bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acclimation to ozone stress in radish: leaf demography and photosynthesis
Authors: HELD A. A. , MOONEY H. A. , GORHAM JAMES N. 
Published: April 2006

summaryWhole plant acclimation to ozone exposure in growth‐chamber cultivated radish (Raphanus sativus L. cv. Cherry Belle) was investigated. The primary goal was to separate developmental from physiological ozone acclimation processes. Plants were grown for 37 days at two different lengths of ozone exposure and a control treatment. After germination, seedlings were transplanted into controlled growth chambers and exposed to daytime (10 h) ozone (0.12 μl 1−1) either on the next day (continuous ozone treatment) or three days later (intermediate treatment) and compared to a control (average ambient ozone concentration (0.01–0.02 μml 1−1). Plants grown in ozone after transplanting accumulated considerably less biomass than the controls, but had higher dry weights than the intermediate treatment, implying an acclimation response. Photosynthetic capacity and nitrogen content of leaves decreased at high levels of ozone exposure resulting in an accelerated leaf senescence. No distinct leaf‐level physiological acclimation to ozone exposure was seen based on gas exchange measurements. As an apparent compensatory response, plants exposed to ozone had higher leaf production rates than control plants, at the expense of root and hypocotyl growth. This developmental, whole‐plant response appeared to be the most effective acclimation response to ozone exposure seen in radish. However, it did not fully compensate for the damage caused by ozone, since plants still showed considerable reductions in growth.
Transition metals and the ability of Sphagnum to withstand the phytotoxic effects of the bisulphite ion
Authors: BAXTER R. , EMES M. J. , LEE J. A. 
Published: April 2006

summary Sphagnum cuspidatum Ehrh. (ex Hoffm.) and Sphagnum recurvum P. Beauv. were collected from the hog surface and minerotrophic lagg zones of two relatively remote ‘unpolluted’ sites in Northern England and North Wales, and two ‘polluted’ sites in the S. Pennines. In addition, surface peat and surface water samples were taken adjacent to the sample points. Sphagnum recurvum from mire surfaces in the S, Pennines and drainage channels at remote sites was exposed to the phytotoxic bisulphite ion (HSO3−), which subsequently rapidly disappeared from the bathing solution (< 6 b). When the same species, taken from mire surfaces at remote sites, was exposed to HSO3−, a much slower disappearance of this ion occurred. Sphagnum cuspidatum from remote sites showed a similar response. Both became bleached and eventually died. Sphagnum recurvum, growing in the drainage channel at the remote site showed a higher extracellular concentration of transition metals an cation exchange sites; a consequence of a higher concentration of the same ions in these telluric waters. At the S. Pennine sites transition metal concentrations in the surface peat were high. Here, as in the drainage channels at the remote sites, the extracellular metal concentrations imparted to the moss the ability rapidly to remove HSO3−, from the growth medium.
The hydraulic architecture of trees and other woody plants
Authors: TYREE MELVIN T. , EWERS FRANK W. 
Published: April 2006

summaryIn this paper, we have reviewed how the hydraulic design of trees influences the movement of water from roots to leaves. The hydraulic architecture of trees can limit their water relations, gas exchange throughout the crown of trees, the distribution of trees over different habitats and, perhaps, even the maximum height that a particular species can achieve. Parameters of particular importance include: (1) the vulnerability of stems to drought‐induced cavitation events because cavitation reduces the hydraulic conductance of stems, (2) the leaf specific conductivity‐of stems because it determines the pressure gradients and most negative water potentials needed to sustain evaporation from leaves, (3) the water storage capacity of tissues because this might determine the ability of trees to survive long drought periods. All of these parameters are determined by the structure and function of anatomical components of trees. Some of the ecological and physiological trade‐offs of specific structures are discussed.

