bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHYSIOLOGICAL RESPONSES OFRIVULARIA ATRATO SALINITY: OSMOTIC ADJUSTMENT IN HYPOSALINE MEDIA
Authors: REED R. H. , STEWART W. D. P. 
Published: May 2006

SUMMARYThe metabolic responses of the topshore cyanobacterium (blue‐green alga)Rivularia atra(Roth) Born, et Flah. have been studied over the salinity range from 0 to 100% sea water. Photosynthetic competence is maintained throughout, showing only minor variation in response to salinity change. Nitrogenase activity is highest in hyposaline media (5 to 25% sea water), decreasing to approximately 55 to 60% in full‐strength sea water. The principal low molecular weight, ethanol‐soluble carbohydrate present within cells ofR. atrais the disaccharide trehalose, occurring at concentrations up to 232 mmol kg−1(cell water) within cells incubated in 100% sea water. Trehalose concentration was found to be dependent upon the salt concentration of the bathing medium, suggesting that it played a role in the maintenance of positive turgor under conditions of varying salinity. Approximately 10 to 12% of the total intracellular trehalose pool was released upon ‘downshock’ [transfer from 100% sea water to 0% (fresh water)]. Regular release of such quantities of carbohydrate in response to ‘downshock’, e.g. on exposure to rain or freshwater at low tide, may be locally important in providing fixed carbon for associated heterotrophic organisms, although it represents a negligible input of fixed carbon to the marine littoral environment.
AN 15N INVESTIGATION INTO NITROGEN ASSIMILATION IN HYDROPONICALLY‐GROWN BARLEY (HORDEUM VULGARE L. CV. CLIPPER) IN RESPONSE TO NITRATE, AMMONIUM AND MIXED NITRATE AND AMMONIUM NUTRITION
Authors: LEWIS O. A. M. , CHADWICK S. 
Published: May 2006

SUMMARYBarley plants (Hordeum vulgare L. cv. Clipper) were grown in pH‐controlled, aerated solution culture with 2 mM inorganic 14N supplied as nitrate alone, ammonium alone or 1 :1 nitrate+ ammonium. At the 20th day of growth the 14N feeding solutions were replaced by 15N feeding solutions and the plants grown in these media for 4 and 8 h before harvesting.In the nitrate‐fed plants at both harvests most of the absorbed and assimilated 16N was found in the shoot. Xylem sap analyses showed that 66% of the 16N supply to the shoot was as nitrate indicating that the shoot was the main organ of nitrate assimilation. In the ammonium‐fed plants there was considerable accumulation of 15N ammonium in the root, where the assimilatory pools saturated quickly with 16N and the highest content of organic 16N was found (in the 4 h harvest). Xylem sap analysis showed that 93% of the 15N exported from root to shoot was as organic N (mainly glutamine) with very little ammonium present, indicating that the root was the major organ of ammonium assimilation. The high 15N shoot content at the 8 h harvest suggested however, that the shoot was the major destination of the root assimilated N. In the mixed‐feed plants, combined root and shoot assimilation was evident, 29 % of the 15N in the xylem sap being in the form of nitrate, indicating a suppression of nitrate ion absorption by ammonium ions.The highest rate of 15N incorporation into organic N, (24.8 μg h−1per plant) occurred in the mixed N‐fed plants (the largest and more robust plants), followed by the ammonium‐fed plants (24.8 μg h−1per plant) (the smallest, least robust plants) and the nitrate‐fed plants (5.6 μg h−1per plant). The lower N assimilation by the nitrate‐fed plants is ascribed mainly to decreased uptake of the nitrate ion in comparison to the ammonium ion.It appears that, for maximum growth and N assimilation of hydroponically‐grown barley, a mixed nitrate‐ammonium N source is required. Nitrate is poorly absorbed but appears to be necessary for the optimum growth of ammonium fed plants by increasing shoot N assimilation or by providing additional electron accepting potential to the roots. The situation could be markedly different in soil grown plants where the ammonium ion is not so readily available.
THE RELATIONSHIP BETWEEN COMBINED NITROGEN UPTAKES AND NITROGEN FIXATION IN AZOLLA‐ANABAENA SYMBIOSIS
Authors: ITO OSAMU , WATANABE IWAO 
Published: May 2006

