bluuebunny/crossref_metadata_2025_split huggingface dataset:
COLONIZATION AND EFFICACY OF DIFFERENT ENDOMYCORRHIZAL FUNGI WITH APPLE SEEDLINGS AT TWO PHOSPHORUS LEVELS
Authors: MILLER DIANE DOUD , DOMOTO PAUL A. , WALKER CHRISTOPHER 
Published: May 2006

SummarySix species of vesicular‐arbuscular mycorrhizal fungi originally isolated from orchard soils were evaluated at low phosphorus (approx. 30 mg kg−1) and high phosphorus (approx. 180 mg kg−1) levels for root colonization and effects on growth of apple (Malus domestica Borkh.) seedlings. Fungi tested were Gigaspora calospora (Nicol. & Gerd.) Gerd. & Trappe, Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, Glomus maculosum sp. ined., Glomus manihotis Howeler, Sieverding & Schenck, Glomus bitunicatum sp. ined., and two isolates of Glomus occultum Walker. Trees grew larger and had higher leaf P concentrations at high soil P than at low soil P regardless of mycorrhizas. At low P, fungal species differed in percentage root length colonized, intensity of colonization, types of mycorrhizal structures formed, and number of spores produced. Fungal species also differed in effects on plant growth. At harvest, five treatments were taller than the non‐mycorrhizal control trees, and two were not. Stem diameter and total dry weight were increased by only three treatments. At high P, no treatment resulted in greater than 5 % of root length colonized, and endogonaceous fungi had little influence on plant growth.
Studies ON THE MYCORRHIZAS OFPINUS SYLVESTRISL. PRODUCEDIN VITROWITH THE BASIDIOMYCETESUILLUS VARIEGATUS(Sw.exFr.) O. KUNTZE
Authors: WARMBRODT ROBERT D. , ESCHRICH WALTER 
Published: May 2006

SummaryThe structure and development of the endodermis and vascular cylinder of ectomycorrhizas ofPinus sylvestrisL. formedin vitrowith the basidiomyceteSuillus variegatus(Sw. ex Fr.) O. Kuntze were studied by light and electron microscopy. With the exception of the sieve elements, the cells of the vascular cylinder and endodermis differentiate relatively close to the apical meristem of the slow growing mycorrhizal rootlets. The endodermis is uniseriate and delimits a vascular cylinder which in most cases is diarch. All endodermal cells develop casparian strips in their anticlinal walls and approximately 50% of them undergo no further changes. The walls of the remaining endodermal cells however, are apparently impregnated with suberin or lipid‐like substances and these cells subsequently disintegrate and collapse. The vascular cylinder of the mycorrhizal rootlets consists of a mostly uniseriate pericycle, tracheids with circular‐bordered pits, sieve cells, variable numbers of vascular parenchyma cells and peripheral phloem parenchyma cells, the so‐called precursory phloem cells. The latter are characterized by high numbers of microfilament bundles and numerous, large aggregates of plasmodesmata which occur in thickened regions of the wall. Upon maturation of the sieve cells, the peripheral phloem parenchyma cells disintegrate and may eventually collapse. Typical albuminous (Strasburger) cells were not encountered in the material examined. By consideration of the structure and distribution of plasmodesmata among the various cell types the feasibility of symplastic and apoplastic transport within the mycorrhizal rootlets is discussed.
UPTAKE AND ACCUMULATION OF ZINC, LEAD AND COPPER IN ZINC AND LEAD TOLERANT ANTHOXANTHUM ODORATUM L.
Authors: QURESHI J. A. , THURMAN D. A. , HARDWICK K. , COLLIN H. A. 
Published: May 2006

SummaryThe amount of zinc, lead or copper accumulated in plants from zinc and lead tolerant and non‐tolerant populations of Anthoxanthum odoratum L. varied depending on whether the plants were tolerant of the metal and on the period of exposure to the solution containing the metal. After one day in zinc, lead or copper‐containing solutions, both tolerant and non‐tolerant plants showed a similar uptake and distribution of each metal, suggesting that uptake was independent of the tolerance characteristics. After 11 d of exposure to each metal, more lead and zinc were present in the roots of tolerant plants than in the roots of non‐tolerant ones. However, there was no change in the uptake and distribution of copper in plants after 11 d of exposure. The evidence for the presence of a mechanism to exclude toxic metals from the shoots is discussed.
GERMINATION RESPONSES TO LIGHT AND ALTERNATING TEMPERATURES IN EUROPEAN POPULATIONS OF DACTYLIS GLOMERATA L.
Authors: PROBERT R. J. , SMITH R. D. , BIRCH P. 
Published: May 2006

