaf size or dry matter production. Sugar beet plants in the field became infested with A. fabae at the 2–3, 4–5 and 6–8 leaf stages. Maximum populations of 800, 2100 and 2200 aphids per plant were recorded, respectively. The pertinent reductions in leaf area were 91%, 67% and 34% at the 10–12 leaf-stage and 79%, 65% and 14% at harvest while the total dry matter produced was reduced by 91%, 79% and 16%. Neighbouring plants of the early-infested sugar beet plants gained significantly higher weights than control plants. Honeydew had no effect on leaf area or dry matter production. The consequences of these results for our understanding of Aphis fabae injury in sugar beet and aphid control in the field are discussed.     

Effect of particulate pollution on rate of transpiration in Shorea robusta at Lalpahari forest

The effect of stone dust deposition on the rate of transpiration in Shorea robusta was studied in three principal seasons in a polluted forest in comparison to an almost non-polluted forest. The extent of particulate pollution was determined by measuring suspended particulate matter in the air and dust fall on leaf surface. Macroscopic and microscopic leaf injury symptoms were studied. Scanning electron microscopic examination of leaf surfaces revealed a number of foliar anomalies. Qualitative determination of rate of transpiration in field condition was done by ‘cobalt chloride method’. It was found that transpiration was diminished as a result of foliar dust deposition which not only caused blockage of stomatal aperture but also physical damage to the leaf surface. Thus, particulate air pollution can be considered as one of the external factors regulating the rate of transpiration in plants.     

植物叶片吸滞PM2.5等大气颗粒物定量研究方法初探——以毛白杨为例

以毛白杨为例,提出一种利用激光粒度仪和天平定量评估植物叶片吸滞细颗粒物(PM_2.5,直径d≤2.5 μm)等大气颗粒物能力的方法——洗脱称量粒度分析法(EWPA),实现了对植物叶片吸滞大气颗粒物质量和粒径分布的直接、准确测定,可操作性强.首先,进行预试验对试验方法的稳定性进行检验;其次,通过对叶片进行清洗、离心洗液、烘干等步骤收集其吸滞的颗粒物,然后对颗粒物称量,并采用激光粒度仪测定颗粒物的粒径分布;最后,利用叶面积和林分叶面积指数数据换算得到单位面积叶片和林分的各径级颗粒物吸滞量.在北京市奥林匹克森林公园内一片毛白杨林分(27 d未经历降雨)中应用该法,测得毛白杨叶片吸滞大气颗粒物的粒径均值为17.8 μm,吸滞PM_2.5、可吸入颗粒物(PM₁₀,d≤10 μm)和总悬浮颗粒物(TSP,d≤100 μm)的体积百分比分别为13.7%、47.2%和99.9%;叶片的PM_2.5、PM₁₀、TSP和总颗粒物吸滞量分别为8.88×10^-6、30.6×10^-6、64.7×10^-6和64.8×10^-6 g·cm^-2;林分的PM_2.5、PM₁₀、TSP和总颗粒物吸滞量分别为0.963、3.32、7.01和7.02 kg·hm^-2.     

Effect of potato seed-tuber age on plant establishment and amelioration of age-linked effects with auxin

Studies were conducted to characterize the effect of advanced potato (Solanum tuberosum L.) seed-tuber age on plant growth potential and whole-plant morphology. Plant growth from single-eye seedcores from 5- to 18-month old `Russet Burbank' seedtubers was compared. Loss in apical dominance was apparent with advanced age. On a per-core basis, the amount of plant dry weight was equal for the two ages at 30 days from planting. However, individual plants from older cores displayed reduced shoot, root and leaf dry weights, leaf area, and leaf number. These effects reflected altered dry-matter partitioning and contributed to an overall change in plant morphology with advanced age. On a total seedcore basis, relative growth rate of plants from older seedcores was greater than that from younger seedcores over the 30 day growth interval. Leaf area ratio was also greater for plants from the older seedcores; however, unit leaf rate was not affected by tuber age and plants from both young and old seedcores assimilated dry matter at the same rate. Age-induced differences in growth indices reflected differences in the degree of plant differentiation over the interval of study. Treating younger seedcores with 1-naphthaleneacetic acid (NAA) prior to planting inhibited overall plant growth. In older cores, NAA stimulated root growth, restored apical dominance, decreased leaf number per plant, and increased average leaf area per leaf. In short, NAA altered the morphology of plants growing from older seedcores to more closely resemble that of plants growing from younger seedcores. While auxin significantly altered plant form, vigor of plants from older seedcores was not fully restored by auxin treatment, indicating that age-reduced vigor of potato seed-tubers is not solely mediated by auxin.     

