bluuebunny/crossref_metadata_2025_split huggingface dataset:
ALLEVIATION OF WATERLOGGING DAMAGE TO YOUNG BARLEY PLANTS BY APPLICATION OF NITRATE AND A SYNTHETIC CYTOKININ, AND COMPARISON BETWEEN THE EFFECTS OF WATERLOGGING, NITROGEN DEFICIENCY AND ROOT EXCISION
Authors: DREW M. C. , SISWORO E. J. , SAKER L. R. 
Published: May 2006

SummaryA study was made of the effects of either 6‐benzylaminopuiine (BAP), a synthetic cytokinin, or calcium nitrate on the response of the shoots of 13‐day‐old barley plants to soil waterlogging. Spraying leaves daily with BAP resulted in small improvements in leaf extension and retarded the premature loss of chlorophyll in the older leaves after 7 days waterlogging, but the rates of accumulation of dry matter and inorganic nutrients in shoots were reduced to the same extent as in unsprayed plants. After a further 7 days waterlogging, during which spraying was discontinued, plants treated with BAP were no longer appreciably different from untreated ones.When calcium nitrate was added daily to the surface of the waterlogged soil, no symptoms of waterlogging damage appeared. Leaf extension, shoot weight, emergence of tillers, chlorophyll concentrations and the accumulation of inorganic nutrients in shoots were similar to those in plants in non‐waterlogged soil after 7 and 14 days. The effect was dependent on the presence of a narrow zone of aerated soil close to the surface, in which root growth and function could continue.When plants were grown for 13 days in aerated nutrient solution, and then transferred to solutions lacking nitrate, the development of leaf chlorosis, the decrease in the concentration of nitrogen in the shoots and their retarded accumulation of dry matter were all similar to that caused by waterlogging. The premature loss of chlorophyll in the older leaves was retarded by spraying with BAP. Chlorosis of the older leaves could also be promoted in plants in aerated nutrient solution by excising part of the root system.Mechanisms by which BAP and calcium nitrate alleviate symptoms of waterlogging damage, and the significance of nitrogen deficiency and root excision in relation to waterlogging damage, are discussed.
THE DIFFERENTIAL TEMPERATURE RESPONSES OF THE GROWTH OF CERTAIN PLANT SPECIES FROM DIFFERENT ALTITUDES. I. GROWTH ANALYSIS OF PHLEUM ALPINUM L., P. BERTOLONII D. C., SESLERIA ALBICANS KIT. AND DACTYLIS GLOERATA L.
Authors: WOODWARD F. I. 
Published: May 2006

SummaryThe growth rates of Dactylis glomerata L. and Phleum bertolomii D.C., which ale essentially lowland species in Britain, show a large response to an increase in day temperature from 10 to 20 ° C. while those of Sesleria albicans Kit. which occurs from sea‐level to 900 m, and Phleum alpinum L. (600 to 1200 m) show little response.These differences can be attributed to the greater leaf‐area ratio, and to the increased rates of both leaf‐initiation and leaf‐expansion of the lowland species at higher temperatures. Net assimilation rates are scarcely affected by temperature. The differences are therefore due to morphogenetic effects and not to differences in the rates of physiological processes.
THE DIFFERENTIAL TEMPERATURE RESPONSES OF THE GROWTH OF CERTAIN PLANT SPECIES FROM DIFFERENT ALTITUDES. II. ANALYSES OF THE CONTROL AND MORPHOLOGY OF LEAF EXTENSION AND SPECIFIC LEAF AREA OF PHLEVM BERTOLONII D.C. AND P. ALPINUM L.
Authors: WOODWARD F. I. 
Published: May 2006

SummaryIndependent temperature control of separate organs of seedling plants of Phleum bertolonii and P. alpinum indicates that the temperature of the first leaf and coleoptile exert the dominant temperature control of specific leaf area (SLA).Rates of leaf extension in the upland species P. alpinum are slower than in the lowland species P. bertolonii. This difference is related in the main to the significantly greater number of cell generations involved in the expansion of the leaf and not to the cell generation time, which does not differ between the species. Experiments with the growth of callus cultures suggest that interspecific differences in the potential for cell growth do not account for the observed differences in leaf extension.In both species the response of SLA to temperature is mainly a consequence of its influence on cell diameter. As a result it is the temperature in the region of cell expansion, within the leaf sheath, that will control SLA.
EFFECT OF HEAT TREATMENT AND THREE PESTICIDES UPON THE GROWTH AND REPRODUCTION OF THE MYCORRHIZAL FUNGUS GLOMUS FASCICULATUS
Authors: MENGE J. A. , JOHNSON E. L. V. , MINASSIAN V. 
Published: May 2006

