bluuebunny/crossref_metadata_2025_split huggingface dataset:
A POST‐GLACIAL POLLEN SEQUENCE FROM LOCH A'MHUILINN, NORTH ARRAN: A RECORD OF VEGETATION HISTORY WITH SPECIAL REFERENCE TO THE HISTORY OF ENDEMIC SORBUS SPECIES
Authors: BOYD W. E. , DICKSON J. H. 
Published: April 2006

SummaryA sequence of lake muds and fen peat deposits from Loch a'Mhuilinn, north Arran, contains evidence for the local vegetation history for parts of the Flandrian Interglacial. The main components of this history are as follows: Sedimentation occurred under open‐water conditions during early Flandrian times. By around 5000 B.P., fen peat was accumulating, and during the 2nd millenium B.P., an unexplained reversion to open‐water conditions occurred.The earliest recorded vegetation immediately predates the Corylus rise and is characterized by Betula‐rich woodland with Juniperus and Salix being present in places. The Corylus rise, occurring at around 8600 B.P., marks the beginning of a period of Corylus‐rich Betula woodland. Subsequent increases of Ulmus, Quercus, Pinus and Alnus pollen represent further forest development. Fluctuations in the composition of this mixed forest are recognized, as can a distinction between areas of Betula‐Quercus, Corylus‐rich and Alnus‐rich woodland.At around 5000 B.P., the vegetational development, previously representing broad regional changes, appears to respond to local processes. Fluctuations in the proportions of trees and Gramineae pollen may reflect vegetational disturbance, although sedimentation processes may be influencing the pollen deposition at this time. This period is followed by apparently greater woodland stability, with minor indications of human activity. By around 4000 B.P., early stages of Calluna‐rich heath are apparent. The development of the heath vegetation is not recorded, but by the 2nd millenium B.P., Calluna heath and grassland appear to be well established in north Arran.The history of Sorbus spp. is examined in as much detail as the fossil evidence allows. By around 6500 B.P., Sorbus aucuparia L. is present in the area, and by around 5400 B.P., evidence for non‐aucuparia Sorbus species is present. This evidence may represent the former presence of 5. rupicola (Syme) Hedl. and/or one or both of the two endemic species 5. arranensis Hedl. and S. pseudofennica E. F. Warb.
Effects of open‐air fumigation with sulphur dioxide on the growth and yield of winter barley
Authors: McLEOD A. R. , ROBERTS T. M. , ALEXANDER K. , CRIBB D. M. 
Published: April 2006

summaryAn open‐air fumigation system was used to expose a winter barley crop (Hordeum vulgare L.) to controlled concentrations of SO2 from November 1982 to July 1983. Monitoring data from a rural site were used as a basis for simulating mean concentrations of 0.023, 0.038 and 0.058 μl 1−1 SO2 at a location where background concentrations were 0.01μl 1−1 SO2. There was no evidence of a reduction or stimulation of crop growth over the winter period. During the spring, the crop in SO2 fumigated plots had a higher green leaf area and dry weight than in control plots which may have resulted from a reduction in the occurrence of the fungal pathogen brown rust (Puccinia Hordei Otth.). After car emergence a delay in senescence of leaves was observed in fumigated plots which gave the plants an extended period for assimilation during grain filling. There was no evidence that the yield of barley was reduced within the range of ambient SO2 concentration in the UK (annual mean 0.03μ1 l−1SO2). However, at 0.058μl 1−1 SO2, reductions in yield were observed. Treatment with 0.023μl 1−1 SO2 produced increased grain yield.
Alleviation and induction of dormancy by temperature in Impatiens glandulifera Royle
Authors: MUMFORD PAULINE M. 
Published: April 2006

summaryEmbryo dormancy in seeds of Impatiens glandulifera Royle can be overcome by maintaining them imbibed at 4 °C. The period of chilling required depends on the age and storage conditions of the dry seed; it decreases with seed age and is reduced by a high storage temperature. Fully imbibed seeds can remain dormant for several years at 20 °C if the stratification requirement is not met. Interrupting stratification at 4 °C with a period at 20 °C increases the chilling requirement in proportion to the length of the warm period. However interrupting stratification by desiccation has no effect on the chilling period required. The ecological implications of these findings are discussed.
Responses ofHedysarum borealeNutt. to mycorrhizas andRhizobium: plant and soil nutrient changes in a disturbed shrub‐steppe
Authors: CARPENTER ALAN T. , ALLEN MICHAEL F. 
Published: April 2006

