bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE UPTAKE AND METABOLISM OF PHOSPHATE BY THE LICHEN HYPOGYMNIA PHYSODES
Authors: FARRAR J. F. 
Published: May 2006

SUMMARY Hypogymnia physodes showed active uptake of inorganic phosphate (Pi) from, very dilute solutions (less than IO5 nmol Pi dm‐3). Approximate values of Vmax and Km compare with published data for phloem and maize roots. Pi absorbed from these dilute solutions was not exchangeable, but that absorbed from solutions of IO5–IO6 nmol Pi dm‐3 was exchangeable. There was some evidence, but not conclusive, that two types of uptake mechanism existed. The metabolism of absorbed Pi was similar to that described in other lichens and included appreciable incorporation into a fraction which may be largely polyphosphate. The ecological significance of this is discussed.Calculations based upon the reported concentration of Pi in rainwater, rates of uptake of Pi by H. physodes from solutions of equivalent concentration, and growth rate (as an indicator of Pi needs) show that the lichen would only need one hour of rain per week to maintain its phosphorus status. It is therefore unlikely that phosphorus limits the growth of the lichen in nature.
THE VIABLE SEED CONTENTS OF ANT‐HILL AND PASTURE SOIL *
Authors: KING T. J. 
Published: May 2006

SUMMARYThe viable seed contents of ant‐hill and pasture soils were estimated in samples from acidic grassland on Rhossili Down, Gower peninsula, South Wales. The pasture soils contained 9150 seeds per m2 and the same mass of ant‐hill soil produced 6121 seedlings per m2, including 4030 of Aira praecox L. Twelve species had at least four times as many seeds in pasture soil than in ant‐hill soil. Most of these species are more abundant in the pasture than on the ant‐hills, perhaps partly through inefficient seed dispersal.
GENETIC VARIATION OF EUCALYPTUS OBLIQUA IN FIELD TRIALS
Authors: BROWN A. G. , ELDRIDGE K. G. , GREEN J. W. , MATHESON A. C. 
Published: May 2006

SUMMARYThe growth and survival of Eucalyptus obliqua seedlings from twenty‐two provenances throughout the range of the species in south‐eastern Australia were studied in three field trials in Tasmania and Victoria. Early results indicated significant variation among provenances for several growth parameters and for survival. Ranking for height was consistent on the two low‐altitude planting sites and similar to that in previously reported glasshouse studies. Within provenances there were also significant differences between families for growth and survival.These results suggest that genetic improvement of the species is possible, not only by selection of the most suitable provenances for particular sites, but also by the selection of superior individual trees within a provenance.
THE LOW TEMPERATURE LIMIT FOR SEED GERMINATION
Authors: SIMON E. W. , MINCHIN ANN , MCMENAMIN MARY M. , SMITH J. M. 
Published: May 2006

SUMMARYAt 2O°C, cucumber and mung bean seeds germinate rapidly. As the temperature is lowered to 14°C, the time required for 50% germination increases with a Ql0 of about 2. However, between 14 and 11°C, Q10 rises to 60–1600 (cucumber) and 87 (mung bean); below 11°C only a small percentage of seeds will germinate. At 10°C, the roots never extend to more than 1.5 mm, while a length of 2.5 mm is necessary for germination. Exogenous supply of various amino acids and hormones fails to alleviate the block to germination in the cold. The mitotic index of root cells in cucumber seedlings is low at 5°C. However, at 22°C the seeds can germinate even under conditions that inhibit mitosis (0.02% colchicine or following γ‐irradiation). There is little indication of leakage from cucumber seeds in the cold. Arrhenius plots of the respiration of imbibed seeds, of the growth of 1‐cm long roots and the respiration of root tips are a1! linear. It is concluded from the high Q10 figures for germination in the cold that the failure of germination may result from a denaturation of proteins.
LOCALIZATION OF CHLORIDE IN LEAF CELLS OF THE HALOPHYTE SUAEDA MARITIMA BY SILVER PRECIPITATION
Authors: HARVEY DIANA M. R. , FLOWERS T. J. , HALL J. L. 
Published: May 2006

SUMMARYChloride has been localized in leaf cells of Suaeda maritima by the silver precipitation technique. The major site of precipitation was the cell vacuole although deposits were found at other sites, particularly in the chloroplasts of plants grown without salt. Considerable loss of chloride from the tissue occurred during the preparative procedure and the validity of the technique is discussed.
TRANSLOCATION AND TRANSFER OF NUTRIENTS IN VESICULAR–ARBUSCULAR MYCORRHIZAS
Authors: COX GUY , TINKER P. B. 
Published: May 2006

