bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of the effects on Canadian boreal forest lichens of nitric and sulphuric acids as sources of rain acidity
Authors: SCOTT MARTHA G. , HUTCHINSON T. C. , FETH MARILYN J. 
Published: April 2006

ABSTRACTThe effects of different levels of nitrate and sulphate in acidic precipitation on the growth of the lichens Cladina rangiferina (L.) Wigg. and C. stellaris (Opiz.) Brodo were compared. Permanent Held plots in a Canadian boreal forest ecosystem received two years of spraying with artificial rains of pH 4.2 (ambient), 3.5 or 2.8, each containing one of four molar ratios of sulphate to nitrate, i.e. sulphuric acid alone, nitric acid alone: 2:1 or 1:2. A substantial fertilization effect was observed when C. rangiferina was watered with rain of pH 2.8, derived from nitric acid alone. Compared with before‐treatment values, gains in mean dry weight (+ 62%) and mean podetial height (+14%) were obtained for this species, in addition to elevated levels of N in air‐dried tissues. Post‐treatment values for the mean dry weight of C. rangiferina were significantly reduced for those podetia sprayed with rain of low pH, derived from sulphuric acid alone. Although podetia of C. stellaris were stimulated by rains of pH 4.2, based on a higher concentration of nitric acid, there was no N fertilization following the most acidic sprays. Data from this study support the view that the N content of acidic rain can cause a short‐term growth stimulation for those species able to absorb nitrate from solution. However, beneficial effects on growth of prolonged fertilization via acid rain inputs are unlikely.
Glutamate dehydrogenases in ectomycorrhizas of spruce (Picea excelsa L.) and beech (Fagus sylvatica L.)
Authors: DELL B. , BOTTON B. , MARTIN F. , LE TACON F. 
Published: April 2006

summaryThe ammonia assimilation enzyme glutamate dehydrogenase as studied in extracts of spruce (Picea excelsa L.) roots, mycelium of a mycorrhizal fungus (Hebeloma sp.) and associated ectomycorrhizas. Evidence from enzyme reactions in crude extracts, electrophoretic patterns and immunological tests Using antibodies raised against purified NADP‐GDH of Cenococcum geophilum Fr. consistently showed that Hebeloma NADP‐dependent GDH was active in spruce ectomycorrhizas. Histochemical studies associated some NADP‐GDH activity with the Hartig net. By contrast, the NADP‐GDH fungal pathway was strongly suppressed in beech (Fagus sylvatica L.) associations with Hebeloma crustuliniforme (Bull. ex St Amans) Quél. and Paxillus involutus (Batsch ex Fr.) Fr.
Ectomycorrhiza formation between Eucalyptus pilularis Sm. and Hydnangium carneum Wallr. in Dietr.
Authors: MOORE A. E. P. , MASSICOTTE H. B. , PETERSON R. L. 
Published: April 2006

summaryEctomycorrhizas were synthesized in growth pouches between Eucalyptus pilularis Sm. and Hydnangium carneum Wallr. in Dietr. Colonization of lateral roots occurred within 14 d after inoculation with the development of a dense white mantle and a paraepidermal Hartig net. Cystidium‐like structures and unusual hyphal coils were present on the surface of the mature mantle. The mantle consisted of distinctive outer and inner portions with small, uniform hyphae comprising the outer mantle and much enlarged and modified hyphae in the inner mantle. Granular deposits were abundant primarily in the inner mantle hyphae as shown by light and fluorescence microscopy. These granules were shown to be polyphosphate through cytochemical tests and the use of energy dispersive X‐ray microanalysis. Phosphorus and calcium were the main elements identified in these granules.
Interactions between desiccation and dark nitrogen fixation in tropical Nostoc commune
Authors: JONES K. 
Published: April 2006

SUMMARYColonies of Nostoc commune in tropical Oahu have normally become desiccated and inactive in nitrogen fixation by between noon and 2 p.m. On rehydration, the desiccated colonies fix nitrogen at the same rate in the dark and the light for at least 2 h. When rewetted in the dark, desiccated colonies fix nitrogen at more than twice the rate of non‐desiccated colonies taken from the light and placed in the dark. The capacity of desiccated colonies to fix nitrogen in the dark when rehydrated is lost during storage for several months, but is rapidly regained after a short period of moist incubation in the light.This ability to fix nitrogen on rewetting in the dark is well suited to a tropical climate where rainfall is mainly at night and when metabolic activity during the day is restricted by the rapid onset of desiccation.
Inhibition of phytopathogenic fungi in vitro by cell free culture media of ectomycorrhizal fungi
Authors: KOPE H. H. , FORTIN J. A. 
Published: April 2006

