bluuebunny/crossref_metadata_2025_split huggingface dataset:
GROWTH AND NUTRIENT ACCUMULATION BY FRUITS OF THE PERENNIAL LEGUME, HARDENBERGIA VIOL ACE A, WITH SPECIAL REFERENCE TO MYRMECOCHORY
Authors: HOCKING P. J. , KORTT A. A. 
Published: April 2006

SummaryThe growth and mineral nutrition of developing fruits of the perennial Australian legume Hardenbergia violacea (Schneev.) Steam (Fabaceae) was studied using plants from a natural habitat near Rankins Springs, central‐western New South Wales, Australia. The accumulation and partitioning of dry matter and 12 mineral nutrients in pods and seeds of fruits is described. Seeds accumulated about 50% of the dry matter of a mature fruit, over 90% of its N and P content, 50 to 75% of its K, Ca, Mn, Cl, S, Zn, Cu and Mg, but less than 50% of its Fe and Na. Over 75 % of the N and P content of pods was redistributed during senescence, although other nutrients and dry matter were not redistributed to the same extent; there was negligible redistribution of Ca, Cl, Na, Fe and Mn from the pod. Redistribution of N and P from the pod could have provided up to 30% of these nutrients accumulated by mature seeds. Concentrations of most nutrients were higher in seeds than pods. The testa made up 60% of the dry matter content of a seed and contained the major proportion of its Ca, Mg, Cl, Na and Mn; the embryo contained most of the seed's contents of N, P, K, S, Zn and Cu.The elaiosomes had less than 5% of the seed's dry matter and mineral nutrient content. The oil content of the elaiosome was 34%, compared to 12% for the embryo. Oleic acid made up over 60% of the fatty acid content of elaiosome oil. Aspartic acid, arginine and glycine were the major amino acids in the elaiosome. The embryo contained 10% of the non‐protein anti‐metabolic amino acid, canavanine, the elaiosome only 1%. Sodium dodecyl sulphate‐polyacrylamide gel electrophoresis showed that the subunit protein compositions of the elaiosome and embryo were different. The composition of the elaiosome is discussed in relation to the nutrition of ants. It is concluded that, in H. violacea, the elaiosome represents a nutritionally cheap means to the plant of achieving secondary seed dispersal by ants.
LOCALIZED INCREASE IN NODULE ACTIVITY BUT NO COMPETITIVE INTERACTION OF COWPEA RHIZOBIA DUE TO PRE‐ESTABLISHMENT OF VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: AMES ROBERT N. , BETHLENFALVAY GABOR J. 
Published: April 2006

SUMMARYCowpea [Vigna unguiculata (L.) Walp.] plants were grown in a split‐root system using a calcined montmorillonite clay (Turface) as the growth medium. At transplanting, either the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus macrocarpum Tul. & Tul. and 100 mg hydroxyapatite (HAP) or 100, 200 or 400 mg HAP kg−1 without the VAM fungus were mixed into side 1 of the split‐root system. Side 2 received only 100 mg HAP kg−1. After 30 d, a combined inoculum of four Rhizobium isolates (TAL169, TAL173, TAL658 and IRC256) was applied to the surface of all pots. At harvest (60 d), root systems were separated from shoots, and nodule activity (acetylene reduction), plant dry weight, nitrogen (N) and phosphate (P) content and the percentage of VAM colonization were determined. There was no significant effect of treatment on either the N or P content of leaves or roots. The VAM fungus, however, significantly (P < 0.01) increased shoot dry weight. Root dry weight and nodule activity were significantly increased only on the VAM side of the split‐root system. Rhizobia from 30 nodules per half‐root system were identified using fluorescent antibody techniques. Strain TAL 173 was detected from 95% of the nodules and neither the VAM fungus nor P application affected competitive interaction by rhizobia for nodulation sites. Our work suggests the existence of a localized, non‐systemic, non‐P‐mediated influence of a VAM fungus on root dry weight and nodule activity in cowpea.
MORPHOGENETIC RESPONSE OF VEGETATIVE BUD EXPLANTS OF ADOLESCENT AND MATURE PICEA GLAUCA (MOENCH) VOSS IN VITRO*
Authors: DUNSTAN DAVID I. , MOHAMMED GINA H. , THORPE TREVOR A. 
Published: April 2006

