bluuebunny/crossref_metadata_2025_split huggingface dataset:
ASPECTS OF RAINFOREST REGENERATION
Authors: CHANDLER G. , GOOSEM S. 
Published: May 2006

SUMMARYMeasurements in two sub‐tropical rainforests demonstrated that (i) in one rainforest succession, total soil phenols varied dramatically throughout the study year with soils from the ‘climax’ rainforest exhibiting highest phenol levels, the nature of these phenolic compounds was not investigated; (ii) in the other rainforest succession, the 55‐year‐old regrowth exhibited highest total phenols, but the level of condensed tannins increased throughout the succession. The highest level of nitrification was observed in soils containing highest total phenols but the addition of ferulic acid decreased nitrification. Studies on Argyrodendron trifoliolatum demonstrated that addition of the phenol, caffeic acid, to nutrient media enhanced leaf concentrations of Zn, Mn and P. Increasing light intensities, however, decreased foliar concentrations of Fe, Zn, Mn and P but had no effect on Ca or N. Plants raised on ammonium −N exhibited higher levels of Fe, Zn, Mn and P than those raised on nitrate–N.Glasshouse trials showed that at low light intensities omission of N, P and N + P did not dramatically enhance leaf phenol production. Almost invariably, an increase in light intensity increased leaf phenols but only one of the four species examined (Syzygium floribundum) exhibited marked responses to nutrient deficiencies at high light intensities, with the omission of nitrogen leading to highest leaf phenols.
THE UPTAKE AND TRANSLOCATION OF TRI‐AND HEXA‐VALENT CHROMIUM AND EFFECTS ON THE GROWTH OF OAT IN FLOWING NUTRIENT SOLUTION AND IN SOIL
Authors: MCGRATH S. P. 
Published: May 2006

SUMMARYTri‐ and hexa‐valent chromium (Cr) were both absorbed by oat and were equally toxic when supplied at 2 to 200 μM in nutrient solution. The proportion of Cr translocated to the shoots was similar, regardless of the form supplied to roots.Adding 750 μg of hexa‐valent Cr per gram of either acid or alkaline soil resulted in large, toxic concentrations of Cr in soil solution. The same amount of trivalent Cr gave smaller Cr concentrations in the soil solution, with more Cr present from acid than from alkaline soils. Nevertheless, increased uptake of Cr and reduced plant yields occurred on both soil types with added trivalent Cr.
MYCORRHIZAL ASSOCIATIONS IN SOME WOODLAND AND FOREST TREES AND SHRUBS IN TANZANIA
Authors: HÖGBERG P. 
Published: May 2006

SUMMARYThe mycorrhizal associations in 47 indigenous Tanzanian trees and shrubs, mainly from less humid areas, were studied. Forty species were found to be endomycorrhizal. One,Uapaca kirkianaMull. Arg. (Euphorbiaceae) was ectendomycorrhizal while six, fourBrachystegiaspp.,Julbernardia globiflora(Benth.) Troup. (Caesalpiniaceae) andMonotes elegansGilg. (Diptero‐carpaceae), were ectomycorrhizal. The results demonstrated a dominance of endomycorrhizal species, which is typical for the tropics and is further reinforced by taxonomic considerations. However, in the Miombo (Brachystegia–Julbernardia) woodlands, a major ecosystem in East and South Central Africa, ectomycorrhizal trees predominate in volume. In three other ecosystems studied – aCombretumwoodland, a groundwater forest and a semi‐evergreen forest–ectomycorrhizal species were absent or almost absent. Nodulated leguminous species appeared to be more common in the fire‐induced woodlands than in the closed forests.
ULTRA‐STRUCTURE AND MICRO ANALYSIS OF THE POLYPHOSPHATE GRANULES OF THE ECTOMYCORRHIZAS OF FAGUS SYLVATICA
Authors: STRULLU D. G. , HARLEY J. L. , GOURRET J. P. , GARREC J. P. 
Published: May 2006