SUMMARYThe cell free culture media of 16 ectomycorrhizal fungi were tested for their ability to inhibit the growth of 23 phytopathogens and one ectomycorrhizal fungus. Extracellular metabolites of seven (44%) ectomycorrhizal fungi, Amanita citrina, Laccaria bicolor, Laccaria Iaccata, Pisolithus tinctorius, Suillns brevipes, Trircholomo flavovirens and Tricholoma pessundatum, inhibited the growth of up to 20 of 24 (83%) fungi tested. Two ectomycorrhizal fungi, P. tinctorius and T. pessundatum, were inhibitory to the ectomycorrhizal fungus, Sphaerosporella brunnea. A microscopic examination at the colony margin of confronted phytopathogenic fungi was made, noting changes in hyphal morphology. A novel feature, hyphal lysis, caused by the cell free culture medium of P. tinctorius, was seen in the two phytopathogens, Truncatella hartigii and Rhizoctonia praticola, and in the hyphae of the ectomycorrhizal fungus, S. brunnea.
Effects of simulated acid rain on growth parameters and yield components of two soybean cultivars
Authors: PORTER P. M. , BANWART W. L. , ZIEGLER E. L. , VASILAS B. L. , HASSETT J. J. 
Published: April 2006

SUMMARYThe effects of simulated acid rain on two soybean [Glycine max (L.) Merrill] cultivars were studied in field experiments in central Illinois. The cultivars,‘Amsoy 71’and‘Williams 82′, were shielded from ambient precipitation and treated twice weekly with applications of 1.05 cm of one of six simulated rain treatments which ranged in pH from 5.6 to 3.0. Each treatment was replicated 12 times in 1983, nine times in 1984, and six times in 1985. Measurements were taken for plant height, chaff dry weight, plant population, lodging, pods/plant, seeds/plant, seeds/pod, mass/seed, and number of low pods. There were small but significant (α= 0.10) effects of treatment acidity in some years for some of the parameters measured. For Amsoy 71, in one of three years, seeds/plant, seeds/pod, and chaff dry weight were reduced by increasing acidity of the simulated rain. In general, Amsoy 71 plants subjected to the more acidic treatments were shorter and had lower lodging in the second and third years of the experiments. For Amsoy 71 there were no significant linear contrasts for the effect of simulated acid rain on plants/ha, mass/seed, and protein concentration of the seed. For Williams 82 there was a small but significant trend for increased seed oil with decreasing pH in 1984 only. For this cultivar there were no significant linear contrasts for the effect of simulated acid rain on plants/hectare, plant height, lodging score, chaff dry weight, low pods, pods/plant, seeds/plant, seeds/pod, or mass/seed. Where changes in either cultivar occurred, the magnitude of these changes over the entire pH range studied was generally 6% or less. Not only was the magnitude of the responses minimal, but the response to simulated acid rain was not consistent between cultivars or in some cases within cultivars from year to year. The response to stimulated acid rain was also small when compared with the potential effect of other stresses such as drought, ozone, disease, insects, and weeds on soybean yield and growth parameters.
The effects of long‐term open‐air fumigation with SO2 on a field crop of broad bean (Vicia faba L.) I. Depression of growth and yield
Authors: KROPFF M. J. , MOOT J. , GOUDRIAAN J. , SMEETS W. , LEEMANS A. , KLIFFEN C. , van der ZALM A. J. A. 
Published: April 2006

