bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NOTE ON THE EVOLUTIONARY STATUS OF ALUMINIUM‐ACCUMULATORS AMONG DICOTYLEDONS
Authors: CHENERY ERNEST M. , SPORNE KENNETH R. 
Published: May 2006

SUMMARYAmong dicotyledons, the ability to accumulate large quantities of aluminium is statistically corre;ated with seven primitive characters. It is especially common among those families that were present in the early fossil history of the group and among tropical rain‐forest families. it is concluded, therefore, that aluminium‐accumulation is itself a primitive character.
UNCOUPLING OF ELECTRON TRANSPORT BY ANIONIC QUINONOID REDOX INDICATOR DYES
Authors: HILL R. , CROFTS A. R. , PRINCE R. C. , EVANS E. HILARY , GOOD N. E. , WALKER D. A. 
Published: May 2006

SUMMARYA considerable range of oxidation‐reduction dyes has been studied with reference to reactions with illuminated chloroplast preparations. Experimental methods included dye‐mediated H+‐and H‐transfer across liposome membranes, comparison of increase in the uncoupling properties with increase of substituting halogen atoms and effect of halogen substitution on distribution of anion between water and octanol. In the absence of halogen substitution a relatively high concentration of a dye is needed for significant uncoupling. Introduction of the sulphonic group ‐SO3Na abolishes the uncoupling effect even in presence of halogen substitution.
ION UPTAKE IN RELATION TO THE DEVELOPMENT OF A ROOT HYPODERMIS
Authors: FERGUSON I. B. , CLARKSON D. T. 
Published: May 2006

SUMMARYThe suberization of the outer cortical cells in the basal zones of maize roots to form a hypodermis reduced the radial movement of phosphate towards the stele. Suberization of these cells appeared to place a far greater restriction on the translocation of phosphate to the shoot than the suberization of the endodermis. Under the same conditions as were used for growing maize, barley roots did not develop a hypodermis, and phosphate movement from the basal zones of the root axes was not restricted.
THE DISTRIBUTION OF THE PROTEIN PHASEOLIN IN THE INTACT PLANT AND CULTURED TISSUES OF PHASEOLUS VULGARIS L.
Authors: FRAME R. , WHEELER C. T. , BOWES B. G. , STEWART‐TULL† D. E. S. 
Published: May 2006

SUMMARYAnalysis of the salt‐soluble protein extracts of leaves, stems, roots, cultured roots and callus tissue derived from the cotyledons of the developing seed show that only the intact plant roots synthesize a protein immunologically similar to the seed storage protein, phaseolin.
ECOLOGICAL PHYSIOLOGY OF THE LICHEN HYPOGYMNIA PHYSODES
Authors: FARRAR J. F. , SMITH D. C. 
Published: May 2006

SUMMARYWhen air‐dry thalli of Hypogymnia physodes are immersed in water, four main features characterize the rewetting phase. (1) There is an immediate and substantial release of gas, the‘wetting burst’. Although the released gas appears to be mostly CO2, it is non‐metabolic in origin and probably the result of a previous adsorption of gas onto polysaccharide sheaths surrounding fungal hyphae. (2) There is a period of 1‐2 h increased respiration,‘resaturation respiration’, which, unlike basal respiration, is cyanide‐sensitive. The cause of resaturation respiration remains obscure, but could result from exposure of respiratory substrate to enzymes from which they are normally separated. (3) There is a brief period (1–2 min) in which there is a rapid loss of organic and inorganic solutes from the thallus. Since water is a structural component of membranes, removal of some of this water during drying probably caused increased permeability so accounting for the losses observed. (4) There is a very rapid recovery of processes including photosynthesis and nutrient uptake. Even 10 s after rewetting, incorporation of 32P was 60% inhibited by DNP.The ecological significance of these features is discussed, particularly in relation to the apparent need of many lichens for periodic drying.
CONTROL BY THE EMBRYOSAC OVER POLLEN TUBE GROWTH IN THE STYLE OF THE AVOCADO (PERSEA AMERICANA MILL.)
Authors: SEDGLEY M. 
Published: May 2006

SUMMARYIn experiments studying pollination of avocado it was observed that an average of sixty‐six pollen grains germinated on the stigma. The tubes penetrated the stigma but about half developed swollen tips and proceeded no further than the base of the stigma. Reduction in tube number continued until between approximately half and three‐quarters of the way down the style (1.75–2.5 mm) a single tube remained to reach the ovary containing a single embryosac. In 50% of the ovaries observed two embryosacs were present in the one ovule and 18% of these attracted two pollen tubes. Control by the embryosac over pollen tube growth is suggested.
GENECOLOGICAL STUDIES OF LEAD TOLERANCE IN GROUNDSEL (SENECIO VULGARIS L.)
Authors: BRIGGS D. 
Published: May 2006

