bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF MECHANICAL FORCES ON THE EXUDATION OF ORGANIC SUBSTANCES BY THE ROOTS OF CEREAL PLANTS GROWN UNDER STERILE CONDITIONS
Authors: BARBER D. A. , GUNN K. B. 
Published: May 2006

SummaryCereal plants were grown for 3 weeks under sterile conditions in solution culture with their roots either unrestricted or growing between glass ballotini.The exudation of both amino acids and carbohydrates was increased when the roots were grown through a solid medium and the total quantity exuded was equivalent to about 9% of the dry matter increment of the roots.
THE RESPONSE OF MYCORRHIZAL AND NONMYCORRHIZAL ROOTED CUTTINGS OF HEATHER (CALLUNA VULGARIS (L.) HULL) TO VARIATIONS IN NUTRIENT AND WATER REGIMES
Authors: BANNISTER P. , NORTON W. M. 
Published: May 2006

SummaryRooted cuttings of heather showed their best dry matter production in drained regimes with a frequent addition of nutrients. Mycorrhizal plants generally showed a decreased production when compared with equivalent non‐mycorrhizal plants, except on drained regimes low in nutrients where the mycorrhizal plants grew better. Concentrations of nitrogen in the shoot and potassium and phosphorus in the root were higher in mycorrhizal than in non‐mycorrhizal plants, effects most marked in well‐drained regimes with the minimum addition of nutrients. In general, alterations in nutrient and water regimes had more significant effects on dry matter production than did the presence or absence of mycorrhiza. It is concluded that mycorrhizal infection may have a beneficial effect in freely drained, infertile, soils that are characteristic of well‐developed heathland.
THE ABSORPTION OF IONS BY MICROORGANISMS AND EXCISED ROOTS
Authors: BARBER D. A. 
Published: May 2006

SummaryMicro‐organisms are present in sufficient numbers on barley roots to account for the differences previously attributed to them in experiments comparing the uptake of rubidium by sterile and non‐sterile excised roots. Experiments with thallium, which is highly phytotoxic at concentrations above 0.2 mM, provide further grounds for rejecting the postulate, based on‘dual absorption isotherms’, that under physiological conditions different mechanisms of absorption operate depending on the external concentration.
MICROBIAL ACTIVITY IN FLORIDA EVERGLADES PEAT
Authors: DICKINSON C. H. , WALLACE B. , GIVEN P. H. 
Published: May 2006

SummaryPopulations of viable bacteria and fungi were shown to exist in various strata of peat formed in the Florida Everglades. The populations present were quantitatively and qualitatively different in three distinct peat‐forming habitats and at various depths in the peat profiles. Relatively few pieces of peat taken from horizons below the surface were colonized by actively growing fungi or actinomycetes. Direct observation of peat confirmed some features of the cultural studies. Bacteria were mostly present in small groups of two to six cells and most of the hyphae recorded were apparently formed by Actinomycetales rather than the fungi. The significance of these data in relation to possible long‐term changes in the peats is discussed.
THE DEVELOPMENT OF CONIDIOPHORES AND CONIDIA IN THE IMPERFECT FUNGUSOEDOCEPHALUM ROSEUM
Authors: COOK BERYL E. 
Published: May 2006

SummaryThe development of conidiophores and botryose solitary blastospores was studied inOedocephalum roseumby light and electron microscopy, and for convenience was divided into several stages. Development was a continuous process with no pause at any stage, although increase in volume of the sporing structure was much reduced during production of the denticles. Cytochemical light microscopy supported electron microscopic observations of distribution of organelles and storage substances in the sporing structure at each stage of development. A Spitzenkörper, comprising two types of unit membrane‐bounded vesicles of different size, was present at the tip of the growing conidiophore. At the time of blow‐out of the denticles, small vesicles, thought to contain wall‐softening enzymes, accumulated in groups around the periphery of the ampulla, and the wall in these regions stretched, becoming thinner, and bulged to form the wall of the denticle initials. Exposed sulphydryl groups were detected in the wall of these bulges. The denticles grew to become tubular, and spherical conidium initials formed at their tips. Electron microscopy showed that membrane‐bounded vesicles were present in all regions of growth and development, and to the exclusion of all other organelles in the tip of the conidiophore, in denticle blow‐outs, in conidium initials and in tips of elongating conidia. In these regions much RNA was detected. The sequence of first occurrences of organelles and storage substances from the young conidiophore tip backwards was also the sequence of their entry into the developing conidia, nuclei being the last of the organelles to enter. During development and growth the wall around the whole sporing structure was not broken at any stage. However, there was a succession of wall layers in each structure during its development, new layers being formed internally and being progressively displaced towards the outside. The new inner wall layer formed by the hypha at the inception of the conidiophore gave rise to the three outer layers of the conidial wall, the inner layer of the conidium being a continuation of the inner layer of the ampulla wall, which was formed before denticle production. Blastospore formation resembled the process of budding in yeasts, in that vesicles probably containing wallsoftening enzymes were present in the region of denticle blow‐out and of budding, and the walls of the denticle and of the yeast bud were made up of parent cell wall material.
PRIMARY PENETRATION PROCESS IN POWDERY MILDEWED BARLEY RELATED TO HOST CELL AGE, CELL TYPE, AND OCCURRENCE OF BASIC STAINING MATERIAL
Authors: LIN M.‐R. , EDWARDS H. H. 
Published: May 2006