SUMMARYThe formation of adventitious shoot primordia on cultured explants from vegetative buds of Picea glauca (Moench) Voss varied with the source tree. The best response, i.e. the highest number of responsive explants (10/25) and of shoot primordia per responsive explant (average 8.1), was found with buds excised from a tree in a natural stand (15 to 18 years old). However, explants from only one other tree of eight natural stand trees responded with shoot primordium formation. By comparison, explants from four out of five orchard trees (scions 25 to 28 years old) produced shoot primordia in vitro.Of the material compared, the explants which were most likely to show shoot primordium formation were from the terminal bud and the nearest lateral buds of a main lateral branch. Explants from similar buds on subdominant branches of highest hierarchy are also included in this category. Finally, the original size did not significantly influence the number of shoot primordia produced on responsive explants 12 weeks after explantation.
SPOROCARPS OF AZOLLA MEXICAN A PRESL I. ISOLATION AND PURIFICATION OF MEGASPOROCARPS AND MICROSPORANGIA*
Authors: TOIA R. E. , BUZBY K. M. , PEPTERS G. A. 
Published: April 2006

SUMMARY Azolla mexicana Presl, a heterosporous aquatic fern, consistently sporulates under routine culture conditions, producing both megasporocarps and microsporocarps in abundance. As a prelude to studies on germ plasm preservation, gametogenesis, embryogenesis, and efforts to establish interspecific hybrids, methods were developed to isolate and separate the reproductive structures. Fertile sporophytes were agitated to release the sporocarps. During this process mature microsporocarps ruptured to release microsporangia. A series of stainless steel sieves, ranging from 1130 to 200 μm in pore size, was used to separate megasporocarps and microsporangia from sporophyte debris and immature microsporocarps. Purified preparations of megasporocarps and microsporangia were obtained using sorbitol step gradients.
FLANDRIAN ENVIRONMENTAL HISTORY OF THE ISLE OF MULL, SCOTLAND
Authors: WALKEER M. J. C. , LOWE J. J. 
Published: April 2006

SUMMARYPollen percentage and pollen concentration data are described from an infilled basin within a Loch Lomond Stadial end moraine at Gribun on the west coast of the Isle of Mull, Inner Hebrides, Scotland. The pollen profile, which is over 13 m deep, spans most of the Flandrian stage and constitutes one of the most detailed records of post–glacial vegetational change for any area in northern Britain. Nine local pollen assemblage zones and five pollen concentration zones are identified in the pollen diagrams, and these can be correlated with biozones recognized in other profiles on Mull. In general, the data from Gribun confirm the spatial and temporal patterns of Flandrian vegetational developments that have been suggested by these earlier studies. However, the high level of biostratigraphic resolution within the Gribun profile places these palaeobotanical and associated reconstructions on a more secure footing, and it is therefore proposed that Gribun be considered as the type site for the Flandrian stage in this area of western Scotland.
THE ANATOMICAL CHARACTERISTICS OF ROOTS AND PLANT RESPONSE TO SOIL FLOODING
Authors: JUSTIN S. H. F. W. , ARMSTRONG W. 
Published: April 2006

SUMMARYNinety‐one plant species from wetland (WL), intermediate (INT) and non‐wetland (NWL) habitats were grown in flooded and drained soils and responses to flooding were assessed in relation to root anatomy and fractional root porosity (FRP).Flooding response and tolerance were related to FRP. Rooting depth increased with FRP in accordance with diffusion model predictions and emphasized the ventilating efficiency of aerenchyma. Major determinants of FRP were cortical cell configurations, closeness of cell packing, the relative proportions of configuration types, porous: non‐porous tissue ratios, aerenchyma development and the type and degree of secondary growth. A classification of cortical types based on cell and aerenchyma patterns is presented.Aerenchyma, both schizogenous and lysigenous, developed preferentially where pre‐aerenchymatous cortical cell configurations (in TS) were radial and particularly, cubic and radial typical of WL and INT species. Aerenchyma rarely formed from hexagonal non‐radial arrays which occur chiefly in NWL and in the outer cortical zones of WL and INT plants. The ventilating potential in non‐aerenchymatous tissue was shown to be greater for cubic (fractional porosity, FP, max. 0–2146) than for hexagonal arrays (FP max. 0˙0931); closer packing greatly accentuated the differences. It is suggested that cubic: hexagonal zonal ratios in roots may reflect a balance between respiratory and mechanical needs.In a majority of WL and INT species, shoot weights were unaffected by or increased with flooding and maximum rooting depths usually much exceeded 50 mm. Cubic packing raised the FRPs, as did aerenchyma which was often much greater under flooding. In the dicotyledonous species, a suppression of secondary growth in some, and a highly porous phelloderm in others, helped maintain high FRP. A minority of species were anatomically and responsively similar to NWL plants; survival under flooding was attributed to shallow rooting.Under flooding, the FRP of almost all NWL species was < 0˙055 due to hexagonal packing, a lack of aerenchyma and, in dicotyledonous plants, secondary growth with scanty phelloderm. Shoot weights were reduced in 50% of cases, rooting depths were <50 mm, and some species died. Some species were exceptional in having cubic and radial packings; a lack of aerenchyma was associated with continuing meristematic activity in the primary cortex.
THE ECTOMYCORRHIZAL INFECTION ZONE AND ITS RELATION TO ACID POLYSACCHARIDES OF CORTICAL CELL WALLS
Authors: NYLUND JAN‐ERIK 
Published: April 2006

