bluuebunny/crossref_metadata_2025_split huggingface dataset:
TRANSLOCATION OF SULPHITE IN VICIA FABA L.
Authors: GARSED S. G. , MOCHRIE ANNE 
Published: May 2006

SummaryThe translocation of radioctivity was studied quantitatively and qualitatively after application of droplets containing Na235SO2 to leaves of Vicia faba L. and using the aphid species Megoura viciae Buckt. to tap sieve elements in the atexn. Concentrations of 4 and 8 mM Nag235SO2 were chosen after studying the effects of a range of sulhite concentrations on 14CO2 fixation.Extracts of leaves contained 35S‐labelled sulphite, sulphate and organic material. Only sulphite and sulphate were labelled in honeydew. The aphids contained sulphate and soluble organic compounds, but no sulphite. Extracts of aphids contained more radioactivity 0.5 h after application of Na235SO2 to the source leaf than after 24 h. It is concluded that incompletely oridized sulphur compounds can be translocated, and the results are discussed with reference to the uptake of the atmospheric pollutant sulphur dioxide and its effects on plant growth and development.
ROOT SIZE, ROOT HAIRS AND MYCORRHIZAL INFECTION: A RE‐EXAMINATION OF BAYLIS'S HYPOTHESIS WITH TROPICAL TREES
Authors: JOHN T.V. St 
Published: May 2006

SummaryA series of 89 Brazilian forest species, for which root characteristics and VA mycorrhizal condition were known, was used to test an aspect of Baylis's magnolioid root hypothesis. A non‐parametric statistical test showed a significant association between magnolioid root characteristics and VA infection.
AN EVALUATION OF TECHNIQUES FOR MEASURING VESICULAR ARBUSCULAR MYCORRHIZAL INFECTION IN ROOTS
Authors: GIOVANNETTI M. , MOSSE B. 
Published: May 2006

SummaryAssessment of infection is an essential part of many studies involving VA mycorrhiza. A summary is given of the range of techniques that have been used. We calculated the standard error of four methods of assessment based on observations of stained root samples either randomly arranged in a petri dish or mounted on microscope slides. The methods are based on presence or absence of infection at root/grid intersect points, on a visual estimate of percentage cortex occupied by fungus or on estimates of length, or presence or absence of infection in root pieces mounted on slides. The number of replicate observations required for a given standard error % infection can be read from the curves provided. The advantages of the different methods of assessment are discussed and reasons given why they all probably overestimate the true values.
THE USE OF POLLEN ISOENZYMES AS AN AID TO THE BREEDING OF FIELD BEANS (VICIA FABA L.)
Authors: GATES P. , BOULTER D. 
Published: May 2006

summaryNon‐specific esterase and glutamate‐oxaloacetate transaminase isoenzymes, extracted from pollen and separated by electrophoresis on acrylamide gel, have been used to identify inbred lines and to measure crossing between them. Isoenzyme patterns were genotype‐specific and were not affected by a range of environmental variables or by prolonged storage of pollen at low temperature.
SOME GENERAL OBSERVATIONS ON ZOOSPORES OF THE CHYTRID RHIZOPHYDIUM PLANKTONICUM CANTER EMEND.
Authors: CANTER HILDA M. , JAWORSKI G. H. M. 
Published: May 2006

SummaryGeneral microscopic observations of zoospores of the chytrid Rhizophydium planktonicum Canter emend, contained within a small glass chamber, have shown that they have strong reactions to visible light. There appears to exist a threshold level of dim light below which zoospores will eventually enter what is termed the ‘state of quiescence’ and above which they will continue to maintain active swimming. Alternations between these two states can he manipulated with ease under the microscope. Free swimming zoospores after a period in dim light or darkness and quiescent zoospores both respond to sudden exposure to bright light.The concentration of zoospores into aggregates of individuals circling at the upper and or lower surfaces of a chamber is recorded. As viewed from above, those uppermost circle in a clockwise direction while those below go round counter‐clockwise.Adherence between zoospores as swimming individuals or in the encysted state has been seen but there is no evidence of any fusion taking place. A specially adapted channel image intensifier made possible the examination of material under infra‐red.
PHOTOREVERSIBLE CONTROL OF HETEROPHYLLY IN HIPPURIS VULGARIS L.
Authors: Bodkin P. C. , Spence D. H. N. , Weeks D. C. 
Published: May 2006

