Field measurements of wind speed and reconfiguration in Arundo donax (Poaceae) with estimates of drag forces

The giant reed (Arundo donax) is well known as a species that can withstand high wind loads without mechanical damage. To examine wind impact, profiles of vertical wind speeds in the plant's natural habitat (southern France) were measured at the edge and within a stand in the main wind direction. Wind speed was recorded simultaneously at five heights. For 75 measurements of within-canopy wind speed profiles, the attenuation coefficient was 4.4 ± 0.5, a value typical for plant stands with very dense canopies. Video recordings proved that A. donax becomes streamlined with increasing wind speed, reducing the projected surface area of leaves and stem. The total projected surface area is a function of wind speed and can be characterized by a second-order polynomial regression curve. For small wind velocities up to 1 m/s, the calculated drag force is proportional to the square of the wind speed. However, when A. donax plants are subjected to higher wind speeds (1.5-10 m/s), the drag force becomes directly proportional to the wind speed. Streamlining is a potentially important adaptation for withstanding high wind loads, especially for individual plants and plants at the edge of stands, whereas in dense stands streamlining probably plays a minor role.     

Biomimetics and technical textiles: solving engineering problems with the help of nature's wisdom

The significance of inspiration from nature for technical textiles and for fibrous composite materials is demonstrated by examples of already existing technical solutions that either parallel biology or are indeed inspired by biological models. The two different basic types of biomimetic approaches are briefly presented and discussed for the "technical plant stem." The technical plant stem is a biomimetic product inspired by a variety of structural and functional properties found in different plants. The most important botanical templates are the stems of the giant reed (Arundo donax, Poaceae) and of the Dutch rush (Equisetum hyemale, Equisetaceae). After analysis of the structural and mechanical properties of these plants, the physical principles have been deduced and abstracted and finally transferred to technical applications. Modern computer-controlled fabrication methods for producing technical textiles and for structuring the embedding matrix of compound materials render unique possibilities for transferring the complex structures found in plants, which often are optimized on several hierarchical levels, into technical applications. This process is detailed for the technical plant stem, a biomimetic, lightweight, fibrous composite material based on technical textiles with optimized mechanical properties and a gradient structure.     

Spatial and temporal variation in RGR and leaf quality of a clonal riparian plant: Arundo donax

Arundo donax L. is a tall perennial reed classified as an emergent aquatic plant. In California, it has invaded riparian zones, where it acts as a transformer species. Because plant growth and leaf quality influence the effectiveness of management techniques, we sought to determine if these characters varied temporally and spatially in a northern California population of A. donax. Tissue C and N content and C:N ratio varied during the growing season. Leaf N was higher in spring and in plants that were closer to a stream. It was significantly negatively related to the clump's distance from the stream but not related to its elevation relative to the stream. Plants near the stream produced taller stems with more leaves per stem than those more distant from the stream. RGR differed across time and space. It was highest in spring prior to the appearance of flowers on a few stems that were >1 year old within the clumps. Decline in RGR as the growing season progressed coincided with the appearance of branches and flowers on stems <1 year old on a few plants within the studied population. RGR was significantly related to the N content and C:N ratio of leaves on mature stems (>1 year old). This implies that the decrease in stem growth reflected changes in nutrient availability within the entire A. donax clump and not just in the growing stems (<1 year old). These findings have implications for timing of management techniques.     

