bluuebunny/crossref_metadata_2025_split huggingface dataset:
A SHEATHING MYCORRHIZA ON PISONIA GRANDIS R. BR. (NYCTAGINACEAE) WITH DEVELOPMENT OF TRANSFER CELLS RATHER THAN A HARTIG NET
Authors: ASHFORD A. E. , ALLAWAY W. G. 
Published: May 2006

SUMMARYEctomycorrhizas have been discovered on the root system of Pisoniagrandis R. Br. (Nyctaginaceae) collected from two islands in the Capricorn group of the Great Barrier Reef, Australia. These mycorrhizas are unusual in that the Hartig net is poorly developed but instead transfer cells develop in the epidermis and cortex of the host root. The wall labyrinth is located precisely on host wall regions abutting the fungus. It is suggested that the development of wall protuberances, with an accompanying amplification of host membrane surface area exactly in the region where transfer between the two symbionts is most likely to occur, is an alternative strategy to Hartig net formation. Pisonia grandis is usually found in locations colonized by seabirds as nesting sites and therefore rich in guano. It is unusual to find an ectomycorrhiza in such a situation, where there is a high input of organic nitrogen and phosphorus at least once a year in addition to a permanently high calcium level, and the nutritional aspects of this association deserve further study.
CHANGES IN FREE AMINO ACID AND AMIDE COMPOSITION DURING FRUIT AND SEED DEVELOPMENT OF GARDEN PEA, PISUM SATIVUM L.
Authors: MURRAY D. R. 
Published: May 2006

SummaryChanges in the free amino acid and amide composition of the developing hull and component parts of the seeds of garden pea, Pisum sativum cv. Melbourne Market, have been recorded. Major differences observed in comparison with field pea include the absence of O‐acetyl homoserine as a prominent component in the hull or seedcoats and the absence of an increase in the relative proportion of asparagine in ageing seedcoats or maturing embryos. Serine was more prominent in young hulls, mature embryos and seedcoats and embryo sac liquid than in field pea, while arginine was less prominent in the maturing cotyledons and the embryo axis.
CYTOLOGICAL STUDIES IN THE GENUS SILENE L.
Authors: GHAZANFAR SHAHINA A. 
Published: May 2006

SummaryFourteen species of Silene in sections Siphonomorpha and Auriculatae were investigated cytologically and karyotypes prepared. Chromosome counts of six species are given for the first time. SAT‐chromosomes were found in S. viridiflora and S. nodulosa. S. boryi and S. vallesia were found to be tetraploids.
LEAF AND FLOWER DEMOGRAPHY OF TRIFOLIUM REPENS L.
Authors: TURKINGTON ROY 
Published: May 2006

SummaryRamets from a single individual of Trifolium repens L. were introduced into pure stands of Agrostis tenuis Sibth., Dactylis glomerata L., Lolium perenne L., Phleumpratense L. and Trifolium repens L. and into a bare soil (control) plot. At weekly intervals for 59 weeks, births and deaths of leaves and flowers, and extension of stolons were recorded. These birth and death statistics were used to calculate life spans, natality and mortality rates, age class distributions and other demographic characteristics of the population of leaves and flowers of T. repens L. Recruitment and death of leaves occurred throughout most of the year; flowers were produced from mid‐March to late October and deaths occurred from April to November. Rates of leaf and flower population change differ between treatments. The average life spans of leaves did not vary significantly between the five treatments but was longer in the control; the timing of births had a strong influence on the expectation of life. Stolon extension rates also varied quite markedly in the presence of different neighbours. A summary table is presented showing the array of responses displayed by this single genotype of T. repens L. in a range of environments.
USE OF THE INDIRECT IMMUNOFLUORESCENT TECHNIQUE TO STUDY THE VESICULAR‐ARBUSCULAR FUNGUS GLOMUS EPIGAEUM AND OTHER GLOMUS SPECIES
Authors: KOUGH J. , MALAJCZUK N. , LINDERMAN R. G. 
Published: May 2006