SummaryThe primary infection process of four near‐isogenic lines of Manchuria barley by Erysiphe graminis f. sp. hordei race CR‐3 was studied. An unknown substance,‘basic staining material’, was associated with papillae when penetration by germinated conidia was unsuccessful but not in penetrated papillae. Genes conferring resistance (ML‐a, Ml‐g, and Ml‐p) delay or reduce the frequency of penetration. The gene Ml‐k has no effect during penetration. Resistance to penetration increased significantly in both susceptible and resistant hosts with increasing cell age. The type of host epidermal cell exhibited different degrees of resistance to penetration. The cells furthest from the guard cells showed the highest degree of resistance. Guard cells were never penetrated.
AN ULTRASTRUCTURAL STUDY OF THE PYRENOID IN CULTURED CELLS OF CHLORELLA VARIEGATA (CHLOROCOCCALES)
Authors: SILVERBERG B. A. , SAWA T. 
Published: May 2006

SummaryElectron microscopical examination of cultured Chlorella variegata, a facultatively heterotrophic species of the genus, revealed the presence of electron‐opaque spheres, or pyrenoglobuli, in the pyrenoid. The pyrenoglobuli, observed both in vegetative cells and autospores, are associated with the pyrenoid thylakoids which are single thylakoidal elements penetrating into the homogeneously granular matrix of the pyrenoid. There appear to be more pyrenoglobuli present in the pyrenoids without starch plates.
EFFECTS OF ROOTSTOCKS AND INTERSTOCK ON CELL DIMENSIONS IN SCION STEMS OF APPLE (MALUS PUMILA MILL.)
Authors: DOLEY D. 
Published: May 2006

SummaryFibre and vessel element dimensions were studied in Cox's Orange Pippin scion stems grafted directly on to the dwarfing M.8 and M.9 rootstocks, or on to the vigorous MM. 104 rootstock with interstocks of MM.104 or the very dwarfing M.20 varieties. In the xylem formed in trees aged between 5 and 7 years, the total cross‐sectional areas of fibres and the lumen of vessels were very closely related to the width of the growth rings. Variations in the ratio (total cell area):(lumen area) and in fibre wall thickness were mostly attributable to intrinsic seasonal effects, as reflected by the position of sampling within the growth ring. Differences in cell length and mean wall thickness of fibres between the rootstocks M.8, M.9 and MM.104/MM.104 were relatively small, whereas the M.20 interstock was associated with significantly smaller values for these attributes. The effects of the rootstocks studied appeared to be exerted through changes in the rate of stem growth as a whole, whilst the very dwarfing interstock altered the relationships between the lateral expansion of cells and the elongation and wall thickening of fibres.
NUMERIGAL METHODS IN QUATERNARY PALAEOECOLOGY
Authors: GORDON A. D. , BIRKS H. J. B. 
Published: May 2006

SummaryComparison of pollen diagrams is an important stage in pollen analytical Investigations as it is the basis for the recognition of regional pollen assemblage zones. Three numerical approaches to the problem of comparing stratigraphical sequences are presented. Their use is illustrated by two contrasting sets of data, one from two sites of Late‐Wisconsin age in central Minnesota, the other from a transect of sites in north‐west Minnesota extending from Late‐Wisconsin to present times. The first approach compares pollen zones at the different sites on two numerical criteria, information radius and concordance. The other two approaches compare sequences on a level by‐level basis; the second method by means of non‐metric multidimensional scaling and the third by a slotting procedure by which levels at one site are slotted between levels at another site on the basis of similarities in pollen composition. The advantages and disadvantages of the three approaches are discussed.
PLASTID DEVELOPMENT IN PRIMARY LEAVES OF PHASEOLUS VULGARIS
Authors: BRADBEER J. W. , GYLDENHOLM A. O. , IRELAND H. M. M. , SMITH J. W. , REST J. , EDGE H. J. W. 
Published: May 2006

