bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the cellular localization of the phenolic pungent principle of ginger, Zingiber officinale Roscoe
Authors: ZARATE RAFAEL , YEOMAN MICHAEL M. 
Published: April 2006

summaryExamination of cryo‐sections from mature rhizomes, immature rhizomes and adventitious roots of ginger, Zingiber officinale Roscoe, showed the presence of yellow‐pigmented cells. There is a correlation between the number of pigrnenteci cells and the amount of [6]‐gingerol, the main pungent principle in ginger, in these organs. It is also shown histochemically and microspectrophotometrically that the yellow cells contain, in addition to flavonoid‐like compounds, possibly cureumin derivatives, phenolics and large amounts of lipid material. Low‐temperature scanning electron microscopy also demonstrates the oil content of these cells. Therefore, it would appear that the site of accumulation of flavonoids, curcumin derivatives, phenolics including gingerol and the essential oils of this spice lies within the same cell type.
Effects of ambient air pollution in open‐top chambers on bean (Phaseolus vulgaris L.)
Authors: SCHENONE G. , FUMAGALLI I. , MIGNANEGO L. , MONTINARO F. , SOLDATINI G. F. 
Published: April 2006

summaryField‐grown bean plants (Phaseolus vulgaris L. ev. Taylor's Horticultural) were exposed to ambient air pollution in open‐top chambers (OTCs) at two sites (urban and rural) in Northern Italy. At each site three OTCs received charcoal/Purafil filtered air (F) and three ambient non‐filtered air(NF). Net photosynthesis, stomatal conductance and transpiration of selected leaves were measured from July to September 1989. The results showed that net photosynthesis of NF plants decreased progressively during the season in comparison with the F ones. The difference was greatest at September (−40% at urban site and −23% at rural she). The maximum impairment of photosynthesis occurred during the ripening of the pods. For about 2 wk in August stomatal conductance of NF plants was greater than that of F plants at both sites. Later in August and in September the situation was reversed and stomatal conductance of NF plants wan significantly lower than that of F ones. By this time a significant negative correlation between net photosynthesis and sub‐stomatal carbon dioxide concentration was found in NF plants at both sites, indicating an increased importance of non‐stomatal limitation of photosynthesis. The measured leaves did not show any visible symptom of damage at the time of the physiological measurements; however brown spots on the upper surface became evident later on 20% of total leaves of NF plants. Ambient ozone is suspected to be the major air contaminant involved in causing the observed physiological effects.
The influence of elevated ozone on freezing tolerance of red spruce seedlings
Authors: WAITE C. E. , De HAYES D. H. , REBBECK J. , SCHIER G. A. , H.JOHNSON A. 
Published: April 2006

summaryLaboratory cold‐tolerance assessments were conducted over two seasons on red spruce (Picea rubens Sarg.) seedlings fumigated with various concentrations of ozone (O3) for one or two growing seasons in three independent experiments at three locations. Ozone fumigations were performed at either Boyce Thompson Institute in Ithaca, NY (BTI), the University of Maine in Orono, ME (UMO), or the US Forest Service Research Laboratory in Delaware, OH (USFS). Acid mist treatments of either pH 3.0 or 4.2 were applied in combination with O2 treatments at USFS, Seedlings fumigated with moderate or high concentrations of O3 were never significantly less cold tolerant than seedlings exposed to charcoal‐filtered (CF) air or low O3 concentrations. In fact, there was a tendency for seedlings fumigated with low concentrations of O3 or CF air to be the least cold tolerant. USFS‐fumigated seedlings receiving the lowest O3 concentration (50/0 nl 1−1, day/night concentration) were least cold tolerant on six of the seven sampling dates and significantly less cold tolerant in October and January. In addition, UMO‐fumigated seedlings receiving CF‐air were significantly less cold tolerant in January than those receiving either ambient air (no chamber or non‐filtered treatments) or elevated O3. Acid mist treatments had little influence on the cold tolerance of red spruce seedlings in autumn and early winter, but in January 1990 seedlings exposed to pH 3.0 acid mist were approximately 6 °C less cold tolerant than those receiving pH 4.2. Following the 1988‐89 winter, freezing injury was evident on all seedlings fumigated at BTI, but differences between 3 x ambient O3 and CF treatments were not significant.
Single and interactive effects of root‐knot nematode and coal‐smoke on okra
Authors: KHAN MUJEEBUR RAHMAN , KHAN M. WAJID 
Published: April 2006

