bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLASTIDS IN THE ROOTS OF PHASEOLUSVULGARIS
Authors: WHATLEY J. M. 
Published: May 2006

SUMMARYIn roots of Phaseolus vulgaris plastid development takes place from the apical meristem both upwards into the root proper and downwards into the root cap. The maximum state of plastid development seems to be achieved in the cortical cells of that part of the primary root associated with mature root hairs. However in these cortical cell plastids the thylakoid system is very limited in extent and no true prolamellar bodies are formed. Farther from the apex of the root proper, in the zone of mature lateral roots, the plastids appear to have undergone dedifferentiation and to have lost whatever thylakoids they once contained. Both the rate of plastid development and the patterns of production of ancillary plastid structures, including starch and membrane–bound bodies, vary in different cell files. The differential distribution of these and other plastid features are summarized in the accompanying diagrams.
THE RELATION OF DIEL PATTERNS OF CELL DIVISION TO DIEL PATTERNS OF MOTILITY IN THE SYMBIOTIC DINOFLAGELLATE SYMBIODINIUM MICROADRIA TICUM FREUDENTHAL IN CULTURE
Authors: FITT W. K. , TRENCH R. K. 
Published: May 2006

SUMMARYFrequency of binary fission in cultures of three strains of the symbiotic dinoflagellate Symbiodinium microadriaticum, isolated from the anemones Aiptasia tagetes, Heteractis lucida and the jellyfish Cassiopeia xamachana, was related to their diel patterns of motility. Under a 14:10 h light:dark cycle, karyokinesis, cytokinesis and motility occur diurnally. The highest frequency of cytokinesis preceded highest motility by 4 to 7 h. Karyokinesis preceded cytokinesis by 1 to 5 h. Generally, the ratio of number of dividing cells to the number of motile cells recorded in exponentially growing cultures was 1:2, suggesting that two motile cells arise from one newly divided zooxanthella. No motile cells were seen in stationary cultures. Algae grown at high irradiance (180/μE m−2 s−1) had higher growth rates and higher levels of motility than those grown at lower irradiance (15 μE m−2 s−1).Under constant light or dark conditions, patterns of cytokinesis and motility were circadian. In darkness the rhythm tapered out after about 1 week. The patterns were evident for up to 7 days in constant dim light, but tended to dampen out with time.These results suggest that current views of the life cycle of S. microadriaticum need to be modified, and we propose some alternatives which are consistent with our observations.
THE ECOLOGICAL INTERPRETATION OF FINE RESOLUTION POLLEN RECORDS
Authors: GREEN D. G. 
Published: May 2006

SUMMARYPreserved pollen records with small intersample time intervals contain information about many processes in plant population and community ecology. A general approach to the ecological interpretation of these records includes the use of time series statistics, indices that reflect population or community dynamics and models of relevant ecological and sedimentological processes. While the problems inherent in traditional pollen analysis remain, the larger data sets generated by close‐interval sampling make it possible to filter out more sampling ‘noise’ and to obtain a stronger ecological ‘signal’.
A MODIFIED FIELD VERSION OF THE WINKLER DETERMINATION OF DISSOLVED OXYGEN FOR TESTING REMOTE SOURCES OF WATER
Authors: WRIGHT R. C. 
Published: May 2006

SummaryA modification of a simple field method (Drew and Robertson, 1974) for the Winkler determination of dissolved oxygen is described. The modification, involving the addition of sulphuric acid and sodium azide as preserving agents rather than the precipitation of manganese hydroxides in the field, gives more accurate results when samples have to be stored before completion of the determination.
AN ASSOCIATION OF PHYTOCHROME WITH THE CHLOROPLAST ENVELOPE MEMBRANES OF SPINACIA OLERACEA L.: A PRELIMINARY OBSERVATION
Authors: HILTON JANET R. 
Published: May 2006

