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PubMed1999

Differences in chemical composition relative to functional differentiation between petioles and laminas of Fraxinus excelsior.

Differences in structural and nonstructural carbohydrates, lignin and chlorophyll, and Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) activity between petioles and leaflets were studied along a canopy light gradient in Fraxinus excelsior L., which has pinnate compound leaves and up to 20% of foliar biomass invested in petioles. Long-term light conditions at the sampling locations were characterized by values of seasonal mean integrated quantum flux density (Q(int), mol m(-2) day(-1)) estimated by combining data from hemispherical photographs at the sampling locations with measurements of global solar radiation above the canopy during the growing season. The contribution of petioles to leaf carbon assimilation was disproportionally lower than that of leaf laminas. Though the light relationships of assimilative compounds-foliar chlorophyll concentration increasing with decreasing Q(int) to improve leaf absorptance, foliar N concentration and Rubisco activity being relatively constant along the light gradient-were similar for both petioles and leaflets, petiole nitrogen and chlorophyll concentrations were only 30% and 10%, respectively, of those of leaflets. Nonstructural carbohydrate concentration was about 20% higher in petioles than in leaf laminas, indicating that petioles also serve as storage tissues for photosynthates. Relationships between foliar structural carbon components and irradiance-increasing lignin (L) and decreasing structural polysaccharide (SP) concentrations with increasing Q(int)-were qualitatively similar for petioles and leaflets. However, petioles had lower L, but higher SP and total investment in structural compounds (L + SP) than leaflets. Greater lignification at high irradiances in leaflets than in petioles was attributed to greater water stresses at high light, and to more variable water contents of actively transpiring leaflets. Low lignin concentration in combination with high osmotically active carbohydrate concentrations in petioles suggest that turgor plays an important role in the mechanical properties of petioles. As a result of lower lignin and protein concentrations, the glucose cost of petiole construction (g glucose per g dry mass) was about 5% lower than that of leaf laminas.

Journal Article↗

PubMed1986

The influence of NaCl on leaf water relations and the proportions of K, Na, Ca, Mg, and Cl in epidermal cells of Fraxinus excelsior L.

The influence of NaCl on leaf water relations was investigated in 3-4-year-old, potted Fraxinus excelsior L. trees. Until midsummer, the application of NaCl to the soil resulted in increased leaf water potentials (Psi) and stomatal diffusive resistances (r(s)). The improved water status seems to be due to a latent injury rather than to an adaptive response of the plant because, despite the initial increases in Psi and r(s), leaf necrosis developed in midsummer. Altered hydraulic resistances were detected at the time the leaves became necrotic. X-ray analysis of frozen, hydrated leaf tissue from NaCl-treated trees showed substantial increases in Ca(2+) and Mg(2+) content in the epidermal cells. These changes in elemental composition of the leaves from NaCl-treated plants may be associated with malfunction of the stomatal apparatus.

Journal Article↗

PubMed2000

Photosynthetic capacity in relation to nitrogen in the canopy of a Quercus robur, Fraxinus angustifolia and Tilia cordata flood plain forest.

We measured gas exchange and various leaf parameters of ash (Fraxinus angustifolia Vahl.) and oak (Quercus robur L.) in the high canopy and of lime (Tilia cordata Mill.) in the lower canopy of a planted, 120-year-old floodplain forest in southern Moravia, Czech Republic. The high-canopy leaves of F. angustifolia and Q. robur had nitrogen concentrations on a leaf area basis (N(area)) that were twice those of low-canopy leaves of T. cordata. Upper-canopy leaves of F. angustifolia had a photosynthetic rate at light saturation (A(max)) of about 16 micromol CO2 m(-2) s(-1), whereas A(max) of the upper-canopy foliage of Q. robur achieved only about two thirds of this value. Contrary to previous investigations of photosynthetic performance in monospecific stands, leaves of the uppermost branches of T. cordata at 15-m height had the highest A(max) and transpiration rate among the species studied. Water-use efficiency (WUE) was low in T. cordata at 15-m canopy height, whereas WUE was significantly higher for Q. robur leaves at 27-m height than for the other species. Leaves of T. cordata at 15-m height showed the strongest relationship between A(max) and N(area) (R2 = 0.90) followed by F. angustifolia (R2 = 0.69). The strong correlation between photosynthesis and nitrogen concentration in T. cordata at 15 m, together with the steep regression slope for the A(max):N(area) relationship, indicated that nitrogen allocation to the photosynthetic apparatus resulted in high nitrogen-use efficiency of light-saturated photosynthesis (PNUE). Despite differences in PNUE among species, PNUE was fairly constant for leaves sampled from the same canopy position, suggesting that single-leaf parameters are matched to optimize PNUE for prevailing light conditions. High PNUE in T. cordata at 15 m partially compensated for the species' subordinate position in the canopy, and may be an important mechanism for its coexistence in highly structured vegetation.