SummaryAn antiserum for spores and hyphae of Glomus epigaeum was developed employing extracted chlamydospore walls as an antigen. The reaction with fungal material was visualized by an indirect immunofluorescent technique. The staining was most intense and uniform on hyphae from root preparations and on the inner spore walls and hyphal attachments from spore preparations. The staining reaction was strongest for G. epigaeum, but G. mosseae and G. deserticola also reacted. The staining reaction appeared to be specific for the genus Glomus, as endomycorrhizal species of Gigaspora, Acaulospora and other soil and root‐inhabiting fungi tested did not react.
A NOTE ON THE RELATIVE PHOSPHORUS AND CALCIUM CONTENTS OF METACHROMATIC GRANULES IN FAGUS MYCORRHIZA
Authors: STRULLU D. G. , HARLEY J. L. , GOURRET J. P. , GARREC J. P. 
Published: May 2006

SummaryThe relative phosphorus and calcium contents of the phosphatic granules of Fagus mycorrhiza were measured before and after phosphate absorption from KH2PO4 solution. Whereas their phosphorus content greatly increased, their calcium content did not, so that the phosphorus: calcium ratio fell. These results are discussed in the context of the cation content of the granules and estimates of the amount of phosphate present in granule form.
THE EFFECT OF NITRATE AND PHOSPHATE ON THE VESICULAR‐ARBUSCULAR MYCORRHIZAL INFECTION OF LETTUCE
Authors: HEPPER CHRISTINE M. 
Published: May 2006

SUMMARYThe application of increasing amounts of nitrate resulted in higher levels of vesicular‐arbuscular mycorrhizal infection in lettuce roots inoculated with Glomus mosseae. This effect was found at three phosphate levels. The application of nutrient solutions containing different concentrations of nitrate and phosphate resulted in different nitrogen and phosphorus levels in the roots. At high concentrations of phosphorus in the roots, infection was inhibited, but at low concentrations the infection level appeared to be related to the nitrogen content of the host tissue. Mycorrhizal infections in low‐nitrogen treatments were poorly developed with very few arbuscules and intercellular hyphae. Two methods of estimating infection (gridline intersect and yield of glucosamine) were compared.
DIFFERENTIAL RESPONSE OF AZOLLA‐ANABAENA ASSOCIATIONS TO HIGH TEMPERATURE AND MINUS PHOSPHORUS TREATMENTS
Authors: TUNG H. F. , WATANABE I. 
Published: May 2006

SUMMARYThe response of Azolla species to high temperature and minus phosphorus (– P) treatments was investigated. Azolla filiculoides was judged the most sensitive to high temperature on the basis of its growth, acetylene reduction activity (ARA), losses in chlorophyll and protein content. The temperature‐tolerant strains like A. pinnata (Cheng Mai and Pu Tiang Zhu) and A. microphylla showed good growth and no senescence even after 6 weeks at 37/29°C provided that plant density was controlled and nutrients were not limiting.The – P treatment reduced both growth and N2‐fixation in the Azolla plants. Its effect was greater on N2‐fixation as measured by ARA, than on growth in the first week of culture in a P‐deficient medium. High temperature did not hasten or enhance the appearance of P deficiency symptoms. A lower endogenous P content was needed to induce physiological disorder in A. pinnata than in A. mexicana and A. microphylla.
A PHYSIOLOGICAL INTERPRETATION OF THE DYNAMIC RESPONSES OF POPULATIONS OF A PLANKTONIC DIATOM TO PHYSICAL VARIABILITY OF THE ENVIRONMENT
Authors: REYNOLDS C. S. 
Published: May 2006

