bluuebunny/crossref_metadata_2025_split huggingface dataset:
A COMPARISON OF THE RESPONSES OF LOLIUM PERENNE L. *, HOLCUS LANATUS L. AND DESCHAMPSIA FLEXUOSA (L.) TRIN. TO A LOCALIZED SUPPLY OF NITROGEN
Authors: ROBINSON D. , RORISON I. H. 
Published: May 2006

SUMMARYThree grasses were grown in a split‐root solution culture experiment in which only a fraction of the root system of each plant was supplied with 4.0 mol m−3 N as NH4NO3. The solutions were labelled with 15NO3 or 15rNH4 during the final 24 h of the experiment. Deschampsia flexuosa, unlike Holcus lanatus and Lolium perenne, showed no reduction in total dry weight production relative to the controls. Proportionately greater increases in specific N‐absorption rate were measured in D. flexuosa compared with H. lanatus and L. perenne. All three species exhibited large changes in root morphology (length : dry weight). In D. flexuosa such changes were confined only to those roots having direct access to N (+ N roots); in H. lanatus and L. perenne this response occurred also in the rest of the root system (‐N roots). The proportion of 15N transported to the ‐ N roots was greater in H. lanatus and L. perenne. Increased transport of ammonium‐N to the shoot was found in D. flexuosa and, it is suggested, this stabilized the root: shoot ratio and maintained maximum relative growth rate. The smaller absolute N demand of D. flexuosa was such that responses to maximize N uptake, to confine to a greater extent the utilization of N to +N roots, and to maintain N supply to the shoot, ensured full compensation for the restricted N supply. The inherently higher N demands of H. lanatus and L. perenne could not be met by increases in specific absorption rates. In addition, the transport of relatively greater amounts of 15N to – N roots rather than to the shoot, and the consequent increase in root: shoot ratios prevented compensation from being achieved to the same extent.Thus, the efficient utilization of dry matter and nutrient resources appear to be important factors enabling D. flexuosa to grow effectively under restricted conditions of nutrient supply.
GENECOLOGICAL STUDIES OF RUMEX CRISPUS L.
Authors: AKEROYD J. R. , BRIGGS D. 
Published: May 2006

SUMMARYSamples from 23 British populations of Rumex crispus L., including material of three principal variants described in this species, were transplanted into two garden trials. It was discovered that some characteristics, which distinguished the variants in the field, were less evident or less clear‐cut in cultivation. However, plants from different habitat types did remain distinct in certain features, in particular, the time of first flowering and pattern of tubercles on the fruits. Some variation between populations within habitat types was detected by the transplant experiments.
GENECOLOGICAL STUDIES OF RUMEX CRISPUSL.
Authors: AKEROYD J. R. , BRIGGS D. 
Published: May 2006

SUMMARYOpen‐pollinated seed was collected from several seed parents in each of 16 British populations of Rumex crispus L., representing the three principal variants of this species. Progeny of these seed parents (family lines) were grown in a garden trial, which revealed statistically significant differences between and within the populations sampled.(1) Coastal plants had denser inflorescences, fewer flowering stems, later anthesis and a greater development of corky perianth tubercles than inland plants.(2) Plants from riverine tidal mud at Tintern were distinct in their exceptional height, more or less uncrisped leaves, lax inflorescences, very early flowering and tubercle pattern intermediate to coastal and inland plants.(3) There was considerable variation between populations within coastal and inland habitats and within family lines. This spectrum of variation suggested that both outbreeding and inbreeding might occur in R. crispus.(4) Many plants from inland populations, with the exception of those from Tintern, flowered in their first year of growth, whereas populations from coastal areas and Tintern flowered in their second (or a later) year of growth.(5) There was evidence of gene flow between coastal and inland variants of R. crispus at ‘points of contact’, especially where coastal habitats had been disturbed. Plants from a few inland sites appeared to be hybrids between R. crispus and R. obtusifolius.(6) In cultivation, inland populations flowered consistently earlier than coastal plants. A similar difference in flowering time was recorded in a field study of a coastal area of Suffolk.
GROWTH CURVE OF THE LICHEN RHIZOCARPON GEOGRAPHICUM
Authors: ARMSTRONG R. A. 
Published: May 2006