SUMMARYEvidence is presented that the granules visible in the vacuoles of the hyphae of the sheath of Fagus sylvatica mycorrhiza in electron microscope (EM) preparations contain phosphorus and calcium. Little phophorus or calcium is present in the clear regions of the hyphal vacuoles. Calcium but not phosphorus is present in considerable quantity in the hyphal walls of the fungal sheath.
ULTRASTRUCTURAL STUDIES ON ARCHEGONIAL DEVELOPMENT IN THE MOSS PHYSCOMITRIUM CYATHICARPUM
Authors: LAL M. , KAUR G. , CHAUHAN E. 
Published: May 2006

SUMMARYOogenesis in the moss Physcomitrium cyathicarpum is characterized by a copious secretion of mucilage into the venter of the archegonium due to the extrusion of numerous vesicles from the egg. Maturation of the egg is not attended by any special event in the nucleus. The cell organelles become redistributed into zones as the egg matures before fertilization.
RHYTHMICITY IN NITRATE REDUCTASE ACTIVITY IN WHEAT EMBRYOS DURING GERMINATION
Authors: DISA SUHAS , GUPTA ADITYA , RAJASEKHAR V. K. , GUHA‐MUKHERJEE SIPRA , SOPORY SUDHIR K. 
Published: May 2006

SUMMARYNitrate reductase (NR) activity, induced by germination in KNO3 showed a strong rhythmicity during the early stages of germination of wheat embryos. Peaks of activity occurred approximately every 12 h. There was no relationship between the amounts of nitrate in the embryos and enzyme activity. The fluctuations in enzyme activity did not appear to be due to reversible inactivation of the enzyme. Some evidence suggests that the fluctuations in enzyme activity may result from a more rapid degradation of enzyme during the decreasing phase of the rhythm.
SURVIVAL OF MYCORRHIZA FORMED BY CENOCOCCUM GEOPHILUM FR. IN DRY SOILS
Authors: PIGOTT C. D. 
Published: May 2006

SUMMARYSeedlings and 2‐year old saplings of Tilia cordata growing in the shade on sandy‐textured soils can survive periods when the water potential of the soil decreases to −18 to −55 bars. Their mycorrhiza formed by Cenococcum geophilum is shown to remain alive. Measurement of rates of water‐loss from seedlings in similar conditions decreases from 16.0 to 26.2 mg h−1 when the soil is wet, to 4.1 to 4.6 mg h−1 when the soil is dry. Calculation of the volume of the mycorrhiza shows that its water content would support transpiration for periods not exceeding 1 h. Survival of the mycorrhiza through long periods of drought is apparently related to the ability of the fungal partner to withstand desiccation.
ACCUMULATION OF CALCIUM OXALATE IN THE MANTLE OF ECTOMYCORRHIZAL ROOTS OF PINUS RADIATA AND EUCALYPTUS MARGINATA
Authors: MALAJCZUK N. , CROMACK K. 
Published: May 2006

SUMMARYCalcium oxalate crystals occur in the mantle of ectomycorrhizal roots of Firms radiata and Eucalyptus marginata. Dense concentrations of these crystals were observed in association with the fungal symbiont of both tree species. It is suggested that oxalate production may enhance nutrient uptake by ectomycorrhizal roots of forest species growing in nutrient impoverished soils. Concentrations of Ca, S, K and P were similar in mycorrhizal root masses of P. radiata and E. marginata.
ULTRASTRUCTURE OF PTEROSPORA ANDROMEDEA NUTTALL AND SARCODES SANGUINEA TORREY MYCORRHIZAS
Authors: ROBERTSON DIANE C. , ROBERTSON J. A. 
Published: May 2006