Carbon Dioxide↗

PubMed2001

Changes in polyamines, auxins and peroxidase activity during in vitro rooting of Fraxinus angustifolia shoots: an auxin-independent rooting model.

Among shoots of Fraxinus angustifolia Vahl raised in vitro, 76% rooted after culture on root induction medium for 5 days in darkness followed by culture on root expression medium for 15 days in light. The addition of 20.7 microM indole-butyric acid (IBA) to the root induction medium did not significantly increase the rooting percentage (88%). Putrescine, spermidine, cyclohexylamine (CHA) and aminoguanidine (AG) enhanced rooting up to 100% (98.66% for AG), when applied during root induction in the absence of IBA, otherwise these compounds inhibited rooting, as did spermine and difluoromethylornithine (DFMO) + difluoromethylarginine (DFMA). The root induction phase was characterized by a temporary increase in endogenous free indole-acetic acid (IAA) and putrescine concentrations during root induction, whereas the root expression phase was characterized by increased peroxidase activity and low concentrations of polyamines. These changes were specifically associated with the rooting process and did not depend on the presence of exogenous IBA, because application of exogenous IBA enhanced the amount of IAA in the cuttings but did not affect rooting or the pattern of changes in polyamines and peroxidase. The effects of CHA, AG and DFMO + DFMA on endogenous concentrations of auxins and polyamines highlight the close relationship between the effects of IAA and putrescine in root induction and suggest that polyamine catabolism has an important role in root formation and elongation.

Biogenic Polyamines↗

PubMed1987

Rapid field measurement of the assimilation rate versus internal CO(2) concentration relationship in green ash (Fraxinus pennsylvanica Marsh.): the influence of light intensity.

Assimilation rate (A) versus intercellular CO(2) concentration (C(i)) relationships for leaflets of five-year-old green ash (Fraxinus pennsylvanica Marsh.) trees were computed from gas exchange measurements obtained in the field with a closed-circuit, portable photosynthesis measurement system comprising an LI-6200 gas analyzer and an LI-6000 computer, (Li-Cor, Inc., Lincoln, Nebraska, USA). Observations were made over a range of light intensities achieved by attenuating direct sunlight with neutral density filters, and over a range of ambient CO(2) concentrations achieved by breathing into the assimilation chamber and then lowering the CO(2) concentration to the desired level with the LI-6200's soda-lime scrubber. Boundary layer conductance was determined by use of a leaf replica made of moist filter paper. Typically, A-C(i) curves at four light intensities were obtained in three to four hours. The initial slope (when A = 0) of the A-C(i) curve obtained at a light intensity of 1750 micromol m(-2) s(-1) (full sunlight) was similar to that obtained at a light intensity of 840 micromol m(-2) s(-1). However, when light intensity was reduced further (to 370 and 160 micromol m(-2) s(-1)), the initial slope of the A-C(i) curve also decreased, indicating that at these light intensities, assimilation was limited by photochemical energy supply, as well as CO(2) concentration.

Journal Article↗

PubMed1990

Drought adaptations and responses in five genotypes of Fraxinus pennsylvanica Marsh.: photosynthesis, water relations and leaf morphology.