SUMMARYSoils from a range of native British habitats for Senecio vulgaris L. have been found to contain significantly different amounts of lead ranging from several hundred parts per million along roadsides and on rubbish dumps to minute quantities in coastal sandy soils. Root growth of seedlings in simple water culture revealed different degrees of tolerance between topodemes to soluble lead, apparently related to the lead content of the soil. Studies of root growth in a range of native soils suggest a more complex relationship between growth and lead content. The genecological implications of these findings are discussed, including the possibility that lead‐tolerant roadside variants may be of recent origin.
STUDIES IN THE VEGETATIONAL HISTORY OF MID WALES
Authors: HANDA S. , MOORE P. D. 
Published: May 2006

SUMMARYThe basal sediments of three pingo basins from the valleys of the Cledlyn and Cletwr in west Wales have been analysed palynologically. The basal pollen‐bearing deposits indicate that sedimentation began in all three basins at a time prior to the invasion of trees and before the initial expansion of Juniperus at the opening of the Flandrian. Radiocarbon dating confirms that the subsequent Juniperus peak is early Flandrian in age rather than belonging to the Allerød interstadial. The vegetational succession documented at the three sites allows a reconstruction of both regional and local developments during the transition from late‐Devensian to Flandrian times. These events broadly resemble those described for other parts of mid Wales, but with certain, notable differences. These sites in the Teifi Valley system have very low proportions of montane and arctic‐alpine types represented in their pollen records; this contrasts markedly with the site previously described from the uplands at Elan Valley. Also they do not give indication of the early Corylus rise which occurred just 20 km north at Gwarllyn. The likely explanation for this is that invasion and spread of Corylus was localized in what is now the Cardigan Bay area and pollen derived from this early expansion was carried to the exposed Mynnedd Bach area, but did not penetrate south‐eastwards into the Teifi Valley region. Evidence from these sites suggests that Pinus sylvestris and Alnus glutinosa were established locally in the area soon after the demise of Juniperus.In addition to providing data on vegetational history in this area, these studies also supply information concerning the origin and decay of pingos during late‐Devensian times. The fact that the basal sediments predate the Juniperus rise demonstrates that the melting of the pingo ice cores and the collapse of their domes occurred before temperatures were high enough to allow Juniperus to attain its maximum flowering potential. This in turn would indicate that pingo ice melt has a lower temperature threshold than Juniperus flowering and that the threshold was therefore crossed first. This being so, it is reasonable to deduce that the pingos could not have survived the late‐Devensian interstadial (Allerød), for during it, even in the uplands, the Juniperus flowering threshold was crossed. All of the pingos examined, therefore, appear to have formed and decayed during the post‐interstadial cold phase (Godwin's zone III).
THE DISTRIBUTION OF EUROPEAN PTERIDOPHYTES: A NUMERICAL ANALYSIS
Authors: BIRKS H. J. B. 
Published: May 2006

SUMMARYThe distribution of 144 species of pteridophyte in sixty‐five areas within Europe was analysed by minimum‐variance cluster analysis and principal co‐ordinates analysis. Fifteen floristic regions and twenty‐one floristic elements were delimited, and the distribution and composition of these are described. Inter‐relationships between the elements and regions are demonstrated, and the major floristic divisions revealed within Europe are discussed. Possible ecological and historical causes for these patterns are considered.
FACTORS AFFECTING THE REDUCTION OF ACETYLENE BY ROOT NODULES OF LUPINUS SPECIES
Authors: TRINICK M. J. , DILWORTH M. J. , GROUNDS M. 
Published: May 2006