SUMMARYTracings of electron micrographs of mycorrhizal roots of onion were measured using an image‐analysing computer and the results were used to derive estimates of the volume occupied by the fungal arbuscules, the increase in volume of host cytoplasm after infection and the area of interface between fungus and host. The average lifespan of an arbuscule was deduced from the proportions of living and senescent arbuscules measured in light microscope preparations. These measurements were used to evaluate two hypothetical mechanisms for transfer of phosphorus from fungus to host. It was concluded that digestion of the fungus by the host was not likely to be a significant factor in phosphorus transfer. Transfer of phosphorus across the membranes of living fungus and host appeared to be a more probable mechanism.
THE VEGETATIONAL HISTORY OF PARTS OF SOUTH AND EAST DURHAM
Authors: BARTLEY DAVID D. , CHAMBERS CARL , HART‐JONES BARBARA 
Published: May 2006

SUMMARYLate‐Devensian and Flandrian deposits are described from six sites in lowland Durham, ranging from Neasham, near Darlington, in the south, to Thorpe Bulmer, near Hartlepool in the north‐east. Pollen diagrams from each site are presented and show the changes in vegetation of the different areas. At Thorpe Bulmer the tundra vegetation of the Older Dryas period gave way to rather open birchwoods in the Allerod and there was then a return to sedge tundra in the Younger Dryas. This sequence is compared with others in Durham, Yorkshire and Northumberland. The Flandrian sequence opens with the development of birchwoods followed by the appearance of the more thermophilous forest trees. There are in the late Boreal and early Atlantic periods local differences in the forest, as for instance in the early establishment of alder at Mordon Carr (7760 B.P.) and the prevalence of pine around Bishop Middleham, the latter being related to the close proximity of Magnesian Limestone. The ‘elm decline’is dated at 5500–5200 B.P. and there are after that a number of clearance phases beginning with small scale clearance by Neolithic people from about 5200 B.P. From the Bronze Age on there are local differences, again presumed to be related to the proximity of Magnesian Limestone and to soil differences. At Bishop Middleham there is a massive clearance of forest and spread of pasturing from 3660 B.P., reaching a maximum at 3360 B.P. (Middle Bronze Age) when cereal cultivation was introduced. Except for Hutton Henry where there was considerable clearance the rest of the area saw only moderate and temporary clearance at this time. At Thorpe Bulmer there is evidence for intensive cultivation of hemp and some cereals from 2064 B.P. (Late Pre‐Roman Iron Age) rising to a maximum in the Roman period (1730 B.P.) and continuing at a low level until the Norman Conquest (852 B.P.). At nearby Hutton Henry there is evidence for extensive agriculture around 1842 B.P. but in the southern part of the region such clearance was not reached until much later (1213 B.P. at Neasham). In all these deposits there are interesting differences in rate of peat growth from one period to another and at Thorpe Bulmer there is a very long break in the sequence.
A LATE PLEISTOCENE AND HOLOCENE POLLEN DIAGRAM FROM LYNCH'S CRATER, NORTHEASTERN QUEENSLAND, AUSTRALIA
Authors: KERSHAW A. P. 
Published: May 2006

SUMMARYThe pollen diagram from Lynch's Crater extends the climatic and vegetation record for the Atherton Tableland back to about 60,000 years B.P. Subtropical rain forest, with abundant Araucaria, was present around the site from before 60,000 B.P. to about 38,000 B.P. and existed under about half the present‐day annual rainfall. This was replaced by sclerophyll vegetation between 38,000 and 27,000 B.P. as a result of a decrease in precipitation, a decrease in temperature or the activities of aboriginal man. In any case the agent of rain forest destruction was probably fire. The record for the last 10,000 years or so is probably incomplete and radiocarbon dates unreliable, but changes during this period are in broad agreement with those evidenced from previously described sites within the area. The sequence from Lynch's Crater provides a basis for the interpretation of many problematical features of present‐day vegetation distributions.
SOME PROPERTIES OF THE SOLUBLE ACID PHOSPHATASES OF ROOTS OF ZINC‐TOLERANT AND NON‐TOLERANT CLONES OF ANTHOXANTHUM ODORATUM
Authors: COX R. M. , THURMAN D. A. , BRETT M. 
Published: May 2006

