bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE GERMINATION OF SOME WOODLAND HERBACEOUS SPECIES UNDER LABORATORY CONDITIONS: A MULTIFACTORIAL STUDY
Authors: SLADE ELIZABETH A. , CAUSTON D.R. 
Published: May 2006

SummaryThe effects of five potentially dormancy‐breaking treatments – potassium nitrate, scarification, ethylene, light, and scarification ‐ were tested on 13 species from deciduous woodland, in a complete factorial experiment. The seeds were about 6‐months‐old and were germinated at 18°. None of the treatments induced germination in Mercurialis perennis or Sanicula europaea. Milium effusum and Silene dioica germinated well over a very wide range of conditions. Stratification promoted the germination of Endymion non‐scriptus, Galium aparine and Veronica hederifolia; while scarification mostly had a depressive effect, except in the cases of E. non‐scriptus and Geranium robertianum where some promotion of germination was discovered. Circaea lutetiam and Veronica montana appeared to have highly specific germination requirements: the former species required nitrate, ethylene, and light in combination; while the latter required nitrate, light and stratification in combination for germination. Geum urbanum germinated well if treated with nitrate alone, while Veronica chamaedrys required light only, and Stachys sylvatica gave good germination with stratification alone. There were also several significant first‐ and second‐order interactions. Where possible, the results are discussed in relation to previous work and to the ecology of the species.
THE BIOLOGY OF AMBROSIA TRIFIDA L. IV. DEMOGRAPHY OF PLANTS AND LEAVES
Authors: ABUL‐FATIH H. A. , BAZZAZ F.A. 
Published: May 2006

SummaryIn low‐density populations of Ambrosia trifida plants grown in monoculture in the field all individuals survived to maturity. The plants had high rates of leaf birth and death. However, under high densities there was death of whole plants and a decline in leaf birth ‐ and death‐rates. Furthermore, under high densities leaves lived longer than did leaves under low density. Thus, regulation of populations in response to density occurs at two levels: whole plants and individual leaves.
MODERN POLLEN SAMPLES FROM WEST GREENLAND AND THE INTERPRETATION OF POLLEN DATA FROM THE BRITISH LATE‐GLACIAL (LATE DEVENSIAN)
Authors: PENNINGTON WINIFRED , Tutin T. G. 
Published: May 2006

SummarySamples of the modern pollen rain, some from lake sediment and some from moss polsters, were taken in two regions of West Greenland in which the climate is respectively low arctic continental and low arctic oceanic: (1) round the head of Söndre Strömfjord at 67° N; and (2) the south‐west of Disko Island at 70° N. The vegetation has been described and analysed by Böcher (1954, 1959, 1963). In Region 1 where the vegetation is a mosaic of xerophilous grassland with Artemisia borealis (steppe) and Betula nana heath, mean pollen percentages from 11 polsters corresponded quite closely with percentage cover for those taxa in the vegetation. Polsters from steppe could be distinguished from heath polsters by higher values for Artemisia in steppe and Ericales (Ledum, Empetrum, Vaccinium, Rhododendron) in heath, but Betula nana and grasses, with the highest values in both pollen and vegetation, showed no consistent difference between polsters of different origin‐presumably showing good pollen dispersal. In four lake samples B. nana was over‐represented by pollen values and Artemisia had a lower mean than in terrestrial samples. In Region 2 where the vegetation is a more oceanic heath in which B. nana is infrequent and Artemisia absent, the pollen samples differ from those of Region 1 in consistently higher values for Cyperaceae and lower values for Gramineae and B. nana: Artemisia is here represented by only the same few grains as the exotic taxa Pinus and Picea. When compared with vegetation cover in Region 2, sedges and B. nana appear to be over‐represented in pollen samples, especially from lakes, and Salix herbacea and the herbs of snow‐bed and heath‐mat communities to be under‐represented.These findings can be used in interpretation of Late Devensian pollen spectra which lack arboreal pollen, and make it probable that: (i) samples from the earliest Late Devensian pollen zones represent an oceanic dwarf‐shrub vegetation in which there was more Salix herbacea and fewer sedges than pollen values suggest; (ii) Betula nana did not at any time form an appreciable part of the vegetation cover; and (iii) Artemisia pollen values provide an index to local vegetation cover, which implies a vegetation mosaic correlated with snow cover during the period of the Loch Lomond Advance (c. 11000 to 10500 B.P.).
COMPARISON OF THE ONION PLANT (ALLIUM CEPA) AND ONION TISSUE CULTURE III. FEEDING OF 14C LABELLED PRECURSORS OF THE FLAVOUR PRECURSOR COMPOUNDS
Authors: TURNBULL A. , GALPIN I. J. , COLLIN H. A. 
Published: May 2006