summaryThe freshwater macrophyte Hippuris vulgaris exhibits heterophylly. During July and August aerial‐type leaves occur even on immersed shoots down to a depth of 15 m in two clear‐water limestone lochs in Scotland. Complementary field and laboratory data indicate that a high intensity photoperiod and temperatures above 10°C are prerequisites for aerial‐type leaf production on submerged shoots. In these conditions, regular injections of additional sucrose, the natural photosynthate, at 05 mol kg−1 fresh weight will not induce the aerial‐type leaf. There is relatively little attenuation of blue light with depth in these lakes and additional blue light just after the photoperiod does not induce the aerial‐type leaf. There is no evidence for an ontogenetic or circadian photoperiodic requirement for the production of aerial‐type leaves, or that heterophylly is mediated by ethylene.However, a low ratio of red (R 660 run) to far red (FR 730 run) light throughout, or very dimly for a brief period just after, the photoperiod treatment regularly induces aerial leaf formation on submerged shoots of any length. A similar low R/FR ratio is found naturally in these lakes in summer at depths where submerged aerial leaves occur. Selective attenuation of far red by lakewaters raises the R/FR ratio steeply with increasing depth. At R/FR ratios above a critical range, which is similar in field and laboratory, aerial leaf formation is inhibited and only submerged‐type leaves are formed. Simply by changing the R/FR ratio, either during or briefly after the photoperiod, transitions between submerged and aerial‐type leaves are repeatedly reversible, implying direct phytochrome control.
NEW EVIDENCE CONCERNING THE ORIGIN OF INLAND RADIATE GROUNDSEL, S. VULGARIS L. VAR. HIBERNICUS SYME
Authors: INGRAM RUTH , WEIR JACQUELINE , ABBOTT RICHARD J. 
Published: May 2006

summaryTriploid hybrids 5. vulgaris L.×S. squalidus L. were synthesized, frequently using a diverse array of radiate and non‐radiate plants of S. vulgaris as the female parent. All hybrids have so far proved sterile when selfed. By backcrossing one hybrid (S. vulgaris L. var. vulgaris×S. squalidus L.) to the female parent, and then selfing the products, several fertile radiate individuals were formed that were tetraploid and resembled S. vulgaris L. var. hibernicus Syme. The implication of these results for the possibility of introgression occurring between S. vulgaris and S. squalidus in the wild is discussed.
THE VEGETATION OF THE SUMMIT ZONE OF MOUNT KINABALU
Authors: SMITH J. M. B. 
Published: May 2006

SummaryThe summit zone of Mt Kinabalu (4101 m) largely comprises exposed rock, but nevertheless includes in its flora plants with various and geographically distant affinities. The vegetation of the zone has not hitherto been adequately described. Eighty‐three plots with 98 vascular plant species were studied. Vegetation types recognized are upper mountain forest (3260 to 3550 m), summit scrub (3720 to 3950 m), sayat‐sayat scrub (3300 to 3800 m), summit heath (3850 to 4020m), three depauperate crevice communities (together 3330 to 4040m), seepage fens (3320 to 3590 m) and sandy depressions (3500 to 4040 m). All except upper mountain forest and the crevice communities are very local in distribution, and none are anthropogenic. Ecological controls are suggested. Disturbed vegetation along the summit path is also described, and alien species are listed. Comparison is made between the vegetation of Mt Kinabalu and; of mountains in New Guinea.
STRUCTURAL STUDIES ON HEALTHY AND NECROTIC YOUNG EPIDERMAL CELLS OF GROWING POTATO SPROUTS
Authors: LYSHEDE OLE B. 
Published: May 2006

SummaryA structural study of pre‐emergence growth stages of potato sprouts is described. Dormant cells contain concentric endoplasmic reticulum. No differences are to be found in the palisade‐like epidermal cells of sprouts at different growth stages. The cells are filled with ribosomes and contain an abundance of other organelles. The thickish outer wall is covered by a thin electron‐dense cuticle.Necrotic epidermal and subepidermal cells were frequently observed. The walls of such cells appear to have decomposed, followed by extrusion to the plant surface of disintegrating cytoplasm that spreads over large areas. The type of necrosis investigated here is believed to be identical to one due to calcium deficiency, described by several previous authors. Its possible pathological aspects are briefly discussed.
OBSERVATIONS ON THE MECHANISM OF CHLOROPLAST DIVISION IN HIGHER PLANTS
Authors: LEECH RACHEL M. , THOMSON W. W. , PLATT‐ALOIA K. A. 
Published: May 2006