SummaryThe influence of the outer covering structures (palea, lemma and pericarp) on the germination response to light and alternating temperatures was investigated in two populations of Dactylis glomerata L. Removal of the palea and lemma was less effective than light or alternating temperatures in promoting germination. Despite quantitative differences, both populations responded similarly to all three factors. Statistical analysis of data transformed to probits indicated mainly additive effects when factors were combined. Selective surgical treatments showed that the structural integrity of the pericarp was also important in germination control. Removal of the palea and lemma followed by the making of a shallow incision in the pericarp close to the embryo, stimulated germination in a very high proportion of individuals (94 %) even at a constant temperature (16°C) in the dark. Elevated oxygen levels promoted germination of intact seeds suggesting that the outer coverings might restrict oxygen access. Evidence is presented that positive pressures (0.03 MPa) applied during gassing led to a reduction in germination.
SYNERGISM BETWEEN CALCIUM IONS AND ABSCISIC ACID IN PREVENTING STOMATAL OPENING
Authors: DE SILVA D. L. R. , HETHERINGTON A. M. , MANSFIELD T. A. 
Published: May 2006

SummaryThe inhibition of stomatal opening inCommelina communisL. by abscisic acid (ABA) appears to be dependent on the availability of calcium ions. Incubation of epidermal strips in 10−6mol m−3ABA had little effect in the absence of calcium, and a factorial experiment showed a highly significant calcium x ABA interaction. The effect of calcium appeared to be on the later stages of the opening process, and might have been the result of an inhibition of potassium uptake by the guard cells. There was no detectable effect of ABA when EGTA was used to chelate calcium from the apoplastic space.The data are consistent with the hypothesis that ABA increases the permeability of the plasma membranes of the guard cells to calcium. Calcium might then operate as a second messenger to regulate the ionic fluxes that determine guard cell turgor.
DIFFERENTIAL EXPRESSION OF DIEL ACID METABOLISM IN TWO LIFE FORMS OF LITTORELLA UNIFLORA (L.) ASCHERS
Authors: AULIO K. 
Published: May 2006

SummaryThe shoreweed Littorella uniflora (L.) Aschers. possesses two life forms differing from each other both in morphological and in biochemical characteristics. The submerged (isoetid) form showed marked fluctuations in the levels of malic acid, as well as in the total titratable acidity, thus meeting the most important biochemical requirement of Crassulacean Acid Metabolism (CAM). In contrast, the terrestrial form, which depends on atmospheric sources of CO2, showed negligible variations in the levels of malate. The isoetid form has wax‐covered, functionless stomata, whereas the stomata of the terrestrial form are operative. Comparison of the two genetically uniform types of Littorella strongly supports the hypothesis that the CAM‐like carbon pathway is selected in submerged plants as an adaptation to the carbon shortage which they experience in daytime.
THE INFLUENCE OF NATURAL AND IN VITRO BUD FLUSHING ON ADVENTITIOUS BUD PRODUCTION IN SITKA SPRUCE [PICEA SITCHENSIS (BONG.) CARR.] BUD AND NEEDLE CULTURES
Authors: SELBY C. , HARVEY B. M. R. 
Published: May 2006

SummaryThe adventitious bud forming ability of Sitka spruce [Picea sitchensis (Bong.) Carr.] buds was found to be dependent upon the time of year at which they were introduced into culture. Adventitious bud production was at a maximum in the latter weeks of March, immediately prior to their natural flushing time, a period when the buds are naturally forming initials for lateral buds and bud scales and are in a highly active physiological state. Throughout the dormant period cultured buds were able to form adventitious buds; however, once the buds were in an advanced state of natural flushing their capacity for organogenesis declined and they became callused and senescent. The enhancement of adventitious bud production with the onset of natural flushing, and the detrimental effects of bud overdevelopment, were simulated by flushing dormant buds in vitro on a cytokinin free medium using juvenile tissues. In vitro flushing of buds from mature trees did not increase their organogenic capacity. Increasing tree age also significantly reduced the number of adventitious buds forming throughout the natural growth cycle.Adventitious bud production in needle cultures, using needles excised from buds flushed to varying extents in vitro, was also found to be reliant upon their developmental state. Needles needed to be in an immature state (approx. 1 to 2 mm long) to produce optimum organogenesis on their basal tissues. Needles that were more differentiated became callused and senescent in culture.To maximize shoot multiplication rates with Sitka spruce bud and needle cultures, tissues need to be in a carefully controlled stage of differentiation. This can probably be best achieved by flushing dormant buds in vitro to precise extents prior to adventitious bud induction.
THE INFLUENCE OF THE PERIODIC FRUITING (FLUSHING) CYCLE ON THE BIOCHEMICAL DEVELOPMENT OF AGARICUS BISPORUS SPOROPHORES
Authors: MINAMIDE TAKAHISA , HAMMOND JOHN B. W. 
Published: May 2006