SummaryThe effects of several heat treatments, a nematicide (DBCP) and two fungicides (ethazole and PCNB) on survival, infection, and sporulation by the mycorrhizal fungus Glomus fasciculatus, were examined. Inocula of G. fasciculatus were killed when exposed for 10 min at 52·5 °C, but not when exposed to 51·5 °C. Although inocula of G. fasciculatus survived a 10 min soaking in PCNB at several concentrations, infection and sporulation on Sudan grass were consistently inhibited by soil drenches with this fungicide. Soil drenches of DBCP (20μg ml−1 H2O) or ethazole (50 μg ml−1 H2O) applied at the time of inoculation with G. fasciculatus did not significantly affect infection and sporulation by the fungus on Sudan grass. However, soil drenches with DBCP (15 to 20 μg ml−1 H2O) and ethazole (10 to 40 μg ml−1 H2O) applied 30 to 60 days after inoculation significantly increased infection and sporulation by G. fasciculatus. All data indicate that the pesticides DBCP and ethazole could be used to reduce contamination and to increase the quantity of inoculum of G. fasciculatus.
EFFECTS OF SHADE ON XYLEM DEVELOPMENT IN SEEDLINGS OF EUCALYPTUS GRANDIS HILL EX. MAIDEN
Authors: DOLEY D. 
Published: May 2006

SummarySeedlings of Eucalyptus grandis were grown under light regimes of 12·6 and 2·8 E m−2 day−1 for 7 weeks, during which time secondary xylem development was studied. The rate of cambial cell division was approximately 50% greater in the high light than in the low light treatment. Rates and durations of fibre expansion were similar, but the rate of wall thickening was almost three times as great in the high as in the low light treatment. Also, the duration of fibre wall thickening was estimated to be 7 days in high light as compared with 21 days in low light. Secondary vessel lumen area and the cross sectional area of vessels per unit area of leaf surface were greater in high than in low light plants, although the proportion of xylem cross sectional area occupied by vessels did not differ significantly between treatments.
A COMPARATIVE STUDY OF ESTABLISHMENT OF PLANTAGO CORONOPUS L. FROM SEEDS SOWN RANDOMLY AND IN CLUMPS
Authors: WAITE S. , HUTCHINGS M. J. 
Published: May 2006

SummaryThis paper reports the results of a study of the establishment of Plantago coronopus L. seeds in the field. Seeds were introduced at a range of densities into plots with intact vegetation, and plots from which the vegetation was removed. Seeds were also sown in a variety of clump sizes on to non‐vegetated plots. The aim of this experiment was to determine whether the density‐dependent germination patterns exhibited by this species in laboratory experiments could also be observed in the field.All treatments exhibited similar patterns of seedling recruitment although different conditions of planting showed quantitatively different responses. During the first 4 weeks after sowing there was rapid seedling recruitment followed by mortality which balanced this recruitment. Eight weeks after sowing, seedling densities were not significantly different from the starting densities in any of the treatments. In particular, the chance of a seed forming an established seedling was not increased when seeds were sown in clumps, thus calling into doubt the ecological benefits of density‐dependent germination responses which have been proposed in previous laboratory studies of the phenomenon. Factors influencing germination and establishment were investigated by means of an autocorrelation matrix. Recruitment of seedlings into the population appears to be limited by the number of adult and seedling plants already present in the population.
PHOTOSYNTHETIC CAPACITIES AND BIOLOGICAL STRATEGIES OF GIANT‐CELLED AND SMALL‐CELLED MACRO‐ALGAE
Authors: RAVEN J. A. , SMITH F. A. , GLIDEWELL S. M. 
Published: May 2006