SUMMARYThe sequence of changes in membranes that occur during the division of young green chloroplasts is described from observations in the electron microscope of thin sections of leaf tissue of Triticitm aestivum var. Maris Dove, Atriplex semibaccata R.Br. and Sesamum indicum var. glauca. Comparative observations of the morphological forms of dividing chloroplasts present in suspensions from young wheat leaves were made using phase contrast and Nomarski interference optics and from thin sections. The isthmus region of the dividing chloroplasts has a similar form in all three species and fuzzy plaques of electron opaque material and some invaginations in the isthmus were frequently observed. The significance of these fuzzy plaques is discussed and a possible mechanism for chloroplast division suggested.
CHARACTERIZATION OF EXTRANEOUS PARTICLES LOCATED ON THE LEAF SURFACE OF SEVERAL PLANT SPECIES
Authors: BAKER E. A. , JEFFREE C. E. 
Published: May 2006

SUMMARYMicroscopic particles, distributed randomly over the leaf surfaces of several plant species, are identified as artefacts arising from contamination by populations of adult whitefly (Trialeurodes vaporarium). The larger particles are shown to be whitefly eggs contained within a capsule. The smaller particles, in the form of grooved ribbons or coils;, form part of a waxy secretion covering the eggs and the whole surface of the adult insect. The waxy material was composed predominantly of glyceryldioctadecenylhexadecanoate.
PALAEOBOTANY AND PLEISTOCENE STRATIGRAPHY IN BRITAIN
Authors: WEST R. G. 
Published: May 2006

SUMMARYThe history of the application of palaeobotany to the development of Pleistocene stratigraphy in Britain is reviewed. Problems arising in the interpretation of pollen assemblages are discussed from palaeobotanical and stratigraphical points of view. Problems of correlation and nomenclature are also discussed.
INHIBITION OF GROWTH OF ECTOMYCORRHIZAL FUNGI IN CULTURE BY PHOSPHATE
Authors: GILTRAP N. J. , LEWIS D. H. 
Published: May 2006

SUMMARYThe influence of pH on the growth of, and carbohydrate utilization by, three ectomycorrhizal fungi in culture was assessed by growing them on glucose, sucrose and raffinose in the presence and absence of 0‐05 M phosphate buffer and 0‐05 M 2‐(N‐morpholino) ethane‐sulphonic acid buffer (MES). This concentration of phosphate significantly inhibited growth of Cenococcum geophilwn and Rhizopogon roseolus on all carbon sources. Suillus bovinus was more tolerant, exhibiting uninhibited growth on glucose, though adaptive growth on both sucrose and raffinose was significantly less in phosphate buffer than in the other two systems. MES had a superior buffering capacity and was less inhibitory to growth of the three fungi than phosphate buffer. The growth of C. geophilum on all carbon sources was uninhibited in MES, although this buffer significantly inhibited adaptive growth by the other two species on sucrose and raffinose, possibly by inhibiting induction or activity of invertase. The use of phosphate buffers by several workers in tests of carbohydrate utilization by ectomycorrhizal fungi will undoubtedly have affected their growth. This may, to some extent, explain differences in patterns of utilization of carbon between isolates of the same species which have been reported by different investigators. These have previously been attributed to variability between strains in utilization of carbohydrate rather than in sensitivity to phosphate. Possible ways by which phosphate inhibits growth are discussed.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA XII. FIELD INOCULATION RESPONSES OF BARLEY AT TWO SOIL P LEVELS
Authors: CLARKE C. , MOSSE B. 
Published: May 2006

SUMMARYThe results are described of a field experiment in which barley was inoculated in the field by‐placing 20 g of soil containing infected roots below each sowing position. Three VA endophytes were used as inoculants and half the plots were given phosphate before sowing. Growth and infection were recorded twice during the experiment and at harvest. In the plots without added phosphate the fresh wt of ears was doubled by inoculation to approximately 100 gm‐2irrespective of endophytes. Added phosphate increased this more than inoculation and weight of ears rose to 200 to 300 gm‐2. With one inoculant dry wt of ears was 35% greater than with phosphate only, but with the other two it was marginally less. The results are discussed in relation to other experiments with barley and to the levels of infection throughout the experiment.
INTERACTION BETWEEN BEIJERINCKIA MOBILIS, ASPERGILLUS NIGER AND GLOMUS FASCICULATUS AND THEIR EFFECTS ON GROWTH OF ONION
Authors: MANJUNATH A. , MOHAN R. , BAGYARAJ D. J. 
Published: May 2006

SUMMARYEffect of inoculation with Gloms fasciculatus, Beijerinckia mobilis and Aspergillus niger, singly and in combination, on growth and nitrogen and phosphorus content of onion was studied. Inoculation with G. fasciculatus or B. mobilis increased the dry wt and nitrogen content of the plant. A. niger inoculation had no significant influence on plant growth. B. mobilis inoculation stimulated the sporulation by VA mycorrhizas. Synergistic beneficial effect due to inoculation with all the three organisms was observed.
STUDIES OF THE AZOLLA PINNATA‐ANABAENA AZOLLAE SYMBIOSIS: GROWTH AND NITROGEN FIXATION
Authors: TUNG H. F. , SHEN T. C. 
Published: May 2006