SUMMARYIn an open‐air Held exposure system for the controlled release of air pollutants, broad bean (Vida faba L.) crops were exposed to elevated SO2 concentrations in three growing seasons, in order to analyse the effects on crop growth under field conditions. The treated plots were exposed to a mean concentration of 165μgm‐3 in 1985, 62μgm ‐3 in 1986 and 74μgm‐3 in 1988. The background concentration was about 10μ m‐3.A reasonably uniform distribution of SO2 concentration was obtained over an area of 8m × 8m and concentrations exceeding the target concentration were rare. In 1985 and 1988, the growth rate of the crop was depressed at the end of the pod‐filling period. This resulted in a reduction of total dry‐matter production of 17% in 1985 and 9% in 1988, and a seed yield reduction of 23% in 1985 and 10% in 1988. In 1986, dry matter growth was not analysed up to the end of the growing season due to a severe infection of Botrytis fabae (Choclate spot disease) infection in the control plot in the middle of the pod‐filling period. Slight B. fabae infections in the control plots only were also observed in 1985 and 1988. In all experiments no significant reductions of dry matter growth were observed in the vegetative and early reproductive phases.
The effects of long‐term open‐air fumigation with SO2 on a field crop of broad bean (Vicia faba L.) II Effects on growth components, leaf area development and elemental composition
Authors: KROPFF M. J. , MOOI J. , GOUDRIAAN J. , SMEETS W. , LEEMANS A. , KLIFFEN C. 
Published: April 2006

SUMMARYFaba bean crops (Vicia faba L.) were exposed to elevated SO2 concentrations in three different years in an open‐air field exposure system for the controlled release of air pollutants. The treated crops were exposed to an average SO, concentration of 165μg m‐3 in 1985, 62μg m‐3 in 1986 and 74μg m‐3 in 1988. The ambient SO2 concentration was about 10 μg m‐3. Plant height, number of internodes and number of pods were not affected by SO2. The specific leaf area was reduced in the plants exposed to SO2 at the end of the growing season. Leaf area development was strongly affected during the pod‐filling period in 1985 and 1988 as a result of leaf injury and defoliation in the fumigated plots. In 1986 a similar trend in leaf area reduction was observed in the early reproductive phase.N and Mg content of the different organs was unaffected by SO2. The S content was strongly elevated in the leaves and pods of the fumigated plants, and the Ca content of the leaves was reduced by SO2. Chlorophyll content of different leaf numbers was unaffected by SO2.
Seasonal and altitudinal variation in Pteridium aquilinum (L.) Kuhn: frond and stand types
Authors: ATKINSON T. P. 
Published: April 2006

SUMMARYThe field ecology of Pteridium aquilinum (L.) Kuhn was studied through a growing season in the northern Malvern Hills. At lower altitudes, stands reached a biomass plateau by late July extending through to late September, while at higher altitudes biomass increment was delayed and curtailed by the shorter growing season. Pteridium retained several competitive characteristics even when altitude and exposure restricted its vigour. With increased altitude, biomass allocation favoured the lamina and the underground portion of the stipe; the stipe‐with‐rachis component was comparatively reduced with a dwarfing of the canopy but a dense packing of pinnae. Adjustment to conditions in the stand, by the emergence and die‐back of fronds, caused frond density to change through the growing season and at different altitudes. Two frond and associated stand types at contrasted altitudes were recognized by morphology and biomass.
Developmental changes in Sitka spruce as indices of physiological age I. Changes in needle morphology
Authors: STEELE M. J. , COUTTS M. P. , YEOMAN M. M. 
Published: April 2006

SUMMARYThere is a paucity of data regarding developmental changes in trees. Measurements of length, width, length/width ratio, perimeter/width and width/height ratios of tranverse sections, projected and total surface areas, dry weight, specific leaf area and the weight of epicuticular waxes per unit leaf area were made on needles sampled from the uppermost whorl of Sitka spruce trees aged 3, 5,10,15, 20 and 38 years. All characteristics, except needle length and the weight of epicuticular waxes, showed asymptotic changes with age that could adequately be described by the Gompertz growth function, and offer potential as indices of physiological age. Asymptotes were reached at different ages (width and the length/width ratio having the slowest rates of change and the perimeter/width ratio, specific leaf area, and the width/height ratio having the fastest) suggesting a predictable sequence of changes. The observed changes in needle morphology are interpreted as a transition from shade to sun leaves.
Cold‐induced dieback of montane spruce forests in the Swedish Scandes – a modern analogue of paleoenvironmental processes
Authors: KULLMAN LEIF 
Published: April 2006