SUMMARYThe photoreceptor phytochrome has been localized in association with many membrane fractions isolated from etiolated plants. However, the presence of chlorophyll precludes similar measurements in light‐grown plants. Phytochrome has now been measured in chloroplast envelope membrane preparations which, when pure, are completely devoid of chlorophyll.
THE UPTAKE OF METHYLAMMONIUM AND DIMETHYLAMMONIUM BY THE DIATOM, PHAEODACTYLUM TRICORNUTUM
Authors: WRIGHT S.A. , SYRETT P. J. 
Published: May 2006

SUMMARYIn agreement with previous work with several different organisms, methylammonium uptake by Phaeodactylum is shown to take place by a mediated transport process with Michaelis–Menten kinetics with a Ks of about 35 μM There was no evidence for more than one mediated uptake system. Uptake of methylammonium shows a strong dependence on metabolism. In contrast, uptake of dimethylammonium is by passive diffusion. Uptake of methylammonium, but not that of dimethylammonium, was Na* dependent although the rate of uptake of both compounds was depressed by increasing K+ concentration. Rates of uptake of both compounds increased as a consequence of nitrogen deprivation of the cells and were depressed by addition of low (ca. 2 to 10 μM) concentrations of ammonium, uptake of methylammonium being the more sensitive to ammonium inhibition. It is concluded that methylammonium is probably taken up by an ammonium transport system and that its use allows more detailed study of the characteristics of that system.
ABSCISIC ACID IN THE NODULATED ROOT SYSTEM OF ALNUS GLUTINOSA
Authors: WATTS S. H. , WHEELER C. T. , HILLMAN J. R. , BERRIE A. M. M. , CROZIER A. , MATH V. B. 
Published: May 2006

SUMMARYEvidence for the presence of abscisic acid (ABA) in the perennial root nodules of Alnus glutinosa (L.) Gaertn. has been obtained by electron‐capture‐detection gas chromatography (GC–ECD), combined gas‐chromatography mass spectrometry (GC‐MS) and GC‐MS using single‐ion monitoring (GC‐SIM). The free‐ABA content of the nodules was shown by GC‐ECD analysis to fluctuate seasonally over the range 101 to 879 ng g−1 fresh weight. No obvious correlations were found between the amount of ABA detected and rates of nodule growth. However, ABA pools in dormant nodules were up to 25 times higher than in those from actively growing plants.
CHANGES IN CARBOHYDRATES AND NITROGENOUS COMPOUNDS IN THE ROOT NODULES OF ALNUS GLUTINOSA IN RELATION TO DORMANCY
Authors: WHEELER C. T. , WATTS S. H. , HILLMAN J. R. 
Published: May 2006

SUMMARYCarbohydrate reserves for overwintering accumulate in the root nodules from late summer and begin to be utilized when leaf fall is virtually complete. It is probable that metabolism of these carbohydrate reserves supports in part the low nitrogenase activity which develops as buds swell and flush in early March, before substantial new photosynthates are translocated to the nodules. Higher rates of photosynthesis as leaves expand, and a reduction in the proportion of photosynthates retained by or translocated to buds as they flush, makes available more photosynthates for translocation to the nodules to support higher nitrogenase activity.Soluble nitrogenous reserves also accumulate as leaves expand. Ammonia accumulates in the spring during early leaf expansion and could be of importance in repressing nitrogenase synthesis in the endophyte, reducing the demands of the nodule for limited supplies of photosynthates until leaf expansion is more advanced.Sections of nodules show that the vesicular form of the endophyte largely degenerates during the winter months and new nitrogenase activity probably develops in new vesicles. Nodule meristematic activity recommences about bud burst. Earlier findings have shown high cytokinin activity in the nodules at this time.
INTERACTIONS OF VESICULAR‐ARBUSCULAR MYCORRHIZAL INFECTIONS AND HEAVY METALS IN PLANTS
Authors: GILDON A. , TINKER P. B. 
Published: May 2006