SUMMARY Azolla pinnata grown in a standard medium and on floodwater under the high light (30 to 120 klx) and high temperature (26 to 35°C) conditions of Malaysia doubled its fresh wt in about 3 and 5 days respectively. The main factor limiting growth and acetylene reduction activity (ARA) of the A. pinnata‐Anabaena assollae symbiotic association on floodwater was phosphorus. Addition of phosphorus (P) to P‐deficient Azolla in floodwater resulted in an immediate increase in ARA followed by an increase in the growth rate. Minus P treatment caused a 50% reduction of ARA but had little effect on the growth rate of Azolla in the first week. Continued culture of Azolla in the minus P medium caused a significant reduction in growth rate, ARA, and the formation of anthocyanin pigment in the fern. Subsequent transfer into a standard medium did not restore its ARA. Full sunlight also reduced the growth and ARA of Azolla, and P modified the response of Azolla to light.
THE STRUCTURE OF THE SPORES OF GIGASPORA MARGARITA. I. THE DORMANT SPORE
Authors: SWARD R. J. 
Published: May 2006

SUMMARYHistochemical tests, light and electron microscopy have been used to investigate the structure of the dormant spore of Gigaspora margarita (Endogonaceae). There is a plug in the neck of the mature spore consisting of a dense matrix of highly osmiophilic material bounded by wall‐like depositions. The complex spore wall is composed of four prominent layers, an inner and outer layer that contain polysaccharide, protein and lipid; a laminated chitinous layer and an ill‐defined‘cementing’layer.The cytoplasm is composed of amorphous material and a variety of granules and particles that form a fine network between large oil droplets. In certain areas the cytoplasm is concentrated and forms two dense regions named the 'synthesizing’and‘nuclear’centres which contain different proportions of various organelles. Two unusual types of organelles found in the cytoplasm of G. margarita spores have been previously described in honey‐coloured, sessile spores of Acaulospora laevis.
THE INFLUENCE OF LIGHT REGIMES DURING FLORAL DEVELOPMENT ON APOMICTIC SEED PRODUCTION AND ON VARIABILITY IN RESULTING SEEDLING PROGENIES OF POA AMPLA AND P. PRATENSIS
Authors: WILLIAMSON CYNTHIA J. 
Published: May 2006

SUMMARYThe influence of five light regimes during the period just prior to ear emergence until anthesis on Poa ampla, three P. pratensis biotypes and on the seedling progenies of an incomplete diallel cross between them, was examined. Both photoperiod and total irradiance affected seedling characters, their variances and dispersions, but the direction and magnitude of response differed between biotypes of P. pratensis. Results from P. ampla indicated that a higher proportion of amphimictic seed matured after 10‐h photoperiodic treatments than after 20‐h treatments. Biotypes differed in their response to light regimes in the period before and after ear emergence. The pollen parent and the interaction between pollen parent and light regime also affected seedling characters and their variances. Canonical analyses of discriminance were used to investigate interactions between seed parents, pollen parents and light regimes. The results are disussed in relation to different stages in apomictic seed production.
FLORISTIC DIVERSITY IN RELATION TO SOIL CHARACTERISTICS IN A LEAD MINING COMPLEX IN THE PENNINES, ENGLAND
Authors: CLARK R. K. , CLARK S. C. 
Published: May 2006

SUMMARYAdjacent species‐rich and species‐poor areas of a limestone outcrop were investigated in a heavy metal mining complex on Grassington Moor, Yorkshire, England, to determine reasons for the differences in their floras. Levels of soil lead, zinc, nitrogen, phosphorus and potassium were determined and the activities of the enzymes urease, acid phosphatase and dehydrogenase in the soil were measured. Soil respiration rates were also determined. The percentages of the variation in species‐density accounted for by each factor were determined using a step‐wise multiple regression technique. Binding of lead in organic forms resulting in low levels of available lead, together with higher levels of the major plant nutrients, were probably the main factors enabling a species‐rich community to occur on one part of the outcrop. Possible ways in which the differences in habitat became established are discussed.
REVERSIBLE EFFECTS OF FARNESOL ON COMMELINA COMMUNIS L.
Authors: MALLOCH K. R. , FENTON R. 
Published: May 2006