SummaryFor 14‐day‐old dark‐grown beans a quantitative study of plastid membrane formation has been made for light‐induced chloroplast development in the primary leaves. During the first 10 h of illumination, thylakoid formation resulted from the rearrangement of the membranes of the prolamellar body. De novo thylakoid formation commenced between 10 and 15 h after the beginning of illumination and resulted, in the course of 160 h of illumination, in a ten‐fold increase in thylakoid membrane. During the course of greening no cell division occurred in the mesophyll cells, plastid expansion took place in all of the mesophyll cells but plastid division only occurred in the spongy mesophyll cells to result in an 11 % increase in the plastid number of the whole leaf during the first 18 h of illumination.When leaves were supplied with d‐threo‐chloramphenicol during greening there was a severe inhibition of thylakoid formation, vesicles were formed in the plastid stroma and rather fewer and larger grana than normal were produced. However, the proportion of thylakoid material in grana was normal. As l‐threo‐chloramphenicol yielded exactly normal chloroplasts it is concluded that thylakoid synthesis was inhibited by d‐threo‐chloramphenicol by the inhibition of the synthesis of one or more thylakoid proteins on the 708 ribosomes of the plastids.
REVERSIBLE EFFECTS OF BORON ON THE ABSORPTION AND INCORPORATION OF PHOSPHATE IN VICIA FABAL.
Authors: ROBERTSON G. A. , LOUGHMAN B. C. 
Published: May 2006

SummaryBoron deficiency reduced absorption of phosphate in whole plants and root segments of Vicia faba. The overall phosphate metabolism of the whole root was unaffected but both the equilibrium pattern and initial rates of esterification were altered in the root tip region. The equilibrium ratio of inorganic phosphate to organic phosphate was not affected. Addition of boron at 10 μM to the deficient plants for 1‐2 h prior to absorption reversed the effects of boron deficiency in both absorption and metabolism of phosphate although it did not stimulate the initial rates of esterification of the absorbed phosphate.
THE EFFECT OF KINETIN AND ABSCISIC ACID ON WATER AND ION TRANSPORT IN ISOLATED MAIZE ROOTS
Authors: COLLINS J. C. , KERRIGAN A. P. 
Published: May 2006

SummaryExudation from the xylem of excised maize roots was studied in roots bathed in solutions containing kinetin or abscisic acid (ABA). Kinetin reduced the water permeability of the roots whilst ABA increased it. The action of both hormones was reversible and both were effective at concentrations of 10‐6M and below. The possible in vivo role of these two hormones is discussed.
EFFECT OF KINETIN ON PLANT‐RESPONSE TO SALINITY
Authors: BENZIONI A. , MIZRAHI Y. , RICHMOND A. E. 
Published: May 2006

SummaryKinetin applied to tobacco plants had a marked dwarfing effect and, in suitable concentration, prevented the appearance of saline‐induced leaf‐necrosis. In experiments lasting for 24 h, kinetin effected a reduction of salt transport from the roots to the shoot, without affecting salt uptake. However, Na+ and Cl‐ analysis of plants exposed to 6 weeks of salination revealed that kinetin accentuated salt accumulation in the shoot and thus the necrosis‐prevention effect of kinetin did not stem from retardation of salt accumulation in the plant. It is suggested that the effect of salinity on leaf‐necrosis was related to its effect on acceleration of leaf senescence and that kinetin prevented salinity damage by retarding cellular senescence and breakdown.
CHARACTERIZATION OF EUCALYPT MYCORRHIZAS BY PYROLYSIS–GAS CHROMATOGRAPHY
Authors: SEVIOUR R. J. , CHILVERS G. A. , CROW W. D. 
Published: May 2006

SummaryThe chemotaxonomic potential of pyrolysis–gas chromatography is evaluated in relation to eucalypt mycorrhizas. The sensitivity of the technique permits good elution patterns to be obtained even from samples as small as single mycorrhizal apices. A simple quantitative measure of dissimilarity between such pyrograms, based on heirarchical analysis of peak heights, is described. Dissimilarity measures obtained from comparisons between defined materials are shown to be correlated with their degree of taxonomic affinity but experimental variability between replicate samples currently limits the comparative value of this method.
INTERGENERIC HYBRIDIZATION AMONG THREE SPECIES OF HETERANTHELIUM, EREMOPYRUM AND HORDEUM, AND ITS SIGNIFICANCE FOR THE GENETIC RELATIONSHIPS WITHIN THE TRIBE TRITICEAE*
Authors: SAKAMOTO SADAO 
Published: May 2006