summaryEffects of coal‐smoke pollutants and the root‐knot nematode Meloidogyne incognita race 1, singly and jointly, were investigated on okra, Abelmoschus esculentus in 1988 and 1989. Plants in clay pots were placed at two sites (Kl and K2), 1 and 2 km away from the stack of a coal‐fired thermal power plant, and also at the Department of Botany, AMU (control site). The mean concentrations of SO2, NO2 and suspended particulate matter (SPM) were 141, 76 and 309 μg m−3 at K1, and 184, 93 and 205 μg m−3 at K2, but the concentrations of the pollutants at the control site were very low. Okra plants at the K2 site showed browning of the leaves, whereas injury was mild at Kl, The intensity of the browning and the impact of nematode disease was appreciably higher in the infected plants at the polluted sites in both the years. The plants grown at the two sites exhibited suppressions in plant growth, yield and photosynthetic pigments, particularly at K2. M. incognita at the control site also caused significant reductions, but joint effects of the nematode and coal‐smoke were synergistic. Nematode reproduction was enhanced at K1, hut was unaffected at K2. Egg laying was reduced by 13 and 27% a1 Kl and K2, respectively. The response of stomata and trichomes to air pollutants was negative and positive at the two sites, respectively, and stomatal opening was directly correlated with the percent suppressions in dry matter production, yield etc.
Deciduous Quercus in the Mediterranean region: tree‐ring/climate relationships
Authors: TESSIER L. , NOLA P. , SERRE‐BACHET F. 
Published: April 2006

summaryComparisons are made between ring‐width response functions relating to precipitation and temperature in 72 Quercus populations (Q. afares Pomel, Q. canariensis Willd., Q. pubesrens Willd. and Q. robur L.) situated in the north and south of the western Mediterranean region. A multivariate procedure applied to the whole set of response functions allows a distinction to be made of three types of response function according to the species considered. Analogies and differences between coded response functions are revealed by the calculation of a mean response, firstly for each species and for the genus, secondly for the groups of response functions derived from the multivariate analysis. For all the populations, and hence for the entire Quercus genus, a direct response to summer precipitation and an inverse response to temperature, especially minimum temperature, are obtained for the summer period. For the other seasons, each species is characterized by a particular behaviour conditioned by the characteristics of the habitat.
Flandrian vegetational history of sout‐heastern England. Stratigraphy of the Brede valley and pollen data from Brede Bridge
Authors: WALLER M. P. , MARLOW A. D. 
Published: April 2006

summaryThe results of palaeoecological analyses and lithostratigraphic investigations are used to reconstruct the Flandrian evolution of a valley in the East Sussex Weald, the Brede. Particular emphasis is placed upon mid‐Flandrian vegetational history. Palynological data collected from one site, Brede Bridge, include detailed resolution of declines in Ulmus and Tilia pollen. Predominantly inorganic sediments were deposited in the valley during the early Flandrian. Marine conditions penetrated the lower valley under the general influence of sea level rise. After c, 6000 BP, peat formation became widespread and Alnus‐dominated communities occupied the valley floor. Despite forest clearance on the adjacent slopes, relatively little sediment was deposited in the period c. 3700 to c. 1800 BP. The lower valley again came under a marine influence after c. 1800 BP. The dryland forests of the valley were, during the mid‐Flandrian, dominated by Tilia. A general upward decline in Tilia pollen through the sequence is attributed to the valley floor widening and the Brede Bridge site becoming more distant from dryland areas. The first signs of human activity accompany the Ulmus decline, though major forest clearance is not evident until the Tilia decline c. 3700 BP. Comparison of the latter event with sires across south‐eastern and southern England offers support for a phase of human expansion in the late Neolithic/early Bronze Age involving the preferential exploitation of areas of lime forest.
CO2 enrichment responses of wheat: interactions with temperature, nitrate and phosphate
Authors: McKEE I. F. , WOODWARD F. I. 
Published: April 2006