SUMMARYThe assimilation and distribution in Azolla pinnata of nigrogen from three different sources of nitrogen–ammonium, nitrate and dinitrogen–were compared. Neither ammonium nor nitrate supplied at 1 mM for 4 days, inhibited acetylene reduction activity (ARA). At higher concentrations, the ARA was less inhibited by nitrate than by ammonium. Of the three nitrogen sources tested, nitrate‐nitrogen was the least available and mobile in Azolla.After incubation with 15N‐labelled nitrogen sources leaves were divided into six branches ranging from young to the old and the distribution of 15N among those branches determined. Ammonium and dinitrogen were preferentially assimilated into younger branches and nitrate into older ones.Alternative labelling with either dinitrogen or combined nitrogen showed that dinitrogen fixation took place simultaneously with the assimilation of ammonium or nitrate, and was less inhibited by nitrate than by ammonium. After 4 days of incubation, about a half of the total nitrogen in Azolla comprised nitrogen newly incorporated from both the medium and atmosphere, and of this about 70 and 30% originated from ammonium and nitrate at 10 mM respectively.It is suggested that, even when Azolla is grown on a medium containing combined nitrogen, Anabaena in the leaf cavities still fixes atmospheric nitrogen and supplies it to the host plants, and that each nitrogen source is incorporated and translocated in a characteristic manner.
NECTAR GUIDE COLOUR CONTRAST: A POSSIBLE RELATIONSHIP WITH POLLINATION STRATEGY
Authors: PENNY J. H. J. 
Published: May 2006

SUMMARYA quantitative photographic survey was made of the spectral structure of the colours of a random selection of wild and cultivated flowers, in the insect and human visible spectra. The survey revealed that the majority of insect‐pollinated flowers possessed nectar guides, of which three types were recognized. Analysis of the contrasts between the nectar guides and the petals revealed that they were apparently most conspicuous in the insect‐visible spectrum. Cultivars were found to have a significantly lower incidence of nectar guides and were also apparently more conspicuous in the human visible spectrum. These results were discussed in relation to possible floral colour adaptation to insect pollinator attraction.
A MODULAR APPROACH TO ANALYSIS OF PLANT GROWTH
Authors: PORTER J. R. 
Published: May 2006

SUMMARYThe previous paper in this series argued that whole plant development is best viewed as a population‐type process in which attention is focused on the production of modular plant parts. This approach is of more relevance to quantifying whole plants architecture than conventional growth analysis. The present paper describes an experiment in which the growth of two cultivars of Fuchsia was followed as a developing system of meristems. The noted features of growth and development were the changes in numbers of meristems as the plants produced flowers, the age distribution of vegetative meristems and the probabilities of transition between different modular states as the plant developed.
SODIUM IONS CAN ELIMINATE THE NORMAL DISPARITY IN ABAXIAL AND ADAXIAL STOMATAL OPENING ON ISOLATED EPIDERMES
Authors: PEMADASA M. A. 
Published: May 2006

SUMMARYA comparative study was made of the effects of KCl and NaCl on abaxial and adaxial stomatal responses to light, CO2and indole‐3‐acetic acid (IAA) on isolated epidermes ofCommelina communis. Although K+and Na+were equally capable of promoting opening, NaCl masked the responses to light, CO2and IAA normally occurring in KCl; thus a specific requirement of K+for normal stomatal responses is suggested. NaCl produced equally wide abaxial and adaxial stomatal apertures, so eliminating the disparity in their opening normally found in KCl; the Na+‐stimulated opening was not a result of a stimulation of K+accumulation in the guard cells. The results suggest that the normal disparity in abaxial and adaxial stomatal opening is specifically linked with differential K+accumulation in the guard cells.
BIOCHEMICAL EFFECTS OF SULPHUR DIOXIDE ON PROLINE METABOLISM IN THE ALGA TREBOUXIA SP.
Authors: EWALD D. , SCHLEE D. 
Published: May 2006

SUMMARYCells of the green alga Trebouxia sp. treated with Na2SO3 (5 × 10−5 to 5 × 10−3 M) for 4, 24, 48, and 72 h show a decreased content of proline and an increase in alanine dependent on incubation time and sulphite concentration.The activity of the NAD‐dependent proline dehydrogenase (EC 1.5.1.2, alternative name, pyrroline‐5‐carboxylate reductase) was measured. In vitro sulphite uncompetetively inhibited the enzyme. In vivo, sulphite concentrations up to 5 × 10−4 M led to enhanced enzyme activity.It is suggested that sulphite influences the proline content in Trebouxia via the last enzyme of proline synthesis, proline dehydrogenase.
MORPHOLOGICAL FEATURES OF SYNTHESIZED ECTOMYCORRHIZAE OF ALNUS CRISP A AND A. RUGOSA*
Authors: GODBOUT C. , FORTIN J. A. 
Published: May 2006