SUMMARYMycorrhizas of Pterospora andromedea Nuttall and Sarcodes sanguinea Torrey were examined with light and electron microscopes. Both plants were found to have a multi‐layered fungal sheath covering the surface of their roots and a Hartig net surrounding the epidermal cells but not penetrating the underlying cortex. Dolipore septa are present in the fungi of both plants. Individual determinate hyphae enter each epidermal cell through the radial wall which is oriented toward the tip of the root. As they penetrate, the epidermal cell wall appears to invaginate forming a fungal peg. The wall of the peg produces numerous protuberances similar to those found in transfer cells. In the combined fungal‐epidermal cell wall of the fungal peg the two walls do not remain distinct and it is impossible to be certain if both continue to the tip. Eventually, the tip of the fungal peg appears to open and form a mebranous sac, delimited by the epidermal cell plasmalemma, containing granular material with fibrillar inclusions which are approximately the size of microtubules. The relationship of the contents of the membranous sac to the contents of the fungal peg is discussed.
ULTRASTRUCTURAL CHANGES OF NOSTOC OF PELTIGERA CANINA IN PRESENCE OF SO2
Authors: SHARMA PAWAN , BERGMAN BIRGITTA , HÄLLBOM LARS , HOFSTEN ANGELICA V. 
Published: May 2006

SUMMARYThe effect of various concentrations of sulphur dioxide (SO2) (0, 10, 100, 1000 p.p.m.) on the infrastructure of the Peltigera canina (L.) Willd ‐ Nostoc symbiosis was investigated in vitro. Ten days incubation with SO2 resulted in the following changes: decreasing number of carboxysomes, increasing number of cyanophycin granules and initiation of akinete‐differentiation. No changes were observed in the general arrangement of the thallus, the wall of either fungus or Nostoc cells, polyglucoside granules and polyphosphate bodies. A decrease in number of carboxysomes indicates a disturbance in photosynthetic ability of the lichen. It also appears that SO2 acts as a stress factor leading to akinete‐differentiation as evidenced by increased number of cyanophycin granules and appearance of akinetes.
EVIDENCE FOR THE ABSENCE OF ECOTYPIC DEVELOPMENT IN ANDROPOGON VIRGINICUS (L.) ON METALLIFEROUS MINE WASTES
Authors: GIBSON D. J. , RISSER P. G. 
Published: May 2006

SUMMARYPopulations of broomsedge (Andropogon virginicus L.) were studied from three sites in northeastern Oklahoma, U.S.A. The sites differed in the levels of the heavy metals lead, zinc and cadmium which had become incorporated into the soil; the highest concentrations were recorded from a mine site, intermediate levels at a nearby old field and normal soil levels at a control site. A greenhouse transplant experiment utilizing clonal segments of the three populations grown on field (mine, old field and control) and artificial (mine tailings and quartz sand) soils showed that on the field soils the mine and control populations demonstrated similar growth characteristics. The old‐field population differed from these populations in terms of ramet survivorship on the soils. These observations do not support the hypothesis of ecotypic differentiation in response to heavy‐metal contaminated soils, but suggest that the control and mine populations were genetically similar in their ability to tolerate the edaphic conditions of the mine site. The old‐field population may have differentiated in response to the high intraspecific competitive regime on its site.
THE TOLERANCE OF TREE ROOTS TO WATERLOGGING
Authors: COUTTS M. P. 
Published: May 2006

SUMMARYRooted cuttings of Picea sitchensis and Pinus contorta were grown with split roots in plastic troughs of soil, to produce 500 mm long woody roots on either side of each plant with the distal parts of the root system growing out into pots at the ends of the troughs. Some roots of primary structure were also present in the troughs. The soil in the trough on one side of the plant was waterlogged while all other parts of the root system remained in freely drained soil. The waterlogging treatment was applied out of doors from April to November.In both species all roots of primary structure in the waterlogged soil were killed, whereas most of the woody roots survived. In the pine, radial growth of the waterlogged part of the woody root was reduced relative to the freely drained control side, and the root tapered from the plant stem towards the centre of the waterlogged zone, then increased again towards the distal end. Growth of pine roots of primary structure in freely drained soil at the distal end of the waterlogged woody root was not reduced compared with the control side. Spruce was more sensitive, and growth of xylem and phloem of the woody root almost ceased at the centre of the waterlogged zone; there was also a carry‐over effect of the waterlogging treatment into other parts of the root system. Growth of the woody root proximal to the waterlogged zone and of the primary roots distal to it were reduced.Enlarged lenticels became abundant on the woody roots of both species at the ends of the waterlogged zone and their frequency decreased towards the centre.The results are discussed in relation to differences in oxygen transport known to occur in woody roots of the two species.
SENESCENCE IN SUBMERGED AQUATIC ANGIOSPERMS: EFFECTS OF HEAVY METALS
Authors: JANA SASADHAR , CHOUDHURI MONOJIT A. 
Published: May 2006