SummarySoluble carbohydrate content, glucose 6‐phosphate dehydrogenase (G6PD) activity and amount, and DNA and RNA content were measured in the tissues of fruit bodies of Agaricus bisporus (Lange) Imbach. developing at different stages of the periodic fruiting cycle. Trehalose content, G6PD activity and G6PD protein were maximal at flush emergence independent of the stage of development of the sporophore. Mannitol accumulated in growing sporophores both during and between the flushes of fruit body production. The RNA content of the gill tissue consistently increased in fruit bodies developing during the flush but sporophores growing between flushes showed a decline in RNA content after early gill development. Gill DNA content doubled just prior to sporulation in sporophores growing during the flush but not in those developing between flushes. The mycelial control of the biochemical development of the fruit body is discussed.
SOME FACTORS INFLUENCING VIABILITY OF ECTOMYCORRHIZAL FUNGAL INOCULUM
Authors: LAPEYRIE F. F. , BRUCHET G. 
Published: May 2006

SummarySeveral criteria have been established for more effective utilization of inoculum of Pisolithus tinctorius (Mich. exPers.) Ckr. & Couch and of Paxillus involutus (Batsch. ex Fr.) Fr. P. tinctorius inoculum prepared on vermiculite‐peat moss medium can be stored up to 19 weeks at 3 °C without damage but P. involutus inoculum cannot be stored for more than two weeks. At 24 °C neither inoculum retained viability for long, emphasizing the need for such inoculum to be applied to host roots in a way which permits rapid infection.A blended inoculum prepared from P. tinctorius grown in liquid culture had a maximum activity, at the age of three weeks, which coincided with its maximum ATP concentration, suggesting that ATP might prove to be a valuable guide to inoculum potential. This inoculum is most tolerant of blending procedures and establishes itself better on both nutrient‐rich and nutrient‐poor substrates when previously grown on nutrient‐poor media.
ENDOPHYTES OF WILD ORCHIDS NATIVE TO ITALY: THEIR MORPHOLOGY, CARYOLOGY, ULTRASTRUCTURE AND CYTOCHEMICAL CHARACTERIZATION
Authors: MARCHISIO V. FILIPELLO , BERTA G. , FONTANA A. , MANNINA F. MARZETTI 
Published: May 2006

SummaryIsolates of Rhizoctonia sp. obtained from the terrestrial orchids Dactylorhiza sambucina (L.) Soó, D. maculata (L.) Soó and Platanthera bifolia (L.) L. C. M. Richard, collected in Piedmont (Italy) were studied in the following characters: macroscopic and microscopic morphology, growth rate, ultrastructure of the septal pore apparatus, number of nuclei per cell and cytochemistry of the hyphal and monilioid cells. On the basis of cultural and morphometric characters, the isolates were divided into three groups, which are described in detail. No perfect stage was produced in culture. Although the identification of species of Rhizoctonia‐like fungi without perfect stages is extremely difficult, a comparison of our data with that in the literature leads to the probable identification of group I isolates as a species of Ceratobasidium, group II isolates as a species of Thanatephorus and those of group III as a species of Tulasnella or Sebacina.
THE EFFECTS OF SULPHUR DIOXIDE ON NET CO2 ASSIMILATION IN THE LICHEN EVERNIA MESOMORPHA NYL.
Authors: HUEBERT D. B. , L'HIRONDELLE S. J. , ADDISON P. A. 
Published: May 2006

SummaryPhysiologically active thalli of the lichen Evernia mesomorpha Nyl. were very sensitive to short‐term fumigations with low concentrations of gaseous sulphur dioxide. Net CO2 assimilation rate (NAR) was significantly reduced after exposure to 0.085 μl l−1 (250μg m−3) SO2 for 1 h or more, and the reduction increased with increasing concentration. Duration of exposure had no significant effect on NAR, indicating the importance of rate of SO2 uptake rather than the total amount absorbed. Respiration was significantly reduced after 4 h or more of exposure to 0.265 μl l−1 (639 μg m−3) SO2 or higher. Recovery of NAR after fumigation was dependent on both SO2 concentration and duration of fumigation, and on the time allowed for recovery. Virtually complete recovery occurred within 24 h after episodes with up to 0.355 μl l−1 (856 μg m−3) SO2 for 1 h and 0.085 μl l−1 SO2 for 4 h. Above these levels, recovery was incomplete or nonexistent after 24 h in clean air. The level of sensitivity found can be attributed to the environmental conditions during fumigation, which prevented thallus desiccation and inactivity. Based on this study, neither the concept of dose (concentration × time) nor that of ‘threshold’ levels of SO2 fumigations are supported. Peak exposures to SO2 for short periods may be of primary importance in determining the survival of lichens in industrial areas.
NITROGEN OXIDES PRODUCED DURING CO2 ENRICHMENT
Authors: MORTENSEN LEIV M. 
Published: May 2006