SummaryData on the growth curve of the lichen Rhizocarpon geographicum were obtained by measuring the radial growth rates (mm per 1.5 years) of 39 thalli from 2 to 65 mm in diameter growing in the same environment. An Aplin and Hill plot (ri–r1 against In r2– In r1) of the data and regression analyses suggested an initial phase of growth (up to a diameter of about 7 mm) in which the relative growth rate increased rapidly. This was followed by a phase in which the relative growth rate fell but the radial growth, rate continued to rise (7 to 20 mm in diameter). Radial growth was then relatively constant until about 45 mm diameter and then declined. The Aplin and Hill model did not fit the data as a whole but may apply for a transient period in thalli between about 7 and 16 mm in diameter. This curve shows some similarities to that suggested by lichenometric studies but differs in showing a less steep decline in growth rate after the ‘great’ period.
CYCLIC VEGETATIONAL AND EDAPHIC CHANGES IN AN ARTHRO CNEMUM COMMUNITY IN SRI LANKA
Authors: de SILVA P. H. A. U. , PEMADASA M. A. , HERATH R. M. 
Published: May 2006

SummaryThe perennial shrub Arthrocnemum indicum dominates in certain saline habitats in Sri Lanka. Its growth‐vigour declines with ageing. As the plant grows into a clump with its radiating prostrate shoots and upright aerial shoots bearing clusters of branches, it traps wind‐borne sand, so developing a hummock. Each clump on its hummock follows a cycle of pioneer, building, mature, degenerate and eroded phases with concomitant vegetational and edaphic changes. This cycle was elucidated in a community on the north‐west coast of Sri Lanka. During upgrade phases of the cycle, fine sand, organic debris and humus continue to accumulate in and around the thickly‐branched, vigorously‐growing Arthrocnemum clump, and this improves the moisture status of the developing hummock; the concentrations of nutrients also increase, as a result of accretion of wind‐borne particles and through reduction (by the closed Arthrocnemum canopy) of nutrient‐loss by wind‐erosion, surface run‐off and leaching. These trends are reversed during the downgrade phases. As the growth‐vigour of ageing shoots declines, the clump becomes increasingly open and the exposed hammock suffers wind‐induced erosion; the moisture status deteriorates as fine sand and organic matter are lost by wind‐erosion, which, together with enhanced leaching, also causes nutrient‐loss leading to soil impoverishment. The eventual death of the Arthrocnemum clump and continued hummock‐erosion complete the cycle. The subordinate Cynodon dactylon occurs more abundantly on degenerating than on developing hummocks; thus, the Arthrocnemum cycle appears to impose an inverse cyclic succession of its abundance. Accordingly, cyclic vegetational and edaphic changes in this community are closely correlated with the phasic development of the dominant A. indicum.
A GROWTH CABINET PROVIDING VARIABLE SPECTRAL PHOTON DISTRIBUTIONS AT HIGH FLUENCE RATES
Authors: HUGHES J. E. , HEATHCOTE L. , BAMBRIDGE K. , BLACK C. R. 
Published: May 2006

SummaryA plant growth cabinet providing a flexible facility for photomorphogenic and photoperiodic research is described. The growth chamber is divided into quarters which are optically isolated, and has a recirculating air‐conditioning system. The various light sources and filters available are discussed in relation to their desirable features. The chosen sources of white light (metal halide discharge lamps) are capable of generating approximately 800 μmol m−2 s−1 (400 to 700 nm). Tungsten‐halogen filament lamps are used to provide longer wavelengths. Infra‐red filters (acrylic sheet and water) reduced heat loading to a negligible level. Data are presented for internode length in plants of Chenopodium album L. grown under different fluence rates of supplementary far‐red light in the new cabinet.
FORMATION OF METACHROMATIC GRANULES FOLLOWING PHOSPHATE UPTAKE BY MYCELIAL HYPHAE OF AN ECTOMYCORRHIZAL FUNGUS
Authors: LAPEYRIE F. F. , CHILVERS G. A. , DOUGLASS P. A. 
Published: May 2006

SummaryAbundant metachromatic granules, presumed to contain polyphosphate, were present in mycelial hyphae of Paxillus involutus (Batsch. ex Fr.) Fr. grown in phosphate‐rich medium, but were absent when the medium lacked phosphate. Phosphorus‐starved hyphae placed into phosphate‐containing solutions developed granules within 3 to 4 h. Most of this period was required for synthesis of granule materials, since phosphate uptake occurred within minutes. Both phosphate uptake and granule formation are active processes, affected by low temperature and respiratory inhibitiors. No special importance seemed to attach to the presence of any of the following cations: Ca2+; Mg2+; K+; or Na+; and two different isolates of P. involutus, one calcifuge and one calcicole, showed no differential effects regarding granule formation in the presence and absence of Ca2+ and Mg2+.
ECTOMYCORRHIZA FORMATION IN EUCALYPTUS
Authors: MALAJCZUK N. , MOLINA R. , TRAPPE J. M. 
Published: May 2006

