bluuebunny/crossref_metadata_2025_split huggingface dataset:
EVENTS AT AND AROUND THE FIRST AND SECONDULMUSDECLINES: PALAEOECOLOGICAL INVESTIGATIONS IN CO. TYRONE, NORTHERN IRELAND
Authors: HIRONS KENNETH R. , EDWARDS KEVIN J. 
Published: May 2006

SUMMARYPercentage and concentration pollen diagrams from the sediments of two adjacent inter‐drumlin hollow lakes near Dungannon, and in two cores from Lough Catherine, suggest that only small reductions in the pollen frequencies of trees such as pine and, at some sites, birch and oak, accompanied reducedUlmusat the elm decline in these parts of Co. Tyrone. They also confirm thatPteridium aquilinumcould sporulate and many herbs were able to flower more freely owing to an opening of the tree canopy. Seventeen radiocarbon dates provide chronologies for the sites and date the elm decline to between 5050 and 5375 B.P., the subsequent start of increased elm pollen percentages to between 5010 and 4850 B.P., and the beginning of a second decline in elm pollen to between 4330 and 4260 B.P. The initial decline in elm pollen values may have been caused by disease and this reduction was superimposed upon a background of small‐scale clearances which continued after a general elm regeneration. The question of a general similarity and causation of the second elm decline in Ireland and elsewhere is considered. Chemical, magnetic and pollen preservation data from the Co. Tyrone sites suggest episodes of erosion occurring at the first elm decline and others at the second elm decline.
ACCUMULATION OF PHOSPHORUS, DRY MATTER AND BETAINE DURING NaCl STRESS OF SPLIT‐ROOT CITRUS SEEDLINGS COLONIZED WITH VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI ON ZERO, ONE OR TWO HALVES
Authors: DUKE E. R. , JOHNSON C. R. , KOCH K. E. 
Published: May 2006

SUMMARYSodium chloride tolerance and phosphorus content were examined in split‐root Carrizo citrange seedlings [Poncirus trifoliata (L.) Raf. ×Citrus sinensis (L.) Osbeck] colonized with a vesicular‐arbuscular mycorrhizal fungus (Glomus intraradices Schenck & Smith) on zero, one or two root halves. Plants were treated with NaCl at 0, 25, 50 or 100 mM, and the degree of stress was measured as reduction of dry matter accumulation and rise in level of leaf proline‐betaine (stachydrine). Shoot and root dry weight production during this period decreased with increasing levels of salt. Absolute reductions were similar for plants inoculated on one vs two half‐root systems, but percentage decreases were less in the latter due to greater overall growth in all treatments. Betaine levels in leaf tissues were positively related to soil salt levels for each mycorrhizal treatment. Significant differences in betaine levels were also detected in plants with and without mycorrhizal fungi, and mean levels tended to be higher for those colonized on one vs two halves of their root system. In contrast, a half‐root system and its fungal symbiont supplied enough phosphorus to allow concentrations of leaf P to equal those of fully infected root systems, yet the two groups did not show equal growth under control conditions or percentage reductions with NaCl stress.
SYNTHESIZED ECTOMYCORRHIZAL ASSOCIATIONS Of SOME AUSTRALIAN HERBS AND SHRUBS
Authors: KOPE H. H. , WARCUP J. H. 
Published: May 2006

SUMMARYThe morphology and development of ectomycorrhizas formed by Pezisa whitei (Gilkey) Trappe, Labyrvnthomyces sp. (Ascomycetes) and Laccaria ohiensis (Mont.) Singer (Basidiomycete) on a range of hosts including Pultenaea obovata Benth., Gompholobium latifolium Sm. (shrubs) and Poranthera microphylla Brongn., Angianthus tomentosus Wendl., Waitssia citrina (Benth.) Steetz and Stvlidium gratninifolium Sw. ex Willd. (herbs) have been studied in a gnotobiotic system in a soil mix low in available phosphate.The associations formed varied from mycorrhizas with well‐defined sheaths enclosing root apices on P. obovata and G. latifolium to less well‐defined ones on the herbs, where associations varied from partial sheathing of roots to discrete patches of fungal sheath to no sheath at all in the association A. tomentosus + P. whitei. A Hartig net was formed in most associations although L. ohiensis formed none with P. microphylla, A. tomentosus and W. citrina. The results showed that the form of a mycorrhiza depended on both partners, not on the fungus or higher plant alone.All plant‐fungus combinations except for A. fomentosus + L. ohiensis showed a significant growth response compared with non‐inoculated plants, which indicated mycorrhizal effectiveness, irrespective of mycorrhizal form, in the growth conditions employed.
THE EFFECTS OF A POLYAMINE BIOSYNTHESIS INHIBITOR ON INFECTION OF VICIA FABA L. BY THE RUST FUNGUS, UROMYCES VICIAE‐FABAE (PERS.) SCHROET
Authors: WALTERS D. R. 
Published: May 2006