SummaryPlants were grown in chambers with CO2 enrichment (1000 μl 1−1) and with or without the addition of 0.85 μl 1−1 nitrogen oxides (NOx).The following species were tested: Lactuca sativa (lettuce), Cucumis sativus (cucumber), Lycopersicon esculentum (tomato), Saintpaulia ionantha, Rosa, Kalanchoe blossfeldiana, Chrysanthemum×morifolium, Helxine soleirolii, Hedera helix, and Nephrolepis exaltata. All species responded positively to an increase in CO2 level from 330 to 1000 μl 1−1. The dry weights of tomato, roses and Saintpaulia responded negatively to the addition of NOx. In tomato, the reduced dry weight was due to reduction in shoot length and leaf area. In roses the stem was shorter and in Saintpaulia the leaves smaller when NOx was added. Furthermore, the time to flowering increased and number of flowers/flower buds decreased in Saintpaulia.
ACCURATE ESTIMATION OF STOMATAL APERTURE FROM SILICONE RUBBER IMPRESSIONS
Authors: WEYERS JONATHAN D. B. , JOHANSEN LIV G. 
Published: May 2006

SummaryThe potential of low viscosity silicone‐based impression material for measuring stomatal aperture on intact leaves was investigated. It was found that the probability of successful replication of Commelina communis L. stomata depended on the width of the stomatal pores. The wider pores in a sample were more likely to be measured, so the resulting estimated mean was an overestimate of the true mean. This bias in estimates of stomatal aperture from impressions was studied and quantified. A transformation is described which was used to adjust apparent aperture measurements from impressions to give more accurate estimates of stomatal apertures on intact leaves of C. communis. Maximum absolute errors due to the bias usually occurred at apparent apertures on impressions of between 2 and 5 μm but were proportionally greatest below 3μm, where they often exceeded 40%. At a given aperture, the error depended upon the dispersion of the stomatal apertures about their mean and was greatest when this was large.
FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS
Authors: COATES D. , RAYNER A. D. M. 
Published: May 2006

SummaryMore than 450 beech (Fagus sylvatica L.) logs, 10 to 20 cm in diameter and 30 to 40 cm long, were cut from freshly felled trees and placed upright 1 m apart with their bases buried up to 10 cm deep in the ground in a plot of about 600 m2 in a mixed deciduous woodland in the Forest of Dean, Gloucestershire, UK. Fungal colonization via the aerial and buried cut surfaces was studied – in some cases following inoculation of basidiospores – using a combination of direct and indirect techniques.A wide variety of ascomycetes, basidiomycetes and fungi imperfecti were identified, by direct observation or following direct incubation of wood samples, from the vicinity of the aerial cut surface within the first six months after cutting. Some such as Coriolus versicolor (L. ex Fr.) Quél. subsequently increased in occurrence, whereas others, including Chondrostereum purpureum (Fr.) Pouz. declined.Isolation onto malt agar from thin sections of wood revealed the presence of some fungi, notably a Fusarium sp., not detected by direct means. In addition, homokaryons of the basidiomycetes Bjerkandera adusta (Willd, ex Fr.) Karst. and C. versicolor were isolated from near the aerial cut surface up to two years after cutting, and, lower down, mostly up until six months after cutting (thereafter heterokaryons predominated). Moreover, evidence was obtained that small volumes of discoloured, but not strongly decayed wood, sometimes contained large numbers of mutually antagonistic individuals (up to 30 per cm3) of the decay species B. adusta, C. versicolor and Stereum hirsutum (Willd. ex Fr.) S. F. Gray.Vertical penetration from the aerial cut surface showed a marked lag phase, such that for the first six weeks after cutting, overt colonization was restricted to about 3 mm depth. Thereafter the depth occupied increased rapidly.
THE PERFORMANCE OF AGROSTIS CAPILLARIS L. GENOTYPES, DIFFERING IN COPPER TOLERANCE, IN RYEGRASS SWARDS ON NORMAL SOIL
Authors: NICHOLLS M. K. , McNEILLY T. 
Published: May 2006