SUMMARYThe ability of two shrubby alders to form ectomycorrhizae with known species of fungus was investigated. Frankia‐ inoculated seedlings of Alnus crispa and Alnus rugosa were raised in growth pouches and inoculated with a pure culture inoculum of potential ectomycorrhizal fungi. Ten of the 46 species of fungi used formed ectomycorrhizae with both Alnus species. Only Alpova diplophloeus showed a well distributed Hartig net; others had a net only proximally, while others had none. These patterns are discussed in terms of more or less rapid Hartig net development. The Hartig net was always confined to the epidermal layer of the root, never completely surrounding it. This situation appears to predominate in the Angiosperms. Colonization of young actinorhizae by Alpova diplophloeus led to the formation of ectomycorrhizal structures.
THE EFFECTS OF SALT WATER AND SOIL TYPE UPON THE GERMINATION, ESTABLISHMENT AND VEGETATIVE GROWTH OF HOLCUS LANATUS L. AND LOLIUM PERENNE L.
Authors: WATT T. A. 
Published: May 2006

SUMMARY Holcus lanatus is the dominant grass over large areas of thin peat soil on the western sea‐cliffs of Lundy Island, exposed to salt spray. Its tolerance of artificial sea water (ASW) on peat or loam soils when grown alone or in mixture with either an agricultural cultivar of H. lanatus, Massey Basyn or with ‘Aberystwyth S. 23’Lolium perenne was investigated. Under salt spray, on peat soil, ‘Lundy’H. lanatus had the highest tillering ability and, unlike the others, its yield was unaffected by the spray. When high levels of salt were applied to the soil, the yield of L. perenne was lowest when it was grown on peat and was also in competition with ‘Lundy’H. lanatus. On peat soil, the agricultural cultivar of H. lanatus was more productive than L. perenne. It was also at least as productive as ‘Lundy’H. lanatus when grown on peat with a high level of salt in the soil solution.When immersed in a solution of ASW, the leaves of L. perenne retained approximately 17 times more salt than did those of either ‘Lundy’ or ‘Massey’H. lanatus. There was no evidence for sodium ions being adsorbed on to the cuticle of any of the grasses. ‘Seeds’ of both L. perenne and ‘Massey’H. lanatus germinated readily in 40% ASW. However, germination of ‘Lundy’H. lanatus‘seeds’ was much reduced at this salt level, especially from intact spikelets, although they germinated readily when transferred to fresh water. The establishment of ‘Lundy’H. lanatus under 120 kg ha−1 day−1 of sea‐salt was slower than that of the other two grasses.
CYANOBACTERIAL MOTILITY AS A TEST OF THE QUANTITATIVE SIGNIFICANCE OF PROTICITY TRANSMISSION ALONG MEMBRANES
Authors: RAVEN J. A. 
Published: May 2006

SummaryA quantitative analysis of energy transmission along membranes by diffusion of buffered protons in the aqueous (N and P) phases on either side of the membrane is presented. In thylakoids of plants with chlorophylls a and b, where proton motive force (pmf)‐generators and pmf‐consumers are laterally separated by up to 1 μm, energy transmission by diffusion of buffered protons in the aqueous phase can occur at the observed in vivo rate with less than a 10% decrement in pmf available to consumers relative to its value at pmf‐generators. However, in motile cyanobacteria, it is concluded that motility cannot be maintained in non‐illuminated portions of the trichome by transmission of proticity along the plasmalemma when the mean distance of transmission exceeds a few micrometres. The transmitted effect of illumination is probably an informational rather than an energetic effect. Energy transmission by lateral proticity transport is essentially a diffusive process, and is subject to similar constraints to those related to the transport of ‘chemical’ energy (e.g. as ATP): suggestions that energy transmission by lateral proticity movement can occur over distances, and at velocities, similar to those of nervous transmission apply to transient states and do not reflect steady‐state power transmission.
EFFECTS OF PERIODS OF LOCALIZED WATER STRESS ON SUBSEQUENT NUTRIENT UPTAKE BY BARLEY ROOTS AND THEIR ADAPTATION BY OSMOTIC ADJUSTMENT
Authors: SHONE M. G. T. , FLOOD ANN V. 
Published: May 2006