summaryRising levels of atmospheric CO2, climate change, and fertilizer pollution provide the ecological imperative for investigating the interaction between plant responses to atmospheric CO2 concentration, temperature and nutrient supply. In this study spring wheat (Triticum aestivum L. cv. Wembley) was grown at 40, 50, 60 and 70 Pa atmospheric CO2, pressure and three experiments were conducted to investigate interactions between growth responses to the CO2 treatment and: (i) temperature (24/16 °C vs. 18/10 °C ‐ day/night), (ii) nutrient solution nitrate concentration (2.5, 5, 10 and 15 mM Ca(NO3)2.4H2O). and (iii) phosphate concentration (0.025 and 0.5 mM KH2PO4), Dry mass and root/shoot ratio increased with CO2 level at the higher temperature. These responses were reversed at the lower temperature. The increase in yield with CO2 enhancement was limited by low rates of nutrient supply in both absolute and relative terms. In the elevated CO2 treatments, the shoot nitrogen concentration was reduced, as was the proportional allocation to the uppermost leaves. These results are discussed with respect to possible physiological mechanisms and potential for improved crop performance in a future, elevated CO2 world.
Carbon balance of tropical tree seedlings: a comparison of two species
Authors: LEHTO TARJA , GRACE JOHN 
Published: April 2006

summarySeedlings of contrasting tropical tree species were grown at two levels of photon flux, and two levels of nutrient supply. The CO2 exchanges of plant organs were measured, in an attempt to account for the overall carbon balance of the plants in terms of the photosynthesis and respiration of their constituent parts (buds, stems, roots and leaves that were recently fully expanded, mature and senescing). On a per plant basis the buds and leaves dominated the carbon balance. High photon flux and high nutrient supply increased the respiration rate. The relative importance of leaves of different age in whole plant photosynthetic production and respiration was different in the two species and was affected by the light regime. Maintenance respiration of both species was about the same (0.036‐0.050 g CO2 g−1 d−1) but the pioneer species Trema displayed a much higher rate of growth respiration than did Milicia.
A postulated role for calcium oxalate in the regulation of calcium ions in the vicinity of stomatal guard cells
Authors: RUIZ L. P. , MANSFIELD T. A. 
Published: April 2006

summaryCalcium ions are known to play an important part in signal transduction in stomatal guard cells. In Cummelina communis L., stomatal opening in isolated epidermis is strongly inhibited if the calcium concentration in the incubation medium is 0.1 mol mol m−3 or greater, It can be assumed that in the intact leaf, the apoplastic concentration of free calcium in the vicinity of the guard cells must be kept below this level if interference with stomatal functioning is to be avoided.When C. communis was grown with 15 mol m−3 calcium in the rhizosphere, the concentration of free calcium in the xylem sap in the shoot was found to be 3.76 mol m−3. A mechanism is clearly needed for reducing this concentration as the sap traverses the apoplast between the xylem and the stomatal guard cells. Evidence is presented here that the deposition of calcium oxalate in cells of the leaf achieves the necessary regulation. The protective role of the six specialized subsidiary cells in this species appears to be specially important.It is suggested that the regulation of apoplastic free calcium may take an important contribution to the effective stomatal control of gas exchange.
Modelling root architecture: are there tradeoffs between efficiency and potential of resource acquisition?
Authors: BERNTSON G. M. 
Published: April 2006

summaryA model is presented that examines the role of variations in the size of root systems as well as size‐independent aspects of architecture on both the efficiency (volume of soil exploited per unit volume of root) and potential of exploitation (volume of soil exploited). This model is unique in that it explores the architecture of actual root systems rather than statistical approximations of root systems. This design allows the assessment of variations m root system size and size‐independent aspects of architecture in realistic covarying combinations. Root systems of Senecio vulgaris L. grown in ambient and double‐ambient atmospheric CO2 concentrations and two watering regimes were used to parameterize the model.There was a clear trade‐off between the efficiency and potential of exploitation. Large root systems showed high exploitation but low exploitation efficiency. Inversely, small root systems showed low potential and high efficiency. Overall, the potential of soil exploitation was more strongly correlated with all measured aspects of root architecture than was efficiency. Root system size (total length or number of root tips) was much more highly correlated with patterns of soil exploitation, efficiency and potential, than were size independent aspects of architecture. These findings art important to studies of root architecture, demonstrating that studies of root system architecture need simultaneously to measure root system size, size‐independent aspects of architecture and in situ patterns of deployment (e.g. trajectories of growth) to understand the functional significance of root architecture.
Non‐hydraulic root‐to‐shoot signalling in mycorrhizal and non‐mycorrhizal sorghum exposed to partial soil drying or root severing
Authors: EBEL ROBERT C. , STODOLA ANN J. W. , DUAN XIANGRONG , AUGÉ ROBERT M. 
Published: April 2006