SUMMARYThe effects of mercuric chloride, lead acetate, cadmium chloride and cupric sulphate on the senescence of isolated mature leaves of three submerged aquatic angiosperms, Potamogeton pectinatus L., Vallisneria spiralis L. and Hydrilla verticillata (L.f.) Royle, were studied. All four compounds decreased the rate of respiration of all the species except that Cu increased the respiration rate of Potamogeton. All the heavy metals hastened senescence of all three species as measured by decreases in the contents of chlorophyll, RNA, protein and dry wt and increases of free amino acid content, tissue permeability, the ratio of acid to alkaline pyrophosphatase activity and the activities of protease and RNase. All metals decreased the ratio of chlorophyll a to b in Potamogeton and Vallisneria but increased it in Hydrilla. Cu seemed to be the most effective metal in inducing deleterious effects in Potamogeton and Vallisneria. Pretreatment of leaves of these plants with kinetin for 12 h or more, significantly reduced the senescence promoted by the heavy metals. Of the three species studied, Hydrilla was most tolerant to the heavy metals applied.
CATABOLITE REPRESSION OF THE SYNTHESIS OF PECTIN‐DEGRADING ENZYMES BY SUILLUS LUTEUS (L. EX FR.) S. F. GRAY AND HEBELOMA OCULATUM BRUCHET
Authors: GILTRAP N. J. , LEWIS D. H. 
Published: May 2006

SUMMARYThe synthesis of pectin‐degrading enzymes in vitro by both Suillus luteus (L. ex Fr.) S. F. Gray, a proven ectomycorrhizal fungus, and Hebeloma oculatum Bruchet, a saprotrophic, non‐mycorrhizal species of a frequently ectomycorrhizal genus, is repressed by glucose. The possibility that a control mechanism, which is based on catabolite repression and which prevents extensive intracellular fungal infection, operates in ectomycorrhizas is discussed.
FACTORS AFFECTING THE SPREAD OF VESICULAR MYCORRHIZAL FUNGI IN SOIL
Authors: WARNER A. , MOSSE B. 
Published: May 2006

SUMMARYThe effect of root density on the spread of vesicular‐arbuscular mycorrhizal infection was measured using Trifolium repens (clover) and Festuca rubra (fescue). Seeds of both host species were sown in large troughs at three different distances apart, which resulted in different root densities that persisted for up to 15 weeks. For clover, colonization (i.e. total length of infected root) and linear spread were favoured by greater root densities, and at the greatest root density colonization seemed to proceed faster than root extension. In fescue, root density was positively related to linear spread up to about 23 cm root cm−3 soil, but greater root density was supra‐optimal for linear spread but not for colonization. Although root density had important effects on the spread of infection, effects of plant species were much greater. Fescue had more total root (five times that of clover), but it supported less linear spread and less than half the total length of infected root.
RELATIONSHIPS BETWEEN HOST AND ENDOPHYTE DEVELOPMENT IN MYCORRHIZAL SOYBEANS
Authors: BETHLENFALVAY G. J. , BROWN M. S. , PACOVSKY R. S. 
Published: May 2006