SummaryThe dynamic responses of Fragilaria crotonensis populations to artificial variations in the mixed depth of the water column of a Lund Tube (Enclosure C, Blelham Tarn) are shown to conform to a descriptive model involving only two environmental variables: mixed depth and optical depth. The physiological interpretation of these responses invokes a second model, relating the rates of net population change to photosynthetic productivity, corrected for respiration, and to in situ sinking loss rates. Population increases coincide with mixing episodes, when it is shown that the maximum photosynthetically‐derived growth rate exceeds the sinking low rate by an amount similar to the observed rate of net gain. Abrupt declines occur when the column rapidly restratifies, at rates explicable in terms of accelerated sinking and sinking‐loss rates, i.e. that there is also an abrupt cessation in growth. Evidence that this effect is due to extreme near‐surface photoinhibition is presented. The ecology of Fragilaria populations is briefly discussed in relation to these findings.
EVIDENCE THAT TEMPERATE EAST NORTH AMERICAN EVERGREEN WOODY PLANTS FOLLOW CORNER'S RULES
Authors: WHITE P. S. 
Published: May 2006

SummaryCoener's rules, first developed for tropical trees, predict a spectrum of woody plant forms, from ones with small leaves, thin twigs (first‐year shoots) and many branches, to ones with larger Waves, thick twigs and few branches. These rules were confirmed for nine broad‐leaved and 12 needle‐leaved evergreen woody plants of temperate eastern North America: for each of these groups, leaf size was positively correlated with twig cross‐sectional area and both of these were negatively correlated with the number of twigs needed to bear 104 cm2 total leaf area. When compared to deciduous trees, characterized in a previous study, broad‐leaved evergreens had leaves that were 85% smaller at a given twig thickness and needed 750% more twigs to bear a given total leaf area (at least when leaves older than 1 year were ignored). Needle‐leaved evergreens bore relatively small leaves but large numbers of leaves per first‐year shoot; they bore fewer twigs per 104 cm2 total leaf area than broad‐leaved evergreens, but more than broad‐leaved deciduous species. Broad‐leaved deciduous trees were characterized by relatively large leaf sizes as a function of twig cross‐sectional area and low numbers of twigs per 104 cm2 total leaf area. Although Corner's rules are a significant index of plant form, a full resolution of the differences between deciduous and evergreen species awaits further study.
CENSUS OF AIRBORNE POLLEN GRAINS IN THE ATMOSPHERE OF ASCOLI PICENO (CENTRAL ITALY)
Authors: FRENGUELLI G. , MINCIGRUCCI G. , ROMANO B. , BRICCHI E. 
Published: May 2006

SummaryHirst's Volumetric Sampler was employed in the aerial survey of atmospheric pollen of Ascoli Piceno. Altogether 67 pollen types are recognized. The highest concentrations of airborne pollen occur in April, May, June, with pollen of Gramineae, Corylaceae, Fagaceae, Urticaceae and Oleaceae predominant.
WATER RELATIONS PARAMETERS OF TWO SICILIAN SPECIES OF SENECIO (GROUNDSEL) MEASURED BY THE PRESSURE BOMB TECHNIQUE
Authors: SALLEO S. 
Published: May 2006

SUMMARYThe possible role in drought resistance played by leaf water potential, osmotic potential, weight‐averaged turgor pressure and bulk modulus of elasticity is studied in mature and young leaves of Senecio Candidus and S. ambiguus. Small water losses cause relatively large reductions in leaf water potential in, S. candidus without greatly altering its osmotic potential. This occurs because S. candidus develops thicker leaf cell walls with high values of leaf bulk elastic modulus. Recovery from water stress is very rapid in this species. Leaf growth is influenced by the structural pattern of the cell walls in that S. candidus leaves complete their expansion within a shorter period of time than those of S. ambiguus. The possible adaptive significance of changing the leaf bulk modulus of elasticity in mature and young leaves of the two species is discussed.
GROWTH RESPONSES OF SITKA SPRUCE SEEDLINGS TO MYCORRHIZAL INOCULATION
Authors: THOMAS G. W. , JACKSON R. M. 
Published: May 2006