CONTENTS

Summary

I.
Introduction
346

II.
Water flow through pipes and the unit pipe model
347

III.
Parameters and concepts to describe hydraulic architecture
349

IV.
Patterns of hydraulic architecture in woody plants
350

V.
Vulnerability to cavitation: relation to hydraulic architecture and drought resistance
354

VI.
Dynamic and steady state models of water flow in trees
355

VII.
The segmentation hypothesis
357

References
359
Evidence for a role for the cell membrane in copper tolerance of Mimulus guttatus Fischer ex DC.
Authors: STRANGE JULIE , MACNAIR MARK R. 
Published: April 2006

summaryThe effect of copper on root growth, K+ efflux and short‐term copper uptake by three isogenic genotypes of Mimulus guttatus Fischer ex DC. differing only in their copper tolerance gene is studied. The tolerant homozygotes do not differ in any way from the heterozygotes. The non‐tolerant homozygotes show greater root inhibition, greater K+ efflux, and greater short‐term Cu2+ uptake. The difference in the uptake parameters is best described by a greater linear diffusion term in the non‐tolerant genotypes. These results suggest that copper damages the cell membrane, and that this damage leads to an increase in the leakiness of the membrane, leading to both greater K+ efflux and Cu2+ influx via diffusion. This suggests that the primary copper tolerance mechanism probably resides in the cell membrane. The rapidity with which the differences between the genotypes is established suggests that the differences are constitutive. It is argued that these results provide further evidence against the involvement of phytochelatins in the primary tolerance mechanism.
Post‐glacial vegetational history of the Oxford region
Authors: DAY S. P. 
Published: April 2006

summaryThe results of pollen, sedimentological, magnetic susceptibility and charcoal particle analysis of two radiocarbon‐dated sequences of organic deposits from the Oxford region are presented. The record from one of the sites, Cothill Fen, extends from c. 10000 to c. 6500 BP, while that from the other site, Sidlings Copse, covers the period from c. 9500 BP to the present.The post‐glacial landscape was initially open, with some Betula and Pinus sylvestris woodland. At Cothill Fen, Corylus avellana populations began to expand at c. 9400 BP, followed by Ulmus at c. 9100 BP, Quercus at c. 8800 BP, and Tilia cordata and Alnus glutinosa at c. 6800 BP. T. cordata probably became dominant on well‐drained soils in the region. At Sidlings Copse, P. sylvestris declined as populations of Quercus and Ulmus expanded, but P. sylvestris persisted around Cothill Fen until t. 7700 BP, perhaps connected with human disturbance of the vegetation.The Ulmus decline at Sidlings Copse is suggested to have resulted from a combination of disease and exploitation of leaf‐fodder, with no major clearance until c. 3800 BP. By c. 3 700 BP no woodland remained around the site, but local regeneration began at c. 1000 BP.
Accumulation and consumption of solutes in swards of Lolium perenne during drought and after rewatering
Authors: THOMAS HENRY 
Published: April 2006

summarySimulated swards of Lolium perenne were grown in containers 0.9 m deep in the glasshouse and subjected to drought for 0 (control) 2, 4, 6 or 8 wk. Leaf growth, water relations and accumulation of solutes (sugars, amino acids and minerals) were measured in mature leaf laminae and in young meristematic leaf bases. The swards were then rewatered and fertilized, and growth and solute changes measured over the next 8 d.After 8 wk of drought leaf extension had stopped, leaf laminae were scorched at the tips, cell membranes were damaged, and osmotic potential (ψs) had fallen to −2.6 and −2.8 MPa in laminae and bases respectively. Hydration (ratio of tissue water to dry matter) declined steadily to less than half control values, but relative water content declined significantly only after more than 6 wk drought. Nearly all osmotic adjustment was the result of these changes in water content, since molarity of total measured solutes on a dry weight basis increased by only 11 % in laminae and fell by 6% in bases.During drought, water soluble carbohydrate contents increased, mostly due to accumulation of large fructan molecules having little effect on ψs. In bases smaller fructans (having degrees of polymerization, DP, of 3–5), glucose and fructose decreased, whereas in laminae fructan of DP3 and sucrose increased. Relatively large amounts of neo‐ketose accumulated in laminae after 8 wk drought. Proline contents of bases increased steadily during drought, whilst in laminae proline contents were generally very low, and increased only after severe drought. Minerals made the major contribution to ψs. Total mineral contents of laminae rose slightly due mostly to accumulation of Ca2+ and Mg2+, whereas in bases mineral contents tended to decline. Phosphate content, however, declined in both bases and laminae.Following rewatering, tissues rehydrated within 2 d. Water potential rose more rapidly than ψs, so that after 2 d turgor temporarily exceeded control values. Leaf extension rates changed almost in parallel with turgor. Carbohydrates in leaf bases changed rapidly: fructans of DP3–5 and fructose initially increased and then declined, whereas sucrose and glucose contents fell by more than 50% and remained low. Proline contents fell to control values within 1–2 d, whereas phosphate contents (already low) continued to decline. The changes were generally more rapid in the bases than in the laminae.The roles of solutes in osmotic adjustment and as substrates for regrowth are discussed. The differences between slow, relatively natural drought and rapid stressing of pot‐grown plants are emphasized.
Evidence for the involvement of ethene in aerenchyma formation in adventitious roots of rice (Oryza sativa L.)
Authors: JUSTIN S. H. F. W. , ARMSTRONG W. 
Published: April 2006