SUMMARYIn 1987 particularly, but also in 1988, primaeval montane coniferous forests of northern Scandinavia experienced needle loss on an unprecedented scale, which affected the character of the entire landscape in certain regions. This study elucidates the dieback event For Norway spruce [Picea abies (L.) Karst.] in an area of the Swedish Scandes. The study includes visual assessment of percentage needle loss, age structure, radial growth and various environmental parameters, along altitudinal transects and within a larger sample plot. Frequency and magnitude of foliage damage were found to be related to elevation. The dieback process of closed forest stands was interpreted as a response to short‐term climatic variability. Damage mainly developed during one of the coldest early winters (December January 1986/7) of this century. In combination with sub‐normal depth of the snow caver, the severe cold promoted exceptionally deep and persistent soil frost in spruce forest stands. It is hypothesized that damage was mainly due to winter/spring drought (frost‐drought). Phenotypically closed forest stands may change in just a few years in response to cooling, a feature which has not been realized previously. The possibility of major retrogressive responses lo short‐term climatic events should therefore be considered in studies of historical biogeography and when modelling vegetation succession. The forest studied was probably established after a severe wind storm in 1837. The restocking process was facilitated by the post‐Little Ice Age warming, but the stands are at present suffering severe dieback due to the recent cooling of the climate. The results stress the potential importance of short‐term climatic disturbance in boreal forest succession. Reasonably, rapid cold‐induced dieback of forest stands may have been a recurrent feature of Holocene forest history in the Boreal zone.
Catabolism of chlorophyll in vivo: significance of polar chlorophyll catabolites in a non‐yellowing senescence mutant of Festuca pratensis Huds.
Authors: THOMAS HOWARD , BORTLIK KARLHEINZ , RENTSCH DORIS , SCHELLENBERG MAYA , MATILE PHILIPPE 
Published: April 2006

SUMMARYDuring dark incubation of excised leaf tissue from Bf 993, a senescence mutant of Festuca pratensis Huds., a highly polar green pigment fraction (PC) increased from negligible amounts at day 0 to maximal concentrations at days 4–6 and declined thereafter. Over the same time‐scale, chlorophyll (chl) was lost from leaves of the normal genotype Rossa without any detectable accumulation of PC. Chromatographic analysis established that PCs are a group of dephytylated derivatives of chl a. Chl‐ protein complexes from 4–day‐senesced Bf 993 tissue were isolated by sucrose gradient centrifugation and PCs identified by thin‐layer chromatography. High levels of PC were associated with the light‐harvesting complex of Photosystem II; Photosystem I yielded none. Cycloheximide, at a concentration sufficient to inhibit yellowing in the normal genotype, completely abolished the appearance of PC in Bf 993. Accumulation of PC‐like pigments in Rossa leaf tissue could be induced by anoxia. It is proposed that PCs are normal intermediates in chl catabolism, which begins with a protein synthesis‐dependent dephytylation, followed by oxidation leading ultimately to open‐chain pyrrole derivatives. The first steps in the breakdown sequence take place while the pigment is associated with proteins in the thylakoid membrane. The metabolic lesion in the Festuca mutant appears to be located downstream of the dephytylation step, leading to an abnormal accumulation of PCs in this genotype.
Pollination, fertilization and fruit development in sycamore (Acer pseudoplatanus L.)
Authors: PIGOTT C. D. , WARR S. J. 
Published: April 2006

SUMMARYSycamore (Acer pseudoplatanus L.) regenerates freely from seedlings in northern England. Even when temperatures are below average in early May, pollen germinates and pollen tubes grow to the base of the style within 3‐5 d of the flowers opening. In (lowers at constant temperatures from 5.5 to 15.5°C, pollen germinates rapidly and a high proportion of pollen tubes reach the base of the style within four days. In natural conditions proembryos are present in fertile ovules 3 weeks after pollination. Fertile fruits grow rapidly until July and then more slowly until September. Large crops of fertile fruit are formed even when temperatures are below normal at flowering and subsequent development proceeds in both warm and cool summers.
Structure and function of the interfaces in biotrophic symbioses as they relate to nutrient transport
Authors: SMITH S. E. , SMITH F. A. 
Published: April 2006