SummaryAn electrophoretic survey of soluble acid phosphatases present in roots of individual plants of Anthoxanthum odoratum from a zinc‐tolerant and a non‐tolerant population showed that eight acid phosphatases differed in their frequency of occurrence between the two populations. No correlation was detected between the presence of any one set of soluble acid phosphatases and the index of zinc tolerance which suggests that there is no one zinc‐tolerant genotype. Mine plants possessed higher soluble acid phosphatase activities than pasture plants; this could account for the higher Km values detected in mine individuals. The sensitivity of soluble acid phosphatase activity to inhibition by zinc was the same both for the four tolerant and nontolerant individuals examined though small intrapopulation differences in the degree of inhibition/ stimulation were observed. It was concluded that soluble acid phosphatases of these roots do not show adaptations to zinc, or, if they do, they are not revealed by the types of measurement made here.
TEMPERATURE ON PHOTOSYNTHESIS AND TRANSPIRATION IN POPULATIONS OF SESLERIA CAERULEA (L) ARD.
Authors: LLOYD N. D. H. , WOOLHOUSE H. W. 
Published: May 2006

SummarySamples of populations of Sesleria caerulea (L) Ard. were grown under controlled conditions. Rates of photosynthesis and transpiration were measured in an open gas system over the leaf temperature range, 7.5°–30°C. Populations differed significantly in light‐saturated photosynthetic rates and these differences resided in the stomatal resistance to CO2 assimilation.
ENDOGENOUS GROWTH REGULATORS IN RELATION TO SIDE SHOOT DEVELOPMENT IN THE TOMATO
Authors: TUCKER D. J. 
Published: May 2006

SummaryA study has been made of the endogenous factors controlling lateral bud initiation and development in the variety Craigella, and two isogenic lines of this variety, Craigella Blind (blbl) and Craigella Lateral Suppressor (isls), in both of which side shoot growth is suppressed to varying degrees. Winter‐ and summer‐sown plants are compared.Lateral Suppressor plants contained higher endogenous levels of auxin in their apices, mature leaves and stems than did normal plants, but lower level of cytokinins in all parts except the stem, where the levels were similar in both types. The levels of abscisic acid‐like substances were consistently higher in the stems of Lateral Suppressor plants than in the corresponding tissue of normal plants, but other plant parts showed a more variable pattern. Lateral Suppressor plants contained higher levels of gibberellin than did normal plants.Blind plants contained higher levels of auxin in the apices and stem than did normal plants, but the levels in mature leaves showed no consistent pattern. Higher levels of abscisic acid‐like substances were present in the stem and axillary buds of blind plants than in normal plants, with again a more variable pattern in other plant parts. The levels of cytokinins and gibberellins varied considerably between the two sowing dates.A possible hormonal mechanism of control of axillary bud development is discussed.
THREONINE/SERINE DEHYDRATASE ACTIVITY IN ANGIOSPERMOUS PARASITES
Authors: NANDAKUMAR S. , KACHRU D. N. , KRISHNAN P. S. 
Published: May 2006

SummaryBoth species of broomrape tested were devoid of L‐threonine dehydratase and L‐serine dehydratase activity. When the seeds of three species of dodder were examined, threonine dehydratase activity was present in two but absent in the third. The enzyme could also not be demonstrated in the seed of a green mistletoe. Absence of threonine/serine dehydratase may be a factor necessitating or associated with the parasitic existence of broomrape. The significance of the presence of threonine dehydratase in some seeds and absence in some others is briefly discussed.
VESICULAR‐ARBUSCULAR MYCORRHIZA IN NATURAL VEGETATION SYSTEMS
Authors: READ D. J. , KOUCHEKI H. K. , HODGSON J. 
Published: May 2006

SummaryThe intensity of vesicular‐arbuscular mycorrhizal infection was assessed in the major vegetation types of east‐central England. All of the most important species of grassland, scrub and woodland were mycorrhizal and each individual of any species normally carried a heavy VA infection. Members of the Gramineae were particularly heavily infected. In limestone grassland, infection extended to members of the Cyperaceae and Juncaceae. Infection levels were high throughout the year, the highest levels occurring in the most nutrient‐stressed situations.Mycorrhiza develops soon after germination, often while seedlings are still in the cotyledon stage. Since numbers of viable Glomus type spores are low, infection is thought to arise from root to root contact rather than from spores. The Ecological implications of the widespread infection are discussed.
ENVIRONMENTAL‐PHYSIOLOGICAL INTERACTIONS IN LICHENS
Authors: MacFARLANE J. D. , MAIKAWA E. , KERSHAW K. A. , OAKS A. 
Published: May 2006