summaryTwo varieties of rice (ev. Norin 36 and RB3) were either grown in stagnant or aerated 1/4‐strength Hoagland's solution with or without exogenous ethene and a range of silver concentrations (an ethene antagonist), or were grown in flooded and drained soils.With cultivar Norin 36, AgNO3 was very effective in reducing porosity by inhibiting aerenchyma development. This effect was antagonized by gassing with increasing concentrations (1 or 2 μ1−l) of ethene. The results are consistent, therefore, with reports that cavity formation in roots is controlled by endogenous levels of ethene. Also, porosity varied with root length, and if a correction was made for this, the inhibitory effect of the silver ion on aerenchyma development appeared to be even greater.For the cultivar RB3, root porosities in solution culture appeared initially to be unaffected by ethene or AgNO2, but root lengths were reduced and root numbers increased by increasing ethene concentration. When these effects on root length were taken into account, it was concluded that ethene had increased root porosity, and AgNO3, had decreased it. Consistent with earlier studies, and with the ethene hypothesis, aerenchyma development in both varieties was also enhanced by soil waterlogging, with percentage porosities 12 units higher in flooded than in drained soil. The porosities of cv, RB3 were higher than those for cv. Norin 36, however, and the regression line of porosity against root length was steeper, indicating a greater predisposition to form aerenchyma in cv. RB3. This was confirmed in solution‐grown roots, where AgNO3 had no significant effect on porosity in stagnant or in aerated roots of cv. RB3, and both 1 and 2 μ1−1 ethene increased the porosity in cv. RB3 roots to a similar level. Silver nitrate, however, did antagonize the effects of 1 and 2 μ1−1 ethene. In contrast, porosity in cv. Norin 36 was progressively reduced by AgNO3.It is concluded that, although there are intervarietal differences in sensitivity, an ethene promotion of gas‐space formation can occur in rice, and ethene should not be ruled out as the endogenous promoter.
Histological analysis of the expression of Agrobacterium rhizogenes rolB‐GUS gene fusions in transgenic tobacco
Authors: ALTAMURA M. M. , ARCHILLETTI T. , CAPONE I. , COSTANTINO P. 
Published: April 2006

summaryThe gene rolB from the T‐DNA of Agrobacterium rhizogenes is capable of directing differentiation of roots in transformed plant cells. A detailed histological analysis of the expression of this gene in transgenic tobacco plants is presented here. Gene fusions between the promoter of rolB and the GUS reporter gene (encoding E. coliβ‐glucuronidase) were utilized: tissue and cell specific GUS activity as driven by a long (1185 base pairs) and a short (306 bp) version of the rolB promoter was visualized histochemically during different phases of plant development, from embryo to flowering. The extended (1185bp) rolB promoter is under developmental control and is specifically active in the initial cells of all types of meristems and in the vascular system (phloem, phloem parenchyma, xylem parenchyma, pericycle and pericycle‐like cells) of mature organs as well as in the central cylinder of the embryo. In contrast, the 306 bp deletion of the promoter is unable to drive expression in menstematic initials but is still active in the vascular system of the seedling.
Sulphate and ammonium in mist impair the frost hardening of red spruce seedlings
Authors: CAPE J. N. , LEITH I. D. , FOWLER D. , MURRAY M. B. , SHEPPARD L. J. , EAMUS D. , WILSON R. H. F. 
Published: April 2006