Oscillations of plants' stems and their damping: theory and experimentation

Free oscillations of upright plants' stems, or in technical terms slender tapered rods with one end free, can be modelled by considering the equilibrium between bending moments and moments resulting from inertia. For stems with apical loads and negligible mass of the stem and for stems with finite mass but without top loading, analytical solutions of the differential equations with appropriate boundary conditions are available for a finite number of cases. For other cases approximations leading to an upper and a lower estimate of the frequency of oscillation omega can be derived. For the limiting case of omega = 0, the differential equations are identical with Greenhill's equations for the stability against Euler buckling of slender poles. To illustrate, the oscillation frequencies of 25 spruce trees (Picea sitchensis (Bong.) Carr.) were compared with those calculated on the basis of their morphology, their density and their static elasticity modulus. For Arundo donax L. and Cyperus alternifolius L. the observed oscillation frequency was used in turn to calculate the dynamic elasticity modulus, which was compared with that determined in three-point bending. Oscillation damping was observed for A. donax and C. alternifolius for plants' stems with and without leaves or inflorescence. In C. alternifolius the difference can be attributed to the aerodynamic resistance of the leaves, whereas in A. donax structural damping in addition plays a major role.     

Arundo donax L. reed: new perspectives for pulping and bleaching. Part 4. Peroxide bleaching of organosolv pulps

A comparative study on TCF (totally chlorine-free) bleachability of organosolv pulps from the annual fibre crop Arundo donax L. (giant reed) was carried out using a simple three-stage peroxide bleaching sequence without oxygen pre-bleaching. ASAM (alkali-sulfite-anthraquinone-methanol), Organocell (alkali-anthraquinone-methanol) and ethanol-soda organosolv pulps were bleached and compared with kraft pulp, as a reference. The final brightness of 76-78% ISO was attained for all tested pulps. The chemical charge required to reach this level of brightness varied for different pulps (despite the equal initial content of the residual lignin) and directly related to starting brightness values. No direct correlation between brightness improvement and lignin removal during bleaching was found, indicating the influence of the specific pulp properties introduced by pulping process on bleaching chemistry. The general higher bleaching response of organosolv pulps from A. donax was noted in comparison with kraft.     

紫竹梅、吊竹梅和鸭跖草气孔分布与比较

用无色指甲油印痕法对鸭跖草科的紫竹梅、吊竹梅和鸭跖草的幼茎、成熟茎、成熟叶鞘的外表皮和幼叶、成熟叶和上、下表皮的气孔分布进行观察。并借助于计算机对三种植物的各器官各部分的气孔分布进行差异性检验和总体比较。结果表明：三种植物的幼茎、成熟茎和成熟叶鞘外表皮的上部、中部、基部的气孔分布均无显著性差异,而幼叶和成熟叶的上、中、下部的气孔分布存在着显著性差异或极显著差异。三种植物的总体比较,只有幼茎无显著性差异。同科不同属的三种植物不同器官的气孔分布存在差异与其遗传和生境条件有关。在植物不同的器官中,叶表面的气孔分布特征可以作为植物分类的佐证。     

紫竹梅、吊竹梅和鸭跖草气孔分布与比较

用无色指甲油印痕法对鸭跖草科的紫竹梅、吊竹梅和鸭跖草的幼茎、成熟茎、成熟叶鞘的外表皮和幼叶、成熟叶和上、下表皮的气孔分布进行观察。并借助于计算机对三种植物的各器官各部分的气孔分布进行差异性检验和总体比较。结果表明 :三种植物的幼茎、成熟茎和成熟叶鞘外表皮的上部、中部、基部的气孔分布均无显著性差异 ,而幼叶和成熟叶的上、中、下部的气孔分布存在着显著性差异或极显著差异。三种植物的总体比较 ,只有幼茎无显著性差异。同科不同属的三种植物不同器官的气孔分布存在差异与其遗传和生境条件有关。在植物不同的器官中 ,叶表面的气孔分布特征可以作为植物分类的佐证。     

Lutte Contre le Chancre à Didymella lycopersici de la Tomate par Chauffage Solaire (Solarisation) des Tuteurs

Solar heating (solarization) of tomato supports for control of Didymella lycopersici stem canker Previous studies have shown that Didymella lycopersici survives mainly in reed canes (Arundo donax) and Eucalyptus stakes used to support tomatoes. The solarization of the supports during the hot months of the year (May-August), by an old transparent plastic film (180μ) which was used for two years as a cover to a plastic tunnel, reduced considerably, and without any cost, the incidence of the disease. In the plots trellised with solarized and unsolarized supports, the percentage of plants with Didymella cankers at the last month of tomato crop was respectively 1.9 and 20.7%. The maximum temperatures recorded in the atmosphere, from May to September vary from 26 oC to 34 oC. The maximum temperatures recorded during the same period under plastic were always higher than 50 oC. U.S.     