SUMMARYCortical cell walls of spruce [Picea abies (L.) Karst.] and pine (Pinus sylvestris L.) were found to contain large amounts of acid polysaccharide, which was absent from all other cell walls studied. In its staining characteristics, calcium content, extractability and structure it was similar to the pectic substance filling intercellular regions in the cortex, xylem and other tissues. The acid polysaccharide also formed a matrix embedding fungal cells of the Hartig net in mycorrhizal roots. Matrix substance in the mantle was of a different character.The distal limit of the acid polysaccharide wall incrustation marked the transition between the differentiation zone of the root tip and the mature cortex, and coincided exactly with the distal limit of the Hartig net and fungal penetration. The endodermis and, where present, the metacutis formed other barriers. Proximally, the onset of senescence and death of cortical cells made mycorrhiza formation impossible, or terminated the existing symbiotic relationship.Thus, ‘the mycorrhizal infection zone’, i.e. the part of the root where fungal colonization could take place, was defined by (a) a particular wall composition and (b) a physiological condition. Such limitation is consistent with the theory of mechanical fungal penetration during mycorrhiza formation‐the pectins increase the cell‐wall flexibility‐as well as the model for host‐mycobiont interaction proposed in an earlier study (Nylund & Unestam, 1982).
ZINC TOLERANCE IN BETULA SPP.
Authors: DENNY HILARY J. , WILKINS D. A. 
Published: April 2006

SUMMARYClones of Betula pendula Roth, and B. pubescens Ehrh., collected as seed from zinc‐contaminated mine tailings, were grown aseptically in a liquid/perlite medium. Three zinc‐tolerant and four non‐tolerant genotypes were compared with respect to extension growth and zinc uptake over a range of external concentrations of zinc. The effect of increasing zinc concentration on total root length and root cell length was also examined. Extension growth declined rectilinearly as the external zinc concentration increased, but the relationship between uptake and external concentration was not rectilinear. After an initial proportional increase, concentrations of zinc in tissues remained constant over much of the range of external concentrations at which some growth was possible. Fresh weight concentrations of zinc in tolerant and non‐tolerant genotypes were similar at similar external concentrations. However, at a characteristic threshold external concentration, control of uptake broke down and plants were inundated with zinc. The decrease in extension growth was found to be due mainly to a progressive inhibition of cell elongation. Zinc tolerance in Betula lies in an ability to maintain proportionally more extension growth at similar internal and external zinc concentrations. Neither a tolerance mechanism involving internal detoxification, nor binding of zinc ions to electronegative sites in the cell walls, are consistent with the results. However, these findings are compatible with a tolerance mechanism involving control of uptake operating at the endodermis.
ZINC TOLERANCE IN BETULA SPP.
Authors: DENNY HILARY J. , WILKINS D. A. 
Published: April 2006

SUMMARYA survey was made of fungi forming ectomycorrhizas with Betula pendula Roth, and B. pubescens Ehrh. on zinc‐contaminated mine tailings. Strains of Paxillus involutus Fr. from toxic and non‐toxic soils were compared. There was no indication of fungal adaptation to zinc at either the inter‐ or intraspecific level. Most of the typical fungal associates of Betula on normal soils were also found on the zinc‐rich soils. The ability of different strains of P. involutus to (a) grow in pure culture on agar, (b) form ectomycorrhizas with Betula, and (c) produce a beneficial growth and zinc uptake response in the associated plant, all in the presence of raised zinc concentrations, was not related to the zinc status of the provenance. The ameliorating influence of P. involutus on zinc toxicity to Betula seemed to be positively linked to the degree of compatibility between fungal strain and higher plant.
ZINC TOLERANCE IN BETULA SPP.
Authors: DENNY HILARY J. , WILKINS D. A. 
Published: April 2006