SUMMARYThe effects of the polyamine biosynthesis inhibitor, difluoromethylomithine (DFMO), on rust infection of the broad bean have been examined. DFMO was sprayed onto leaves at 0.025, 0.1 and 0.4 mM before and after inoculation. DFMO was also applied to leaf halves in order to examine the possible translocation of the inhibitor to untreated leaf halves (systemic treatment). DFMO gave good control of rust infection, irrespective of the treatment. DFMO applied after inoculation was more effective than a pre‐inoculatory treatment when used in non‐systemic tests. When used as a systemic treatment on leaf halves, pre‐inoculatory application of DFMO was more effective. DFMO did not affect plant growth or endogenous concentrations of poly amines. The possible use of DFMO in the control of a range of plant diseases is discussed.
ELECTROPHORETIC VARIATION IN TRIAZINE‐RESISTANT AND SUSCEPTIBLE POPULATIONS OF AMARANTHUS RETROFLEXUS L.
Authors: WARWICK S. I. , BLACK L. D. 
Published: May 2006

SUMMARYPatterns of electrophoretic variation in seven enzyme systems were investigated in one triazine‐resistant and nine susceptible populations of Amaranthus retraflexus L. collected along an 800 km north‐south transect in southern Ontario, Canada. The resistant population occurs in a field in which continuous maize production and intensive use of atrazine had been combined over a 15–year period. The nine susceptible populations were collected from both waste ground and cultivated fields. One would expect the genetic make‐up of the triazine‐resistant population to be simpler than that of susceptible populations as a result of founder effects from a single or only a few resistant founder plants. Our results confirmed this prediction. The resistant population showed a marked reduction in genetic variation, as compared with susceptible populations. One enzyme, GDH, was monomorphic in all 10 populations, the other six enzymes (IDH, GOT, 6PGD, PGI, LAP and MDH) showed varying degrees of phenotypic polymorphism. The resistant population was variable for three of the seven enzyme systems examined. This was in contrast to the homogeneity observed in triazine‐resistant populations of Chenopodium album L. from Ontario. Differences in within‐population phenotypic polymorphism among the nine susceptible populations of A. rctroflexus were not correlated with habitat or latitude of collection sites.
THE EFFECTS OF SODIUM CHLORIDE ON GROWTH AND NITROGEN FIXATION IN CASUARINA OBESA MIQ.
Authors: REDDELL PAUL , FOSTER R. C. , BOWEN G. D. 
Published: May 2006

SummaryIn the field, nodulation of Casuarina obesa Miq. was found at sites with salinity levels up to 28 mg Cl−g−1soil. A subsequent glasshouse study examined effects of step‐wise additions of NaCl on plant growth and symbiotic nitrogen fixation in C. obesa seedlings nodulated by Frankia from two sources. Irrespective of Frankia source, plant growth declined above 0.15 mg NaCl g−1soil, but some growth still occurred at 15 mg NaCl g−1soil. Nitrogen fixation also decreased above 0.15 mg NaCl g−1soil, with total nodule weight being reduced at NaCl levels greater than 0.15 mg NaCl g−1soil for both Frankia sources. However, increasing NaCl markedly reduced the N fixed mg−1nodule weight for only one Frankia source: N fixed mg−1nodule was reduced by 60% at 1.5 mg NaCl g−1soil and inhibited at 15 mg NaCl g−1soil. Electron micrographs of the ‘effective’ nodules from the high‐salt treatment showed Frankia infected cells to have low (putative) Cl−levels when compared with adjacent uninfected cells.At levels of 1.5 and 15 mg NaCl g−1soil both Na+and Cl−accumulated in shoots. Electron micrographs of shoots from the 15 mg NaCl g−1soil treatment showed Cl−to be concentrated in the intercellular spaces and in the hypodermal cells.The success of plantings of salt tolerant Casuarinaceae such as C. obesa requires the selection of highly salt tolerant plant and Frankia genotypes.
COMPARISON OF YIELDS OF SEVERAL CULTIVARS OF FIELD‐GROWN SOYBEANS EXPOSED TO SIMULATED ACIDIC RAINFALLS
Authors: EVANS LANCE S. , LEWIN KEITH F. , OWEN ELIZABETH M. , SANTUCCI KAREN A. 
Published: May 2006