Genotypic variation in photosynthesis and plant water relations during drought, and in leaf and seedling morphology were examined in greenhouse-grown Fraxinus pennsylvanica Marsh. (green ash) from five populations located along an east-west transect from New York State to South Dakota. During a 17-day drought, South Dakota seedlings, from the most xeric habitat, maintained the highest net photosynthesis and leaf conductance, and New York seedlings, from the most mesic habitat, exhibited the lowest net photosynthesis and leaf conductance. All populations except New York adjusted osmotically during the 17-day drought, by the end of which New York seedlings had the highest osmotic potentials at full and zero turgor. Tissue elasticity increased in New York seedlings, but decreased in Nebraska seedlings during the drought. Leaves of South Dakota seedlings were the most xerophytic. They were smaller in area and greater in thickness and specific mass than leaves of other sources. Leaves of New York seedlings were thinner than those of the other genotypes and among the largest. Seedlings from South Dakota were smaller than those of the other populations.

Journal Article↗

PubMed1999

The Progression of Cavitation in Earlywood Vessels of Fraxinus mandshurica var japonica during Freezing and Thawing.

For an examination of the progression of cavitation in large-diameter earlywood vessels of a deciduous ring-porous tree, potted saplings of Fraxinus mandshurica var japonica Maxim. were frozen and then thawed. The changes in the amount and distribution of water in the lumina of the current year's earlywood vessels during the course of the freezing and thawing were visualized by cryo-scanning electron microscopy. When samples were frozen, most of the current year's earlywood vessels were filled with water. After the subsequent thawing, the percentage of cavitated current-year earlywood vessels gradually increased with time. All of the current year's earlywood vessels were cavitated within 24 h, and only limited amounts of water remained in the lumina of earlywood vessels. Similar cavitation of earlywood vessels was observed after thawing of frozen, excised stem pieces. In contrast, many vessels of the current year's latewood retained water in the lumina during freezing and thawing. These observations indicate that the cavitation of the current year's earlywood vessels is not produced during freezing but progresses during rewarming after freezing in F. mandshurica var japonica.

Journal Article↗

PubMed1967

Germination of Excised Fraxinus ornus Embryos With and Without Phleomycin.

In excised embryos of Fraxinus ornus, the first macroscopic sign of germination is a curvature near the root apex. Histological studies show that this curvature is due to cell elongation on the convex side and is accompanied by cell division. Metabolic changes, manifested by the disintegration of protein bodies and tissue differentiation, also occur during this time. In embryos treated with phleomycin cell division is completely inhibited but elongation, root hair formation, disintegration of protein bodies, and differentiation are still detectable. Phleomycin also drastically inhibits the formation of chlorophylls and the fresh weight increase of embryos.

Journal Article↗

PubMed1980

Growth Responses and Adaptations of Fraxinus pennsylvanica Seedlings to Flooding.

Flooding induced several physiological and morphological changes in Fraxinus pennsylvanica seedlings, with stomatal closure among the earliest responses. Subsequent changes included: reduction in dry weight increment of roots, stems, and leaves; formation of hypertrophied lenticels and production of adventitious roots on submerged portions of the stem above the soil line; leaf necrosis; and leaf abscission. After 15 days of stomatal closure as a result of flooding, stomata began to reopen progressively until stomatal aperture was similar in flooded and unflooded plants. Adventitious roots began to form at about the time stomatal reopening began. As more adventitious roots formed, elongated, and branched, the stomata opened further. The formation of adventitious roots was an important adaptation for flooding tolerance as shown by the high efficiency of adventitious roots in absorption of water and in high correlation between the production of adventitious roots and stomatal reopening.

Journal Article↗

PubMed1998

Regulation by uniconazole-P and gibberellins of morphological and anatomical responses of Fraxinus mandshurica seedlings to gravity.

The present study deals with roles of gibberellins (GAs) in gravitropic responses of woody stems of horizontally-positioned, 2-year-old seedling of Fraxinus mandshurica Rupr. var. japonica Maxim. The application of uniconazole-P, an inhibitor of GAs biosynthesis, to stem nodes at various concentrations significantly inhibited not only righting the stems but also wood formation. The application of GAs (GA3 and GA4) in combination with uniconazole-P negated the inhibitory effect of the treatment of uniconazole-P alone. The GAs alone did not affect wood formation, however, both GAs increased wood formation on both the upper and lower sides of horizontal stems with an increase in the concentration of combined uniconazole-P. In all of the seedlings, tension wood was formed on the upper side of stems. The application of uniconazole-P alone at various concentrations did not inhibit the formation of tension wood fibres.