summaryEffects of inoculation ofHedysarum borealessp.borealeNutt. (Fabaceae) with mycorrhizal fungi (topsoil inoculum) andRhizobium(pure inoculum) were studied in the field in southwestern Wyoming, USA. After 3 years, plants receiving both inocula had greater total aboveground biomass and leaflet biomass, more leaves, higher aboveground nitrogen and phosphorus contents and greater survival than plants which received single or no inoculum. Soil 20–40 cm deep (where roots were concentrated) beneathHedysarumindividuals from all treatments had a lower concentration of total nitrogen than did soil between plants.Hedysarumplants, inoculated or not, apparently extracted sufficient nitrogen from the soil, as they had similar leaflet nitrogen concentrations.Hedysarumdecreased the size of the pool of soil nitrogen even withRhizobiuminoculation on disturbed land in a semi‐arid environment during the first 3 years of growth.
Evidence against a key role for metallothionein‐like protein in the copper tolerance mechanism of Deschampsia cespitosa (L.) Beauv.
Authors: SCHULTZ CAROLINE L. , HUTCHINSON THOMAS C. 
Published: April 2006

SUMMARYThe role of sulphur and copper‐inducible thiol‐rich protein in the copper tolerance‐ of the grass Deschampsia cespitosa (L.) Beauv. was investigated. Sulphur deficiency, induced by growing tillers in nutrient solution without sulphur had no effect on the copper tolerance of two clones from a site contaminated with copper and nickel. In contrast sulphur deficiency increased the susceptibility of two non‐tolerant clones from an uncontaminated site‐to copper toxicity. Tolerance of a copper‐tolerant clone screened from seed of a non‐tolerant population was unaffected by sulphur deficiency. Sulphur deficiency reduced the amount of copper‐inducible thiol‐rich protein in roots of both the tolerant and non‐tolerant clones exposed to excess copper. Roots of the tolerant clones grown in micronutrient copper solutions without sulphur for 26 d and then exposed to 1.61 μM copper for a further 4 d both produced 75% less copper‐inducible thiol‐rich protein than those grown with sulphur. In an experiment with one of the tolerant clones, the amount of thiol‐rich protein did not increase between 4 and 30 d of exposure to excess copper despite a 43% increase in copper in the cell‐free extract. Sulphur deficiency reduced the amount of thiol‐rich protein to a lesser extent in the non‐tolerant clones, with a 57% decrease in one clone and a 31% decrease in the other. In the presence of sulphur both non‐tolerant clones produced considerably more thiol‐rich protein when exposed to excess copper than did the tolerant clones.
The effects of polyamine biosynthesis inhibitors on infection of Hordeum vulgare L. by Erysiphe graminis f. sp. hordei Marchal
Authors: WEST H. M. , WALTERS D. R. 
Published: April 2006

SUMMARYThe effects of the inhibitors of polyamine biosynthesis, 2‐difluoromethylornithine (DFMO), (E)‐2‐(fluoromethyl) dehydroornithine (Δ‐MFMO), (K)‐2‐(fluoromethyl) dehydroornithine methyl ester (A‐MFMO. CM3), 2‐hydrazinoornithine, (2R,5R)‐6‐heptyne‐2,5‐diamine (RR‐MAF), 2‐difiuorornethylarginine (DFMA), cyclohexylamine (CHA) and methylglyoxal‐bis (guanylhydrazone) (MGBG) on infection of barley Leaves (Hordeum vulgare L.) by Erysiphe graminis f.sp. hordei Marchal, were examined. Various concentrations of the inhibitors were sprayed onto barley leaves ev. Golden Promise as post‐inoculation treatments. DFMO, MGBG and a combination of the two were also applied as pre‐inoculation treatments. Each inhibitor substantially reduced mildew infection. DFMO was as efficient as the more recently developed ornithine analogues. With the exception of the DFMA treatments, post‐inoculation sprays were more effective than pre‐inoculation ones. When DFMO, MGBG and DFMA were sprayed onto leaves at different times, DFMO and MGBG most effectively controlled mildew when sprayed on the third day after inoculation. DFMA was more efficient as a pre‐inoculation treatment. Addition of polyamines to DFMO sprays increased mildew infection, compared to that resulting from the DFMO treatment alone, but infection was less than in the controls.
The effect of the gp gene on fruit development in Pisum sativum L.
Authors: PRICE D. N. , HEDLEY C. L. 
Published: April 2006