SummaryData are presented which show that the photosynthetic and respiratory characteristics of the giant‐celled alga Chaetomorpha darwinii are those of a shade plant (denned physiologically in terms of rates of photosynthesis at light and inorganic carbon source saturation, and the irradiance required to saturate photosynthesis and to compensate respiration by photosynthesis). This is in agreement with previous suggestions that giant‐celled algae have the characteristics of ‘shade plants’, while small‐celled macroalgae can be either ‘sun plants’ or ‘shade plants’. A comparison of giant‐celled algae with small‐celled macro‐algae in terms of ecological strategies has been made, using previously published data on Enteromorpha intestinalis, Chaetomorpha linum (‘fugitive’small‐celled), Chaetomorpha darwinii, Hydrodictyon africanum (‘stressed’ giant‐celled), Cham corallina (‘canopy‐dominant’/‘stressed’ giant celled) and Laminaria digitata (‘canopy‐dominant’ small celled), as well as new data on net and mass spectrometric measurements of O2 exchange in L. digitata. It is suggested that the ability of giant‐celled algae to compete as ‘canopy dominants’ may be related to cytoplasmic streaming in the ‘absence of many (or any) plasmodesmatal barriers to diffusion providing an efficient means of long‐distance transport in a differentiated plant, as an alternative to phloem‐type translocation in small‐celled ‘canopy dominants’. The significance of the giant‐celled habit in ‘stressed’ macroalgae is not clear, although the absence of giant‐celled algae from the ‘fugitive’ category may be related to their limited capacity for rapid growth relative to small‐celled algae.
THE REGULATION OF K+ UPTAKE BY RYEGRASS AND WHITE CLOVER ROOTS IN RELATION TO THEIR COMPETITION FOR POTASSIUM
Authors: DUNLOP JAMES , GLASS A. D. M. , TOMKINS B. D. 
Published: May 2006

SummaryThe regulation of K+ influx into roots of Westerwolds ryegrass (Lolium multiflorum Lam.) and white clover (Trifolium repens L.) seedlings has been studied. In low salt plants the absorption isotherms had the same Michaelis constants (Km) but ryegrass had a greater maximum rate of influx (Vmax) than white clover. When the potassium contents of the roots were increased the difference in Vmax diminished but the Kms increased, the value for white clover increasing much more rapidly than the value for ryegrass. The data gave very similar Hill plots for both species which suggests that the molecular mechanisms responsible for the regulation of potassium absorption have strong similarities. The practical implications of the findings are considered and it is suggested that under conditions where competition for potassium is important the specific rate of potassium absorption for ryegrass could be two to five times faster than that for white clover.
VEGETATIONAL CHANGE AND THE INFLUENCE OF PREHISTORIC MAN IN THE SOMERSET LEVELS
Authors: BECKETT S. C. , HIBBERT F. A. 
Published: May 2006

SummaryPollen analysis and radiocarbon dating of profiles from three sites in the Somerset Levels has allowed the construction of both pollen percentage and influx diagrams. The results are used to discuss the timing of vegetational change within the area of study and to quantify further the effect of man on such changes as are recorded.
INFLUENCE OF PLANT INTERACTIONS ON VESICULAR‐ARBUSCULAR MYCORRHIZAL INFECTIONS. I. HOST AND NON‐HOST PLANTS GROWN TOGETHER
Authors: OCAMPO J. A. , MARTIN J. , HAYMAN D. S. 
Published: May 2006

SummaryMycorrhizal infections formed by different endophytes were examined in 10 crop species grown separately and in pairs in sterilized and unsterile soils. No infection was observed in cabbage, kale, rape or swede (in the supposedly non‐mycorrhizal family Cruciferae) and only traces were seen in sugar beet (supposedly non‐mycorrhizal Chenopodiaceae) when these plants were grown alone. However, slight (< 5 %) infection (cortical mycelium and vesicles, but no arbuscules) developed in some when a mycorrhizal host plant was present and there were many clumps of endophyte mycelium on their root surfaces, usually attached to entry points which had often aborted. Glomus fasciculatus‘E3’ was a more infective endophyte than Gigaspora margarita. Infection was usually well developed in the host plants barley, lettuce, maize, potato and onion. It was depressed only in a few pairs but no more by the presence of a ‘non‐host’ plant than by a host plant. The results suggest that the barriers to mycorrhizal infection in ‘non‐hosts’ are intrinsic and more probably related to characteristics of the root cortex or epidermis than to any infection‐inhibiting factors that might be released in root exudates.
CARBOHYDRATE METABOLISM IN THE LEAFY LIVERWORT, PLAGIOCHILA ASPLENIOIDES (L.) DUM. VAR. MAJOR NEES
Authors: SULEIMAN A. A. A. , LEWIS D. H. 
Published: May 2006