SUMMARYThe application of farnesol to isolated epidermis of Commelina causes stomatal closure and death of guard cells. Experiments are reported in which the toxic effects were reduced by manipulation of the assay conditions. Reversible stomatal closure by farnesol was observed in intact plants. These results are discussed in relation to similar physiological effects in Sorghum and the possible role of farnesol as an endogenous antitranspirant.
THE ACID INVERTASES OF THE DEVELOPING THIRD LEAF OF OAT
Authors: GREENLAND A. J. , LEWIS D. H. 
Published: May 2006

SUMMARYSoluble acid invertases, obtained from the developing third leaf of oat, were fractionated by gel filtration and ion‐exchange chromatography. Gel filtration separated two peaks. Isoenzyme II (85 × 103 daltons) was the dominant form in the non‐emerged leaf but decreased in activity after leaf emergence. The activity of isoenzyme I (143 × 103 daltons) remained constant throughout leaf development and was dominant in mature tissues. Ion‐exchange chromatography separated two discrete peaks (A and B) and a composite peak (C), comprised several isoenzymes. The activities associated with A, B and C varied considerably during leaf development. One or more of the isoenzymes of invertase in peak C was the predominant invertase at all stages of leaf development. These observations are discussed in relation to the role and control of synthesis of invertases during development.
MYCORRHIZAL INFECTION AND GROWTH OF TRIFOLIUM SUBTERRANEUM: COMPARISON OF NATURAL AND ARTIFICIAL INOCULA
Authors: SMITH F. A. , SMITH S. E. 
Published: May 2006

SUMMARYMycorrhizal infection and growth of Trifolium subterraneum have been measured, using plants grown in soil/sand mixtures containing natural inoculum, and plants grown in sterilized soil/sand mixtures to which mycorrhizal T. subterraneum roots were added as an artificial inoculum. As control treatments, plants have been grown in sterilized soil/sand mixtures without the addition of roots, or in soil/sand mixtures with the addition of non‐mycorrhizal roots.In one experiment, the two methods of inoculation resulted in similar increases in leaf numbers and in weight. In the second experiment, the growth responses of plants artificially inoculated were less than those of plants with natural inoculum and this was related to delayed mycorrhizal infection. In the third experiment, mycorrhizal infection was again delayed when artificial inoculum was used: this experiment was terminated before increases in weight occurred. The extent and location of mycorrhizal infection from artificial inoculum depended on the location (in the pots) of the added inoculum. The advantages and disadvantages of these two methods of studying mycorrhizal infection are assessed in relation to the different aims of investigations of the mycorrhizal symbiosis.
TRANSLOCATION AND TRANSFER OF NUTRIENTS IN VESICULAR‐ARBUSCULAR MYCORRHIZAS
Authors: COOPER KAREN M. , TINKER P. B. 
Published: May 2006

SUMMARYThis paper reports the effects of environmental variables on the movement of phosphate by external hyphae of the mycorrhizal fungus Glomus mosseae, infecting Trifolium repens (white clover), across a barrier in soil‐agar/agar split‐plate cultures. Increasing the transpiration rate of the host increased the total P translocated by the fungus: the maximum rate obtained at full transpiration was 2·3 times that at low transpiration. Temperature also affected P transport, which was at a maximum at 15 to 25°C, but at 5°C only a small amount of P was transported. The maximum P flux in the hyphae, calculated for 20 to 25°C and a moderate host transpiration rate, was 2 × 10‐9 mol cm‐2 s‐1. A cytoplasmic streaming inhibitor (cytochalasin B) prevented detectable movement of P across the barrier by the fungus and consequently had inhibited either the uptake or translocation of P by the fungus. Osmotic potentials of 1 or 2 bars in the medium from which 32P was being absorbed did not appreciably alter the rate of transport of P.The results support the general conclusion that translocation of P in the hyphae occurs normally by protoplasmic streaming but there may also be a‘bulk flow’of hyphal contents under a water potential gradient.
OBSERVATIONS ON THE MYCORRHIZAL STATUS OF SOME ALPINE PLANT COMMUNITIES
Authors: READ D. J. , HASELWANDTER K. 
Published: May 2006

SUMMARYIn some Austrian alpine plant communities, levels of vesicular‐arbuscular mycorrhizal infection are highest in closed herb‐rich communities of intermediate altitudes (1900 to 2500 m). In fertilized hay meadows of lower altitudes (1600 m) and in the nival zone above 3000 m, endogonaceous infection is light. In the latter, it is mainly by the fine endophyte, Glomus tenuis. Many plants throughout the altitudinal range of the survey are infected with dark septate hyphae and, in the Cyperaceae, this is the dominant infection. Ectomycorrhizas occur on some herbaceous species as well as on Salix up to 2500 m. The possible significance of the infection patterns is discussed.