SUMMARYPhotosynthetic activity in the yellow pods of gp.gp lines has been compared with that in normal Gp.Gp pods. As expected from a previous structural study, the occurrence of aberrant plastids in the mesocarp resulted in reduced activity in the gp.gp lines.Illuminated green fruits, 5–16 d post‐anthesis showed net uptake of CO2, from the atmosphere. Positive carbon gain was extended until d 28 in deseeded pods. Conversely, in yellow (gp.gp) fruits no net uptake of CO2, from the atmosphere was observed at any stage, even in deseeded pods, but carbon losses in the light were restricted compared with those in the dark, indicating some photosynthetic activity.Analysis of the photosynthetic machinery within the yellow pods showed considerable differences in the effect of the gp gene on the mesocarp and endocarp layers. Compared with those of green pods, concentrations of RuBP carboxylase in the mesocarp were depressed, and the Hill reaction activity of isolated chloroplasts was virtually undetectable. However, in the parenchyma layer of the endocarp, RuBP carboxylase reached higher concentrations than in Gp.Gp pods, and Hill reaction rates were comparable. There was little difference between the lines in their PEP carboxylase concentrations in either tissue.
Action of ozone on foliar gas exchange in Glycine max L. Merr: a potential role for endogenous stress ethylene
Authors: TAYLOR GEORGE E. , ROSS‐TODD B. MONTY , GUNDERSON CARLA A. 
Published: April 2006

SUMMARYA rapid surge in the foliar production of ethylene (C2H4), a growth regulator, is a well documented phenomenon in plants experiencing a variety of environmental stresses. The physiological significance of this stress‐induced C2H4 is not resolved. Because exogenous C2H4 can induce changes in foliar gas exchange in a variety of plant species, we tested the hypothesis that the endogenous production of stress C2H4 due to the representative environmental stress of ozone (O3) is linked to observed changes in stomatal conductance to water vapour (gsH2o) and carbon dioxide assimilation (A) in Glycine max (L.) Merr. This objective was accomplished using seedlings in hydroponic culture which were administered aminoethoxyvinylglycine (AVG), a metabolic inhibitor of stress C2 H4 synthesis, and subsequently challenged with O3. The responsiveness to O3 stress of gsH2O and A was either substantially diminished (A) or eliminated GS, H2O) when stress C2H4, production in the leaf interior was metabolically inhibited by AVG. These data support the hypothesis that the rapid surge in production of stress CJJH, in response to chronic‐level stresses in general and O3 specifically is not simply an indicator of the plant's physiological activity but rather is a chemical messenger or trigger that subsequently mediates some of the notable changes in carbon gain, stomatal physiology, and water use.
Growth and maintenance respiration in leaves of bean (Phaseolus vulgarisL.) exposed to ozone in open‐top chambers in the field
Authors: AMTHOR JEFFREY S. 
Published: April 2006

SUMMARYBean (Phaseolus vulgarisL. CV. pinto) plants were grown in pots in open‐top chambers in the field and exposed to three ozone (O3) regimes at a rural site in northwestern New York state: (1) charcoal‐filtered air with O3concentrations during the day of about 40–50% ambient (CF), (2) charcoal‐filtered air with O3added to attain approximately ambient concentrations in real time (1 ×), and (3) charcoal‐filtered air with O3added to attain approximately twice ambient concentrations in real time (2×). Unifoliate leaf blade relative growth rate (RGR) and specific dark respiration rate were measured on 214 plants 12‐ to 17‐d‐old. For a given plant age, RGR was significantly reduced by increasing O3dose, and for a given RGR, specific respiration rate was significantly increased. When the specific respiration rate was mathematically partitioned into growth and maintenance components, it was found that thegrowth coefficientwas unaffected by O3but themaintenance coefficientwas significantly increased by increasing O3dose: 7.3% between the CF and 1×treatments, and 25% between the 1×and 2×treatments. These results corroborate earlier findings with plants grown in high light conditions in chambers and exposed to 10 or 90 nl O31−1, and suggest that ambient levels of O3inhibit plant growth in part by diverting respiratory substrate from growth to maintenance and repair processes.
Efficacy of native vesicular‐arbuscular mycorrhizal fungi after severe soil disturbance
Authors: STAHL PETER D. , WILLIAMS S. E. , CHRISTENSEN MARTHA 
Published: April 2006