SUMMARYSymbiotic associations of soybeans and the vesicular–arbuscular mycorrhizal fungus Glomus fasciculatus were grown to maturity in a sand‐perlite rooting medium watered with a nutrient solution containing growth‐limiting amounts of soluble phosphorus. Development of fungal mycelia external and internal to the host plant's root system was measured by determining chitin in isolated fungal mycelium, in the rooting medium, and in the mycorrhizae. The biomasses of the extra‐ and intraradical mycelia were calculated from the values of chitin obtained spectrophotometrically. The amount of total fungal biomass relative to that of the host plant varied throughout the lifespan of the association and reached a maximum of 2.3 % 10 weeks after planting. The amount of intraradical mycelium increased throughout the host plant's life span. Extraradical fungal structures attained a maximum weight at the onset of logarithmic growth of the soybean pods and decreased thereafter. Cessation of the rapid growth phase of G. fasciculatus lagged behind that of the host plant's vegetative structures, but appeared to be related to pod development. The fungus to root dry wt ratio was 12–3% at senescence. The ratio of extra‐ to intraradical mycelium decreased throughout the association's lifespan. Since the extraradical hyphae are the organs responsible for enhanced nutrient uptake this ratio is proposed as an index of the endophyte's usefulness to the host. High values for this usefulness index coincided with significant growth enhancement of the host plant. Source–sink relationships in the host appear to be a determining factor in the growth of the fungal endophyte.
AMINO ACID NUTRITION IN THE BLUE‐GREEN ALGA NOSTOC MUSCORUM
Authors: VAISHAMPAYAN A. 
Published: May 2006

SUMMARYThe L‐isomers of 21 amino acids have been screened for their ability to serve as carbon or nitrogen sources for growth of the het+ nif−11 heterocystous and non‐nitrogen fixing mutant strain of the blue‐green alga Nostoc muscorum by a simple test system combining the use of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) (an inhibitor of photosynthetic assimilation of CO2) and the auxotrophic (non‐nitrogen fixing) characteristic of the mutant. The amino acids glutamate, alanine, tyrosine and cysteine were toxic; glutamine, histidine, asparagine, tryptophan and serine were utilized as nitrogen sources; arginine, proline and phenylalanine were utilized as carbon sources; leucine, isoleucine, lysine, methionine, valine and citrulline were utilized as sources of both carbon and nitrogen; aspartate, threonine and glycine served neither as carbon nor nitrogen sources.
EFFECTS OF TWO SPECIES OF V A MYCORRHIZAL FUNGI ON DROUGHT TOLERANCE OF WINTER WHEAT*
Authors: ALLEN MICHAEL F. , BOOSALIS MICHAEL G. 
Published: May 2006

SummaryRoots and soils from western Nebraska fields of native and planted grasslands, and winter wheat of varied fallow‐wheat cultivation duration, were evaluated for vesicular–arbuscular (VA) mycorrhizal root infection and spore numbers and types. Increased cultivation decreased percentage mycorrhizal infection in wheat and reduced spore numbers of Glomus fasciculatus, the dominant VA mycorrhizal fungus in these soils. Spore numbers of other VA mycorrhizal fungi did not change significantly with cultivation although mean numbers of G. mosseae increased with continued wheat production. Water relations and growth were determined for greenhouse‐grown non‐raycorrhizal, G. fasciculatus‐infected, and G. mosseae‐infected wheat in wet and dry soils. Stomatal conductances were higher in mycorrhizal than in non‐mycorrhizal plants in both wet and dry treatments. Stomatal closure in‐mycorrhizal plants occurred at lower leaf water potentials (Ψ1) and after greater desiccation than in non‐mycorrhizal plants, but some leaves of G. mosseae‐infected plants showed no stomatal response to drought and continued to transpire at Ψ as low as ‐4.1 MPa. Leaf osmotic adjustment was greatest for G. fasciculatus‐infected plants. Non‐mycorrhizal and G. fasciculatus‐infected plants had equal dry wts in both wet and dry conditions. Infection by G. fasciculatus appeared to increase wheat drought tolerance while infection by G. mosseae did not.
THE DYNAMICS OF GROWTH AND NUTRIENT ACCUMULATION BY FRUITS OF GREVILLEA LEUCOPTERIS MEISSN., A PROTEACEOUS SHRUB, WITH SPECIAL REFERENCE TO THE COMPOSITION OF XYLEM AND PHLOEM SAP
Authors: HOCKING PETER J. 
Published: May 2006