Internal and external regulation of plant organ stoichiometry

Internal differences between plant organs are caused by the functional differentiation of plant tissue, whereas external supply rates of elements constrain nutrient uptake. Previous studies have concentrated on foliar or whole‐plant stoichiometric response to the environment, whereas investigation of organ‐specific comparisons is still pending. We explore C:N:P ratios of stems, leaves, diaspores and belowground organs in marsh plants, and evaluate the influence of environmental constraints using standardised major axis regression (SMA). For a pooled dataset, SMA resulted in distinct patterns of isometric and anisometric slopes between plant organs. Bivariate line‐fitting for a split dataset of four ecological groups revealed that species of the frequently inundated marsh had higher N:C ratios than those of the infrequently inundated marsh. The influence of nutrient availability was detectable in decreased P:C and increased N:P ratios in P‐poor sites. Across ecological groups, leaves and diaspores showed higher elemental homeostasis than stems and belowground organs. Any change in N:C ratios of belowground organs and diaspores in response to the environment was accompanied by an even stronger internal change in stem N:C ratios, indicating a pivotal role of stems of herbaceous plants in ecosystem processes. We found distinct patterns of C:N:P ratios in plant organs related to their internal function and external environmental constraints. Leaves and diaspores showed a higher degree of homeostasis than stems and belowground organs. We detected a clear external signal in element:element ratios of plant organs, with low soil P translating into lower tissue P:C ratio and stronger N retention in leaves as a response to salt stress.     

Variation in Arundo donax stem and leaf strength: Implications for herbivory

We determined leaf and stem strength for Arundo donax from plants grown in different geographic areas and at different times within their growing cycle. Mean leaf strength for plants collected within California was 1.72 Newtons (N) and ranged from 0.36 to 6.32 N, based on 1170 individual determinations. For leaves collected from 30 plants within four states between July 11 and 20, 2007, mean leaf strength was 1.58 N based on 936 determinations. Values ranged from 0.24 to 4.90 N. Overall, leaf strength showed statistically significant changes depending on the sampling date, sampling location, type of leaf sampled, and position within the leaf where the measurement was taken. In general leaf strength was greater near the base of the leaf and decreased with distance away from the base; leaf strength changed as the growing season progressed; and first year leaves had leaf strength values about 25% greater than leaves produced on stems >1-year old. This represents two of the three age categories of leaves which may be present on giant reed at any one time. Stem strength and stem wall thickness were strongly correlated (Kendall's Tau b = 0.92, P < 0.0001, N = 26). Linear regression indicated that mean stem strength decreased by approximately 6.8% (95% confidence limits 5.8-7.7%) from one node to the successive node progressing from the stem base to the shoot tip. These results imply that the ability of biological control agents to damage A. donax leaves may not be the same across the locations this plant occurs or at all times during the growing season within a given location.     

Local, efflux-dependent auxin gradients as a common module for plant organ formation

Plants, compared to animals, exhibit an amazing adaptability and plasticity in their development. This is largely dependent on the ability of plants to form new organs, such as lateral roots, leaves, and flowers during postembryonic development. Organ primordia develop from founder cell populations into organs by coordinated cell division and differentiation. Here, we show that organ formation in Arabidopsis involves dynamic gradients of the signaling molecule auxin with maxima at the primordia tips. These gradients are mediated by cellular efflux requiring asymmetrically localized PIN proteins, which represent a functionally redundant network for auxin distribution in both aerial and underground organs. PIN1 polar localization undergoes a dynamic rearrangement, which correlates with establishment of auxin gradients and primordium development. Our results suggest that PIN-dependent, local auxin gradients represent a common module for formation of all plant organs, regardless of their mature morphology or developmental origin.     