SummaryRainfall acidity response functions for crop yield and growth are necessary to predict the overall impacts on crop yields of ambient and/or anticipated levels of acidic rain. The experiment described herein was performed at Brookhaven National Laboratory to determine the effects of simulated rainfalls of pH 5.6, 4.4, 4.1 and 3.3 on seed yields of four cultivars of field grown soybeans. (Glycine max Merrill). Soybeans were chosen because previous results suggested that certain varieties of this crop are sensitive to rainfall acidity and because they are an economically important crop in the United States. Sixteen plots per treatment were used. Plants were grown using standard agronomic practices under automatically moveable rainfall exclusion shelters which minimized changes in the plants' microclimate. Soybeans of cv. Amsoy shielded from ambient rainfalls and exposed to simulated rainfalls of pH 4.4, 4.1 and 3.3 exhibited yields that were 11.5, 10.4 and 11.7%, respectively, below those of plants exposed to rain of pH 5.6. The comparable figures for other cultivars were as follows: Asgrow 3127– 14.5, 12.2 and 9.0%; Corsoy ‐ 13.7, 12.7 and 7.8 %; Hobbit ‐ 9.2, 6.2 and 16.6%. Most of the observed decreases in seed mass per plant and per unit area for these four cultivars appear to have resulted from a corresponding decrease in pod number per plant.
DEFORESTATION, CANNABIS CULTIVATION AND SCHWINGMOOR FORMATION AT CORS LLYN (LLYN MIRE), CENTRAL WALES
Authors: FRENCH C. N. , MOORE P. D. 
Published: May 2006

SummaryPollen and macrofossil diagrams from the schwingmoor sediments of Llyn Mire are presented. Prior to the formation of the schwingmoor, Cannabis sativa was cultivated around Llyn lake, first to the east and later to the west of the basin. Despite Cannabis cultivation so close to Llyn, there is no evidence to suggest that the lake was used for retting purposes.A period of woodland clearance occurred immediately after the Cannabis cultivation and this process may have been responsible for the changes which led to schwingmoor formation in the basin. It is suggested that increased soil erosion into the lake, together with some eutrophication, encouraged the colonization of the lake surface by a floating mat of vegetation. The schwingmoor was formed in historic times by a floating carpet of such taxa as Carex rostrata, Sphagnum recurvum and Sphagnum section Subsecunda. The mat was initiated in the western part of the basin.The use made of Cannabis/Humulus pollen density as a marker horizon in these studies demanded that these pollen taxa should be adequately separated, and the large numbers of grains of this type present in the sediments permitted the employment of numerical methods based on pore protrusion, which are described here.
REPAIR OF PHOTOINHIBITORY DAMAGE IN ANACYSTIS NIDULANS 625 (SYNECHOCOCCUS 6301): RELATION TO CATALYTIC CAPACITY FOR, AND ENERGY SUPPLY TO, PROTEIN SYNTHESIS, AND IMPLICATIONS FOR μmax AND THE EFFICIENCY OF LIGHT‐LIMITED GROWTH
Authors: RAVEN JOHN A. , SAMUELSSON GORAN 
Published: May 2006