SUMMARYA number of parameters affecting acetylene reduction by root nodules of Lupinus angustifolius, L. cosentinii and L. luteus have been studied.Acetylene reduction could be satisfactorily measured in air provided a sufficiently high pC2H2 was used. However, evacuation of air from containers was not harmful to the nodule system. The maximal rate of acetylene reduction occurred at 23°C but the rate was hardly less at 33°C. Plant age had a marked effect upon the rate of acetylene reduction in its nodules. Rates of acetylene reduction in nodules were maintained at high levels after the onset of flowering but rapid reduction in nodule activity occurred after pods were filled. Decapitation of plants had little or no effect on acetylene reduction by the nodules, but removal of the nodules reduced their activity by 70–85%. Brief rinsing of the nodules and rapid drying with blotting paper had little effect on their acetylene reducing activity, but prolonged wetting markedly decreased it.Nodulated roots and whole plants responded similarly to pO2. Acetylene reduction was zero in the absence of oxygen, increased to a maximum rate by 0.2–0.25 atm O2, remained constant up to 0.4–0.5 atm O2, and then declined sharply to nearly zero at 0.9 atm.We detected no diurnal rhythm, attributable to effects of light on supply of photosynthate, with any of the three species.
THE INVOLVEMENT OF FLAVOUR VOLATILES IN THE RESISTANCE TO DOWNY MILDEW OF WILD AND CULTIVATED FORMS OF BRASSICA OLERACEA
Authors: GREENHALGH J. R. , MITCHELL N. D. 
Published: May 2006

SUMMARYThe possible involvement of flavour volatiles in the resistance of Brassica oleracea L. seedlings to cabbage downy mildew (Peronospora parasitica (Pers. ex Fr.) Fr.) was investigated using seedlings of a number of commercial Brassica oleracea cultivars. Flavour volatiles are primarily released as a result of tissue damage in brassicas. Only one cultivar tested was resistant to the disease and its tissue macerates yielded the greatest concentration of volatiles. One of these compounds, allyl isothiocyanate, proved to be highly toxic to the pathogen and was produced in much greater concentrations in macerates of cotyledon than first leaf tissue. The ability of seedlings to produce allyl isothiocyanate in large amounts following tissue damage may inhibit the growth of Peronospora parasitica in resistant seedlings. Wild populations of Brassva oleracea L. subsp. oleracea (wild cabbage) were also tested for disease resistance, and the highest proportions of resistant seedlings were found in those populations containing high levels of flavour volatiles. The longest established wild populations possessed the highest average concentrations of flavour volatiles, and it is suggested that selective breeding has resulted in a reduction in the amounts of these compounds in cultivated forms. This change may be a contributory factor towards the lack of resistance shown by modern cultivars.
CELL PRODUCTION BY ROOT CAPS
Authors: CLOWES F. A. L. 
Published: May 2006

SUMMARYFour independent methods show that the cell‐doubling time of the first tier of cap initials is about 10 h in roots of Zea growing at 23°C. By the fourth tier the cell‐doubling time lengthens to about 90 h due to cells going out of cycle though these can go on synthesizing DNA. The first four tiers produce enough cells to renew the cap in from 22 to 33 h. This high rate of cell production is confirmed by observing the transit of cells marked by caffeine along the length of the cap. Although some cells reach the tip of the cap quickly, others remain within the meristem for 24 h without dividing. The results are discussed in relation to work on other plants and to the anomalous cell cycles of the cap meristem of Zea.
AN ANALYSIS OF COMPETITIVE ABILITY IN THREE PERENNIAL GRASSES
Authors: MAHMOUD A. , GRIME J. P. 
Published: May 2006

SUMMARYCompetitive interactions between three perennial grasses of contrasted ecology were investigated using an experimental design which permitted measurement of the effects of paired species upon each other. Under productive conditions, each pairing resulted in the total elimination of one species and the order of competitive ability was Arrhenatherum elatius > Agrostis tenuis > Festuca ovina. Under conditions of severe nitrogen stress, the impact of competition upon yield was reduced but the order of competitive ability was unaffected. The results suggest (1) that competitive abilities above and below ground are interdependent and covariable and (2) that the ability to compete for mineral nutrients may be of relatively minor importance in the adaptive physiology of species colonizing very infertile soils.
SOME EFFECTS OF THREE HERBICIDAL AUXINS ON STOMATAL MOVEMENTS
Authors: PEMADASA M. A. , JEYASEELAN K. 
Published: May 2006