SummaryUltrastmcture of Eucalyptus ectomycorrhizas initiated by compatible, host‐specific fungi and by broad‐host range fungi was compared with that of roots inoculated with incompatible, conifer‐specific ectomycorrhizal fungi. The results indicate little difference in morphology between ectomycorrhizas formed by compatible, host‐specific fungi and those formed by broad‐host‐range fungi. However, interaction between eucalypt roots and incompatible fungus species known to be conifer‐specific induced either deposition of tannins in root tissue or, in the case of the Pseudotsuga‐speciiic Suillus lakei, a characteristic hypersensitive reaction which resulted in lysis of hyphae and of epidermal and outer cortical cells of roots.
CANOPY STRUCTURE AND MICROCLIMATE OF TWO WET GRASSLAND COMMUNITIES
Authors: FLIERVOET L. M. , WERGER M. J. A. 
Published: May 2006

SummaryIn two adjacent wet grasslands, a Cirsio‐Molinietum and a Senecioni‐Brometum, in the Netherlands, above‐ground phytomass, leaf area index (LAI), and canopy structure were measured at peak flowering season, during three consecutive years. Microclimate profiles in the canopies were measured. The Cirsio‐Molinietum produced a smaller phytomass with a larger LAI than the Senecioni‐Brometum, and the stem/leaf ratios were different too. Relative distribution of phytomass and leaf area in the canopies were remarkably constant during the three years and independent of total values. Differences in canopy structure including differences in vertical arrangement of phytomass and leaf area, leaf angles and leaf sizes result in differences in light interception patterns, air temperatures and saturation deficits within the canopies, and in soil temperatures. These differences are interpreted in terms of relative growth rates of the constituent species and photosynthetic performances of the vegetation types.
INDUCTION OF CYTOCHROME P‐450 IN INTACT MUNG BEANS
Authors: HENDRY G. A. F. , JONES O. T. G. 
Published: May 2006

SummaryInduction of cytochrome P‐450 in intact plants is described for the first time. Geraniol and from‐cinnamate, substrates for plant cytochrome P‐450 reactions, induce the formation of cytochrome P‐450 when fed to seedlings of mung bean [Vigna radiata (L.) Wilczek. cv. Berken, syn Phasealus aureus Roxbl, The carbon monoxide difference spectra of the induced forms of cytochrome P‐450 have absorbance maxima of 449 nm (with geraniol) and 451 nm (with cinnamate) compared with the endogenous form at 452 nm and indicate the presence of multiple forms of cytochrome P‐450. The induction of cytochrome P‐450 was suppressed by feeding laevulinic acid or cyctoheximide, inhibitors respectively of haem and protein synthesis. The use of solvents for the dilution and uptake of water‐insoluble inducing compounds is described, together with the effect of such solvents on plant microsomal cytochromes.
OXYGEN DIFFUSION IN PEA
Authors: ARMSTRONG W. , HEALY M. T. 
Published: May 2006

SummaryThe apical oxygen concentrations in the primary roots of agar‐grown pea plants were assayed polarographically with the roots immersed in anaerobic media, their laterals present or excised, and with or without the sub‐apical regions jacketed in a solid agar.Oxygen concentrations declined for several days following emergence as a function of accumulated demands of primary and lateral Touts for oxygen, internal diffusive resistance, and radial oxygen leakage from both primary root and laterals. Under the combined influence of all these factors (unjacketed roots with laterals), primary root apices could become totally anoxic when only 4 to 6 d old. Total apical anoxia did not occur however if lateral roots were excised, Or if sub‐apical regions of the roots remained encased in the solid agar. In these roots the decline in apical oxygen concentration continued for about 7 d of growth, after which the trend was reversed, and at 40 d apical concentrations as high as 7% were recorded. The anoxic state, which after 4d had characterized unjacketed roots with laterals, was also alleviated m approx. 10 d; at 40 d apical oxygen concentrations had risen to 3.5 to 4.5%.Respiratory rates in the primary root declined both with distance from the apex and with time. IT was concluded that it was chiefly these effects which accounted for the subsequent elevation of the oxygen concentrations in the primary‐ apex.It is pointed out that the oxygen demands of flooded soil might even lead to apical anoxia m the roots of 2‐d‐old plants. However, it is also tentatively suggested that, since respiratory decline can restore a better balance between oxygen demand and internal supply in pea roots, the ageing pea plant may become eventually somewhat less sensitive to soil waterlogging.
RESPONSES OF ADAXIAL AND ABAXIAL STOMATA TO LIGHT AND WATER DEFICITS IN SUNFLOWER AND SORGHUM
Authors: TURNER N. C. , SINGH D. P. 
Published: May 2006