SummaryPreviously published data on photoinhibition in Anacystis nidulans (Richt.) Drouet 625 (=Synechococcus Naeg. 6301) in the presence (gross rate) and absence (net rate) of an inhibitor of protein synthesis, and on the rate of repair of photoinhibitory damage, are analysed. The analysis makes assumptions about the relationship between changes in the efficiency of photosynthesis and changes in the number of undamaged photoreaction two reaction centres, the number of photoreaction centres of photoreaction two per unit cell volume, and the Mr of the photodamageable polypeptide associated with photoreaction two. With this background, the rate of protein synthesis (mol amino acid incorporated (m3 cell volume)−1 s−1) which is required to just balance the rate of protein destruction in gross photoinhibition, or to support the rate of protein synthesis in repair, is computed. The conclusions drawn from this analysis are:(1) Repair of (gross) photodamage which is known to be submaximal requires rates of protein synthesis up to 1/10 of the rate of net protein synthesis at the μmax of Anacystis nidulans, and about 1/50 of the maximum possible capacity for protein synthesis deduced from the RNA content of Anacystis nidulans and the RNA‐based protein synthesis capacity of Escherichia coli.(2) The rates of protein synthesis computed in (1) use up to 1/5 of the ATP production rate from oxidative phosphorylation in darkness and up to 1/10 of the ATP production rate (including photophosphorylation) at an incident photon flux density of 5 μmol photon (400 to 700nm)m−2 s−1(3) Cells subject to photoinhibitory damage, and its repair, have an additional requirement for protein synthesis and ATP generation over cells not subject to photoinhibition. These additional requirements may limit both μmax and the efficiency of light‐limited growth.
THE DISTRIBUTION OF DRY MASS AND PHOSPHORUS IN AN EVERGREEN FYNBOS SHRUB SPECIES,LEUCOSPERMUM PARILE(SALISB. EX J. KNIGHT) SWEET (PROTEACEAE), AT DIFFERENT STAGES OF DEVELOPMENT
Authors: JONGENS‐ROBERTS S. M. , MITCHELL D. T. 
Published: May 2006

SummaryThe distribution of dry mass and phosphorus (P) in the proteoid shrub,Leucospermum parile(Salisb. ex J. Knight) Sweet, was determined at three stages of development following fire, over one year in coastal fynbos vegetation, South Africa. At the seedling stage, a mobilization of P was observed from the hypocotyl and cotyledons to the canopy (40% of total P). The numbers and dry mass of proteoid roots increased between eight and ten months after the fire when there was an apparent decline in total seedling P. The one‐ to two‐year‐old plants showed rapid vegetative growth, the leaves being the major storage organs for P. In the final stage of development (five‐ to six‐year‐old plants), flowering and seed production caused a reduction in P levels in the non‐reproductive parts of the plant and up to 20% of the total P accumulated in the inflorescences. There was a winter peak in root production and P content for one‐ to two‐year‐old plants which had root/shoot ratios of 0.77 and 0.48 respectively; the ratio fell to below 0.2 in the five‐ to six‐year‐old plants. The non‐mycorrhizal root systems ofL. parileare dominated by the tap root (up to 88% of total root) but the majority of the roots within the rhizosphere were from neighbouring species.
YIELD RESPONSE OF DAVIS SOYBEANS TO SIMULATED ACID RAIN AND GASEOUS POLLUTANTS IN THE FIELD
Authors: JOHNSTON J.WILLIAM , SHRINER D. S. 
Published: May 2006

SummaryThe yield response of soybeans (Glycine max (L.) Merr. cv. Davis) to simulated acid rain in the presence of ambient or less‐than‐ambient levels of gaseous pollution was determined in the field. Open‐top chambers were used to alter the levels of gaseous pollutants. An automatic rain simulation system was used to exclude ambient rain and apply rain simulants during natural rain events. These simulations mimicked natural rain events with respect to volume, duration, intensity and frequency. In addition, the intervals between simulated and natural rain events were the same, and therefore many of the potential experimental artifacts associated with scheduled rain simulant applications in earlier research were avoided. Variables measured in the experiment included seed, oil, and protein yield, stem weight, numbers of pods and seeds, and weight per seed. There were no statistically significant rain or chamber treatment effects on the measured variables except for weight per seed and protein yield. The presence of open‐top chambers, when compared with plots without chambers, caused yield variables to be reduced 15 to 20%. There was no evidence to suggest that the response to rain acidity was affected by exposure to ambient or less‐than‐ambient levels of gaseous pollution.
EMISSION OF ETHYLENE BY OAT PLANTS TREATED WITH OZONE AND SIMULATED ACID RAIN
Authors: PELL E. J. , PUENTE M. 
Published: May 2006

