bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE INFLUENCE OF VESICULAR‐ARBUSCULAR MYCORRHIZAS ON PHOSPHORUS TRANSFER BETWEEN PLANTS
Authors: HEAP ALISON J. , NEWMAN E. I. 
Published: May 2006

SUMMARYIn six experiments Lolium perenne L. and Plantago lanceolata L. were grown together in pots. Two experiments also included L. perenne alone, P. lanceolata alone, or L. perenne + Trifolium repens L. In five of the experiments prior sterilization of the soil followed by reinoculation was used to obtain two treatments, one having plants infected with vesicular‐arbuscular mycorrhiza, the other non‐mycorrhizal. The shoots of some plants in each pot (‘donors’) were injected with 32P. After a week these shoots were removed, and after a further week the remaining plants (‘receivers’) were harvested and their 32P content determined.In all experiments and species‐combinations there was some 32P transfer to the shoots of both mycorrhizal and non‐mycorrhizal receiver plants. The amount of transfer in mycorrhizal treatments was 2 to 8‐fold greater than in non‐mycorrhizal treatments, except in one experiment where mycorrhizal infection was very low. There was no clear difference between the different species combinations in the amount by which phosphorus transfer was enhanced by mycorrhizas. These results show that mycorrhizas can increase phosphorus transport between plants, but do not show whether there is direct transport from one root to another via interconnecting hyphae or whether the phosphorus must leave the donor root before being taken up by mycorrhizal hyphae.
THE HOST‐PARASITE RELATIONSHIP BETWEEN ZIZANIA CADUCIFLORA TURCZ. AND USTILAGO ESCULENTA P. HENN. IV. GROWTH SUBSTANCES IN THE HOST‐PARASITE COMBINATION
Authors: CHAN YUK‐SIM , THROWER L. B. 
Published: May 2006

SUMMARYThe mycelial and sporidial stages of Ustilago esculenta could synthesize IAA in vitro, especially if the medium contained tryptophan. Extract from culms of its host, Zizania caduciflora, contained tryptophan and was a suitable medium for the production of IAA. Significant levels of IAA occurred in non‐sporulating and sporulating culms. The culms also contained three cytokinins (presumed to be zeatin and zeatin riboside with one unidentified). Total amounts of cytokinins were (kinetin equivalents): unswollen culm, 8·5 μg 100 g‐1; non‐sporulating culm, 11·9 μg 100 g‐1; sporulating culm, 1·3 μg 100 g fresh wt‐1. U. esculenta was able to produce zeatin in culture but the other cytokinins originated from the host or host‐parasite combination. A possible sequence of events is proposed to explain the formation of gau sun from the flowering culm.
THE RESOURCE COSTS OF GENDER AND MATERNAL SUPPORT IN AN ANDROMONOECIOUS UMBELLIFER, SMYRNIUM OLUSATRUM L.
Authors: DOUST J. LOVETT , HARPER J. L. 
Published: May 2006

SUMMARYIn hermaphrodite flowers the various organs are potentially in competition with each other for resources translocated via the peduncle. It is an interesting question to ask: in what proportions does a plant with hermaphrodite flowers allocate various potentially limiting resources between these potentially ‘competing’ organs – between sporophylls and organs of attraction (petals, nectaries) and between stamens and pistils? The question becomes even more interesting in an andromonoecious species in which the plant supplies resources to both male and hermaphrodite (perfect) flowers.In the biennial andromonoecious umbellifer Smyrnium olusatrum L. a constant ratio of one hermaphrodite flower to four staminate flowers was found to be maintained despite a fivefold range in both total flower number and total plant dry wt produced by surgery and nutrient depletion.The allocation of nitrogen, phosphorus and potassium in floral organs was studied in S. olusatrum that had received various experimental treatments.The ratio of resource allocated to sporophylls and to ancillary attractive organs was found to remain relatively constant whereas the allocation to the two types of attractive organs (petals and stylopodia) tended to vary with the experimental manipulations. The relative allocation of nutrient resources to male and female activities was scarcely altered by the treatments. Before fertilization plants distributed a greater (c. fivefold) proportion of phosphorus to male than to female organs. However, the cost of placental support of developing embryos reversed the ratio such that at seed maturity a greater proportion of phosphorus (c. × 2) had been allocated to seed than to stamens.
HIGH TEMPERATURE‐INDUCED INACTIVATION OF SPOROPHYTIC SELF‐INCOMPATIBILITY IN IPOMOEA FISTULOSA
Authors: PRABHA KIRAN , SOOD RENUKA , GUPTA SHRISH C. 
Published: May 2006