SummaryThe responses of adaxial and abaxial stomata to light and water deficits were followed in normally‐oriented and inverted leaves of sunflower (Helianthus annuus L. cv. Hysun 30) and sorghum (Sorghum bicolor (L.) Moench cv. RS 610) In both species, but especially in sunflower, the adaxial and abaxial stomata closed at the same leaf water potential. However, as a water deficit was imposed, the stomata facing away from the light source, i.e. abaxial stomata in the normal leaf and the adaxial stomata in the inverted leaf, closed more rapidly than the stomata facing the light source. In both sorghum and sunflower the resistance of the adaxial epidermis was higher than that of that abaxial at the same photon flux densities; in sunflower, but not in sorghum this was correlated with the stomatal frequency. The sorghum stomata acclimated to High light, i.e. the adaxial stomata in a normal leaf and the abaxial stomata in an inverted leaf had high resistances on inversion, but the resistance decreased slowly over a per tad of days. Acclimation was not the sole factor involved in the difference in response to light of adaxial and abaxial sorghum stomata. Short‐term leaf inversion reduced the rate of net photosynthesis by 20 to 30% at all photon flux densities.We conclude that adaxial stomata in sorghum, hut not in sunflower, differ inherently from stomata in their response to light. However, in both species there was no inherent between adaxial and abaxial stomata to rapidly‐imposed water deficits.
EFFECTS OF SIMULATED ACTDIC RAIN ON YIELDS OF FIELD‐GROWN SOYBEANS
Authors: EVANS L. S. , LEWIN K. F. , PATTI M. J. 
Published: May 2006

SummaryAn experiment was performed during the summer of 1982 to determine the effects of simulated acidic rain on seed yields on two commercial cultivars of soybeans grown according to standard agronomic practices. Plants were shielded from all ambient rainfalls automatically by two amount exclusion covers and exposed to simulated rainfalls m quantities equal to the average amount of rainfall that occurs at the site. Seed yields of cv. Amsoy exposed twice weekly to simulated rain of pH 4.1, 3.3 and 2.7 were, respectively, 3.0, 9.0, and 12.8% below yields of plants exposed to simulated rain of pH 5.6. A treatment‐response function of seed yield vs rainfall pH for Amsoy was y= 10.20+0.587 x and had a correlation coefficient of 0.96 (y is seed mass per plant and x is the pH of the simulated rain). For cv, Williams, seed yields of plants exposed to simulated rainfalls of pH 5.6, 4.1, 3 3 and 2.7 were 11.5, 10.5, 11.4 and 11.4 g, respectively. A treatment‐response function of seed yield vs rainfall pH for Williams was y= 11.13 + 0.016x which had a correlation coefficient of 0.038. Plants of Amsoy and Williams grown in plots adjacent to the exclusion shelters had mean seed yields of 11.4 and 9.8 g per plant, respectively. Seed yield per plant was dependent upon number of pods per plant because the number of seeds per pod did not vary among treatments for each cultivar.
DIFFERENTIAL EFFECTS OF OZONE AND SULPHUR DIOXIDE ON THE FINE STRUCTURE OF SPINACH LEAF CELLS
Authors: MIYAKE HIROSHI , FURUKAWA AKIO , TOTOSUKA TSUMUGU , MAEDA EIZO 
Published: May 2006

SummarySpinach (Spinacia oleraceaL. cv, New Asia) plants were continuously fumigated with 0.5 μ11−2O3and 1.0 μ11−1SO2singly or in combination. The leaf tissues were examined by electron microscopy at various intervals until they were necrosed. The first indication of O3injury was swelling of thylakoids in the chloroplasts, which was followed by swelling of Golgi bodies, endoplasmic reticulum and nuclear envelopes. The internal space of the mitochondrial cristae was reduced. Later the chloroplasts were deformed. Sulphur dioxide injury first appeared as swelling of the stroma and deformation of the chloroplasts. Swelling of thylakoids appeared later. After both treatments the ceils ultimately collapsed and their contents were aggregated. When O3and SO2were supplied simultaneously, the appearance and development of injury were markedly accelerated compared with either of the single fumigations. The cells mainly showed the features of SO2injury following simultaneous fumigation.
UPTAKE OF [14C]GLUCOSE BY ASYMBIOTIC AND MYCORRHIZAL ORCHID PROTOCORMS
Authors: HADLEY G. 
Published: May 2006