Summary Grevillea leucopteris is a large xeromorphic shrub from nutrient‐deficient sandy heathland in south‐western Australia. The fruit of G. leucopteris is a follicle which contains two seeds. Leaves and follicles have very low levels of essential nutrients, but seeds have very high levels, especially N, P and trace elements, as well as substantial oil reserves (30% w/w). Grevillea leucopteris appears to be a Ca accumulator because of the very high concentrations of this element in leaves, follicles and seeds.Phloem exudate from incisions in fruiting branches and xylem sap were used to study transport of nutrients to fruits. Phloem sap had 14 to 17% sugar. Glutamine was the major amino compound in xylem and phloem sap. Arginine comprised 37% of the N in xylem sap but was absent in phloem, suggesting its release from storage pools in roots and stems and metabolism in leaves. K dominated the mineral spectrum of phloem sap, and Ca that of xylem. Ca levels in xylem and phloem sap were very high (200 and 500 μg cm−2 respectively), and K: Ca ratios were very low: xylem 0.5: phloem 3.7. The phloem: xylem concentration ratio for all minerals was 8.7. Reduced transpiration by enclosing fruits in plastic bags or foil changed their K: Ca ratios from 0.95 to 3.13 or 4.48.Each fruit used 11.5 cm3 of water during growth, 76% estimated to arrive in the xylem, the rest via the phloem. The water use efficiency of G. leucopteris fruits was 29.9 cm−3 g−1 dry matter produced, close to values reported for mesomorphic species such as lupin and pea. The high levels of Ca in G. leucopteris fruits are due to high levels of Ca in transport fluids rather than elevated transpiration.
MODULATION, BY PHENOLIC COMPOUNDS, OF ENDOGENOUS MANGANESE DURING IAA‐INDUCED GROWTH IN AVENA COLEOPTILE SEGMENTS: AN ELECTRON SPIN RESONANCE STUDY
Authors: KRISHNA T. MOHAN , BHARTI SUDHAKAR 
Published: May 2006

SummaryThe behaviour of endogenous manganese (Mn2+) was studied by electron spin resonance spectroscopy during growth induced by indol‐3‐ylacetic acid (IAA) and modulated by phenolic acids in Avena coleoptile segments. Oat coleoptile segments show a characteristic sextet hyperfine spectrum which is similar in appearance to the sextet of Mn2+ In aqueous solution. Endogenous Mn2+ shows a concentration response to IAA, Coleoptile segments treated with p‐hydroxy benzoic acid and 2,4‐dicblorophenol, which inhibit IAA‐induced growth, show a decline in the concentration of endogenous Mn2+. Chlorogenic acid and caffeic acid, which synergize IAA‐induced growth, keep endogenous manganese in the reduced state (i.e. Mn2+) probably by donating electrons in the reaction. It appears that conditions inhibitory to IAA‐induced growth are associated with a decreased level of tissue Mn2+ while those stimulatory to growth seem to be associated with a higher level of endogenous Mn2+. The changes in endogenous Mn2+ may be mediated either by complex formation or by a change in the redox state.
INFECTION DEVELOPMENT AND INTERACTIONS BETWEEN VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI
Authors: WILSON J. M. , TRINICK M. J. 
Published: May 2006

SummaryThe response of mycorrhizal infection to changes in inoculum density was similar in form forGlomus tenuisandGlomus monosporus. Nevertheless,G. tenuisproduced considerably more infection per propagule unit than did G.monosporus, probably due to a greater ability ofG. tennisto produce secondary infection points. When mixed inocula of the two fungi were used, both the time of harvest and the frequency of each fungus in the inoculum influenced the competitive effects.Glomus tenuiswas slow to form infection points, and was less aggressive thanG. monosporusat 12‐ and 24‐day harvests. By 36 days the two fungi were equally aggressive and the amount of infection produced by each fungus was directly proportional to its frequency in the inoculum.