西北干旱区荒漠植物叶片和细根碳、氮、磷化学计量特征

植物的叶片和细根是植物地上部分和地下部分最重要的营养器官,其碳(C)、氮(N)、磷(P)化学计量特征反映了植物的养分限制状况及叶片与细根间的协同作用,开展叶片与细根化学计量关系的研究,对认识植物养分利用策略及元素间平衡关系有重要意义。对西北干旱区21种荒漠植物叶片与细根C、N、P含量进行了测定,分析了C、N、P含量及其计量比在不同生活型及不同器官间的关系。结果表明:1)西北干旱区荒漠植物叶片与细根C含量相对稳定,叶N、P含量高于细根,说明在干旱生境中,植物对养分的分配侧重于地上部分,以完成其正常的生命活动;叶片与细根的N ∶ P无显著差异,有明显的保守性,表明植物地上与地下部分养分吸收策略与分配规律具有一致性;2)不同生活型植物叶片和细根的C、N、P含量及C ∶ N、C ∶ P存在显著差异,灌木与禾草具有较高的C ∶ N和C ∶ P,杂类草具有较高的N、P含量,说明灌木与禾草倾向于保守型养分适应策略,杂类草倾向于快速生长的资源竞争策略;3)21种荒漠植物叶片与细根N、P含量间均存在显著的正相关关系,表明西北干旱区荒漠植物体内N、P元素间存在相互作用;4)植物叶片与细根间C、N、P含量及C ∶ N、C ∶ P存在等速生长关系,表明植物光合产物和养分在地上与地下部分间的分配具有平行的比例关系,但这种关系受生活型影响。上述结果表明西北干旱区不同生活型植物在恶劣生境中存在不同的养分适应策略,且地上与地下部分的养分利用策略及分配规律存在协同作用,这为进一步认识西北干旱区荒漠植物的养分利用策略提供了试验基础。     

The laccase-catalyzed modification of lignin for enzymatic hydrolysis

The efficient use of cellulases in the hydrolysis of pretreated lignocellulosic biomass is limited due to the presence of lignin. Lignin is known to bind hydrolytic enzymes nonspecifically, thereby reducing their action on carbohydrate substrates. The composition and location of residual lignin therefore seem to be important for optimizing the enzymatic hydrolysis of lignocellulosic substrates. The use of lignin-modifying enzymes such as laccase may have potential in the modification or partial removal of lignin from the biomass. In this study, the effect of lignin modification by laccase on the hydrolysis of pretreated spruce (Picea abies) and giant reed (Arundo donax) was evaluated. The substrates were first treated with laccase and then hydrolyzed with commercial cellulases. Laccase modification improved the hydrolysis yield of spruce by 12%, but surprisingly had an adverse effect on giant reed, reducing the hydrolysis yield by 17%. The binding properties of cellulases on the untreated and laccase-treated lignins were further studied using isolated lignins. The laccase treatment reduced the binding of enzymes on modified spruce lignin, whereas with giant reed, the amount of bound proteins increased after laccase treatment. Further understanding of the reactions of laccase on lignin will help to control the unspecific-binding of cellulases on lignocellulosic substrates.     

Effects of Light Spectral Quality on Morphogenesis and Source–Sink Relations in Radish Plants