SummaryThe nitrogenase activity in Peltigera polydactyla was examined during varying periods of darkness and after re‐illumination. There was an immediate decrease in activity of about 50% when the lichen was darkened, followed by a progressive further decrease of activity with time. Recovery to the original level of activity on re‐illumination showed an increasing lag as the dark period was extended. The effect of an external carbon source on nitrogenase activity was also examined and very large increases in activity were induced in the light, by both 2% glucose and mannitol. The decrease during a dark period was, however, still very marked.
ELECTRON‐MICROSCOPICAL STUDIES ON THE PHYCOBIONT COCCOMYXA SCHMIDLE
Authors: PEVELING ELISABETH , GALUN MARGALITH 
Published: May 2006

SummaryThe ultrastructure of the phycobiont, Coccomyxa, was compared in some asco‐ and basidiolichens. All phycobionts investigated contained a single cup‐shaped chloroplast, multivesicular bodies and large storage bodies. In the chloroplast of the phycobionts in ascolichens, many plastoglobuli occurred regularly whereas, in those of the basidiolichens, no plastoglobuli were present. The multivesicular bodies were associated with varying numbers of vesicles and storage bodies. The storage bodies increased when the lichens were kept dry for several months. By cytochemical tests, the lipid nature of these bodies was suggested. The possible function of the different structures is discussed in comparison with the ultrastructure of other lichens.
DISPERSAL AND CHANGES IN THE LOCAL DISTRIBUTIONS OF EVERNIA PRUNASTRI AND RAMALINA EARINACEA
Authors: TAPPER RICHARD 
Published: May 2006

SummaryChanges in the distributions of Evernia prunastri and Ramalina farinacea along an elm avenue have been recorded for 52 months. During this time colonization by Evernia prunastri and Ramalina farinacea has occurred over a distance of 30 m. A mathematical method is described to relate the distribution of thalli to the distance of ropagule dispersal. This method may be applicable to other situations where colonization is occurring and the source of plant propagules is known.
THE BREAKDOWN OF PARAQUAT AND DIQUAT BY SOIL FUNGI
Authors: SMITH S. N. , LYON A. J. E. , SAHID ISMAIL BIN 
Published: May 2006

Summary Mucor hiemalis, Zygorhynchus heterogamous, Aspergillus niger and Penicillium frequentans were incubated in media containing either [methyl‐14C] paraquat or [ethylene‐14C] diquat. Aspergillus niger liberated 14CO2 from both herbicides and Penicillium frequentans only from paraquat. Mucor hiemalis and Zygorhynchus heterogamous were unable to release 14CO2 from either. Those species able to degrade paraquat or diquat have correspondingly low intracellular levels of the herbicides and are able to tolerate high concentrations in the medium. By contrast, species unable to break them down are characterized by high intracellular levels and by their inability to grow at low concentrations. Tolerance to these herbicides appears to be the result of an ability to degrade them.
A SCANNING ELECTRON MICROSCOPIC STUDY ON THE DEVELOPMENT OF TENDRILS OF PARTHENOCISSUS TRICUSPIDATA SIEB. & ZUCC.
Authors: JUNKER STEFFEN 
Published: May 2006

SummaryThis report describes a scanning electron microscopic study on the surface of developing tendrils of Parthenocissus tricuspidata Sieb. & Zucc. Epidermal cells of mature branchlets are densely covered with minute corrugations which we shall call microplicae, while the epidermis of immature branchlets is smooth. Epidermal cell surfaces of pads first appear very folded, but develop into a densely packed pattern of hemispheres. When stimulated, heavy exudation of a sticky fluid enables the pad to adhere to a support. Subsequently, epidermal cells nearest the point of contact elongate extensively and divide periclinically, whereas the remaining epidermal cells swell and undergo anticlinal divisions. The adhesive fluid passes through the wall o epidermal cells, accumulates under the cuticle causing the latter to bleb, and is finally exuded from a hole in the cuticular blebs.
STUDIES ON THE INTERACTIONS BETWEEN THE EMBRYONIC AXIS AND THE COTYLEDONS DURING GERMINATION IN PISUM SATIVUM L.: THE INFLUENCE OF INCUBATION CONDITIONS
Authors: BRYANT J. A. , HACZYCKI S. J. 
Published: May 2006

SummaryThe effects of removal of the embryonic axis on the development of enzyme activities in the cotyledons of peas have been studied. Excised cotyledons incubated aseptically in large culture vessels show greater increases in acid ribonuclease and acid phosphatase activities than do cotyledons of intact seeds. In excised cotyledons incubated aseptically in Petri dishes, neither enzyme exhibits the normal increase in activity observed to intact seedlings. The significance of these results is discussed.
A BIOSYSTEMATIC STUDY OF THE CREEPING SPEARWORTS AT LOCH LEVEN, KINROSS
Authors: GIBBS P. E. , GORNALL R. J. 
Published: May 2006