SummaryVolemitol, sucrose and starch are the principal photosynthetic products of the leafy liverwort Plagiochila asplenioides (L.) Dum. var. major Nees. but the quantitatively most abundant carbohydrates, fructans, do not rapidly incorporate 14C from 14CO2. The limited amount of starch present turns over rapidly but sucrose and especially volemitol do so very slowly and much 14C incorporated during a short pulse remains in these compounds after prolonged periods in the dark (up to 4 months). The liverwort grows under these conditions and 14C incorporated during the pulse passes into insoluble polymers. Loss of chlorophyll is also slow and tissue is photosynthetically viable after such long periods in the dark. Exogenous glucose, fructose and sucrose are absorbed and metabolized in the dark similarly to CO2 in the light except that there is enhanced incorporation into fructans. Exogenous mannitol is absorbed but poorly metabolized.Results are discussed in relation to polyol‐ and fructan‐containing angiosperms and algae, and from both biochemical and ecological viewpoints.
SEASONAL CHANGES IN NEAR INFRARED REFLECTANCE RATIO AND SANDING CROP BIOMASS IN A SALT MARSH COMMUNITY DOMINATED BY HALIMIONE PORTULACOIDES (L.) AELLEN
Authors: JENSEN ARNE 
Published: May 2006

SummaryNear infrared (715 to 1000 nm) reflected radiation and standing crop biomass were measured in a Halimione portulacoides shrub community during the growing seasons of 1975 and 1976. The amount of near infrared radiation that was reflected was strongly correlated with the total standing crop of photosynthetic tissue. During the growing season of 1977 the quantity of near infrared radiation reflected from the vegetation was used to predict the amount of standing crop of photosynthetic tissue in the community. The predicted values were within 10 % of the measured values obtained by the use of a harvest technique. In addition the amount of reflected near infrared radiation was found to be strongly correlated with leaf area index of the vegetation.
POLLEN ANALYSES OF SEDIMENTS FROM LOUGH INE AND BALLYALLY LOUGH, CO. CORK, S.W. IRELAND
Authors: BUZER JENNY S. 
Published: May 2006

SummaryPollen analyses of post‐glacial sediments from the marine Lough Ine and freshwater Ballyally Lough are described.Lough Ine was found to have been formerly a freshwater basin. The oldest sediments, banded clays with no microfossils, were probably glacial outwash deposits. These were overlain by post‐glacial sediments; late‐glacial deposits were missing. By comparison with radiocarbon‐dated diagrams from other sites the marine transgression is tentatively dated at c. 4000 b.p. The lowest sediments from Ballyally Lough can be assigned to Mitchell's zone VI, the Boreal period.The post‐glacial vegetational development of both loughs and the surrounding area is discussed.
PHOTOSYNTHESIS BY AQUATIC PLANTS: EFFECTS OF UNSTIRRED LAYERS IN RELATION TO ASSIMILATION OF CO2 AND HCO3−AND TO CARBON ISOTOPIC DISCRIMINATION
Authors: SMITH F. A. , WALKER N. A. 
Published: May 2006

SummaryWe review and reassess experimental evidence which indicates that the unstirred layers of solution bathing aquatic plant cells or organs represent a major factor limiting their rate of photosynthesis under natural conditions. Unstirred layers may also limit membrane transport of HCO3− where this occurs. Some authors have suggested that aquatic plants carry out C4photosynthesis and cite in support measurements of discrimination between 13C and 12C. We propose that this discrimination can also be a manifestation of the presence of unstirred layers or membrane transport or both.
THE SECRETORY CYCLE OF DIONAEA MUSCIPULA ELLIS
Authors: ROBINS R. J. , JUNIPER B. E. 
Published: May 2006

SummaryThe fine structure of the digestive glands of Dionaea muscipula is described and the changes that occur in the cells following stimulation were examined quantitatively. Significant cyclic alterations were found in the volume of the vacuole and of the labyrinthine walls. The architecture of these walls was examined in detail. The mitochondria were shown to become considerably more condensed and often to adopt elongated profiles. The endoplasmic reticulum showed a decrease in area, but appeared to change from a storing to a synthetic role, acquiring numerous polysomes. These obSérvations are discussed in terms of the function of the gland.
THE SECRETORY CYCLE OF DIONAEA MUSCIPULA ELLIS.
Authors: ROBINS R. J. , JUNIPER B. E. 
Published: May 2006

SummaryThe cellular mechanisms involved in the storage and synthesis of secretory proteins in the glands of the carnivorous plant Dionaea muscipula were examined. Important roles for a sub‐compartment of the vacuole and smooth endoplasmic reticulum were demonstrated by high‐resolution autoradiography and cytochemistry. It is shown, for the first time in a carnivorous plant, that de novo protein synthesis occurs during the secretory phase of activity and that part of this protein is directly secreted.
THE RESPONSE OF ROOT ACID PHOSPHATASE ACTIVITY TO HEAVY METAL STRESS IN TOLERANT AND NON‐TOLERANT CLONES OF TWO GRASS SPECIES
Authors: COX R. M. , HUTCHINSON T. C. 
Published: May 2006