SUMMARYHot water treatments (50–55 °C) given to the stigmatic ends of excised pistils, just before pollination, overcame the self‐incompatibility barrier in Ipomoea fistulosa, a species with sporophytic self‐incompatible system. The minimal dose for inactivation of this barrier is treatment at 50 °C for 2 min but the optimum response is after 6 to 8 min. On increasing the temperature to 55 °C the optimum response is achieved in a shorter time. The changed, compatible behaviour, is reversed if pollination of the stigma is delayed for a day after the heat treatment. The rate of recovery of self‐incompatibility depends on the initial heat treatment given to the stigma.
EXPERIMENTAL ANALYSIS OF FLUORIDE SUSCEPTIBILITY OF GRAPE VINE (VITIS VINIFERA L.): FOLIAR FLUORIDE ACCUMULATION IN RELATION TO AMBIENT CONCENTRATION AND WIND SPEED
Authors: DOLEY D. 
Published: May 2006

SummaryThree cultivars of Vitis vinifera L. (Chardonnay, Gordo and Traminer) were exposed to ambient gaseous fluoride concentrations of 0.37 to 6.0 μg F m−3 for 60 to 159 d during four successive growing seasons. In two growing seasons plants were fumigated for either 4 or 24 h d−1. The rate of accumulation of fluoride by leaves of each variety was independent of the presence or absence of visible injury. Within the range of conditions tested, fluoride accumulation was best described as the product of an accumulation coefficient characteristic of the variety, ambient fluoride concentration, duration of exposure, and wind speed at the top of the plant canopy. Leaves exposed to fluoride for 4 h d−1 accumulated fluoride more rapidly with respect to the dose (ambient concentration × exposure time) than did leaves exposed for 24 h d−1. The application of the findings to the study of fluoride accumulation in the field is discussed.
QUANTITATIVE DETERMINATION OF SIEVE‐TUBE DIMENSIONS IN RICINUS, CUCUMIS AND MUSA
Authors: MILBURN J. A. , KALLARACKAL J. 
Published: May 2006

SummaryThe percentage cross‐sectional area of sieve tubes in the phloem of Ricinus communis L. var. Gibsonii, Cucumis myriocarpus Naud. and Musa sp. L. (cv. Williams) was determined from thin serial sections stained for callose fluorescence. A new maceration method was developed to measure the percentage cross‐sectional area as well as the dimensions of a large number of sieve‐tube members in Ricinus.Determinations of the proportion of sieve tubes in the phloem showed that this varied in different plants, and also in different parts of the same plant. Except in Cucumis, the petiole showed a much higher proportion when compared with stem and fruit stalk. The measurements of the diameter and length of sieve tube members in Ricinus revealed interesting distribution patterns.
A THERMOGRADIENT BAR APPARATUS FOR THE STUDY OF THE GERMINATION REQUIREMENTS OF BURIED SEEDS IN SITU
Authors: THOMPSON K. , WHATLEY J. C. 
Published: May 2006

SummaryAn apparatus is described which enables a layer of soil, containing naturally‐buried seeds, to be subjected to controlled temperature fluctuations over the range 5 to 30 °C, in the presence or absence of light. Results obtained from the use of this apparatus are presented for 14 species, all common constituents of the buried seed bank and nearly all weeds of arable land or pasture. At least partial inhibition of germination by darkness was found in all 14 species and stimulation of germination by temperature fluctuations in all but one. In some cases germination was inhibited by very large fluctuations.There was some evidence that a requirement for temperature fluctuations may be induced by burial. The ecological significance of the results and the limitations of the thermogradient apparatus are discussed and some further applications of the apparatus are suggested.
GENECOLOGICAL STUDIES OF URTICA DIOICA L, II, PATTERNS OF VARIATION AT WICKEN FEN, CAMBRIDGESHIRE, ENGLAND
Authors: POLLARD A. J. , BRIGGS D. 
Published: May 2006

SummaryAn extreme genetic variant of Urtica dioica L. (stinging nettle), differing from the common plant in its paucity of stinging hairs, tall unbranched growth form, long narrow leaves and late flowering, occurs in large numbers at Wicken Fen, Cambridgeshire, England. Evidence from experimental cultivation of plants collected as adults and as seed along a transect across and beyond the boundaries of Wicken Sedge Fen suggests that:

Significant gene flow into the Sedge Fen occurs by both seed and pollen transport.
Pollen flow has significant within‐population effects also, acting to even out variation expressed in the adult generation.
Patterns of variability in adults do not indicate that natural selection is acting to limit the range of variability contained in the seed population.
Selection may, however, be occurring, since for this long‐lived perennial, patterns of variability may be more related to historical factors than to current ones.
MEMBRANE POTENTIAL COMPONENTS OF THE MARINE FUNGUS DENDRYPHIELLA SALINA (SUTH.) PUGH ET NICOT. POSSIBLE INVOLVEMENT OF CALMODULIN IN ELECTROPHYSIOLOGY AND GROWTH
Authors: BROWNLEE C. 
Published: May 2006

Summary Dendryphiella salina has membrane potentials of around −250 mV. Inhibition of respiration produced large, rapid and reversible depolarizations, which suggests the presence of an electrogenic pump. The Ca2+‐calmodulin inhibitor trifluoperazine in the micromolar range reversibly depolarized the membrane potential and irreversibly (or only slowly reversibly) decreased membrane conductance. Trifluoperazine inhibited hyphal extension but did not alter branching, although branching was stimulated at the hyphal tips following removal of the inhibitor.
THE RESPONSES OF SIX BROADLEAVED TREES DURING LONG‐TERM EXPOSURE TO SO2 AND NO2
Authors: FREER‐SMITH P. H. 
Published: May 2006

SummaryIn three experiments young trees were exposed to SO2 and NO2, singly and in mixtures, at concentrations of 110 nl l−1 or 100 nl l−1 for 5 d each week, and their growth was compared with that in clean air.Exposure of Populus nigra during the summer and autumn (11/6/80 to 12/11/80) showed that greater than additive and additive growth inhibitions occurred in SO2 and NO2 during the growing season. Exposure to SO2 during dormancy (29/1/81 to 9/4/81) delayed leaf growth in the following spring, but the presence of NO2 did not influence this effect. Detailed observations of a few plants of six species during summer and winter fumigation (23/3/81 to 17/5/82) confirmed that the responses were influenced by season, and showed that pollutant effects can change during continuous exposures. In SO2 the growth effects did not occur to Tilia cordata, Malus domestica, Betula pendula and P. nigra until the second year of exposure, but in Betula pubescens and Alnus incana decreases of dry weight occurred in the first year. Nitrogen dioxide alone initially stimulated the shoot growth of T. cordata, B. pendula and A. incana, but these effects were lost for T. cordate and B. pendula in the second season of exposure. Inhibitory effects on a number of parameters developed more rapidly in SO2+ NO2 mixtures than in SO2 alone. In most instances the nature of these responses altered after overwintering, with the damage done by SO2 becoming more marked and the beneficial effects of NO2 being lost.The responses to SO2 and NO2, were variable, depending on species, on the duration of exposure and the time of year. Sequential observations of the shoots suggested that the physiology of growth influenced pollution sensitivity. Foliar blemish, senescence and abscission were the main symptoms of injury in SO2 and SO2+ NO2, and the severity of these effects was well correlated with the magnitude of the decreases in dry weight.
THE POSSIBILITY OF CELL PLATE‐INDUCED PLASTID DIVISION IN A FLOWERING PLANT
Authors: STAFF I. A. , PARTHASARATHY M. V. 
Published: May 2006

SummaryPlastid division, presumably caused by constriction by a developing cell plate, is described as seen once in a seedling root ofXanthorrhoea thorntoniiR. Tate (Monocotyledonae). Such a method of plastid division for a higher plant is novel, and may be caused either by an anomalous or a normal cell division. Similar types of plastid division have been observed in the green algae, bryophytes and lycopods with low numbers of plastids, so that it is possible that the occurrence of such a phenomenon is a rare but natural event in angiosperms. If constriction in an abnormal position of the plastid is forced by the cell wall, then heredity of the plastid derivatives may be perturbed. The involvement of the developing cell plate as an agent that might sometimes cause ‘sister’ plastids of a plastid division to go to different cells is a possibility that has, in the past, been overlooked for angiosperms.
THE EFFECT OF GREENING ON FLAVOUR PRODUCTION IN CELERY TISSUE CULTURES
Authors: WATTS M. J. , GALPIN I. J. , COLLIN H. A. 
Published: May 2006