SummarySample sub‐populations, each of six plants, were chosen for high, mid and low tolerance of copper from each of two naturally‐occurring copper tolerant populations and from tolerant individuals selected from a cultivar of Agrostis capillaris L. The naturally‐occurring ecotypes came from a closed sward community at Drws y Coed, and from an open community at Parys Mountain, both copper mines in North Wales. Clonal replicates of all plants were introduced into swards of perennial ryegrass cvs. S23 or S24, growing on normal soil at the University of Liverpool Botanic Gardens. S23 plots were cut eight times between June 1977 and July 1978, whilst S24 plots were cut 3 times during the same period. Half the experimental plots received N, P, K, fertilizer; the rest received none.Plants selected from the cultivar (selected) produced most dry matter, and with infrequent defoliation flowered freely in competition with ryegrass. Those taken from Parys Mountain mine spoil produced least dry matter and no inflorescences. Drws y Coed plants were intermediate in dry matter and inflorescence production. These results may reflect differences in population density in the habitats from which the populations were sampled.Sub‐populations chosen for high, mid or low copper tolerance within the selected and Drws y Coed populations did not differ significantly in dry matter yield. By contrast under certain circumstances Parys Mountain plants with low tolerance outyielded other more tolerant plants.These results are considered with respect to growth strategies adopted by plants growing on and off copper mine sites.
EFFECT OF ENVIRONMENT ON PERCENTAGE FEMALE RAY FLORETS PER CAPITULUM AND OUTCROSSING POTENTIAL IN A SELF‐COMPATIBLE COMPOSITE (SENECIO VULGARIS L. VAR. HIBERNICUS SYME)
Authors: ABBOTT RICHARD J. , SCHMITT JOHANNA 
Published: May 2006

SummaryTen lines of radiate groundsel (Senecio vulgaris L. var. hibernicus Syme) were raised in growth cabinets over a wide range of nutrient and temperature conditions to determine the effect of environment on female ray floret number, total floret number, percentage female ray florets and seed number per capitulum. Despite considerable variation in percentage female ray florets per capitulum among capitula within lines, the mean expression of the character remained relatively stable over all environments and lines tested with a mean over all treatments equal to 16–4%. Thus, the marked variation in outcrossing rate that has been reported for radiate groundsel in the wild is unlikely to result from variations in mean percentage of female ray florets per capitulum induced by changes of temperature or nutrient status.The most frequent number of ray florets per capitulum recorded was 8, a Fibonacci number, found in 39·6 % of 821 capitula sampled. Moreover, the overall mean for total floret number was 56 which approximates very closely to another Fibonacci number, 55. This might suggest that the expected proportion of ray to total florets in each capitulum, based on Fibonacci numbers, would be 8/55 or 14–54%. The actual recorded mean value for percentage ray florets per capitulum exceeded this ‘expected’ value as most capitula surveyed bore more than 8 florets (59–2 % of sample).Seed set per capitulum was always below 100 % and varied over environments. A consequence of this finding is that future studies of the relationship between percentage female ray florets per capitulum and outcrossing potential in self‐compatible Compositae will need to consider the distribution of seed produced by female ray florets and hermaphroditic disc florets within the capitulum.
THE BLUE LIGHT EFFECT AND ITS INTERACTION WITH PHYTOCHROME IN THE CONTROL OF NITRITE REDUCTASE ACTIVITY IN SORGHUM BICOLOR WILLD.
Authors: RAJASEKHAR V. K. , SOPORY SUDHIR K. 
Published: May 2006

SummaryIrradiation with red light for 5 min stimulated nitrite reductase activity in 5‐d‐old etiolated seedlings of Sorghum bicolor. The stimulation was less when measured after a subsequent dark period of 12 h than after one of 24 h. A short period of irradiation with blue light did not alter the enzyme activity nor did it elicit any effect even if given for 4–6 h prior to the red light irradiation. Exposure to blue light for 12 h prior to the red light treatment increased the enzyme activity, when measured after 12 h of darkness, to the same level as that obtained by red light irradiation alone followed by 24 h of darkness. Blue light given continuously for 24 h increased nitrite reductase activity and this increase was inhibited by 6‐methylpurine (5 μg ml−1) or cycloheximide (25 μg ml−1). Transfer of seedlings to continuous white light for 6 h after treatment with a pulse of red light followed by 24 h of darkness, or with continuous blue light for 24 h, revealed an independent action of blue light and light operating via phytochrome, in the control of nitrite reductase activity. The accumulation of nitrate was unaffected either by a red light pulse followed by a subsequent dark period, or by continuous blue light. In contrast, continuous white light led to an increased accumulation of nitrate.