Summary Heteranthelium is a monotypic genus in the tribe Triticeae represented by an annual diploid species, H. piliferum. The spike of this species is quite different from other members of the tribe. In an attempt to elucidate the genetic relationships to other genera of the tribe, H. piliferum was crossed with various species of Aegilops, Agropyron, Eremopyrum, Henrardia and Hordeum.From these crosses F1 hybrids of (i) Heteranthelium piliferum (2x) ×Eremopyrum bonaepartis (2x) and (2) Heteranthelium piliferum×Hordeum depressum (4x) were produced. At the same time F1 hybrids of (3) Eremopyrum bonaepartis×Hordeum depressum was also obtained. The hybrid under (i) showed subnormal growth and the shape of the spikes was of Eremopyrum type, while the spikelets were intermediate. Growth of the hybrid under (2) was vigorous and the spike morphology was intermediate between the parents. A solitary spikelet with two glumes and a single spikelet at each rachis node like the Heteranthelium parent was observed but no rudimental spikelets which are the characteristic of Heteranthelium were found.Growth of the hybrid under (3) was very vigorous and the shape of the spikes was of Hordeum type. However, floral construction at each rachis node was very complicated. Rachis nodes with three glumes and a single spikelet were the most common. Sterility of all three combinations was complete.Average chromosome pairing per cell of the F, hybrids was in (i) 0.04 bivalents and 13.93 univalents, in (2) 0.00 trivalents, 5.06 bivalents and 10.88 univalents, and in (3) 0.00 quadrivalents, 0.01 trivalents, 5.50 bivalents and 9.97 univalents. Judging from the chromosome pairing in (i), (2) and (3), a high bivalent formation in (2) and (3) is attributable to autosyndesis of chromosomes derived from the Hordeum parent. It is concluded that there is no homology among the genomes of those three species.Considering morphological features, geographical distribution, intergeneric cross‐ability and genetic relationships of Heteranthelium piliferum, it is concluded that the monotypic genus Heteranthelium is a distinct entity in the tribe Triticeae. This taxon has evolved as an annual during the process of adaptation to rather dry habitats of the Mediterranean climatic regions in the course of generic differentiation of the tribe.
A STATIC NON‐OVERLOAD POLLEN COLLECTOR
Authors: TAUBER HENRIK 
Published: May 2006

SummaryA static pollen collector developed for unpowered field operation was subjected to wind tunnel tests to assess its sampling efficiency for a range of pollen sizes and varying wind velocities. The pollen collector and the testing procedure is described. It was found that the catch of particles is independent of whether the collector is operated with or without a roof. Within experimental errors the collection of pollen and spores is proportional to the orifice area. The collection efficiencies vary somewhat with size of pollen grains and with wind velocity, but in most cases less so than would be the case with a static sampler operated by impaction. At wind velocities around 2 m/s, which is close to average natural wind speeds in the lower atmosphere in forested areas, collection efficiencies thus are the same for big and small pollen grains. The overall efficiency of the collector is low, as is always the case with an unpowered collector that operates mainly by gravity settling. In return, the collector is designed to give a smooth flow of air over the orifice at all wind velocities and therefore a fairly predictable catch of pollen grains with varying conditions.
GROSS CHEMICAL CHANGES OCCURRING IN THE LEAF OF SIN APIS ALBA DURING PHOTOPERIODIC INDUCTION OF FLOWERING
Authors: KINET J. M. 
Published: May 2006

SummaryVegetative plants of Sinapis alba L. were induced to flower by exposure to a single 22‐h long day. At various time intervals after the start of the inductive treatment, leaves were collected and their gross chemical composition analysed. Chlorophyll and RNA contents were determined spectrophotometrically, starch content was determined by means of the anthronc method, proteins by the biuret method and DNA using the diphenylamine reaction. No change was found in fresh weight, chlorophyll, RNA and DNA contents of leaves of induced plants. There was, however, a tremendous increase in dry weight, starch, and protein contents of these leaves, culminating around 3.0 h after the start of the long day. The significance of these events is discussed in relation to photoperiodic induction in Sinapis.
ULTRASTRUCTURE OF THE INTERACTION BETWEEN PHYTOPHTHORA INFESTANS AND LEAVES OF TWO CULTIVARS OF POTATO (SOLANUM TUBEROSUM L.) ORION AND MAJESTIC
Authors: SHIMONY CARMELA , FRIEND JOHN 
Published: May 2006