SUMMARYLeeks were grown on a γ‐irradiated soil selected for its low copper status, in a factorial experiment with additions of phosphorus and copper, and with or without inoculation with Glomus mosseae. There was no response in growth to added phosphorus, but responses to added copper and to inoculation. The results indicate that an infection with mycorrhizal fungi can increase the supply of copper to the host plant, in conditions where increased phosphorus nutrition does not increase dry weight. It is suggested that copper is absorbed and translocated by mycorrhizal hyphae in a manner analogous to that which occurs for phosphorus.
SENSITIVITY OF FOREST PLANT REPRODUCTION TO LONG RANGE TRANSPORTED AIR POLLUTANTS:
Authors: COX R. M. 
Published: May 2006

SUMMARYAlthough some studies have been made of the direct effects of wet deposition of acid on plants, few have examined its effects on plant reproductive processes. Reported here are the relative sensitivities of pollen germination and pollen tube growth from 13 forest species to a range of acidities found in ambient rainfall. In vitro assays indicate that pollen of all species tested was significantly influenced by pH's from 56 to 26. Two‐thirds of the species tested had pollen that was significantly inhibited in germination by pH 30 (1000 μEq H+I−1) whereas few effects were observed at pH 4–6 (25 μEq H+I−1). Broad‐leaved tree pollens were more sensitive to pH than those of conifers, and those of the understorey and ground flora species tested were of intermediate sensitivity. It is of concern that all values of LD50 for pollen germination response to initial culture pH were within the range of acid rain events in eastern Canada. Further research is required into the in vivo responses, to determine if reproduction in plants with sensitive pollen is inhibited by ambient levels of acid deposition.
GROWTH ANALYSIS OF SOYBEAN EXPOSED TO SIMULATED ACID RAIN AND GASEOUS AIR POLLUTANTS
Authors: NORBY R. J. , LUXMOORE R. J. 
Published: May 2006

SUMMARYGreenhouse‐grown soybean plants [Glycine max (L.) Merr. cv. Davis] were exposed to simulated acid rain (pH 2.6 to 5.6) and gaseous air pollutants (SO2+ O3) to determine how effects on short‐term physiological processes are integrated into whole‐plant response. Injury to expanding leaves, characterized by marginal necrosis and leaf deformation, was induced by twice‐weekly exposure to simulated rain of pH 2.6 and to a lesser extent pH 3.4. Growth inhibition resulted only from exposure to rain of pH 2.6, and there were no significant pH x air pollution interactions. Growth analysis from periodic harvests indicated that inhibitory effects of rain of pH 2.6 were mediated through a reduction in leaf area ratio (LAR). The alteration in LAR was not attributable to reduced allocation of dry matter to leaves but to lower specific leaf area caused by leaf deformation. There were no effects of rain pH on unit leaf rate. A second experiment confirmed the lack of growth inhibition from simulated rain with pH > 3.4. Cumulative water use, a measure that integrated aspects of root size, leaf area, and physiology, was remarkably similar in plants exposed to pH 3.4, 4.2, or 5.6 simulated rain. These experiments suggest that vegetative growth of soybeans may be adversely affected by acid rain if pH is low enough to cause physical injury to leaves and loss of photosynthetic area.
GROWTH ANALYSIS OF THE SEEDLINGS OF BALSA, OCHROMA LAGOPUS
Authors: WHITMORE T. C. , WOOL‐KHOON GONG 
Published: May 2006

SUMMARYIn a glasshouse near Oxford, under conditions similar to a large gap in lowland tropical rain forest, young seedlings of balsa, Ochroma lagopus Swartz, had an estimated unit leaf rate (net assimilation rate) of 33 g m−2 week−1 compared to 44 g m−1 week−1 for Helianthus annuus. The energy conversion efficiency was 05 and 0–6 % of incident radiation 300 to 3000 ran respectively.Unit leaf rates of woody plants have almost always been found to be lower than those of Helianthus, when both are grown side by side. The lowest rates relative to Helianthus are in Agathis, the only shade‐tolerant genus yet examined.
CARBON FIXATION IN ORCHID AERIAL ROOTS
Authors: GOH C. J. , ARDITTI J. , AVADHANI P. N. 
Published: May 2006