SummaryThe relationship between greening and production of flavour compounds was investigated in blanched and green young (10‐week) and mature (20‐week) celery plants, and in colourless and green celery cell suspensions. In the young plants the concentrations of limonene and other terpenoids increased in the petiole and leaf‐extract as the level of chlorophyll increased. In the cell cultures, greening was induced by transferring cells to a medium where 2,4‐dichlorophenoxyacetic acid (2,4‐D) was replaced by 3,5‐dichlorophenoxyacetic acid (3,5‐D). During the first subculture, phthalides were produced in the growth phase, but were present in trace amounts only in the second and third subculture. Limonene, however, increased after the first subculture and during the growth phase of the third subculture was comparable to the levels in the young celery plant. Greening and aggregation of the cells had also increased by the third subculture in the 3,5‐D‐containing medium. It was suggested that phthalide production was stimulated by the transfer from a 2,4‐D‐ to a 3,5‐D‐containing medium, but as the level of aggregation and greening increased in the culture, phthalide production was reduced and limonene production increased. Electron and light microscope pictures showed that, despite the greening and aggregation, there was no chloroplast formation or cell differentiation in the cultures incubated with 3,5‐D. The role of greening in stimulating the formation of celery flavour compounds in tissue cultures is discussed.
AN ENDOMYCORRHIZA‐ECTOMYCORRHIZA SUCCESSION ASSOCIATED WITH ENHANCED GROWTH OF EUCALYPTUS DUMOSA SEEDLINGS PLANTED IN A CALCAREOUS SOIL
Authors: LAPEYRIE F. F. , CHILVERS G. A. 
Published: May 2006

SummarySeedlings of Eucalyptus dumosa A. Cunn. ex Schau., derived from a parent tree growing in a patch of calcareous soil, grew very poorly or not at all in that same soil unless they had formed abundant mycorrhizas. Other seedlings of that tree, planted in non‐calcareous soil from the same locality, grew well with negligible mycorrhizas. Similar results were obtained using synthetic calcareous and non‐calcareous potting mixtures. E. dumosa appears therefore to be primarily a calcifuge species, which becomes secondarily or facultatively calcicole as a consequence of mycorrhiza formation. Inflow of calcium into the seedlings with many mycorrhizas was the same as that into seedlings with few, but phosphorus inflow was greater into the mycorrhizal system. Mycorrhizas were presumably more effective at mobilizing and accumulating phosphate from insoluble calcium phosphates in the calcareous substrates than were uninfected roots.Early infection of the seedlings was almost entirely by VA endomycorrhizal fungi, in contrast to the ectomycorrhizal fungi which are usual in eucalypts. Most of the growth stimulus seemed to be associated with these early endomycorrhizas. Ectomycorrhizas formed later and tended to replace the endomycorrhizas. The ectomycorrhizas which succeeded the endomycorrhizas in inoculated pots were of a different type (hyaline) from those (black) which developed spontaneously, presumably from airborne spores, on uninfected roots in uninoculated pots.
PHOTOSYNTHESIS BYFONTINALIS ANTIPYRETICA
Authors: MABERLY S. C. 
Published: May 2006

SummaryRates of net photosynthesis of the aquatic mossFontinalis antipyreticaHedw. were measured at seven levels of photon irradiance and five or six concentrations of CO2at the ambient temperature of the collection site, Esthwaite Water, in four months during a year. The effect of each factor on rates was assessed by fitting the data to models using non‐linear and linear regressions. There was no evidence for photoinhibition. The light compensation point was generally low compared with published values. The CO2compensation point was similar to that of C3plants. The slope of photosynthesisvsCO2concentration increased linearly with temperature in a manner consistent with the effects of boundary‐layer resistance. Other estimated and calculated variables are presented and discussed. Rates of saturated gross photosynthesis, compensation points and indices of degree of saturation varied with the level of the second factor. The results emphasize the interaction between photon irradiance, CO2concentration and temperature and the necessity of taking all these into account when studying the effect of one of these factors on photosynthesis.
PHOTOSYNTHESIS BY FONTINALIS ANTIPYRETICA
Authors: MABERLY S. C. 
Published: May 2006