summaryOur objectives were (1) to determine if arbuscular mycorrhizal symbiosis could modify leaf response to non‐hydraulic root‐to‐shoot communication of soil drying in Sorghum bicolor (L.) Moench, and (2) to compare the sensitivity of leaf growth and stomatal conductance (Cs) to the non‐hydraulic signal. Seedlings were grown in a greenhouse with root systems split among four pots. Treatments were applied in a 2 (colonized or not colonized by Glomus intraradices Schenck & Smith) × 2 (roots severed or dried) × 4 (roots in 0, 1, 2 or 3 pots dried or severed) experimental design. Plants with roots in three pots dried or severed showed reduced leaf elongation, Cδ and leaf water potential (Ψ) compared with fully watered (control) plants and thus were probably hydraulically affected by root treatment. Drying of severing roots in one pot did not affect leaf elongation, Cδ or Ψ in either mycorrhizal or non‐mycorrhizal plants. In non‐mycorrhizal plants having two pots dried, final leaf area and total leaf length were reduced by 18 and 10%, respectively, relative to controls. Stomatal conductance of these half‐dried non‐mycorrhizal plants remained unchanged, suggesting that the decrease in leaf growth was not hydraulically induced. Non‐mycorrhizal plants having roots severed in two pots continued to have leaf growth similar to that of the controls, suggesting that growth reductions in half‐dried non‐mycorrhizal plants did not result from a reduction in root water gathering capacity. Mycorrhizal symbiosis appeared to eliminate inhibition of leaf growth that was not hydraulically induced, because mean leaf area and total leaf length were not reduced in half‐dried mycorrhizal plants, relative to controls. However, final leaf area of mycorrhizal plants having one or two pots dried was negatively correlated with the product of drying rod mass and the time for which roots were exposed to mild drought, suggesting that mycorrhizal plants were also susceptible to growth inhibition that was not hydraulically induced. Reductions in leaf extension rate that were not hydraulically induced, when viewed as a function of actual soil matric potential, were similar in mycorrhizal and non‐mycorrhizal plants, suggesting that the differences in overall growth inhibition between half‐dried mycorrhizal and non‐mycorrhizal plants may have been related to differences in soil drying rate.
The development of mycorrhizal infection in cucumber: effects of P supply on root growth, formation of entry points and growth of infection units
Authors: BRUCE A. , SMITH S. E. , TESTER M. 
Published: April 2006

summaryThis paper describes an experiment in which the effects of soil phosphorus (P) on root growth and mycorrhizal colonization of Cucumis salivus L. were studied. The aim was to determine the relative contributions of root growth, formation of new infections and growth of infections within the root to the % colonization. Plants were harvested daily between 7 and 24 d. Added P had no effect on root or shoot f. wt or on root length up to 14 d. After that time plants given additional P grew well, but those with no added P grew poorly and showed signs of P deficiency. Increase in root length with added P was due both to an increase in the number of root apices produced per unit length of root per unit time and to an increase in the mean rate of extension of those apices. Effects of P on the % colonization of the roots by the mycorrhizal fungus Glomus intraradices Schenk and Smith were apparent before any effects on root length were observed. The length of the lag phase was not affected by addition of P. The rate of formation of new entry points was similar with and without added P up to 15 d, and reduction in % colonization up to this time could be attributed entirely to reduction in the rate of growth of infection units within the roots. Later, there was a marked increase in the rate of formation of (secondary) entry points in the absence of added P, which was not observed when P was added. At 15, 20 and 25 d, additional plants were harvested to quantify the development of arbuscules and vesicles in colonized regions of the roots. At all three times, numbers of arbuscules and vesicles were lower with added P. We conclude that at very early stages of colonization P exerts its effect via reduced growth of infection units. After approx. 2 wk, an increase in the rate of growth in length of roots and low rates of formation of secondary infections also contribute to the low values of % colonization.
Mycorrhizal fungus propagules in the jarrah forest
Authors: BRUNDRETT MARK C. , ABBOTT L. K. 
Published: April 2006