SummaryExperiments were conducted to determine whether acidic rain either exacerbated or predisposed Avena sativa L. cv. ‘Ogle’ to ozone injury as measured by foliar emission of ethylene. Three sets of experiments were conducted. Experiment I: Plants were exposed to 588 μg m−3(0.30 ppm) ozone from 0830 to 1130 h. Plants were treated from 1300 to 1400 h with simulated acidic rain at pH 2.8, 3.8, 4.6 or 5.6. Experiment II: treatments were the same as in Experiment I except that only simulated acidic rain of pH 2.8 was utilized and larger numbers of plants per treatment were included. Experiment III: plants were treated with simulated acidic rain of pH 2.8 from 1500 to 1600 h followed by exposure to 588 μg m−3 ozone the next day (1200 to 1500 h). At the end of each experiment, ethylene emission was determined for a pooled sample of the first and second leaf of each plant. Seventy‐two hours after the experiment foliar injury was assessed. Acidic rain of pH 2.8 and 3.8 induced small lesions on the foliage but never induced increases in ethylene emission. Ozone induced flecking on the foliage and initiated significant increases in ethylene production. Ethylene emission was not affected by interactions between ozone and acidic rain in any of the experiments.
THE EFFECT OF AERATION ON COLONY DIAMETER, SPORANGIUM PRODUCTION AND ZOOSPORE GERMINATION OF PHYTOPHTHORA CINNAMOMI
Authors: DAVISON E. M. , TAY F. C. S. 
Published: May 2006

SummaryThe reduced aeration which occurs in waterlogged soil was simulated in the laboratory using O2/N2 gas mixtures, and its effects were studied on six isolates of Phytophthora cinnamomi Rands. Mycelial growth of five isolates grown on agar under a flowing atmosphere, and sporangium production by all of the isolates grown in bubbled liquid culture, were severely reduced under anaerobic conditions. Three of the isolates showed an increase in the number and rate of development of sporangia with increasing O2 concentration of the gas stream. The other isolates showed no increase in the number of sporangia formed at dissolved O., concentrations above 1.3 mgl−1. There was no effect of O2 concentration, either during growth (13.5 or 21% O2) or germination, on the proportion of zoospores that germinated on agar or on initial growth of germ tubes. However, after 19 h, the total length of germ tubes including branches increased with increasing O2 concentration during germination. The number of branches in 11 of the 12 combinations examined was also positively correlated with O2 concentration.
EFFECTS OF PHOSPHORUS ON THE FORMATION OF MYCORRHIZAS BY GIGASPORA CALOSPORA AND GLOMUS FASCICULATUM IN RELATION TO ROOT CARBOHYDRATES
Authors: THOMSON B. D. , Robson A. D. , ABBOTT L. K. 
Published: May 2006

SummaryWe compared the effects of phosphorus (P) supply on the formation of vesicular‐arbuscular (VA) mycorrhizas in Trifolium subterraneum L. by Gigaspora calospora (Nicol. & Gerd.) Gerd. and Glomus fasciculatum (Thaxter sensu Gerd.) Gerd & Trappe.For both fungi, increasing the supply of P decreased the percentage of root length infected. At low P, this decrease was associated with a reduction in the growth of the fungi inside the root. At higher P, the growth of the fungi outside the root was also reduced. These detrimental effects of P on the growth of both mycorrhizal fungi were correlated with reductions in the concentrations of soluble carbohydrates in root extracts and root exudates but were not correlated with the concentrations of free amino‐nitrogen in extracts or exudates.The percentage of root length infected by G. calospora was decreased to a greater extent than that of G. fasciculatum with increasing P supply. This could partially be explained by the lower concentrations of soluble carbohydrates in the roots of plants inoculated with G. calospora. Additionally, the percentage of root length infected by G. calospora appeared to be more sensitive to reductions in the supply of soluble carbohydrates than that of G. fasciculatum.Growth responses to inoculation were dependent on the species of mycorrhizal fungus and the P level. Enhancements and depressions in the growth of tops could be explained in terms of increased and decreased P uptake.
ISOLATION AND STRUCTURAL CHARACTERIZATION OF SOIL‐Borne AUXILIARY CELLS OF GIGASPORA MARGARITA BECKER & HALL, A VESICULAR–ARBUSCULAR MYCORRHIZAL FUNGUS
Authors: JABAJI‐HARE S. H. , PICHÉ Y. , FORTIN J. A. 
Published: May 2006

SummarySoil‐borne auxiliary cells of Gigaspora margarita Becker & Hall have been investigated with light and electron microscopy. The cell wall is composed of four prominent layers and autofluoresces intense yellow under blue light. Histochemically, it contains polysaccharides and lipids. The cytoplasm is composed of amorphous material, nuclei and a variety of osmiophilic granules. In old and moribund auxiliary cells and subtending hyphae, gram‐negative bacterium‐like structures (BLS), sometimes dividing, were colonizing the senescent cytoplasm. These BLS were surrounded by peripheral membranes and their cytoplasm was clearly differentiated into electron‐dense and transparent areas.