Dose-Response Relationship, Drug↗

PubMed1999

[Pharmacological and clinical effectiveness of a fixed phytogenic combination trembling poplar (Populus tremula), true goldenrod (Solidago virgaurea) and ash (Fraxinus excelsior) in mild to moderate rheumatic complaints].

Besides the well-known nonsteroidal antiinflammatory drugs (NSAID) for the treatment of rheumatic pain herbal medicine can also be applied successfully. Plants with antirheumatic efficacy include Fraxini cortex, Populi cortex/folia and Solidaginis herba. This review focuses on pharmacological and clinical efficacy of a combination of Fraxinus cortex, Populus cortex/folia and Solidago herba. Antiinflammatory and analgetic properties were shown in pharmacological tests. Clinical studies conducted in the indications of the different subtypes of rheumatic diseases such as rheumatoid arthritis or osteoarthritis pointed out a similar efficacy compared to NSAID applied in average dosages. Even the rate of adverse effects of the herbal combination was half of that registered in NSAID treated patients within the clinical studies.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2000

Secoiridoid glucosides from Fraxinus americana.

Investigation of the leaves of Fraxinus americana led to the isolation of five secoiridoid glucosides, demethylligstroside, (2"R)- and (2"S)-2"-hydroxyoleuropeins, fraxamoside and frameroside, together with 18 known compounds. Their structures were determined on the basis of spectroscopic studies and chemical evidence.

Journal Article↗

PubMed2000

Secoiridoid glucosides from Fraxinus americana.

Glucosides↗

PubMed2001

Hydraulic properties of individual xylem vessels of Fraxinus americana.

Studies of the hydraulic properties of xylem vessels have been limited to measurements of whole plant or whole stem segments. This approach allows the longitudinal transport properties of the ensemble of vessels within a stem to be determined, but provides little information on radial transport. Here the xylem of Fraxinus americana L. has been examined using a new method that allows the transport properties of individual vessels to be examined. One goal of this study was to quantify transport parameters relevant to embolism repair. The longitudinal conductivity of vessel segments open at both ends (i.e. no end walls) agreed with values predicted by the Poiseuille equation. Radial specific conductance (conductance per unit area) was approximately six orders of magnitude lower than the longitudinal conductance of the vessel segment normalized by the cross-sectional area of the vessel lumen. There was a step increase in the radial specific conductance of previously gas-filled vessels when the delivery pressure exceeded 0.4 MPa. This is consistent with the idea that positive pressure, required for embolism repair, can be compartmentalized within a vessel if the bordered pit chambers are gas-filled. The diffusion coefficient for the movement of gas from a pressurized air-filled vessel was of the same order of magnitude as that for air diffusing through water (1.95 e(-9) m(2) s(-1)). Estimates of the time needed to displace all of the gas from an air-filled vessel were in the order of 20 min, suggesting that gas removal may not be a major limitation in embolism repair.

Biological Transport↗

PubMed2000

[Effect of different nitrogen forms on growth of Fraxinus mandshurica seedlings].

The effect of NO3(-)-N and NH4(+)-N and their different supply ratios on the growth of Fraxinus mandshurica seedlings was studied by sand culture in greenhouse. The highest seedling growth was obtained at a NH3(-)-N/NH4(+)-N ratio of 75/25 in nutrient solution. The growth of seedlings declined with the increasing ratio of NH4(+)-N to NO3(-)-N. Excessive NH4(+)-N inhibited root growth, and the root/shoot ratio of the seedlings significantly decreased as the NH4(+)-N/NO3(-)-N ratio was over 50%. Increasing NH4(+)-N in nutrient solution led to the decrease of net photosynthetic rate, the increase of phosphorus content in plant tissues, and the decrease of Zn and Fe contents. The pH value of cultural medium was affected markedly by nitrogen form, which was increased with increasing NO3(-)-N and decreased with increasing NH4(+)-N in nutrient solution. The pH value was up to 7.22 in the medium contained NO3(-)-N alone, while decreased to 4.20 only with NH4(+)-N.