SUMMARYField and greenhouse experiments were conducted to determine whether the VA mycorrhizal fungi present on a site before surface coal mining could form effective mycorrhizas in the disturbed soil on the site after mining. The disturbed soil had different physical, chemical and morphological characteristics than the soil on the site prior to perturbation.Artemisia tridentata subsp. WyomingensisBeetle and Young (Wyoming big sagebrush), inoculated or not with VA mycorrhizal fungi, was planted on the field site both as seed and as container‐grown seedlings. The native VA mycorrhizal endophytes produced only limited amounts of mycorrhizal infection in the disturbed soil (approximately 20% of total root length) and after 2 years were found to have no significant effect on the establishment, growth or survival of sagebrush plants. In the greenhouse study, mycorrhiza development and efficacy was compared in native sagebrush‐grassland soil and disturbed soil from the reclamation site with identical concentrations of mycorrhizal inoculum (19 propagules g−1). Mycorrhiza development in native soil greatly exceeded that in disturbed soil after 45 d growth (50vs.10% of total root length). Also, native mycorrhizal fungi effected significant increases in biomass production (+ 70%) and tissue phosphorus content (+ 70%) in sagebrush‐grassland soil but not in reclamation soil. The ecological implications of these results are discussed.
On the relative importance of convective and diffusive gas flows in plant aeration
Authors: BECKETT P. M. , ARMSTRONG W. , JUSTIN S. H. F. W. , ARMSTRONG J. 
Published: April 2006

summaryThe importance of through flow convection of gases is recognized hut the notion that convection of a non‐through flow type might play n major role in plant aeration is challenged. It is shown that this convection discovered recently in deep‐water rice, and which could operate also in almost any submerged root system, must be subordinate to diffusion in the plant's aeration process and will al best have only minimal influence on root aeration.
Interaction between Glomus mosseae and Erwinia carotovora and its effects on the growth of tomato plants
Authors: GARCIA‐GARRIDO J. M. , OCAMPO J. A. 
Published: April 2006

summaryThe effect of inoculation with Erwinia carotovora pv. carotovora on tomatoes with or without VA mycorrhizal infection by Glomus mosseae was studied in a greenhouse trial. E. carotovora decreased the growth of nonmycorrhizal tomato plants, but neither growth nor the percentage of total root length with VA infection were reduced in mycorrhizal plants. Protection of tomato against the pathogen and reduction in the number of colony‐forming units of E. carotovora in the rhizosphere of mycorrhizal plants were independent of concentration of P in the plant and the timing of inoculation with the two microorganisms. The possible mechanisms of the resistance induced in tomato plants by G. mosseae against E. carotovora are discussed.
The extent and time‐course of mountain blanket peat erosion in Ireland
Authors: Bradshaw Richard , McGEE Edward 
Published: April 2006

SummaryErosion of upland blanket pent is widespread in Britain and Ireland and suggestions for its initial causes have included recent human disturbance and changes in the mechanical stability of the peat masses through time. A survey of blanket peat in five mountain areas in Ireland revealed extensive erosion in all areas, and two cores of mountain lake sediment contained inwashed peat in their upper sections. Detailed analysis of the core from the Wicklow Mountains revealed pollen evidence for initial peatland development, tree clearance and eventual peat erosion. The inwashed peat contained abundant Sphagnum leaves.Peat inwash began 1500 years ago in Donegal, N.W. Ireland and 3000 years ago in Wicklow near the east coast. The occurrence of erosion over these time periods does not suggest that recent human activity and changes in land‐use are the original causes of erosion. Recent human activity has merely intensified erosion that probably originated from peat flows or the development of natural drains in mature peat masses developing on sloping ground.
Phosphate influx and extracellular phosphatase activity in barley roots and rose cells
Authors: LEE R. B. 
Published: April 2006

SUMMARYThe rate of phosphate influx, and the activity of extracellular phosphatase, were measured simultaneously in root systems of intact, sterile barley plants (Hordeum vulgareL.) of widely differing P status. Similar measurements were made on suspension cultures of rose cells (Rosasp.) starved of P for various periods. Under the experimental conditions used, extracellular phosphatase activity greatly exceeded phosphate influx but there was a very significant correlation between the two. The possiblity of the extracellular phosphatase being involved in phosphate transport is discussed.
A correlation between intracellular calcium and incident irradiance in Nostoc 6720
Authors: SMITH R. J. , WILKINS A. 
Published: April 2006