SummaryThe effects of 2, 4‐dichlorophenoxyacetic acid (2,4‐D), 2, 4,5‐trichlorophenoxyacetic acid (2,4,5‐T) and 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) on stomatal opening on illumination of excised, turgid leaves of Stachytarpheta indica were studied by microscopic examination of epidermal strips fixed in absolute ethanol. All three herbicides prevented wide opening of stomata and accumulation of potassium in the guard cells; hydrolysis of stomatal starch was hindered by 2, 4,5‐T and MCPA and hastened by 2, 4‐D. Carbon dioxide‐free air was effective in compensating substantially the effects of 2, 4,5‐T and MCPA but not of 2, 4‐D. It is concluded that 2, 4,5‐T and MCPA arrest light‐induced stomatal opening partly by disturbing the carbon dioxide balance in the leaf and partly by hindering starch hydrolysis and potassium accumulation in the guard cells, whereas 2, 4‐D appears to exert a more direct effect, probably by affecting the membrane permeability, on guard cells although inhibition of potassium accumulation may also be partly involved in its action.
SUCCULENCE, CATIONS AND ORGANIC ACIDS IN LEAVES OF KALANCHOE DAIGREMONTIANA GROWN IN LONG AND SHORT DAYS IN SOIL AND WATER CULTURE
Authors: PHILLIPS R. D. , JENNINGS D. H. 
Published: May 2006

SummaryLeaves of Kalanchoe daigremontiana grown in short days in John Innes compost possessed a higher water content per unit dry weight than leaves of similar age from long‐day plants. For both treatments, the older the leaf the greater the water content. The effect of short days was to reduce dry weight production. When plants were grown in water culture, the differences were less marked and there was no significant difference in water content between leaves on the same plant. It is believed that, in water culture, the plants were not subjected to so large a water stress. Calcium was the major cation in the leaf, with a concentration some three to seven times that of potassium. The concentration of sodium was low but, under certain conditions, dry weight production was reduced when this cation was not added to the medium. The total concentration of organic acids never exceeded 210–230 μquiv. cm−3, if the total concentration of calcium, potassium and sodium did not also reach this value. Above this concentration an increase in total acid was accompanied by an equivalent increase in the total concentration of the three cations. Such an increase was only observed in long‐day plants. The results are discussed in relation to the control of dark fixation in CAM plants.
UPTAKE AND METABOLISM OF INSECT METABOLITES BY LEAVES AND TENTACLES OF DROSERA SPECIES
Authors: CHANDLER G. E. , ANDERSON J. W. 
Published: May 2006

SummaryWhen insects (Drosophila melanogaster) were supplied with [35S]sulphate, methionine sulphoxide, cysteine, cysteic acid and taurine became labelled. When the insects were applied to the leaves of Drosera hinata, label in the plant was associated with methionine sulphoxide, cysteine, cysteic acid and sulphate but not taurine. Application of [35S]sulphate to the leaves of D. binata produced a similar labelling pattern except that cysteic acid was not labelled. There were some differences in sulphur metabolism between axenic cultures and field grown plants; axenic cultures, for example, did not incorporate 35S‐label into methionine sulphoxide.
VESICULAR‐ARBUSCULAR MYCORRHIZA IN SOME NIGERIAN SOILS AND THEIR EFFECT ON THE GROWTH OF COWPEA (VIGNA UNGUICULATA), TOMATO (LYCOPERSICON ESCULENTUM) AND MAIZE (ZEA MAYS)
Authors: SANNI SHERIFF O. 
Published: May 2006

SummarySpores of fungi forming vesicular‐arbuscular mycorrhiza were collected from Ibadan, Iwo and Egbeda series at the experimental plots of Federal Department of Agricultural Research, Moor Plantation, Ibadan. These were used to inoculate cowpea, maize and tomato. The presence of vesicular‐arbuscular mycorrhiza was detected in the roots of these plants after a few weeks of growth. Dry weights of roots and shoots, and total P and N were determined. There was a positive correlation between the presence of vesicular‐arbuscular mycorrhiza and the amounts of P and N in the tissues.
VESICULAR‐ARCUSCULAR MYCORRHIZA IN SOME NIGERIAN SOILS: THE EFFECT OF GIGASPORA GIGANTEA ON THE GROWTH OF RICE
Authors: SANNI SHERIFF O. 
Published: May 2006

SummaryAzygospores of Gigaspora gigantea isolated from soil in Moor Plantation area were used to inoculate rice in a glasshouse experiment. There was a positive correlation between the presence of vesicular‐arbuscular mycorrhiza, the numbers of spores in individual root system and the growth of rice. Better growth was observed in mycorrhizal plants than either control or treatment with strengite alone.
FUNGAL POLYOL METABOLITES IN THE CONTROL OF CARBOHYDRATE METABOLISM OF MYCORRHIZAL ROOTS OF BEECH
Authors: WEDDING RANDOLPH T. , HARLEY JOHN L. 
Published: May 2006