SummaryCallus and onion leaf tip material were exposed to [14C]cysteine, [14C]serine or [14C]valine and the distribution of labelling in the amino acids and cysteine derivatives assessed after two to fourteen days. With [14C]cysteine and serine radioactivity was found in the callus in a range of amino‐acids and in the flavour precursor compounds, S‐methyl‐L‐cysteine sulphoxide and S‐trans‐prop‐1‐enyl‐L‐cysteine sulphoxide, particularly in the former precursor. [14C]valine was much more metabolically inert and little distribution of radioactivity occurred. In comparison the shoot tip showed a more active metabolism of [14C]serine and cysteine than callus but again much less activity with [14C]valine. With all three compounds, however, the heaviest labelling in the shoot tip was in the cysteine derivatives, particularly the main flavour precursor of the intact onion, S‐trans‐prop‐1‐enyl‐L‐cysteine sulphoxide. When unlabelled cysteine derivatives were fed to callus, S‐trans‐prop‐1‐enyl‐L‐cysteine sulphoxide was formed. The presence of this precursor compound in callus showed that the callus was capable of synthesizing 5‐trans‐prop‐l‐enyl‐L‐cysteine from early intermediates, such as the amino‐acids, and by a pathway similar to that in the intact plant.
ACTION OF GROWTH REGULATORS ON LUCERNE GERMINATION AND GROWTH UNDER WATER STRESS
Authors: ROSS HEATHER A. , HEGARTY T. W. 
Published: May 2006

SummaryLucerne seeds (Medicago sativa L.) were germinated in a range of polyethylene glycol (PEG) and sodium chloride (NaCl) solutions in the presence and absence of kinetin with ethrel. In addition, seeds were germinated in water and transferred to PEG and NaCl solutions, and root growth was measured. The water potentials at which there was 50% germination inhibition and at which 50 % of the germinated seeds failed to grow after transfer were determined. Kinetin and ethrel together completely removed the block to germination through osmotic stress, allowing germination to proceed at the same water potential as growth. The action of kinetin and ethrel was studied by following the processes of cell expansion and division during germination and early growth. The control of germination by water stress was through cell expansion, and the initiation of this process was shown to be stimulated in the presence of the growth regulators. Cell division although initially permitted in their presence, was later inhibited causing a decline and finally cessation of seedling growth.
ADAPTATION OF VESICULAR‐ARBUSCULAR MYCORRHIZAE TO EDAPHIC FACTORS*
Authors: LAMBERT D.H. , COLE H. , BAKER D. E. 
Published: May 2006

SummaryIn three field soils, birdsfoot trefoil (Lotus corniculatus L.) transplants infected with mycorrhizal fungi from 42 soils showed no clear superiority of strains from these individual soils after a year's growth. Differences among strains decreased with time and were only significant for all three soils at the first cutting. There were low‐level correlations between yield and various chemical properties of the soils from which the cultures were derived. In the greenhouse, with sterilized soils low in P, trefoil yield was always greatest when the inoculum used was indigenous to the soil in which the plants were grown as compared to inocula from five different soils. These results suggest that indigenous strains of mycorrhizal fungi may possess an adaptation to edaphic factors and that the performance and persistence of strains otherwise more efficient in nutrient uptake may be limited by their lack of adaptation.
THE ULTRASTRUCTURE OF COLEOPTILE CELLS IN DRY RICE (ORYZA SATIVA L.) GRAINS AFTER ANHYDROUS FIXATION WITH OSMIUM TETROXIDE VAPOUR
Authors: ÖPIK HELGI 
Published: May 2006

SummaryColeoptiles from dry rice grains were prepared for electron microscopy by anhydrous fixation with OsO4 vapour. The cells were much shrunken, with highly folded walls; nuclei, plastids, mitochondria and lipid bodies all showed irregular outlines indicative of shrinkage and mutual compression. Some membranes were represented only by an electron‐transparent lamella, but in the plasmalemma a tripartite structure could be discerned. A significant finding was that the plasmalemma was continuous and unbroken (as were other cellular membranes), in complete contrast to the situation seen after aqueous fixation, when many breaks occur in the plasmalemma. Such breaks must be attributed to stresses set up between the plasmalemma and the cell wall as the cells are hydrated during fixation. Difficulties were encountered in identifying organeiles, contrast being low and less detail being visible than after aqueous fixation.
REPRODUCTIVE BIOLOGY OF STELLARIA LONGIPES GOLDIE AS REVEALED BY A CULTIVATION EXPERIMENT
Authors: PHILIPP M. 
Published: May 2006