summaryTwo‐year‐old seedlings of red spruce [Picea rubens Sarg. syn. P. rubra (Du Roi) Link] were grown in open‐top chambers supplied with charcoal‐filtered air near Edinburgh, Scotland. Between May and November 1988, plants were exposed to mists containing NH4+, SO42− and NO3− ions at concentrations of 1.6 mol m−3 and H+ at 3.2 mol m−3, in pairwise combination and all together. The mists were applied twice weekly at a rate of 2 mm precipitation equivalent per application. Treatment with H2SO4 severely damaged the plants after 3 wk; the concentration for this treatment was therefore reduced from 1.6 mol m−3 to 0.5 mol m3, and new plants were substituted, in June 1988. Frost hardiness was assessed by freeze‐testing detached shoots, then measuring rates of electrolyte leakage. No effects of the mist treatments were detected during the early stages of frost hardening, but on 31 October, shoots that had received sulphate and ammonium ions were less hardy than ‘control’ shoots treated with deionized water. The temperature which killed 20% of shoots was 14 °C higher, and the temperature which killed 56% of shoots was 7 °C higher than for ‘control’ shoots. Acidity per se had no effect on frost hardiness; nitrate ions had no effect and may have mitigated the effects of sulphate when applied together.The results confirm earlier data, and indicate that uptake of NH4+ and SO42− ions can disturb the frost‐hardening process. There are important implications for pollution control strategies in the northeastern United States, if damaging interactions between frost hardiness of red spruce and pollutant deposition are linked to ammonium and sulphate rather than nitrate ions.
Mineral nutrition and mycorrhizal infection of seedling oak and birch
Authors: NEWTON A. C. , PIGOTT C. D. 
Published: April 2006

summaryIn order to assess the importance of nutrient uptake and mycorrhizal infection for the establishment of seedlings of pedunculate oak (Quercus robur L.) and silver birch (Betula pendula Roth.), seedlings were grown on two nutrient‐poor soils and sequential harvests taken throughout the first growing season. Seedlings were artificially established in two woodland sites and in pots of soil collected from each field site.The pattern of nutrient depletion from oak cotyledons indicated that the initial N and P contents were completely utilized by the production of the first flush of leaves after 7 wk. Similarly, growth of birth in acid‐washed sand ceased after the production of the first pair of leaves. Growth rates of field‐grown seedlings were lower than those of pot‐grown seedlings in each case, such that pot‐grown plants were three times larger than field‐grown plants by the final harvest. Nutrient losses in abscised foliage constituted a significant proportion of the total nutrient uptake of both species: between 14 and 35 % of N, P and K was abscised in the case of birch. Taking losses of nutrients in abscised foliage into account, nutrient budgets of field‐grown seedlings were either slightly positive, or not significantly greater than zero.The onset of ectomycorrhizal infection of field‐grown plants was 2–4 wk more rapid than that of pot‐grown plants; initial infection of field‐grown seedlings was observed 3 wk after outplanting. Percentage infection of field‐grown seedlings tended to be higher than in pots throughout the growing season, by up to 40%. Different mycorrhizal types displayed contrasting patterns of development: for example, Paxillus involutus (Batsch) Fr. tended to increase rapidly, to maximum percentage infections of over 30 %; whereas Cenococcum geophilum Fr. was consistently recorded at 10% infection. The role of mycorrhizal infection during seedling establishment is discussed in the light of these results.
Mineral nutrition and mycorrhizal infection of seedling oak and birch
Authors: NEWTON A. C. , PIGOTT C. D. 
Published: April 2006