summarySeasonal variations in the capacity of propagules of vesicular‐arbuscular mycorrhizal (VAM) and ectomycorrhizal (ECM) fungi to form associations in natural habitat soils were investigated by bioassays. These bioassays involved bait plants which? were grown in intact cores of forest soil to assess mycorrhiza formation by hyphal networks and other propagules of YAM or ECM fungi. Soil cores were collected from the same positions along a transect at different times of the year from a diverse sclerophyllous forest community dominated by Eucalyptus marginato (jarrah) and E. calophylla (marri) trees in the mediterranean (winter rainfall) climatic zone of Western Australia. Seasonal fluctuations in mycorrhiza formation by propagules of VAM or ECM fungi, or colonization by particular VAM endophytes (identified by their morphology within roots), were not substantial. Thus hyphal networks and other mycorrhizal fungus propagules in this soil maintained u similar capacity to colonize roots throughout the rear, even during extended periods of summer drought. It appeared That low light levels in the glasshouse could reduce the capacity of bait plants to form mycorrhizas during the winter. Substantial spatial variability in mycorrhizal fungus inoculum levels between the transect locations where cores were collected persisted through time, but variations in the relative cover of host or non–host plants at these locations were not sufficient to explain these patterns.
Spatial distribution and temporal persistence of discrete genotypes of the ectomycorrhizal fungus Laccaria bicolor (Maire) Orton
Authors: DE LA BAST1DE PALL Y. , KROPP BRADLEY R. , PICHÉ YVES 
Published: April 2006

summaryA field study was conducted to determine the spatial distribution and temporal persistence of Laccaria bicolor (Maire) Orton genotypes associated with naturally colonized Norway spruce [Picea abies (L.) Karst.] in a plantation. Groups of sporophores around three trees Were mapped and collected over two to tour consecutive autumn seasons to isolate cultures and determine their genetic relatedness by mating type and randomly amplified polymorphic. DNA (RAPD) analysis. Annual sporophore distribution varied significantly on all sites, with an increase in the mean radial distance from the trees over the study period. Sporophore distribution was discontinuous and characterized by clumped groupings around trees. Sporuphores with the same mating type and disparate distributions were present on each of two sites during the sample period. RAPD analysis for each of the six random primers detected the same DNA polymorphisms for all dikaryotic isolates tested from a given site over the sample period. These results provide evidence that a single genetic individual of L. bicolor can remain associated with a host root system for at least 3 yr and vary significantly in us spatial distribution. This is the first instance in which the persistence of specific genotypes of an early–stage ectomycorrhizal fungus has been demonstrated for a tree colonized by natural sources of inoculum. The implications of these findings are discussed in relation to the ecology and succession of ectomycorrhizal fungi.
Ericoid endophytes of Western Australian heaths (Epacridaceae)
Authors: HUTTON B. J. , DIXON K. W. , SIVASITHAMPARAM K. 
Published: April 2006

summaryThe presence of ericoid endophytes was Confirmed in hair roots of 14 species of Epacridaceae native to the mediterranean south‐west of Western Australia. The phenology of infection was followed in 2‐yr‐old seedlings of Astroloma xerophyllum D.C. (Sond.) and showed increasing infection up to a peak (40% of hair roots infected) in late winter and a decline to zero infection during summer (December February). Over 400 isolates of root‐inhabiting fungi of 14 species from seven genera of native Epacridaceae were obtained. All isolates were dark‐coloured, sterile and slow growing tin potato dextrose agar. Based on morphological characteristics, eight isolates were selected for further investigation. Detailed analysis of morphological and cultural features was used to create three groups, two of which were infective with cuttings of the common Epacridaceae species. Lysinema ciliatum. The groupings based on rnorphological characteristics were reflected in the pectic zymogram patterns of the isolates. Pectic zymogram analysis of ericoid fungi revealed that none of the Australian isolates matched fungi known to be infective with Ericaceae [Hymenoscyphus ericae (Read) Korf. & Kernen and Oidiodendron spp.] even though all isolates appeared morphologically similar with similar growth rates.