SUMMARYOrchid aerial roots contained chlorophylls and were shown to be capable of photosynthesis. 14CO2 feeding in the light showed that the C3 pathway was operating during the day. Aerial roots also exhibited diurnal acidity fluctuations typical of crassulacean acid metabolism (CAM) and malate was the only labelled compound isolated after night 14CO2 feeding. CO2 exchange patterns in aerial roots were consistent with CAM CO., fixation during the night hours. The rate of photosynthetic CO., fixation in the light was much greater than the rate of CAM CO2 fixation in the night. Measurements of CO2 exchange, however, showed little or no net uptake indicating that these roots were not completely autotrophic.
OIDIODENDRON GRISEUM ROBAK: AN ENDOPHYTE OF ERICOID MYCORRHIZA IN VACCINIUM SPP.
Authors: COUTURE M. , FORTIN J. A. , DALPE YOLANDE 
Published: May 2006

SUMMARYOsmium tetroxide was used to sterilize the surface of roots of Vaccinium angustifolium and V. corymbosum in order to isolate mycorrhizal fungi. Three isolates of sterile mycelium, all of similar cultural appearance, were obtained from V. angustifolium and were proved capable of forming ericoid mycorrhizas under aseptic conditions. Three isolates were also obtained from V. corymbosum and all formed conidiophores identified as Oidiodendron griseum Robak; they also formed ericoid mycorrhizas under aseptic conditions.
HYPHAL UPTAKE AND TRANSPORT OF NITROGEN FROM TWO 15N‐LABELLED SOURCES BY GLOMUS MOSSEAE, A VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS *
Authors: AMES R. N. , REID C. P. P. , PORTER L. K. , CAMBARDELLA C. 
Published: May 2006

SUMMARYCelery (Apium graveolens L.) plants were grown in pots in which the root system was separated from the soil in a side chamber by a fine mesh screen. The side chamber was treated with either an organic (ground plant tissue) or inorganic [(NH4)2SO4] source of 15N. Mycorrhizal (Glomus mosseae) and control (non‐mycorrhizal) plants were exposed to 15N over a period of 30 days (inorganic‐15N) or 88 days (organic‐16N). Mycorrhizal and control plants did not differ in shoot dry weight or shoot P content. Dry weight of root was reduced in the mycorrhiza treatments. Mycorrhizal plants derived significantly (P= 0.01) more 16N, from both N sources, than did control plants. In the inorganic‐N treatment, 15N in mycorrhizal plants was significantly (P= 0.001) and positively correlated with percent mycorrhizal fungal colonization (r= 0.58), number of hyphal crossings (±10 μ diameter) through the mesh into the area of 15N placement (r= 0.76), total length of hyphae per gram of soil (r= 0.74), and length of hyphae of 5 μ diameter in the soil (r= 0.77). No correlations were found between the 16N content of mycorrhizal plants and any parameter in the organic‐N treatment. The 16N content of control plants was not correlated with hyphal length in the outer chamber and there were no hyphal crossings of the size ( 10 μ diameter) which was counted for the mycorrhiza treatments. The presence of the organic matter (ground plant tissue) increased the total length of saprophytic hyphae per gram of soil but decreased the number of vesicular‐arbuscular mycorrhizal fungal hyphae crossing into the area of 16N placement. The mean flux of N through the hyphae of G. mosseae was 7.42 × 10−8 mol N cm−2 s−1 for the inorganic‐N treatment over a 30‐day period, and 1.74 × 10−8 mol N cm−2 s−1 for the organic‐N treatment over an 88‐day period.
PHOSPHORUS ACQUISITION IN FOUR CO‐EXISTING SPECIES FROM MONTANE GRASSLAND
Authors: ATKINSON C. J. 
Published: May 2006

SUMMARYPhosphorus acquisition was examined in four co‐existing species from montane grassland. The effect of inorganic phosphate (Pi) concentration on relative growth rate was studied and an attempt was made to determine whether inorganic or organic phosphates are the immediate sources of phosphorus for these plants using assays of Pi uptake kinetics and of root surface phosphatases. These data are also used to assess whether the availability of phosphorus might limit plant growth in this montane grassland.Potential uptake rates are unlikely to limit growth via Pi supply. There appears to be no preference for a specific phosphate source for growth with any species examined. Mycorrhizal infection does not appear to be a prerequisite for successful phosphate acquisition in these co‐existing species.
DEVENSIAN LATE‐GLACIAL AND FLANDRIAN VEGETATIONAL HISTORY AT HOCKHAM MERE, NORFOLK, ENGLAND
Authors: BENNETT K. D. 
Published: May 2006