SummaryIn cultivation experiments with Stellaria longipes sensu lato. from Greenland, the life history has been thoroughly studied, in order to find out how female plants in this gynodioecious/gynomonoecious breeding system are favoured in relation to the hermaphrodite plants. It seems that the maintenance of the female plants is determined by a combination of differences in length of the reproductive cycle, number of flowers per plant, number of seeds per capsule, and the sex segregation in the populations. Other factors, which might be sex linked, such as the area of cotyledons and germination pattern, may be important.
PLEISTOCENE FOREST HISTORY IN EAST ANGLIA
Authors: WEST R. G. 
Published: May 2006

SummaryThe East Anglian Pleistocene succession records eight temperate stages with forest and also interstadials with forest in two of the intervening cold stages. The forest histories of these temperate stages and interstadials are described. The records through the Pleistocene of the tree genera involved are considered. The forest assemblages in each of four substages of the temperate stages (pre‐temperate, early‐temperate, late‐temperate, post‐temperate) are compared. The development of heath in the temperate stages is also examined. Floristic and phytogeographic changes indicated by the palaeobotanical evidence give information on Tertiary‐relic genera and on extinctions, and have a bearing on the problem of the history of cold stage refugia. The success or failure of particular genera in response to the stress of climatic change is discussed. Finally, comparisons are made with Pleistocene forest history in north‐west Europe.
PLASTID GROWTH AND DIVISION IN PHASEOLUS VULGARIS
Authors: WHATLEY JEAN M. 
Published: May 2006

SummaryThe sizes and numbers of plastids were determined in the cells of the upper epidermal and upper palisade layers during development of the primary leaf of Phaseolus vulgaris. Plastids of both epidermal and palisade cells divide at all stages of plastid development, but division ceases soon after the plastids become mature. The process of plastid division involves both extension growth and fission. During growth of the primary leaf within a seed developing on the parent plant, plastids in both the epidermal and the palisade cells show little overall growth in size. During germination epidermal cell plastids remain small but plastids in palisade cells increase considerably in size as the leaf expands. Populations of potentially dividing plastids can be identified by the characteristic distribution of their size classes which, when set out graphically, give curves of distinctive shape.Cell division takes place during development of the primary leaf both prior to and following dormancy. Plastid division also occurs during these two periods. However, within each cell the plastids do not divide in synchrony. Nor are the periods of cell and plastid division synchronized, for the plastids continue to divide during the phase of maximum leaf expansion, when cell division has ceased but while cell extension continues. In the primary leaf of Phaseolus the overall number of cycles of plastid division exceeds that of cell division by between two and three cycles.
SEXUAL STRATEGIES IN PLANTS
Authors: LLOYD DAVID G. 
Published: May 2006

SummaryIt is postulated that in one reproductive session the level of maternal expenditure of an angiosperm plant is determined by a temporal series of controls on the number of potential fruit in which an investment is made. The serial adjustment hypothesis has three parts:A. The amount of maternal expenditure is regulated at many developmental units, particularly single flowers and fruit, at three principal sequential stages – the determination of flowers, the development of ovaries and the maturation of fruit.B. At each stage, the initiation or continuation of an investment requires an amount of available resources above a certain threshold. Hence maternal expenditure is continually adjusted to the resources available at each developmental site.C. The pattern of controls that maximizes the maternal fitness of a plant is selected. Many factors affect the relative advantages of regulation at the three stages, therefore species and sexual morphs appear to vary widely in their proportional use of the three stages.Regulation of flower determination has the general advantages of offering bidirectional adjustment of maternal investment, maintaining a constant ratio of maternal to paternal investment, and reducing wasted expenditure. The later stages, ovary and fruit regulation, allow secondary adjustments of maternal investment in unpredictable circumstances and permit adjustment of the relative numbers of polliniferous and seminiferous flowers. The relative advantages of restricting the numbers of developing ovaries, or of maturing fruit, depend principally on the extent to which differences in the capacity of flowers to mature fruit are evident before anthesis.
SEXUAL STRATEGIES IN PLANTS
Authors: LLOYD DAVID G. , WEBB C. J. , PRIMACK RICHARD B. 
Published: May 2006