SUMMARYAseptic cultures of Paxillus involutus Fr. and clones of Betula pendula Roth, and B. pubescens Ehrh. were used in experiments, involving X‐ray microanalysis and split‐plate culture, to investigate the mechanism of ectomycorrhizal amelioration of zinc toxicity to Betula. Results imply that as the fungal mycelium colonizes fresh soil, zinc is adsorbed to the surface of hyphae, thereby lowering the concentration of zinc in the soil solution surrounding roots. In consequence, less zinc is taken up, and growth is better than in the non‐mycorrhizal condition. The results also show that the metal may be adsorbed to electronegative sites in the hyphal cell walls and extra‐hyphal, polysaccharide slime. The possible dual role of this slime in fungus/Betula compatibility and the amelioration mechanism is discussed.
WATER STRESS MODIFIES INTRASPECIFIC INTERFERENCE BETWEEN RUST (PUCCINIA LAGENOPHORAE COOKE)‐INFECTED AND HEALTHY GROUNDSEL (SENECIO VULGARIS L.)
Authors: PAUL N. D. , AYRES P. G. 
Published: April 2006

SUMMARYPopulations of groundsel (Senecio vulgaris L.) were grown in the field in bottomless containers which allowed roots to penetrate freely into the natural soil profile. The 36 plants within each population (equivalent to 1250 m−2) were either all inoculated with the rust Puccinia lagenophorae Cooke, all rust free, or were a 1:1 mixture of the two. Rain was excluded from all populations by small shelters. Half the populations were subjected to mild drought, whilst remaining populations were well‐watered. Rust significantly reduced shoot dry weights, especially in droughted populations. The frequency distributions of shoot dry weight showed significant inequality (were strongly skewed) in all treatments and populations. Inequality of the frequency distribution of shoot dry weight was increased in rusted populations because infection increased the proportion of suppressed individuals. Again the effect of rust was most pronounced under conditions of drought and particularly in mixture. Rust significantly lowered mean shoot water potential (ψ) in dry monocultures and in both wet and dry mixtures. Values of ψ at harvest in suppressed, rusted individuals in mixtures were often highly negative. Compared with dry monocultures, water stress in mixtures was ameliorated in the healthy, but exaggerated in the rusted, components. The more negative values of ψ in rusted populations were the result of changes in frequency distributions as well as in mean values. Under dry conditions status in the dry weight hierarchy was closely correlated with ψ These changes are interpreted as reflecting the reduced ability of the root systems of rusted plants to compete for limited water.The competitive ability of control over rusted groundsel, as measured by relative crowding coefficient (Ker), was 1–09 under well‐watered conditions but increased to 1˙51 under drought. In both well‐watered and droughted populations, the greater impact of rust on the population hierarchy of mixtures was reflected in the inverse relationship between the status of sub‐classes, based on shoot weight and class Ker. It is concluded that water stress probably plays a crucial role in determining the impact of rust on mixed populations in the field.
WHEN IS A CHROMOPLAST?
Authors: WHATLEY J. M. , WHATLEY F. R. 
Published: April 2006

SummaryChromoplasts are heterogeneous organelles and their carotenoids can be associated with several different structural elements including globules, tubules and membranes. In the flower petals of some species, carotenoids are absent or present only in trace amounts. Nevertheless, the plastids in such flowers can closely resemble or even be indistinguishable in structure from chromoplasts.
THE EFFECT OF MANGANESE ON ROOT EXTENSION OF GEUM RIVALE L., G. URBANUM L. AND THEIR HYBRIDS
Authors: WALDREN S. , DAVIES M. S. , ETHERINGTON J. R. 
Published: April 2006

SummaryRoot elongation of Geum rivale and G. urbanum grown in nutrient solution decreased as manganese concentration was increased above 25 mg dm−3, especially in G. urbanum. Prior exposure of roots to 25 mg Mn dm−3increased their capacity for subsequent elongation in manganese solutions, the effect of such pretreatment being most pronounced in G. rivale. G. rivale was significantly more tolerant of 50 mg Mn dm−3than G. urbanum. Efflux of potassium from root segments, used as a measure of membrane permeability, was significantly higher in G. urbanum than in G. rivale at this concentration. Tolerance of 50 mg Mn dm−3by progeny of hybrid individuals was generally related to morphological intermediacy, although there were some noticeable exceptions. Manganese tolerance of hybrids could not be consistently related to their known tolerance of waterlogging.
COMPARATIVE STUDIES OF PLANT GROWTH AND DISTRIBUTION IN RELATION TO WATERLOGGING
Authors: WALDREN S. , ETHERINGTON J. R. , DAVIES M. S. 
Published: April 2006