SUMMARYUnder glasshouse and field conditions, different mycorrhizal fungi differ in their effect upon the growth and nutrient status of seedlings of Sitka spruce [Picea sitchensis (Bong.) Carr]. Seedlings inoculated with ‘E‐strain’ fungi, the dominant mycorrhizal fungi of nurseries, and grown in forest soil in the glasshouse and in field plots were smaller than those inoculated with either Thelephora terrestris Ehrh. Fr. or Laccaria laccata (Scop, ex Fr.) Cooke.
INTERSPECIFIC PLANT ASSOCIATION EFFECTS ON VESICULAR–ARBUSCULAR MYCORRHIZA OCCURRENCE IN ATRIPLEX CONFERTIFOLIA
Authors: MILLER R. M. , MOORMAN T. B. , SCHMIDT S. K. 
Published: May 2006

SUMMARYEarlier studies with the shrub Atriplex confertifolia (Chenopodiaceae) suggested that the occurrence of mycotrophy was related to the community from which root samples were obtained; plants in disturbed areas were non‐mycotrophic, while those growing in native areas possessed infection. Upon closer examination when neighbouring plants were studied, the level of mycorrhizal infection of Atriplex confertifolia was found to be related to its interspecific plant associations. When Atriplex confertifolia occurred solitarily, or in the presence of non‐mycorrhizal A. gardneri, it was non‐mycotrophic. However, when occurring near grasses or Artemisia spinescens, it possessed mycorrhiza infection. What appeared to be a community effect for the occurrence of mycorrhiza is nothing more than an association effect in which level of infection is related to the degree of mycorrhizal host plant cover. In disturbed communities little chance occurs for encountering a neighbouring mycorrhizal plant, while native plant communities are composed primarily of mycorrhizal counterparts.
CYTOKININS AND THE REGENERATION OF PLANTLETS FROM SECONDARY EMBRYOIDS OF WINTER OILSEED RAPE, BRASSIC A NAP US SSP. OLEIFERA
Authors: LOH C.‐S. , INGRAM D.S. , HANKE D. E. 
Published: May 2006

SUMMARYIt was shown that only a small proportion of haploid (= amphihaploid; n= 19) secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera) grew into plants when transferred to a medium without plant growth regulators. The majority grew abnormally and formed further secondary embryoids on their surfaces. It was then found by experiment that an effective method of inducing leaf initiation and reducing secondary embryogenesis was to transfer the secondary embryoids to a basal medium supplemented with 6‐furfurylaminopurine (kinetin; 10−4 M), alone or in combination with low concentrations of indole‐3‐acetic acid. Roots were initiated by further transfer of the cultures to basal medium without plant growth regulators. The plantlets so produced were normally haploid and were suitable for growing on into whole plants. The reduction of secondary embryogenesis by cytokinins is discussed in the general context of response by plant tissues to plant growth substances.
EFFECT OF IRRIGATION, WATER SALINITY AND ROOTSTOCK ON THE VERTICAL DISTRIBUTION OF VESICULAR‐ARBUSCULAR MYCORRHIZA IN CITRUS ROOTS
Authors: LEVY Y. , DODD J. , KRIKUN J. 
Published: May 2006

SUMMARYThe effects of rootstock, irrigation regime and water salinity on the vertical distribution of vesicular‐arbuscular mycorrhiza (VAM) of citrus roots were investigated in the field. Rootstocks differed in the uniformity of the vertical distribution of VAM, notably, Rough lemon exhibited a uniform vertical distribution and Sour orange a non‐uniform distribution with decreased VAM infection at depth. Decreasing the interval between irrigations reduced VAM infection of Sour orange, especially in the upper layers of soil. Increased salinity of irrigation‐water reduced VAM in deep layers of soil.
DEVENSIAN LATE‐GLACIAL AND FLANDRIAN VEGETATIONAL HISTORY AT HOCKHAM MERE, NORFOLK, ENGLAND
Authors: BENNETT K. D. 
Published: May 2006