SummaryIn cultures of Goodyera repens Br. infected with its natural mycorrhizal endophyte, Ceratobasidium Cornigerum (Bourdot) Rogers, 14C supplied as glucose reached a peak in the external mycelium within 48 h but accumulated in protocorms over several days. Uptake directly from the substrate into non‐infected protocorms was much slower with less incorporation of 14C into insoluble material than occurred in infected protocorms. There was a similar pattern of uptake from two Ceratobasidium spp. into Dactylorhiza purpurella (T. & T. A. Steph) Soó but the amount of glucose accumulated was less using a natural endophyte than with an isolate originally obtained from rice plants. Using an un‐named Cymbidium hybrid in symbiosis with Ceratobasidium sp. from D. purpurella, there were low rates of uptake into both non‐infected and infected protocorms. 14C from glucose appeared in mannitol and trehalose in mycelium but mainly in glucose, fructose and sucrose in the orchid, with traces of trehalose in infected tissue. In freshly‐infected protocorms, only trehalose became labelled in the pre‐digestive phase of infection and there was no evidence of transfer of 14C from fungus to host before digestion of hyphae occurred.
POLLEN GERMINATION INHIBITORS IN EXTRACTS OFBRASSICA OLERACEAL. STIGMAS
Authors: HODGKIN T. , LYON G. D. 
Published: May 2006

SummaryPollen germination inhibitors were shown to be present in extracts of stigmas from twoBrassica oleraceaL. lines by thin‐layer chromatographic bioassay. Some inhibitors were common to extracts of unpollinated, self‐pollinated and cross‐pollinated stigmas whilst others were only detected m stigma extracts following self‐incompatible self‐pollinations. With sampling times of 2, 4 and 24 h after pollination, inhibitors from self‐pollinated stigmas were at their highest concentration approximately 2 h after pollination but were declining by 4 h, and were virtually absent by 24 h. A possible role for these pollen germination inhibitors in inhibiting pollen growthin vivois noted.
THE BREAKING OF DORMANCY IN HAZEL SEED BY PRETREATMENT WITH ETHANOL AND MERCURIC CHLORIDE
Authors: JEAVONS R. A. , JARVIS B. C. 
Published: May 2006

SummaryPretreatment of intact hazel (Corylus avellana L.) seed with either ethanol or mercuric chloride alone is without effect in stimulating subsequent germination of seeds in the light. However, when treated with ethanol then soaked in mercuric chloride solution, intact seeds germinate when subsequently sown in light. Treatment with ethanol and mercuric chloride does not replace the light‐requirement of intact seeds. The effect of such treatment is similar to that of removal of the testa. Ethanol may be replaced by diethylether, chloroform or n‐propanol.
RHIZOSPHERE BACTERIAL POPULATION RESPONSES TO ROOT COLONIZATION BY A VESICULAR‐ARBUSCULAR MYCORRH1ZAL FUNGUS *†
Authors: Ames R. N. , Reid C. P. P. , Ingham E. R. 
Published: May 2006

SummaryA mixture of bacteria and a vesicular‐arbuscular mycorrhizal fungus isolated from field‐collected sods of blue grama (Bouteloua gracilis (H.B.K.) Griffiths) were tested for their interaction in the rhizosphere of pot‐grown blue grama plants. Populations of the inoculated bacterial species and actinomycete populations, as influenced by the presence or absence of Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe, were enumerated by dilution plate counts from rhizosphere and non‐rhizosphere soil samples. Total bacterial counts and the population of one bacterial species in the non‐rhizosphere soil of pots containing plants were significantly greater than in soil of pots without plants. The population of two bacterial species and actinomycetes were not significantly different in the non‐rhizosphere soil of both mycorrhizal and non‐mycorrhizal plant treatments when compared to the soil of pots without plants. In the rhizosphere of mycorrhizal plants, the total bacterial population and colony counts of one of the four bacterial isolates, when expressed as colony‐forming units (CFU) per gram of root dry weight, were significantly reduced compared with controls. The numbers of CFU per gram of rhizosphere soil of one bacterial species were significantly increased by the presence of the mycorrhizal fungus. Although no significant negative correlation was observed between populations of bacterial species in the rhizosphere soils, significant positive correlations between specific bacterial populations depended on whether or not the roots were mycorrhizal.