The accumulation of dry matter and the content of major phytohormones in the aboveground and underground plant parts, as well as light curves and the diurnal course of photosynthesis in the leaves were studied in radish (Raphanus sativusL.) plants of different ages that were grown under red (RL) or blue (BL) light. As seen from the rapid increase in plant biomass, the development of storage organs (hypocotyl or tap root) started on the 14th day after the emergence of seedling of the BL plants and on the 21st day for the RL plants. Conversely, RL stimulated biomass accumulation in the aboveground parts (petioles and stems) already in the early stages of plant development. Light spectral quality only slightly affected the activity and the diurnal course of photosynthesis. The GA content was ten times higher in the aboveground parts of the RL plants than those of the BL plants. The hypocotyl of the BL plants contained much higher amounts of cytokinins and IAA than that of the RL plants. The specific responses of the source–sink relations to the light quality were related to the distribution of various phytohormones between the aboveground and underground parts of the plants: RL increased the content of gibberellins (GA) in the aboveground parts of plants, thus increasing their sink activity, whereas BL stimulated the synthesis of cytokinins and IAA in the hypocotyl and enhanced its development. Light quality-specific morphogenetic responses were reversed when plants were treated with exogenous GA or paclobutrazol, an inhibitor of GA synthesis. The treatment of the BL plants with exogenous GA stimulated petiole and hypocotyl elongation and induced stem formation. The treatment of the BL plants with paclobutrazol led to shortened petioles, the flattening of the storage organ, and the disappearance of the stem.     

Use of wastewater as a nutrient solution in a closed gravel hydroponic culture of giant reed (Arundo donax)

The objective of this experimental work was to examine the efficiency of giant reed (Arundo donax L.), as a source of biomass production and as a biofiltering device for sewage effluents. Two giant reed populations were cultivated in a closed gravel hydroponic system, where pig's waste was used as a nutrient solution. The results showed that stem biomass production varied from 12 to 23 kg DM m(-2) yr(-1), more than the ordinary production in the soil. According to stem analysis, for the first two years, there was an average infiltration rate of 31 g m(-2) yr(-1) total N, 7.5 g m(-2) yr(-1) total P, 18.8 g m(-2) yr(-1) K, 2.1 g m(-2) yr(-1) Ca, 2.1 g m(-2) yr(-1) Mg, 0.27 g m(-2) yr(-1) Fe, 0.02 g m(-2) yr(-1) Mn, 0.14 g m(-2) yr(-1) Zn and 0.08 g m(-2) yr(-1) Cu. During the third year, when a nutrient solution with added P was used, the average infiltration rate for most elements increased by 46% and for P by 169%.     

The physiological activity of volatile substances of plants in air and water media

Physiological effects of volatile substances released by the overground as well as by the underground organs of higher plants were studied. The activity of the volatile substances was tested both when these substances were allowed to act directly in the air and when they were dissolved in water in the form of solutions. Plants which do not contain essential oils or which are not rich in them as well as those abounding in essential oils and other volatiles were used in the experiments. The physiological activity of the volatile substances was tested on rye seedlings. The overground as well as underground mature organs of the tested plants were found to release volatile substances causing, when acting directly, in the majority of cases an inhibition of the growth in length and of the formation of dry matter in rye seedlings. A pronounced inhibition of the growth of rye seedlings was brought about especially by the volatile substances of “aromatic” plants such as common dill, wild thyme, yarrow milfoil, garden thyme, marjoram, etc. The volatile substances released by the organs of “non-aromatic” plants like sugar-beet, common sunflower, quackgrass, etc., were found to bring about a significant inhibition of the growth of rye seedlings, too. The volatile substances released by the plant organs were found to be altogether absorbable in water and physiologically active also in the form of water solutions. With the exception of volatile substances from hemp and quackgrass leaves, which brought about a mild stimulation of the dry matter formation in rye seedlings, inhibitory effects of these solutions were found to prevail in all cases. Most effective were the solutions of the volatiles from some of the “aromatic plants”. An assay for olefines in the atmosphere of the experimental vessels demonstrated that in almost all cases ethylene is being released by the plant organs.     