Hydrogen-Ion Concentration↗

PubMed2000

[Occurrence and control of frost in Tilia amurensis and Fraxinus mandshurica young plantations].

The changes of minimum temperature periodical biological phenomena and frost in yound Tilia amurensis and Fraxinus mandshurica plantation stands were systematically analyzed based on the vertical gradient observation and plot investigation. Meanwhile, the resistance of Tilia amurensis to late frost was also studied. The results showed that the phenophase of T. amurensis was later than that of F. mandshurica. Influenced by significant temperature inversions in this area, the phenophase of T. amurensis and F. mandshurica changed regularly in different aspects and slope positions. The sprouts on west slope started earlier than that on east slope. The higher they grew on the slope, the earlier they sprouted, with the earliest sprout at the top of slope. Late frost in this area only took place when the trees were sprouting, but air temperature decreased significantly at the same time. The degree of injury from the late frost could be controlled effectively by selecting suitable site. Sites down the slope, especially the east slope, were not suitable for T. amurensis and F. mandshurica plantation in this research area. Chemical treatment and biological shading could prevent late frost injury through putting off sprout. Mixed plantations could prevent F. mandshurica and T. anurensis from late frost injury significantly, and the frost injury index and the proportion of the tree number of different injury grades were lower than those in pure stands.

Climate↗

PubMed2003

[Quantification comparison of spatial pattern of soil seed bank of Fraxinus mandshurica in two stands].

The spatial pattern of soil seed bank of Fraxinus mandshurica were examined by geostatistics in two stands with different densities, tree species composition and ground plants, in the Northeast of China. A sampling grid of 559 points, at each point a sample was located, was established according to regular grid design at three spatial scales (cell size were 0.5 m x 0.5 m, 1 m x 1 m, and 2 m x 2 m) in each plot. Spatial pattern were quantified by using semivariance analysis, fractal dimension and Kriging maps. The object of this paper is to quantify the spatial pattern of seed bank, to compare its variations between two stands, and to explore what sort of mechanism would control its variations. The results indicated seed distribution showed appreciable heterogeneity within stand and clearly difference between the two stands. In plot 1 (mixed stand), seed bank, with a mean of 158.1 +/- 96.7 seeds.m-2, higher sill (C0 + C = 0.549) and 4.25 m scales, has a stronger spatial pattern. There were a high autocorrelated variation (89.4%) and lowly random variation (10.6%) at this scale. However, at scale from 5 m to 31.3 m, its autocorrelated variation ranged 51.4%-69.8% and random variation ranged 30.2%-47.6%, also has distinctly mosaic patterns. Fractal dimension (D) analysis showed that the D values was relatively lower(1.728-1.865), their coefficient of variation only about 26.7%-68.35%, indicated that there was a high self-similarity of patch shapes of seed bank. In plot 2 (pure stand), with a mean of 57.4 +/- 44.7 seed.m-2, and lower sill (C0 + C = 0.125), spatial patterns were not so strong as plot 1, which has a smaller scale (2.59 m). Its spatially autocorrelated variation was 56.8% and randomly variation was 43.2%. Over the scale there were no clearly autocorrelated spatial patterns. Fractal dimension analysis showed higher D value (1.906-1.960), and their coefficient of variation varying wildly (69.51%-134.14%), implying highly random variation and more complex patch shapes. The differences of spatial pattern of seed bank between the two stands were likely to be due to spatial heterogeneity at the level of stands.

Seeds↗

PubMed1992

Study of the anti-inflammatory activity of Populus tremula, Solidago virgaurea and Fraxinus excelsior.

Aqueous/alcoholic extracts of Populus tremula, Solidago virgaurea and Fraxinus excelsior (components of Phytodolor N) were tested individually and in 3 different combinations for anti-inflammatory activity using carrageenan induced edema and/or adjuvant induced arthritis of the rat paw. The tested combinations as well as the individual extracts significantly reduced the paw edema to varying degrees and also dose dependently inhibited the arthritic paw volume. The anti-inflammatory activity of the combinations was respectively comparable to the tested doses of diclofenac.

Animals↗