SummaryEight enzymes concerned with carbohydrate metabolism, extracted and partially purified from mycorrhizal roots of beech, were studied to determine the possible role of a number of sugar alcohols (polyols) as effectors for the carbohydrate metabolism of the roots.Various patterns of inhibition of these enzymes by different polyols were found. Mannitol and threitol were the most effective of the polyols studied in terms of the number of enzymes affected and the apparent inhibition constants for the affected reactions. None produced an activation of the enzyme reactions.The possible significance of these enzyme inhibitions as indicating ways in which the presence of the sheath of fungal mycelium may alter the utilization of carbohydrate in the tree and result in translocation to the symbiotic fungus, and the relation of these findings to the known characteristics of mycorrhizas are discussed.
THE PHYSIOLOGY OF SYMBIOSIS IN GOODYERA REPENS
Authors: PURVES S. , HADLEY G. 
Published: May 2006

SummaryIn asymbiotic culture, Goodyera repens germinated and grew well in the presence of 1% glucose and potato extract. Growth on trehalose, a fungal sugar, was comparable with that on glucose. Infected protocorms which grew best on a cellulose carbon source were larger than asymbiotic ones on all media tested.Asymbiotic protocorms grew slowly and acquired high levels of starch while infected material grew rapidly without accumulating starch. When starch‐rich protocorms were infected, their starch became depleted while their growth rate increased, indicating that the fungus suppressed starch synthesis by its host.When green plantlets were fed with 14CO2, infected plantlets showed greater incorporation into insoluble substances than did asymbiotic ones.
SEASONAL VARIATION IN THE SECONDARY PHLOEM FROM THE MAIN TRUNKS OF WILLOW AND SYCAMORE TREES
Authors: LAWTON JUNE R. 
Published: May 2006

SummaryThe structure of the phloem near to the cambium is described for mature trees of Salix fragilis L. and Acer pseudoplatanus L. Changes in the structure of the phloem were investigated by light and electron microscopy. Measurements of the dimensions of the sieve tube elements show that those formed during the winter months are small in diameter and that the area of phloem formed from June to September is greater and the diameter of the individual sieve tubes larger. In both species there are some sieve tubes close to the cambium with open pores in the sieve plates throughout the year. The extent of callose deposition of the sieve plates, as shown by u.v. fluorescence microscopy, can be correlated with the age of the sieve tubes. The sieve plates in Acer are simple and those in Salix, compound and very oblique. The depth of phloem showing callose fluorescence changes during the year. There is an increase in the depth of phloem with open pores on the sieve plates through to September in both Willow and Sycamore, which can be correlated with a natural increase in temperature and day length.
RADIOCARBON DATING OF FLANDRIAN POLLEN ZONES IN WALES AND NORTHERN ENGLAND
Authors: HIBBERT F. A. , SWITSUR V. R. 
Published: May 2006

SummaryThe boundaries of Flandrian pollen assemblage zones at three sites within the British Isles have been dated by the radiocarbon method and corresponding zones have been found to exhibit a broad synchroneity. The mean sedimentation rates for the deposits fall within the range for other British and north European sites.
CYTOKININS IN XANTHIUM STRUMARIUM L.: SOME ASPECTS OF THE PHOTOPERIODIC CONTROL OF ENDOGENOUS LEVELS
Authors: HENSON I. E. , WAREING P. F. 
Published: May 2006

SUMMARYThe effects of photoperiod on cytokinin levels in Xanthium strumarium L. were examined using a single photoperiodic cycle. Increasing the night length from 6 to 16 h resulted in a progressive decline in cytokinin levels in leaf laminae and buds. Interruption of a 16‐h dark period midway by either a 5‐ or 60‐min light‐break at least partially negated the depressive effect of the dark period on cytokinin levels. All peaks of cytokinin activity were similarly affected by short day treatment. The reduction of cytokinin levels in response to a long dark period was dependent upon the presence of leaves greater than 1.0 cm in length but not upon the presence of buds. While exposure of the entire plant to a single long dark period led to a marked reduction in cytokinin levels in the leaf laminae, no such reduction was apparent in leaves which were exposed individually to a long night (with the rest of the plant, including the majority of the leaves, left in long day). The latter treatment did, however, lead to a partial reduction in the cytokinin flux from the detopped root system. Bark ringing of the stem between roots and leaves prior to photoperiodic treatment largely prevented the short day‐induced decline in cytokinin levels in both leaf laminae and root exudate. These results are taken to indicate the existence of a shoot‐to‐root signal capable of moderating cytokinin production in the root system.