SummaryDrought and low soil water potentials depress nutrient uptake by roots, but their capacity for recovery when the soil is re‐wetted has received less study. We investigated the uptake in barley of labelled phosphate and calcium from sand culture following periods of drought or treatment with polyethylene glycol 4000 (PEG) of the surface layers of the sand, with the lower portion of the root system receving ample nutrients and water. Drought diminished uptake and translocation of both nutrients and caused death of fine lateral roots, but after 3 days of re‐wetting, uptake per unit fresh weight of roots was comparable with that of well‐watered control plants despite apparent collapse of some of the cortical cells of the seminal axes. The activity of new nodal roots that grew during the 3‐day re‐wetting period alleviated the earlier depression of nutrient absorption. Effects of PEG (−0.8 MPa) were less severe and nodal roots grew through this medium with no apparent damage. The tips of these roots seemed to become osmotically adjusted largely by enhancement of their sugar content, but we found little evidence of such adjustment in those parts of the seminal axes exposed to PEG. Rapid growth of nodal roots assisted by osmotic adjustment may be of adaptive significance in ensuring resumption of nutrient and water uptake following periods of water deficit.
POPULATION DIFFERENTIATION IN FESTUCA RUBRA L. AND AGROSTIS STOLONIFERA L. IN RESPONSE TO SOIL WATERLOGGING
Authors: DAVIES M. S. , SINGH A. K. 
Published: May 2006

SummaryTwo populations of Agrostis stolonifera and seven populations of Festuca rubra from salt marsh and inland habitats were grown on a free draining soil and at two levels of soil waterlogging. The growth of A. stolonifera was stimulated by soil waterlogging while that of F. rubra was depressed. There was no difference between the two populations of A. stolonifera in growth response to waterlogging but the inland population had a greater Fe concentration in the shoots when grown on waterlogged soil than the salt marsh population. In F. rubra the yield of the salt marsh populations was generally less depressed by soil waterlogging than that of populations from free draining soils; the salt marsh populations also had lower concentrations of Fe and Mn in the shoot on the continuously waterlogged soil than the inland populations. It is concluded that the evolution of a degree of waterlogging tolerance has occurred in the salt marsh populations of F. rubra in response to the periodic flooding by sea water in their native habitats.
THE EFFECT OF SALINITY ON LEAF WATER RELATIONS AND CHEMICAL COMPOSITION IN THE SUB‐ANTARCTIC TUSSOCK GRASS POA COOKII HOOK F.
Authors: PAMMENTER N. W. , SMITH V. R. 
Published: May 2006

SummaryIsolated tillers of the sub‐Antartic Maritime tussock grass Poa cookii responded to high concentrations of NaCl (0.3 to 0.7 M) in the root medium by markedly accumulating Na in the older leaves. Concomitant with this was a decline in leaf water potential (φ), osmotic potential (φ) and fresh weight: dry weight ratio. Inorganic solutes accounted for a greater proportion of the measured φ in older than in younger leaves and Na was the most important cation contributing to measured values of φ and φ Changes in the K, Ca and Mg concentrations in leaves exposed to NaCl in the root medium were related to changes in leaf water content rather than to remobilization of these elements within the plant. The results are interpreted as demonstrating a mechanism preventing injuriously high levels of Na in young, metabolically active tissue, rather than an osmoregulatory phenomenon. This suggests that P. cookii cannot be considered to be a true halphyte despite its frequent occurrence in the salt spray zone of many sub‐Antarctic islands.
VESICULAR‐ARBUSCULAR MYCORRHIZA IN FIELD‐GROWN CROPS II. EFFECT OF INOCULATION ON GROWTH AND NUTRIENT UPTAKE IN BARLEY AT TWO PHOSPHORUS LEVELS IN FUMIGATED SOIL
Authors: JAKOBSEN I. 
Published: May 2006

SummaryThe effect of inoculation with vesicular–arbuscular mycorrhizal fungi on the growth of barley in the field was studied at two levels of soil P on plots fumigated with methyl bromide. During the vegetative phase, growth and P uptake was influenced only by soil P; P uptake in the period from earing until maturity was negligible in uninoculated plots. Final production of dry matter was increased by 20 % on average by inoculation and by 40 % by soil P. In contrast, the final P uptake was increased by 100% by inoculation and only by 50% by soil P. Concentrations of bromide in shoots were high and inoculation increased the uptake of bromide, Zn and Cu significantly. Mycorrhizal infection in inoculated plots was first observed 25 days after seedling emergence, and final infection levels were c. 50% in contrast to 12 % without inoculation. The introduced endophyte had spread 30 cm horizontally during the growth period of 96 days.
ORIGINS OF DECAY IN LIVING DECIDUOUS TREES: THE ROLE OF MOISTURE CONTENT AND A RE‐APPRAISAL OF THE EXPANDED CONCEPT OF TREE DECAY
Authors: BODDY LYNNE , RAYNER A. D. M. 
Published: May 2006