SUMMARYThe sediment and pollen stratigraphy of a radiocarbon‐dated sequence from a lake on the eastern margin of Breckland is described. The record extends from 12620 to 1620 B.P. From 12620 to 9560 B.P. the vegetation was an open Betula woodland. Movement of sand by wind was one factor keeping the vegetation open. Between 9560 and 9255 B.P. a denser Betula woodland developed, to be replaced by a closed woodland dominated by Corylus avellana, with Pinus sylvestris, Ulmus and Quercus. During this period, Quercus gradually replaced P. sylvestris on the local sandy soils. Corylus avellana remained the woodland dominant until about 7140 B.P., when it was replaced by Tilia cordata. Alnus glutinosa expanded in response to raised water levels at about 6800 B.P., Fraxinus excelsior became an important component of the local woods, also replacing C. avellana. The elm decline occurred in two phases, at 6000 and 4500 B.P. Substantial forest clearance did not begin until about 2500 B.P. The spread of heath vegetation on the Breckland began at about 2250 B.P.
SUBSTRATE FLOW AND UTILIZATION IN THE RHIZOSPHERE OF CEREALS
Authors: WHIPPS J. M. , LYNCH J. M. 
Published: May 2006

SUMMARYWheat and barley plants were grown for 3 weeks with their roots in sterile or non‐sterile sand or irrandiated or non‐irradiated soil and with their shoots in an atmosphere containing 14CO2 at constant specific activity and at approximately atmospheric concentration. The sealed pots were regularly flushed with air and the total quantity of radioactivity lost from the pots as respiratory 14CO2 and the amounts present in the plant rhizoplane, rhizosphere and bulk soil were analysed. Measurements of bacterial numbers allowed calculations of the utilization of the carbon released from the roots of the sand‐grown plants. The relevance of the techniques used and the implications of carbon loss for the plant and associated microorganisms are discussed.
EFFECTS OF LOCALIZED AND OVERALL WATER STRESS ON ASSIMILATE PARTITIONING IN BARLEY BETWEEN SHOOTS, ROOTS AND ROOT EXUDATES
Authors: SHONE M. G. T. , WHIPPS J. M. , FLOOD ANN V. 
Published: May 2006

SUMMARYPolyethylene glycol 4000 (PEG) at an osmotic potential of −0.3 MPa had no effect on uptake of 14CO2 and partitioning between shoots and roots in barley. When an osmotic potential of −0.8 MPa was applied to the upper zone of the root system, total 14CO2 uptake and partitioning were unaffected but assimilate accumulated in the tips of nodal roots exposed to PEG. There was a parallel accumulation of soluble sugars. Transport of assimilates to the seminal root system declined. Exudation of soluble, labelled compounds by the roots was markedly diminished. When PEG was supplied to the upper root zone at −0.8 MPa and the lower zone at −0.6 MPa total 14CO2 uptake and assimilate transport declined, but there was still some accumulation of labelled compounds and soluble sugars in the nodal root tips and root exudation was diminished. The results are discussed in relation to assimilate partitioning, growth and osmotic adjustment in nodal roots.
APPLICATION OF SUPERPHOSPHATE TO MYCORRHIZAL PLANTS SITIMULATES SPORULATION OF PHOSPHORUS‐TOLERANT VERSICULAR‐ARBUSCULAR MY CORRHIZAL FUNGI *
Authors: SYLVIA D. M. , SCHENCK N. C. 
Published: May 2006