SummarySynthetic interspecific hybrids and backcross progeny of Ranunculus flammula L. and R. reptans L. have been compared for their morphology, phenotypic response to submersion, fertility, and breeding system, with transplant specimens of R. reptans‐like plants from Loch Leven. The two species were found to be fully inter‐fertile. The Loch Leven transplants were found to show a striking similarity to backcross progeny of F1 interspecific hybrids ×R. reptans, thus providing experimental evidence for the introgressive hybrid status of these plants as proposed by previous authors.
EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON THE GROWTH AND CYTOKININ CONTENT OF TWO POPULATIONS OF DACTYLIS GLOMERATA (COCKSFOOT)
Authors: MENHENETT ROGER , WAREING P. F. 
Published: May 2006

SUMMARYThe effects of photoperiod (8 or 16 hr, SD or LD) and temperature (low or high, 8° or 20°C) on the growth and cytokinin content of Norwegian and Portuguese populations of Dactylis glomerata (Cocksfoot) were investigated.In general, conditions which promote active leaf growth (LD or high temperature) of plants of the Norwegian population tend to result in lower levels of cytokinin bases and/or nucleosides and in higher levels of ‘nucleotide’ cytokinins than conditions which lead to reduced growth rate (SD or low temperature). In some ‘transfer’ experiments the changes in hormone levels preceded detectable changes in growth rate. Cytokinins which behaved similarly to zeatin and zeatin riboside on Sephadex LH 20 columns were detected.The lack of response to application of exogenous zeatin or 6‐benzylaminopurine, together with the data on endogenous cytokinins, suggests that the level of cytokinin bases and nucleosides was not limiting the growth rate of the Norwegian population in SD at 8°C. However, if ‘nucleotide’ cytokinins are significant for growth rate under unfavourable conditions then this class of hormone may be involved in the responses to day length and temperature.
CYTOKININS IN XANTHIUM STRUMARIUM L.: THE METABOLISM OF CYTOKININS IN DETACHED LEAVES AND BUDS IN RELATION TO PHOTOPERIOD
Authors: HENSON I. E. , WAREING P. F. 
Published: May 2006

SUMMARYEndogenous cytokinin activity in leaves and buds of Xanthium strumarium L. (as estimated by the soybean callus bioassay) declined by about 80% during the 24 h following detachment from the plant. The decline in activity was little influenced by the photoperiod to which the detached organs were exposed.When zeatin was supplied to detached leaves it underwent rapid metabolism. The main cytokinin‐active metabolite, which was readily detectable an hour after the start of zeatin uptake, eluted from a Sephadex LH20 column with the same elution volume as zeatin riboside. Substantial differences due to photoperiod, in either the rate or the pattern of zeatin metabolism, were not detected.
PROMOTION OF ROOT INITIATION BY GIBBERELLIC ACID IN LEAF DISCS OF TOMATO (LYCOPERSICON ESCULENTUM) CULTURED IN VITRO
Authors: COLEMAN WARREN K. , GREYSON RICHARD I. 
Published: May 2006

SUMMARYGibberellic acid (GA3) stimulated the rooting of tomato leaf discs cultured on a defined nutrient medium in continuous darkness. In the presence of 2 × 10−4 M tryptamine, GA3 significantly enhanced root initiation over the concentration range of 1 × 10−8 M to 1 × 10−4 M. GA3 could be replaced by GA4/7 but not by kinetin. Indole‐3‐lactic acid was a highly active indole derivative in the induction of rooting in the tomato leaf discs. This effect was significantly enhanced by GA3. Possible reasons for this observation are discussed.
MAXIMUM PHOTOSYNTHETIC RATE‐A CASE STUDY IN APPLE
Authors: AVERY D. J. 
Published: May 2006

SUMMARYWidely different rates of carbon dioxide assimilation by apple leaves have been reported. Data from forty‐nine papers are examined and likely reasons for their variation are deduced. Many studies were made on glasshouse‐grown plants, the leaves of which can have a very different structure and photosynthetic capacity from those grown outdoors. Other biological aspects including the influence of fruits are discussed. Leaf temperatures have rarely been measured but there is evidence that excessive temperatures occurred in some studies and many other assimilation rates were probably decreased by less obviously extreme conditions. The rates of air flow employed have often been inadequate for true assimilation rates to be obtained. However, many rates higher than those normally quoted have been obtained by several workers including the author and it is concluded that the maximum photosynthetic rate of apple leaves in normal air is at least 35 mg CO2 dm−2 h−1.