SummaryElectron microscopy was used to follow the course of infection of leaves of a susceptible (Majestic‐r) and a resistant (Orion‐R1) potato variety by Phytophthora infestans (race 4). Shortly after penetration, an infection vesicle was formed in both varieties but the subsequent stages of infection differed. In Majestic, hyphae spread both intra‐and intercellularly and even 48 h after inoculation there were still juvenile‐type hyphae inside mesophyll cells which appeared undamaged. In Orion juvenile parts of hyphae were not seen in or near intact cells later than 7–12 h after inoculation. Orion cells died at an early stage, but death of the fungus only occurred more than 12 h after inoculation.These results are discussed in relation to current hypotheses concerning hypersensitivity and it is suggested that a toxin is produced by the interaction of the fungus with Orion.
CARBOHYDRATE METABOLISM IN THE FUNGUS DENDR YP HI ELLA SALINA V. THE PATTERN OF LABEL IN ARABITOL AND POLYSACCHARIDE AFTER GROWTH IN THE PRESENCE OF SPECIFICALLY LABELLED CARBON SOURCES
Authors: LOWE D. A. , JENNINGS D. H. 
Published: May 2006

Summary Dendryphiella salina was grown in a sea‐water nitrate medium with the following specifically labelled carbon sources: [1‐14C]‐, [2‐14C]‐, [6‐14C]‐glucose, [1‐14C]‐ribose and [1‐14C]‐glycerol. The data for distribution of 14C in polysaccharide hydrolysable with 1.0 N H2SO4 indicate that much of it is produced directly from glucose but there is confirmation of other studies that some is synthesized from mannitol. The distribution of label in arabitol is consistent with synthesis from ribose via xylulose. High activity is consistently found in carbon 3 of arabitol which is only explicable in terms of randomization in glycerol and the transketolase exchange reaction previously demonstrated to occur in rat liver.
THE EXTENSION ZONE OF STAGE I SPORANGIOPHORES OF PHYCOMYCES BLAKESLEEANUS
Authors: TRINCI A. P. J. , HALFORD ELIZABETH A. 
Published: May 2006

SummaryThe length of the extension zone of stage I sporangiophores of Phycomyces blakesleeanus was determined from measurements of the apical region which responded phototropically to unilateral illumination; the extension zone varied in length from 50 to 950 μm. A significant relationship was observed between extension zone length and growth rate. The length of the extension zone of the sporangiophores could also be determined by measuring the length of the tapered region of their tips.
EFFECT OF LIGHT ON ASCOSPORE DISCHARGE BY FIVE FUNGI WITH BITUNICATE ASCI
Authors: BROOK P. J. 
Published: May 2006

SummaryExperiments on ascospore discharge from naturally developed perithecia were conducted in a wind tunnel. Discharge by Venturia pirina, V. rumicis and Venturia sp. was stimulated by light, particularly by red, but also by green and blue. There was always a sharp decline in discharge rate after perithecia of these species and of V. inaequalis were plunged from light into darkness. In V. inaequalis a high rate of discharge persisted for several minutes after the change to darkness. It is postulated that in these bitunicate fungi a photoreaction is involved in the rupture of the exoascus tip. Coleroa circinans, another bitunicate species, discharged its ascospores equally readily in light and darkness.
MOVEMENT OF ETHYLENE FROM ROOTS TO SHOOTS, A FACTOR IN THE RESPONSES OF TOMATO PLANTS TO WATERLOGGED SOIL CONDITIONS
Authors: JACKSON MICHAEL B. , CAMPBELL D. JOAN 
Published: May 2006

SUMMARYEpinastic growth by petioles of tomato (Lycopersicon esculentum Mill., cv. Moneymaker) is stimulated by waterlogging the soil and the responding leaves and other shoot parts contain higher concentrations of ethylene than those of non‐waterlogged plants. Waterlogged soil also contains increased amounts of ethylene in solution and the possibility that ethylene from this source can move to the shoots of waterlogged plants has been tested by applying the gas to the roots of plants growing in water culture. When concentrations of 2 ppm and above are supplied in this way, petiole epinasty develops in association with increases in ethylene extracted from the responding petioles. When 100 ppm is applied to the roots, increases in ethylene in the petioles precede the development of epinastic growth. Use of [14C] labelled ethylene indicates that the gas can move rapidly, unchanged from roots to shoots. The movement of ethylene and epinastic growth are both reduced if plants are previously steam‐girdled near the base of the stem, suggesting that much ethylene moves by a route other than the transpiration stream. Ethylene supplied to the roots is shown to promote adventitious rooting and downward rolling of the young leaf laminae and to modify the orientation of shoot growth in the tomato mutant‘diageotropica’.It is proposed that increases in soil ethylene and movement of the gas to the shoot system are factors contributing to the development of epinasty and other responses of the shoots to waterlogging the soil.