SUMMARYRecent reports of Ca2+ dependency in cyanobacterial processes, which include photosystem II, nitrogenase activity, heterocyst differentiation and trichome motility, question whether Ca2+‐mediated regulation is present in these phototrophic prokaryoles. Such regulation would require that the intracellular concentration of Ca2+ varies within an appropriate range. Several of these Ca2+‐dependent processes respond to treatments which artificially alter the intracellular Ca21+ content, but a physiological or environmental effect has not been demonstated.The effect of changes in the incident irradiance upon the proportion of heterocysts and the intracellular content of Ca2+ in Nostoc 6720 have been investigated. Both the proportion of heterocysts (heterocyst frequency) and the cellular content of Ca2+ (assessed by 45Ca24 incorporation in long labelled cultures) were negatively correlated with incident irradiance. The efflux of Ca2+ from darkened cultures was decreased suggesting that the accumulation of intracellular Ca2+ at low incident irradiance might result from decreased efflux. Orthovanadate, a non specific inhibitor of Ca2+ in Anabaena variabilis, enhanced both the cellular content of Ca24 and heterocyst frequency which suggests that direct inhibition of Ca2+ efflux is able to mimic the effects observed on decreasing irradiance.
Fructan biosynthesis in excised leaves of Lolium temulentum L.
Authors: CAIRNS A. J. , POLLOCK C. J. 
Published: April 2006

SUMMARYFollowing the initiation of soluble carbohydrate accumulation in excised illuminated leaves of Lolium temulentum L., extractable sucrose: sucrose fructosyl transferase activity rose concomitant with the onset of fructan synthesis Extractable enzyme activity was sufficient to account for rates of fructan accumulation in vivo The major trisaccharide products of transferase activity in vitro were isokestose and kestose. This differed from the patterns of trisaccharide accumulation in vivo, where isokestose and neokestose predominated.Excised leaves treated with inhibitors of protein synthesis and of RNA metabolism accumulated water‐soluble carbohydrate at similar rates to control tissue, but did not convert sucrose into fructan. Inhibitor treatment also prevented increase in extractable sucrose: sucrose fructosyl transferase activity, suggesting that initiation of fructan biosynthesis was mediated by altered patterns of gene expression. These results are discussed in relation to the control of the synthesis of the oligofructosides characteristic of this tissue.
The form and outcome of mycelial interactions involving cord‐forming decomposer basidiomycetes in homogeneous and heterogeneous environments
Authors: DOWSON C. G. , RAYNER A. D. M. , BODDY LYNNE 
Published: April 2006

SUMMARYThe mycelial interactions of strains of six cord‐forming wood‐inhabiting basidiomycetes were studied both against each other and against other fungi including Armillaria species on 2% malt extract agar, in wood lengths, and in non‐sterile soil. Generally, cord‐formers could be ranked in a combative order Phanerochaete velutina (DC ex Pers.) Parmasto =Phanerochaete laevis (Fr.) Erikss. & Ryv. > Steccherinum fimbriatum (Pers. ex Fr.) Erikss. =Hypholoma fasciculare (Huds. ex Fr.) Kummer =Phallus impudicus (L.) Pers. > Tricholomopsis platyphylla (Pers. ex Fr.) Sing. However, the outcome of interactions varied considerably according to circumstances. For example, in soil systems it depended on the extent to which encounters occurred between mycelia growing out from the wood inoculum blocks or within the inocula themselves. This depended in turn on the relative size of the inoculum blocks used for each strain.Encounters between like mycelia growing out into soil led to the formation of persistent mycelial connectives between the inoculum blocks. However, those between unlike mycelia elicited discolouration and lytic reactions following either contact ('mycelial interference') between different species, or fusion and somatic incompatibility between different strains of the same species. Such reactions were followed either by replacement of one system by the other, or the development of mycelium‐free zones of soil between deadlocked colonies.After 3 months all pairings of cord formers against systems of Armillaria bulbosa (Barla) Kile and Watling, A. cepestipes Vel. f. pseudobulbosa Romagn. & Marxmuller and A. mellea (Vahl ex Fr.) Kummer in soil resulted in the colonisation of the Armillaria inocula to varying degrees and the death of virtually all associated rhizomorphs.