SummaryIn this review we compare the structure and function of the interfaces between symbionts in biotrophic associations. The emphasis is on biotrophic fungal parasites and on mycorrhizas, although necrotrophic parasitic associations and the Rhizobium/legume symbiosis are mentioned briefly. We take as a starting point the observations that in the parasitic associations nutrient transport is polarized towards the parasite, whereas in mutualistic associations it is bidirectional. The structure and function of the interfaces are then compared. An important common feature is that in nearly all cases the heterotrophic symbiont (whether mutualistic or parasitic) is located topologically outside the cytoplasm of the host cells, in an apoplastic compartment. This means that nutrient movements across the interface must involve transport into and out of this apoplastic region through membranes of both organisms.Basic principles of membrane transport in uninfected cells are briefly reviewed to set the scene for a discussion of transport mechanisms which may operate in parasitic and mycorrhizal symbioses. The presence and possible roles of ATPases associated with membranes at the interfaces are discussed. We conclude that cytochemical techniques (used to demonstrate the activity of these enzymes) need to he extended and complemented by biochemical and biophysical studies in order to confirm that the activity is due to transport ATPases. Nevertheless, the distribution of activity appears to he in accord with polarized transport mechanisms in some pathogens and with bidirectional transport in mycorrhizas. The absence of ATPases on many fungal membranes needs re‐examination.We emphasize that transport mechanisms between mycorrhizal symbionts cannot be viewed simply as the exchange of carbon for phosphate. Additional features include provision for transport of carbon and nitrogen as amino acids or amides and for ions such as K+ and H+ involved in the maintenance of charge balance and pH regulation, processes which also occur in parasitic associations. Interplant transport of nutrients via mycorrhizal hyphae is discussed in the context of these complexities. Some suggestions for the directions of future work are made.

CONTENTS

Summary
1

I.
Introduction
2

II.
The availability of nutrients to the symbionts
3

III.
Structure of interfaces between symbionts
4

IV.
Identity of nutrients transferred: an overview
12

V.
Membrane transport: basic principles
14

VI.
Transport at the interface of biotrophic symbioses
15

VII.
Regulation of pH in biotrophic symbioses
25

VIII.
Conclusions:
26
Effects of high soil moisture on formation of ectomycorrhizas and growth of karri (Eucalyptus diversicolor) seedlings inoculated with Descolea maculata, Pisolithus tinctorius and Laccaria laccata
Authors: BOUCHER N. L. , MALAJCZUK N. 
Published: April 2006

SummarySeedlings of Eucalyptus diversicolor P. Muell. I noculated with the ectomycorrhizal fungi Descolea maculata Bougher (two isolates), Pisolithus tinctorius (Pers.) Coker & Couch and Laccaria laccata (Scop, ex Fr.) Berk. & Br. were raised under glasshouse conditions in a yellow sand at a gradient of four soil moisture levels ranging from above field capacity to near waterlogged. All fungi enhanced growth of seedlings above that of uninoculated seedlings, but in soils near saturation there was no response to inoculation. Reduced mycorrhizal formation in relation to increasing soil moisture occurred to various degrees for all fungi. This was particularly marked with Pisolithus tinctorius. In contrast, Laccaria laccata maintained a relatively high number of mycorrhizal roots at all moisture levels applied, except at the wettest soil treatment. An isolate of D. maculata from a swamp environment did not produce a greater number of mycorrhizal roots at high soil moisture than an isolate of this species from a forest environment.
Botrytis cinerea kills groundsel (Senecio vulgaris) infected by rust (Puccinia lagenophorae)
Authors: HALLETT S. G. , PAUL N. D. , AYRES P. G. 
Published: April 2006

SummaryInoculation of healthy groundsel (Senecio vulgaris L.) with Botrytis cinerea Pers at 1.24 × 106conidia ml −1 caused 10% mortality, and only 40%, mortality when plants were abiotically wounded before inoculation. However, all plants previously infected by rust (Puccinia lagenophorae Cooke) died after inoculation with B. cinerea. Mortality was most rapid it plants were inoculated with B. cinerea as rust colonies first erupted through the host's epidermis. A reduction in the concentration of conidial inoculum increased time to death, and concentrations below 015 × 103 conidia ml−1 failed to cause 100 % mortality within the 32 d of the experiment. Death of plants was associated with the growth of B. cinerea into stem bases; a reduction in the density of rust lesions on leaves had no effect on the time from inoculation to the appearance of foliar symptoms, but increased time‐to‐kill. There was little variation m virulence between isolates of B. cinerea made from different groundsel or ragwort (Senecio jacobaea L.) populations. Similar interactions between biotrophic fungi and opportunistic pathogens have occasionally been noted previously; their importance in natural vegetation processes and possible relevance to the biocontrol of weeds is discussed.