Summary Geum rivale L. and G. urbanum L. were grown in drained, continuously flooded or transiently flooded compost for 21 weeks. Leaf and root material harvested after this time was analyzed for Fe, Mn, Ca and P. Mn and Fe concentrations in roots and leaves of both species were increased by flooding. Higher Fe concentrations accumulated in the roots, while Mn was present in roughly equal concentrations in both roots and leaves. Leaf Ca concentration of both species was higher than that of roots. Although Ca concentrations were significantly higher in G. rivale than in G. urbanum, there were no readily interpretable effects of waterlogging. P concentration was decreased in leaves and increased in roots of flooded G. urbanum, although there was much less effect of flooding on P concentration in G. rivale. Fe may be precipitated by phosphate in G. urbanum roots, but this may lead to P deficiency in shoots and roots, resulting in poor growth of this species in waterlogged soil. A different mechanism of Fe immobilization is likely to occur in G. rivale, which does not result in phosphorus deficiency.
AN ANALYSIS OF THE INFLUENCE OF CLONE SIZE AND STOLON CONNECTIONS BETWEEN RAMETS ON THE GROWTH OF GLECHOMA HEDERACEA L.
Authors: SLADE ANDREW J. , HUTCHINGS MICHAEL J. 
Published: April 2006

SummaryTwo experiments were conducted in which the influence of size of clones and the persistence of stolon connections on subsequent development were examined in Glechoma hederacea. In the first experiment, clones were grown from either one unrooted ramet or from either one, two or three connected, rooted ramets, for 8 weeks, in either nutrient‐rich or nutrient‐poor sand. The survival, number of ramets and dry weight of the clones produced were dependent on the number of established ramets at the start of the experiment. Clones in nutrient‐rich sand developed a greater number of ramets, stolon branches, total length of stolon, mean leaf area per ramet and total leaf area per clone than clones of corresponding initial size in nutrient‐poor sand. In the second experiment, the stolon connections between ramets of G. hederacea clones growing in boxes were either left intact or severed soon after each ramet had rooted. After 10 weeks of growth, the total dry weight of the intact clones and the mean dry weight of their ramets were significantly greater than the corresponding values for severed clones. The spatial distribution of ramets showed marked differences between the treatments. Severed clones produced a greater number of rooted ramets within the boxes and a smaller number of unrooted ramets beyond the box edges than intact clones. Density of ramets more than doubled when stolons were severed.Maintenance of stolon connections in G. hederacea is advantageous because it improves the probability of daughter ramet survival, promotes rapid lateral expansion of the clone and reduces inter‐ramet competition through the production of fewer, larger ramets.
THE DYNAMICS OF AN EXPERIMENTAL POPULATION OF SALVIA LYRATA: THE POPULATION CAGE APPROACH APPLIED TO PLANTS
Authors: SHAW RUTH G. , ANTONOVICS JANIS 
Published: April 2006

SummaryWe report a four‐year study of the dynamics of a population of Salvia lyrata L., growing in a greenhouse. The study exemplifies the population cage approach, which has been the basis of many long‐term studies of dynamics of animal populations for over 50 years, but which has been overlooked by plant population biologists. The cohort of plants that founded the population had a very high probability of survival and, as adults, produced the greatest numbers of seeds and seedlings. Thereafter, the numbers of individuals in each stage class declined. This decline appeared to be a consequence of density‐dependent processes. At the conclusion of the study, the population density was far lower than at the onset. The behaviour of the population differed from that of the population of S. lyrata studied in a nearby mown field in several respects, including timing of seedling emergence, average size of individuals and final density. Likely causes of these differences are discussed. We recommend the use of population cages in further studies of plant populations. Because it facilitates long‐term observation, this approach can be of great use in elucidating the dynamic consequences of demography.
TRANSPORT OF SUGAR IN PHYTOPHTHORA PALMIVORA (BUTL.) BUTL.
Authors: SHEARD J. , FARRAR J. F. 
Published: April 2006

SummaryThe kinetics of uptake of sucrose, glucose and fructose by Phytophthora palmivora are all biphasic. At low concentrations, glucose and fructose share a common, high‐affinity, hexose carrier, and sucrose is probably hydrolyzed extracellularly at these concentrations before the transport of the resultant hexoses by this carrier. At higher concentrations, a low‐affinity carrier may transport sucrose directly, but this carrier appears to have a higher affinity for glucose than sucrose. Activity of neutral invertase (β‐D‐fructofuranoside fructohydrolase) in both soluble and particulate (cell‐wall) preparations is considerably in excess of the highest rates of sucrose uptake.