summaryIn order to determine the effect of fertilizers on the growth, nutrient uptake and ectomycorrhizal infection of seedling oak (Quercus robur L.) and birch (Betula. pendula Roth.), N, P and K fertilizers were applied in a factorial design to plots of seedlings artificially established ph two woodland sites on nutrient‐poor soils. A parallel series of pot experiments were undertaken using the sajne design, in order to eliminate the effects of neighbouring mature trees on growth and mineral uptake.Fertilizer addition increased the growth of birch in both pot and field experiments, and on both soil types, by up to 39 %. In contrast, fertilizer addition had little effect on growth of oak, other than to increase dry mass by 11 % in one of the pot experiments. Application of N, P and K generally increased the foliar concentration of the respective nutrient, by up to 49%. However, a number of negative effects of fertilizer application were recorded, particularly in the case of foliar P. For example, application of N K and N × K reduced the foliar P of birch by up to 35 % in pots.Fertilizer application to both species tended to reduce ectoniycrrhizal infection, both in pots and in the field. These effects were more pronounced for birch than oak, and a greater number of effects were recorded in pots than in the field. In general, N had the greatest effect. For example, the number of mycorrhizal tips of birch in pots was reduced to 38 % of the control value, following N application. Application of P and K also reduced mycorrhizal infection, although the results of the analyses differed depending on how mycorrhizal infection was assessed.The relative proportions of a number of the ectomycorrhizal types were also influenced by fertilizer addition. Although the proportion of most types was reduced, two types [formed by Paxillus involutus (Batsch) Fr. and Scleroderma citrinum Pers.] increased in some of the treatments where they were dominant. For example, application of N to birch in pots increased the proportion of P. involutus mycorrhizas to 172% of the control.The interactions between the effect of fertilizers on growth, nutrient uptake and mycorrhizal infection are discussed, and some implications for forest management are highlighted.
Seed developmental patterns inBanksia attenuataR. Br. andB. laricinaC. Gardner in relation to mechanical defence costs
Authors: STOCK W. D. , PATE J. S. , RASINS E. 
Published: April 2006

summaryA comparison is made of the phenologies of infructescence, follicle and seed growth development of two species ofBanksiawith particular reference to nutrient provision of dissimilarly sized seeds and associated mechanical defence costs. Follicles and seeds ofB. attenuatadeveloped sequentially while the smaller seededB. laricina, exhibited an almost synchronous pattern of development. Seed nitrogen loading, assayed by temporal changes in amino pool sizes in different parts of the seed, was confined to a relatively short period (± 3 months) prior to infructescence desiccation in both species. Prolonged infructescence development in the larger seededB. attenuatacannot therefore be interpreted simply as a mechanism for extending time available for mobilization of scarce nutrients within the plant, but may be a result of selective pressures related to the development of large woody structures around the seeds which provide mechanical defence against predators. BothBanksiaspp. make relatively large investments of carbon, but not of nitrogen, in defence structures (up to 5·5 g per seed inB. attenuata) which in plants with low photosynthetic rates could have associated penalties in terms of N required for photosynthetic enzymes. Sequential development of follicle and then seed assumes significance, since nitrogen used in photosynthesis to provide carbon to the follicle can subsequently be mobilized from the leaf and redeployed in seed protein synthesis. The often held view that larger seeds require longer maturation periods is not universal as, in theBanksiaspp. examined, defence costs and photosynthetic capacity might play a more dominant role in determining seed developmental patterns.
Population variation in Spartina anglica C. E. Hubbard
Authors: THOMPSON J. D. , McNEILLY T. , GRAY A. J. 
Published: April 2006

summaryClonal replicates of Spartina anglica C. E. Hubbard were reciprocally transplanted into cleared plots and undisturbed vegetation in three adjacent zones on the Dee Estuary salt marsh, Cheshire, England. The aim of the investigation was to examine whether clones from these populations show a differential response to the range of naturally occurring environmental variation. Clone survival was significantly lower in the pioneer zone relative to the sward and mature marsh zones and was greatest in plants from the pioneer population in all transplant sites. Tiller number per plant was consistently greater in the pioneer population, increased with increasing marsh elevation and the removal of natural vegetation in the mature zone, and, for the pioneer and mature populations, showed a significant clone x environment interaction effect. The norms of reaction showed marked differences between clones in the pattern of response to environmental variation, but joint regression of clone means on overall means showed that very few clones had a linear response. Several morphological characters showed significant interactions with environmental effects in ANOVA, but only for total plant biomass in the pioneer population did this reflect a linear increase in more favourable environments. Differences in overall stature quantified by the pattern of morphological character correlations indicated the occurrence of different morphological forms within the populations. The differences in performance and plasticity are discussed in the context of the successional development of these populations, and the possible influence of age‐related somatic variation.