SummaryThe inhibition by zinc of phosphatase activity in dialysed root extracts was determined for zinc‐tolerant and non‐tolerant clones of Anthoxanthum odoratum L. Similarly the inhibition by copper of this enzyme activity in root extracts of copper‐tolerant and non‐tolerant clones of Deschampsia cespitosa (L.) Beauv. was also determined. It was found for both species that the relationship between the in vitro percentage inhibition of enzymatic activity and the tolerance index of each clone, changed after exposure to sub‐lethal concentrations of the respective metal in water culture. The enzyme activity in the root extracts of the tolerant clones was found to be significantly less inhibited by the particular metal, than those of the non‐tolerant clones only when the plants were previously exposed to the particular metal in vivo. Since exposure of the roots to metal appeared to induce a positive reaction in tolerant material, it is suggested that physiological and biochemical investigations of metal tolerance may be more informative if plants that have been pre‐stressed by a particular metal are used. This should enable a better recognition of adaptive components of metabolism. Examples of such an approach and its implications are discussed.
THE SECRETORY CYCLE OF DIONAEA MUSCIPULA ELLIS. V. THE ABSORPTION OF NUTRIENTS
Authors: ROBINS R. J. , JUNIPER B. E. 
Published: May 2006

SummaryThe absorption pathway is studied, using chloride ion as a marker, in relation to the ultrastructure of the gland. The relative importance of the symplast and apoplast as pathways of absorption is considered and it is suggested that the former is the primary route for metabolites moving into the leaf. Quantitative ultrastructural evidence is presented to support this. It is shown that the labyrinthine walls have a highly polar distribution and it is proposed that this is partially concerned with absorption, but has a more important role in the excretion of water. A model is proposed to explain bi‐directional flow within the gland.
MORPHOLOGICAL AND PHYSIOLOGICAL VARIATIONS IN CLONES OF ASTERIONELLA FORMOSA HASSALL
Authors: HAPPEY‐WOOD CHRISTINE M. , HUGHES DAVID I. 
Published: May 2006

SummaryThe morphology of Asterionella formosa isolated from two contrasting lakes has been studied. During four months in culture the valve length of five isolates decreased. Greater variation in valve length was observed in the strain from Llyn Coron, resulting in the separation of two morphologically distinct clones from the original isolate. Two cultures of the diatom from Llyn Padarn exhibited a more regular decrease in cell size. All strains had similar chlorophyll‐a levels in relation to cell volume.Most rapid growth, but smallest yields, in batch cultures, were characteristic of the two large‐celled clones from Llyn Coron, whereas the small‐celled clone from this lake exhibited the slowest growth rate, but maximum yield. Thus morphological change which is accompanied by physiological differences may occur in a culture derived from a single parent colony. The growth characteristics of the two strains from Llyn Padarn were more similar than those of the three isolates from Llyn Coron.The rapidly growing large‐celled strain from Llyn Coron had a high photosynthetic rate. So had one isolate from Llyn Padarn, but a large proportion of fixed carbon was lost extra‐cellularly by this strain, which may account for its slower growth rate. Photosynthetic rates of the small‐celled isolate from Llyn Coron and the second isolate from Llyn Padarn were low. A range of photosynthetic efficiencies were recorded and these were related positively to the maximum photosynthetic rate. The rapidly photosynthesizing Padarn strain, which had the lower chlorophyll‐a content per cell, was the most efficient. The pattern of distribution of photosynthate for this strain from Padarn differed from the other isolates. In addition to the large proportion lost extracellularly, it had a higher level of protein synthesis. The presence of extracellular products reduced the photosynthetic rate, and differences were noted in the response to light intensity between A. formosa from the two lakes.Morphological and physiological variations were confirmed in A. formosa. The situation is complex, since morphologically similar strains isolated on different occasions from Llyn Padarn showed contrasting physiological behaviour and, during culture, morphological types were distinguished in the isolate from Llyn Coron, which also differed physiologically.
THE GENECOLOGY OF LAWN WEEDS
Authors: WARWICK S. I. 
Published: May 2006

SUMMARYResults from an experiment in which trampling was simulated indicated that in Plantago major and Poa annua the genetically‐determined prostrate growth forms were in general better able to withstand trampling damage than the corresponding erect growth forms. The effects of trampling stress were found to differ between species, between treatments for each species, and in the degree to which different aspects of growth and reproduction appear to be affected within a given species. Estimates of coefficients of selection acting against the erect growth forms were particularly high for reproductive characters, with values of 0.78 to 0.79 for Plantago major and 0.46 to 0.66 for Poa annua.Problems in the design of experiments investigating trampling stress are discussed.