芦苇耐脱水能力的生理生态学分析

甘肃省河西走廊分布有不同生态环境的芦苇,包括沼泽芦苇、盐化草甸芦苇和沙丘芦苇。盐化草甸芦苇和沙丘芦苇表观出很强的耐脱水能力。 测定与植物耐脱水能力相关的SOD、CAT和POD活力,表现为SOD活力以沙丘芦苇最高,盐化草甸芦苇次之,沼泽芦苇最低,但CAT和POD则以沼泽芦苇高于其它生境芦苇。用聚丙烯酰胺垂直板电泳方法分析这3种酶同工酶谱,结果表明,3种不同生境芦苇的SOD同工酶谱基本相同,均有9条酶带,但沙丘芦苇和盐化草甸芦苇的CAT和POD同工酶带数比沼泽芦苇分别增多3条和2条。这些结果证明,芦苇在自然选择压力下形成的耐脱水能力与基因调控的酶多型性相关。     

Nitrogen dioxide at an ambient level improves the capability of kenaf (Hibiscus cannabinus) to decontaminate cadmium

As reported previously, atmospheric nitrogen dioxide (NO2) at an ambient level increased plant size and the contents of cell constituents. We investigated this effect of atmospheric NO2 on decontamination of cadmium (Cd) by kenaf (Hibiscus cannabinus). Seventeen-day-old seedlings of kenaf were grown in air either with NO2 or without NO2. (Plants were exposed to 100 +/- 50 ppb NO2 for 10 d under irrigation of 0.1% Hyponex supplemented with 20 microM CdCl2.) Plants were then harvested and the biomass of stems, leaves, and roots, as well as the content of Cd in the organs, was determined. The stem and root biomass per plant were 1.25-1.27-fold greater in +NO2 plants than in -NO2 plants. The Cd content per stem was more than 30% greater in +NO2 plants than in -NO2 plants.     

铜递进胁迫对芦竹生理指标、富集能力的影响

通过测定叶片中叶绿素含量、过氧化氢酶（CAT）、过氧化物酶（POD）和超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量、脯氨酸含量及质膜透性,研究了不同浓度铜胁迫对芦竹幼苗植株的生理指标及富集能力的影响。结果表明：随铜处理浓度的增大,叶片中叶绿素含量、POD、SOD和CAT活性均呈先升高后降低的趋势,当铜处理浓度在100mg·kg^-1时,叶绿素含量、CAT活性达到最大值,而POD、SOD活性在200mg·kg^-1处理时达到最大值。MDA含量、脯氨酸含量及质膜透性均随铜浓度增大而升高,当铜处理浓度在800mg·kg^-1时,叶片中的MDA含量、脯氨酸含量及质膜透性达到最大值。检测芦竹中铜含量的分布规律为根（地下部分）〉茎、叶（地上部分）,当铜处理浓度未达800mg·kg^-1时,转运系数小于1,富集系数大于1。结果表明芦竹对铜污染土壤具有一定耐受力。     

Effects of insect attack to stems on plant survival,growth, reproduction and photosynthesis

Studies of insect herbivory have mostly focused on leaf‐feeding even though most woody plant biomass is stem tissue. Attack to stems has the potential to be more detrimental to plant performance than attack to leaves. Here we asked how severe is the impact of insect stem herbivory on plant performance. We quantify the effect of insect stem herbivory via a meta‐analysis of 119 papers in 100 studies (papers by the same authors were treated as the same study). These studies involved 92 plant species and 70 species of insect herbivore (including simulated herbivory). Attack to plant stems reduced plant performance by an average of approximately 22%. Stem herbivory had greatest impacts on plant and branch survival, which was reduced by 63%. Measures of plant reproduction and vegetative biomass were reduced by 33% and 16% respectively, while measurements of photosynthetic rate were not significantly different between plants with and without stem herbivore attack. Stem herbivory led to a decline in leader performance but an increase in performance of laterals, highlighting the importance of plant compensation. Juvenile plants were more severely affected by stem herbivory than adult plants, and studies conducted in greenhouses found more severe effects than studies conducted in the field. Stem herbivory did not have a significant effects on any of the non‐performance responses measured (defence compounds, SLA, root:shoot, phenology and plant carbon and nitrogen). We compare our results with results from various meta‐analyses considering herbivory on other plant parts. The impact of insect herbivory to stems on plant performance appears at least as severe as insect herbivory to roots and leaves, if not more.