SummarySeventeen angiosperm species were examined to determine the degree to which the plants of each sexual morph limit their maternal investment during one reproductive session at three successive floral stages (flower determination, pre‐anthesis ovary development, and post‐anthesis fruit maturation). The results indicate that species and sexual morphs differ dramatically in the relative use they make of the three stages. Both the flower number per inflorescence and the proportion of flowers with developed ovaries are generally less variable in species with inflorescences which have well denned sequences of flower development. In most species, the variability among the plants of one morph is greater in the frequency of fruit maturation than in the frequency of ovary development. Much of the intra‐morph variation in both the frequency of ovary development and the frequency of fruit maturation appears to be non‐genetic. In most of the morphs examined, the frequencies of ovary development and fruit maturation are not correlated with the number of flowers per plant or with each other. The results provide circumstantial evidence in support of the hypothesis of serial adjustment of maternal investment.
PERFECT STATES OF RHIZOCTONIAS ASSOCIATED WITH ORCHIDS. III
Authors: WARCUP J. H. , TALBOT P. H. B. 
Published: May 2006

SummaryFurther Rhizoctonia isolates from Australian orchids have been induced to fruit in culture. The perfect states obtained include three new species of Ceratohasidium, C. angustisporum, C. globisporum, and C. papillatum, a new species of Tulasnella, T. irregularis, and a new species of Ypsilonidium Donk emend. Talbot, Y. anomalum Talbot.
THE SECRETORY CYCLE OF DIONAEA MUSCIPULA ELLIS
Authors: ROBINS R. J. , JUNIPER B. E. 
Published: May 2006

SummaryAutoradiography has been used to track the path of secretion in the digestive glands of Dionaea muscipula. Neither the dictyosomes nor dictyosomal vesicles appear to be involved, but radio‐label is lost rapidly from the endoplasmic reticulum and small osmiophilic vacuoles directly into the cell wall. Radiolabel is subsequently lost from the large osmiophilic vacuoles and accumulates in the small vacuoles. The effects of colchicine and cytochalasin B are complex. Both decrease the enzymatic activity of the secretion, but not the protein content, suggesting effects on the synthesis and discharge of secretion not directed against microtubules or microfilaments. It is proposed that the discharge of secretion occurs by direct fusion of ER to the plasmalemma or via vesicles and vacuoles derived from the ER.
AUTECOLOGICAL STUDIES OF TRIFOLIUM MOLINERII AT THE LIZARD PENINSULA, CORNWALL
Authors: MARTIN M. H. , FROST L. C. 
Published: May 2006

Summary Trifolium molinerii (T. incarnatum ssp. molinerii) is shown to be a strongly maritime plant growing typically in head deposits on schistose cliffs and a member of the Thero‐Sedetum anglici Association of Malloch, (1971). Principle co‐ordinates analysis of quadrat data separated eight groupings, which are interpreted in terms of environmental factors in particular in relation to position on the cliff profile. The status of the clover is discussed and, although biotic influences and human interference are important factors in its present distribution, the plant is considered to be native.
THE REQUIREMENT OF AQUATIC BRYOPHYTES FOR FREE CO2 AS AN INORGANIC CARBON SOURCE: SOME EXPERIMENTAL EVIDENCE
Authors: BAIN JANET T. , PROCTOR M. C. F. 
Published: May 2006

SummaryTwenty bryophyte species were tested for photosynthetic uptake of bicarbonate by immersing plants in 2.0 mM and 0.2 mM NaHCO3 and monitoring rise in pH. Equilibrium values were clustered around pH 9.0 and pH 8.0 in the two solutions, indicating limitation by free CO2 and inability to use bicarbonate. Anthoceros husnotii reached a maximum pH value of 9.5 in 2.0 mM NaHCO3, suggesting possible, although inefficient, bicarbonate uptake. Four species of bicarbonate‐using plants tested for comparison gave final pH values in the range of 10.1 to 10.9. Field measurements gave results consistent with the laboratory experiments. Availability of CO2 to bryophytes growing in different aquatic habitats is discussed and their ecology is considered in light of the results.
Studies IN FESTUCA 12. MORPHOLOGY, DISTRIBUTION AND CYTOGENETICS OF F. DONAX, F. SCARIOSA AND THEIR HYBRIDS, AND THE EVOLUTIONARY SIGNIFICANCE OF THEIR FERTILE AMPHIPLOID DERIVATIVE
Authors: BORRILL MARTIN , KIRBY MADELEINE , MORGAN GARETH 
Published: May 2006