SUMMARYAnalysis of the basin morphometry of Hockham Mere suggests that the lake basin is of a shape in which sediment is likely to be focused. Consideration of three long pollen diagrams through the deposits shows that focusing of organic post‐glacial sediment began at about 9255 B.P., and continued until the lake basin had filled, during the mid post‐glacial. The sediments deposited before 9255 B.P. are highly inorganic, and have remained concentrated near the edge of the basin, where they were initially deposited. The pollen accumulation rate diagram, from the deepest part of the basin, cannot be understood without considering the changing pattern of sediment distribution within the lake, and it is suggested that pollen concentrations may yield a more reliable interpretation of the development of vegetation in the surrounding landscape than can be obtained from pollen accumulation rates.
THE INFLUENCE OF PHYTOCHROME PHOTOEQUIILIBRIUM ON GIBBERELLIN‐LIKE SUBSTANCES AND CHLOROPHYLL CONTENT OF CHLOROPLASTS OF HORDEUM VULGARE L.
Authors: HILTON JANET R. 
Published: May 2006

SUMMARYThe mediation by phytochrome of the amount of gibberellin (GA)‐like substances extractable from etioplasts is well documented. Results presented here show that phytochrome mediates the amount of GA‐like substances extractable from Hordeum vulgare L. chloroplasts, and changes in the chlorophyll a/b ratio of chloroplasts. The results are discussed in relation to shade detection and the efficiency of photosynthesis in the natural environment.
THE DEVELOPMENT OF MYCORRHIZA ON SEEDLINGS OF FAGUS SYLVATICA L.
Authors: WARREN WILSON J. , HARLEY J. L. 
Published: May 2006

SUMMARYIn beech seedlings during their first growing season, both in pot experiments and in natural woodland conditions, the root tips passed through a developmental sequence in which the elongation rate progressively declined, root diameter decreased, the root cap became smaller, and tissue differentiation approached nearer to the apex. Such a spatially precocious differentiation is characteristic of mycorrhizas, where it has generally hitherto been regarded as a consequence of fungal infection, but in these seedlings it was a normal developmental change associated with progressive decline in activity of the root meristem, and was independent of the presence of mycorrhizal fungi. Indeed, mycorrhizal infection occurred only when a root tip had passed through this sequence and elongation had nearly or completely ceased. The formation of mycorrhiza caused a resumption of slow elongation, and a constriction in the root marked the position of the root tip at infection: the mycorrhizal region was swollen owing to cortical cells being expanded in the transverse plane. Certain features of the structure of the root of the host varied quantitatively with the species of mycorrhizal fungus. An attempt is made to identify those aspects of mycorrhizal structure which resulted from normal root development and those which were induced by the fungus.
PHYSIOLOGICAL STUDIES ON TEMPERATE LICHEN SPECIES I. A MATHEMATICAL MODEL TO PREDICT ASSIMILATION IN THE FIELD, BASED ON LABORATORY RESPONSES
Authors: PATERSON D. R. , PATERSON E. W. , KENWORTHY J. B. 
Published: May 2006

SummaryA model has been constructed to predict assimilation in four lichen species using climatological data. Gas exchange of the lichens has been measured in the laboratory in response to seasonal, light, temperature and moisture changes. By fitting polynomial equations to the response curves, the model predicts assimilation on the basis of these variables. A comparison of weight changes measured in the field with assimilation values predicted by the model using climatological data measured in the field, shows that the model gives realistic predictions over periods of 1 month. The model also permits the importance of the various environmental parameters to be examined, singly and in combination. Predicted assimilation values on climatically different days suggest that moisture is the single most important factor governing lichen growth – the assimilation gains during one rainy summer day can counteract the losses of five dry days. The model can now be extended to examine possible reasons for lichen distribution.
UNUSUAL ‘TUBULAR CLUSTERS’ IN THE PLASTIDS OF A DUCKWEED (LEMNA PAUCICOSTATA) MUTANT INCAPABLE OF PHOTOSYNTHESIS AND AMMONIUM ION UPTAKE
Authors: MONSELISE EDNA BEN‐IZHAK , PORATH DAN , TAL MOSHE 
Published: May 2006