Formation,Transport and Retention of Aggregates in a River‐Lake System (Spree,Germany)

The formation, particle size distribution, structure and retention of aggregates were studied in a river‐lake system of the lowland River Spree and factors influencing these processes were evaluated. Samples were taken from the inflow and outflow of a flushed lake, as well as along the adjacent flowing reach of the River Spree, between April 2001 and May 2002. The aim was to record the influence of the seasons and different turbulence intensities on the size, shape, composition, abundance and transport properties of the particles. As additional parameters, the phytoplankton biomass, the concentration of suspended particulate matter, the concentrations of nutrients and the discharge were measured. The abundance of the particles showed a strong seasonality in the investigated period, which closely correlated with the concentrations of suspended particulate matter and particulate organic matter in the water column. The organic carbon content of the suspended matter varied between 37% (dry weight) in summer and about 14% in winter. The concentration of particles ranged between 500 and 2500 particles/ml. The number of particles was significantly lower upstream from the lake than at the downstream transects. The majority of the aggregates in the River Spree were smaller than 500 µm, most of the particles even showing a diameter less than 50 µm. Many particles, above all algae, were washed out of the lake Neuendorfer See into the adjacent flowing reach of the River Spree. Algae influenced the abundance of the particles and contributed to the formation of aggregates with their stickiness. In the river flowing section large particles were formed by turbulence structures, whilst simultaneously the number of smaller particles decreased in the water column caused by aggregation processes. In general, an increasing flow velocity and discharge rate resulted in a larger amount of aggregates in the water column. On the other hand, particle abundance was reduced in the flow direction when the flow velocity was low. Under these conditions particles were retained by sedimentation and benthic filter‐feeding. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effects of above- and belowground herbivory on growth,pollination, and reproduction in cucumber

Plants experience unique challenges due to simultaneous life in two spheres, above- and belowground. Interactions with other organisms on one side of the soil surface may have impacts that extend across this boundary. Although our understanding of plant–herbivore interactions is derived largely from studies of leaf herbivory, belowground root herbivores may affect plant fitness directly or by altering interactions with other organisms, such as pollinators. In this study, we investigated the effects of leaf herbivory, root herbivory, and pollination on plant growth, subsequent leaf herbivory, flower production, pollinator attraction, and reproduction in cucumber (Cucumis sativus). We manipulated leaf and root herbivory with striped cucumber beetle (Acalymma vittatum) adults and larvae, respectively, and manipulated pollination with supplemental pollen. Both enhanced leaf and root herbivory reduced plant growth, and leaf herbivory reduced subsequent leaf damage. Plants with enhanced root herbivory produced 35% fewer female flowers, while leaf herbivory had no effect on flower production. While leaf herbivory reduced the time that honey bees spent probing flowers by 29%, probing times on root-damaged plants were over twice as long as those on control plants. Root herbivory increased pollen limitation for seed production in spite of increased honey bee preference for plants with root damage. Leaf damage and hand-pollination treatments had no effect on fruit production, but plants with enhanced root damage produced 38% fewer fruits that were 25% lighter than those on control plants. Despite the positive effect of belowground damage on honey bee visitation, root herbivory had a stronger negative effect on plant reproduction than leaf herbivory. These results demonstrate that the often-overlooked effects of belowground herbivores may have profound effects on plant performance.     

森林植物耐荫性及其形态和生理适应性研究进展

耐荫性是植物在低光环境下的生存和生长能力,对森林植物群落演替起重要作用,植物对遮荫的适应机制已成为生态学的研究热点.本文综述了森林植物的耐荫性及其在形态和生理方面的适应性,分析了森林植物在生长性状、生物量分配、树冠结构、叶片形态生理、叶片解剖结构、光合参数、碳水化合物分配、水分和养分的利用等方面对遮荫产生的可塑性响应,最后对目前研究存在的问题进行了分析,展望了未来的研究内容和方向.