SummaryIt is argued that the development of decay in living hardwoods can best be explained in terms of the unsuitability of functional sapwood for mycelial establishment owing to its high moisture content and lack of easily assimilable nutrients other than within living cells. Decay occurs when these limitations are removed by any mechanisms which prevent or interfere with the normal functioning of sapwood. Recent concepts of decay in living trees have implied an active host defence against infection. This view is discussed against the alternative that non‐specific mechanisms which maintain sapwood function will, by their very nature, prevent establishment of ‐ycelium of decay and stain fungi. The significance of mixed microbial communities in the development of decay is discussed, particularly in relation to the supposed requirement for specific sequences to overcome host defences.
A HOLOCENE POLLEN DIAGRAM FROM LYNCH'S CRATER, NORTH‐EASTERN QUEENSLAND, AUSTRALIA
Authors: KERSHAW A. P. 
Published: May 2006

SummaryPollen analysis of this core from Lynch's Crater provides a more detailed and continuous Holocene record than has been obtained previously from the site. The pattern of dry‐land vegetation changes appears broadly similar to those from other sites covering this period from the Atherton Tableland, though problems of dating do place some restriction on temporal correlations between them. Swamp forest is recorded for the first time within the region from pollen and plant macroremains, and this existed from the time of arrival of rainforest, probably about 8500 years B.P. until between 6000 and 4500 B.P. Firing by Aborigines in addition to climate change is considered to have been an important factor in swamp forest destruction and in the promotion of subsequent changes in swamp vegetation.
GENOTYPIC VARIATION IN THE RESPONSE TO SUB‐OPTIMAL TEMPERATURES OF GROWTH IN TOMATO (LYCOPERSICON ESCULENTUM MILL.)
Authors: PAUL E. M. M. , HARDWICK R. C. , PARKER P. F. 
Published: May 2006

SummaryA growth analysis of plants raised under controlled environment conditions was used to examine the response to temperature of five contrasting tomato cultivars bred for outdoor production. Curves were fitted to the data of dry weight and leaf area and, to compensate for ontogenetic drift, instantaneous values of growth analysis parameters were calculated from these curves at a specific growth stage. Differences in relative growth rate which could be exploited in a breeding programme were not detected, though there were large differences in the components of relative growth rate. These were, however, compensatory within a cultivar. It was concluded that in order to select a genotype with improved growth rate it would be necessary to disrupt the compensation mechanism between the components of relative growth rate.
THE DEPENDENCE OF SUNTRACKING IN LAVATERA CRETICA L. UPON CARBON DIOXIDE AVAILABILITY
Authors: FISHER F. J. F. , WRIGHT M. 
Published: May 2006

SummaryWhen CO2 is withheld from the leaves of Lavatera cretica L., the normal phototropic tracking response to an oblique light source becomes weakened within 60 min and after 2 h is eliminated altogether. If CO2 is also withheld throughout a preceding 24 h dark period, even the initial tracking response in the light under carbon dioxide deprivation is eliminated. Normal tracking resumes in both cases when CO2 is again provided. Alternating directions of oblique illumination, under normal atmospheric CO2 levels, produce a synchronized response cycle with a short phase lag, but carbon dioxide deprivation results in the adoption of a neutral intermediate position. The results are in accord with the hypothesis that uneven distribution patterns in photosynthetic activity, resulting from the oblique illumination of the lamina, lead to the pulvinar turgor gradients responsible for suntracking movements in this species.
INJURIES TO LICHEN ULTRASTRUCTURE CAUSED BY SULPHUR DIOXIDE FUMIGATIONS
Authors: HOLOPAINEN TOINI , KÄRENLAMPI L. 
Published: May 2006

SummaryEffects of SO2 (0.05,01, 0.3 and 1.0 ppm) fumigations on the ultrastructure of the lichens Bryoria capillaris (Ach.) Brodo & D. Hawksw. and Hypogymnia physodes (L.) Nyl. were studied with a transmission electron microscope. All concentrations of SO2 caused characteristic ultrastructural symptoms. These were always observable before light microscopic and visible changes in thalli.Sulphur dioxide injury in the Trebouxia phycobiont cells of both species began as swelling and deformation of mitochondria, stretching of the chloroplast envelope and deformation of pyrenoglobuli. Later, stretching of thylakoids and degeneration of pyrenoid, chloroplast stroma, nucleus, mitochondria and cytoplasm were observable. It was typical of the later stages of SO2injury that thylakoids remained visible for a long time. The degree of injury in the algal cells increased with increasing SO2 concentration and duration of exposure. The fungal cells showed ultrastructural symptoms, swelling of mitochondria and vesiculation of the mesosome‐like organelle, only at the highest concentration (1.0 ppm) of SO2. The experimental results are consistent with many earlier observations on natural material collected from industrial environments. Relationships between the ultrastructural and physiological changes caused by SO2 are discussed.