SummaryLight‐grown plants of the wild type 6746 strain and the mutant strain 1073 of Lemna paucicostata were compared. It was confirmed that this photosynthetically defective mutant is dependent on supply of sucrose for its growth. Moreover it was found that it is unable to take up NH4+ in the absence of added sucrose; addition of a‐oxoglutarate did not allow ammonium ion uptake.In the mutant, mitochondria are unusually long and distorted and in its chloroplasts the grana contain many more thylakoid membranes than in the wild‐type chloroplasts of the same age. Moreover, at all ages, the presence of specific new structures known as ‘tubular clusters’ can be detected; tubular clusters differ from prolamellar bodies found in etioplasts. In addition, both strains produced in young fronds, upon standing in darkness for 28 h, prolamella bodies with typical crystalline structure.A possible connection between the tubular clusters and physiological aberrations of the mutant is discussed.
DINOPHYTE FLAGELLA: A COST‐BENEFIT ANALYSIS
Authors: RAVEN J. A. , RICHARDSON KATHERINE 
Published: May 2006

SummaryThe mobility of dinophytes allows them to migrate dielly, in a vertically stratified environment, between deeper regions where concentrations of nutrients (principally nitrate) are higher but light low, and less deep regions with lower nutrient concentrations but more light. When there is a substantial (several metres) depth range in which dinophytes can grow but, at any given depth, growth is restricted by both nitrate and light availability, vertical migration from a deeper station at night to a less deep station during the day could increase the availability of light and nitrate to a dinophyte cell over a complete light‐dark cycle.Cost‐benefit analysis shows that the benefits of migration (increased acquisition of photons and nitrate relative to non‐migratory cells) could very substantially exceed the costs (the energy and nitrogen required to produce and operate the flagella apparatus and any additional nitrate or photon‐harvesting machinery which may be required as a result of migration). It is therefore concluded that, in some habitats, vertical migration could increase the growth rates of dinophytes. The occurrence of such increases under natural conditions, and their selective significance, await further investigation.
TAPHONOMY OF PROSPECTIVE PLANT MACROFOSSILS IN A RIVER CATCHMENT ON SPITSBERGEN
Authors: HOLYOAK D. T. 
Published: May 2006

SummaryRepresentation of recent plant parts in fluvial sediments and in the vegetation of a braided‐river catchment on Spitsbergen was studied quantitatively in order to provide a model for taphonomy of plant macrofossils during cold stages of the British Pleistocene. The area studied on the Adventelva is in a region with continuous permafrost and on a river that has high (nival) peak discharges in early summer, features that were also present in the British lowlands during the Pleistocene cold stages.Deposition of ‘prospective macrofossils’ in silts of channels on the Adventelva floodplain occurred mainly during the decline from the early summer peak of discharge. Surface runoff overland was much the most important process by which ‘prospective macrofossils’ reached river channels, and this accounts for them giving a surprisingly even overall representation of the abundance of similar parts in the vegetation. Taxa having ‘prospective macrofossil parts’ that were under‐represented in the deposits had parts that were: (a) very small, (b) of soft or perishable texture, (c) firmly attached to stems, (d) neither deciduous nor renewed annually, or (e) they were plants growing on the river floodplain. Taxa with parts over‐represented in the deposits were: (a) those with parts that break into numerous identifiable fragments, or (b) they were plants growing in localized areas of late snow‐lie.