SUMMARYSporulation of Gigaspora margarita, Glomus clarum, Gl, mosseae and Gi. Heterogama was increased significantly after established pot cultures of bahiagras were drenched with superphosphate. However, sporulation of Gl. Etunicatum, Gl. Macrocarpum and Gi. Gigantean was reduced by the superphosphate drench. Generally, improved sporulation after application of superphosphate was associated with phosphorus (P)‐tolerance of the mycorrhizl fungi. Gigaspora margarita, Gl. Clarum and Gl. Mosseae could colonize roots in soil that had 199 mg kg −1of acid‐extractable P. The other fungi could not colonize roots in this high‐P soil. Removal of shoots, application of herbicide, and stresses from drought and exposure to cold and dark did not affect spore numbers significantly.
ENDOMYCORRHIZAS IN THE GENTIANACEAE
Authors: JACQUELINET‐JEANMOUGIN S. , GIANINAZZI‐PEARSON V. 
Published: May 2006

SUMMARYThe identity of mycorrhizal fungi in the Gentianaceae was investigated by inoculating Gentiana lutea L. with fungi from orchid, ericoid and vesicular‐arbuscular endomycorrhizas. Results clearly demonstrated that mycorrhizas in G. lutea are formed by vesicular‐arbuscular mycorrhizal fungi but have a very unusual morphology.
THE MYCORRHIZAL ASSOCIATIONS OF SOME AUSTRALIAN ASTERACEAE
Authors: WARCUP J. H. , McGEE P. A. 
Published: May 2006

SUMMARYSome 80 species of Australian Asteraceae were examined for their ability to form ectomycorrhizal associations. Twenty‐seven species, all but one belonging to the tribe Inuleae, were found to form both ectomycorrhizas and vesicular‐arbuscular mycorrhizas. Species found to form ectomycorrhizas belong to Angianthus (sensu stricto), Podolepis, Pogonotepis, Waitzea, Helichrysum (pro parte) and Helipterum (pro parte); all are annual or perennial herbs. Four species shown to form ectomycorrhizas gave significant growth responses to inoculation with either an ecto‐or endomycorrhizal fungus in soil low in available phosphate.
RELATIONSHIPS BETWEEN SEED WEIGHT, ASH CONTENT AND SEEDLING GROWTH IN TWENTY‐FOUR SPECIES OF COMPOSITAE
Authors: FENNER M. 
Published: May 2006

SUMMARYThe relationship between seed weight, embryo weight, ash content and maximum size attained by seedlings dependent on their own food reserves was investigated in 24 species of Compositae.The fraction of total seed weight contributed by the seed coat increased with seed weight from 15 % in Erigeron canadensis to 61 % in Tragopogon pratensis. Seedling weight was proportional to embryo weight raised to the power of 2/3. That is, the larger the embryo the less carbon it assimilated per unit weight of embryo. The relative growth rate of the seedlings during the first 3 weeks was inversely proportional to In embryo weight. The root weight ratios of the seedlings were inversely proportional to In embryo weight. The ash content of the seeds was negatively correlated with their weight but absolute mineral content per seed was directly proportional to maximum seedling size attained, regardless of seed size.It is postulated that the relatively larger seed coats of big seeds are a defence against increased risk of predation. The ash contents and root weight ratios of the seedlings suggest that the growth of small seedlings is limited by soil nutrients and that of large seedlings by light.
EFFECT OF ETHYLENE ON GIBBERELLIC ACID‐I NDUCED PROTEASE ACTIVITY IN WHEAT ALEURONE LAYERS *
Authors: VARTY K. , ARREGUIN L. B. , MÜGGENBURG R MA. I. , MIJANGOS M. J. L. , TREJO B. A. 
Published: May 2006

SUMMARYEthylene‐stimulated gibberellic acid‐induced protease synthesis in isolated wheat aleurone layers (Triticum aestivum L.) by about 60%. Ethylene did not change the isoelectric focusing pattern of protease isoenzymes, indicating that the hormone promoted only quantitative changes in protease synthesis rather than activating genes for different proteolytic enzymes. The pH optimum and Km of the enzyme with respect to N,N'‐dimethylhaemoglobin were 3.5 and 0.102% respectively. The purified protease consisted of a single polypeptide with a molecular weight of 43 700 daltons. These physical characteristics of gibberellic acid‐induced protease were unaffected by ethylene.