SummaryEnvironmental variables in the North Bay of Esthwaite Water, where the aquatic moss Fontinalis antipyretica Hedw. grows, were measured over a year. Steep depth profiles often existed in the water column of about 1 m, with lower pH and higher alkalinity 01m above the sediment where F. antipyretica was found. Consequently, CO2 concentration was higher at depth than at the surface. The North Bay generally had higher CO2 concentrations than the centre of the lake. The survival of F. antipyretica in this productive lake probably results partly from these elevated concentrations of CO2.Nutrient limitation of production was discounted since tissue levels of phosphorus and nitrogen were about six and four times greater respectively than suggested limiting levels of these nutrients. Rates of photosynthesis, respiration and production were calculated from the field data and the previously‐determined measurements of the effect of photon irradiance, CO2 concentration and temperature on photosynthesis. In all the four months studied, no single factor appeared to be predominantly limiting. Calculations suggested that in November, photon irradiance and in March, temperature were the major factors limiting production, both as a result of physical conditions. In August, low CO2 concentration, caused by the activity of dense phytoplankton, was the major factor limiting production.
PHYTOCHROME REGULATION OF EXTRACTABLE CYTOCHROME OXIDASE ACTIVITY DURING EARLY GERMINATION OF BROMUS STERILIS L. AND LACTUCA SATIVA L. CV. GRAND RAPIDS SEEDS
Authors: HILTON J. R. , OWEN P. D. 
Published: May 2006

SummaryPhytochrome‐induced changes in the activity of cytochrome oxidase, the respiratory enzyme involved in the terminal oxidation of substrates of the tricarboxylic acid cycle, have been detected during the early stages of germination prior to radicle protrusion. Photoreversible changes in extractable enzyme activity have been demonstrated in the seeds of two species; Lactuca sativa, in which germination is promoted by Pfr, and Bromus sterilis, in which germination is inhibited by Pfr.
RESPONSES OF RADISH CULTIVARS TO LONG‐TERM AND SHORT‐TERM EXPOSURES TO SULPHUR DIOXIDE, NITROGEN DIOXIDE, AND THEIR MIXTURE
Authors: GOKZIK S. , ASHMORE M. R. , BELLF J. N. B. 
Published: May 2006

SummarySix cultivars of Raphanus sativus L. were fumigated continuously with 400 fig m−3 sulphur dioxide (SO2) or nitrogen dioxide (NO2), or their mixture at 400 fig m−3 for each gas, for 20 d, after which plants were exchanged between treatments and subjected to 3 h fumigations with higher concentrations of the same gases. SO2 reduced hypocotyl dry weight in three cultivars, while NO2 had no significant effect; large reductions in hypocotyl dry weight occurred in all six cultivars in the gas mixture. All long term fumigation treatments tended to reduce the amount of leaf injury caused by subsequent exposure to a mixture of 1300 fig m−3 SO2 and 950 fig m−3 NO2 for 3 h. Long‐term fumigation with NO2 alone tended to increase the amount of leaf injury caused by subsequent exposure to SO2 alone. A decrease in 35SO2 uptake was found in plants which had been given long‐term fumigation with SO2 or with SO2+ NO2.
STUDIES ON THE MYCORRHIZAS OF PINU SYLVESTRIS L. PRODUCED IN VITRO WITH THE BASIDIOMYCETE SUILLUS VARIEGATUS (SW. ex Fr.) O. KUNTZE
Authors: WARMBRODT R. D. , ESCHRICH W. 
Published: May 2006

SummaryEctomycorrhizas of Pinus sylvestris L. synthesized in vitro with Suillus variegatus (Sw. EX Fr.) O. Kuntze were studied by light and electron microscopy. Approximately two months following innoculation of germinated seedlings of Pinus sylvestris with the fungus, the host showed well‐developed ectomycorrhizas each consisting of a fungal mantle, tannin layer and Hartig net region surrounding the endodermis and root vascular cylinder. The mantle formed by the mycosymbiont was 3 to 10 hyphae deep and covered the root tip completely but did not invade the cells of the apical meristem. The tannin layer consisted of dead host cells, apparently derivatives of the root cap, containing electron‐dense deposits. Fungal cells which did not differ in appearance from those forming the mantle and the Hartig net were appressed to the tannin layer, partly embedded in an electron‐dense mucilaginous substance. The fungal hyphae in the Hartig net region were up to several cells in thickness but did not penetrate the protoplasts of the root cortex cells nor the intercellular spaces beyond the endodermis. The presence of plasmodesmata in the cell walls not separated by the fungal hyphae indicated that symplastic continuity of the root cells in the Hartig net region was not completely disrupted. The ultrastructure of the various cells of the mycorrhizas plus examination of free‐hand sections indicate that the mycorrhizas, at the time of fixation, were viable associations. The structure of the mycorrhizas produced in vitro is compared and discussed with respect to naturally occurring mycorrhizas on the same host species.