Summary

The morphology and distribution of the phenotypically dissimilar diploid species Festuca donax and F. scariosa have been examined.
Production of the fertile amphiploid hybrid F. donax×F. scariosa, by colchicine treatment of hybrid seeds, and of triploids by backcrossing the amphiploid to the parents, has made possible a study of preferential pairing in these genotypes. The S and D genomes had considerable and approximately equal ability to pair preferentially in the SSD and SDD hybrids. The amphiploid had marked bivalent pairing, segregated little, and was seed and pollen fertile.
These results put in perspective previous studies based on diploid hybrids between sections Scariosae and Montanae, and suggest a greater degree of differentiation of the genomes of these two sections than previously supposed. They are nevertheless more closely related to one another, than to F. pratensis.
The caryopsis apex in diploids of Scariosae and Montanae sections is pubescent. The presence of this pubescence has therefore been surveyed in broad‐leaved fescue polyploids. It occurs only in polyploid species of the Moroccan Atlas mountains and is apparently another of the features they inherited from F. scariosa. Pubescence of the leaf auricle region is absent from diploid F. scariosa, from F. pratensis and related Lolium species, but present in diploid Montanae species. Enhanced auricle‐zone pubescence occurs in the fertile Cl and C2 amphiploids of F. scariosa (glabrous) and F. donax (pubescent). This suggests that diploids of section Montanae could be the gene source of the auricle pubescence present in broad leaved fescue polyploids exemplified by hexaploid tall fescue.
THE RESPONSES OF CONIFERS TO SOME OF THE ADVERSE FACTORS ASSOCIATED WITH WATERLOGGED SOILS
Authors: SANDERSON P. L. , ARMSTRONG W. 
Published: May 2006

SUMMARYThe effect in solution culture of iron(II), acetic and butyric acids and ethylene on rooted cuttings of Sitka spruce and Lodgepole pine has been studied and compared with the effects of anoxia. A relative growth rate parameter is employed to reveal changes in the rate of root growth. Possible mechanisms of toxicity and detoxification are suggested and the greater tolerance of Lodgepole pine is discussed in relation to its superior gas transport system. Conclusions are drawn concerning the role played by each of the toxic factors in the field situation.
CUTICLE DEVELOPMENT IN THE STOMATAL REGION OF POPULUS CLONES
Authors: PALLARDY S. G. , KOZLOWSKI T. T. 
Published: May 2006

SUMMARYCuticle development and degree of stomatal occlusion of three Populus clones varied with growth environment and leaf type (early or late leaves). Whereas stomatal occlusion by cuticular components was negligible in plants of all clones grown in a moist controlled environment, heavier cuticle deposition and stomatal occlusion were found on abaxial surfaces of early, but not late leaves, of field‐grown clones. Hence these Populus clones responded adaptively to the more xeric field conditions in a fashion that would restrict both stomatal and cuticular water loss. The cuticle around the stomatal apparatus of all clones was ridged, with elaborate stranded patterns emanating from the stomata. Stomatal ledges were found in all clones studied, and ledge aperture was not closely related to pore aperture of the guard cells because of variation in the point of attachment of the ledges to the outer lateral wall of the guard cells. Because stomatal pore and ledge apertures are independent, stomatal impressions (which reproduce ledge aperture only) should not be used to estimate stomatal aperture unless it can be shown that ledges are not present.
COMPOSITION OF LIPIDS IN ROOTS OF SIX CITRUS CULTIVARS INFECTED WITH THE VESICULAR–ARBUSCULAR MYCORRHIZAL FUNGUS, GLOMUS MOSSEAE
Authors: NAGY S. , NORDBY H. E. , NEMEC S. 
Published: May 2006

SUMMARYThe lipid compositions of infected (Glomus mosseae) and noninfected fibrous roots of sweet orange, sour orange, rough lemon, Carrizo citrange, Cleopatra mandarin and Rangpur lime were studied. Infected roots of all cultivars contained significantly more phospholipids and triglycerides than did their noninfected controls. Campesterol was found at significantly higher percentages of free sterols, whereas cholesterol and β‐sitosterol were detected at lower percentages in infected roots when contrasted to their respective controls. Three unknown fatty acids (A, B, and C) were detected in infected roots but not in noninfected roots. Unknowns A, B and C made up 46 to 52 % of the fatty acids in the triglycerides, 31 to 41 % in the total lipids and 7 to 20 % in the phospholipids.