bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA III. INCREASED UPTAKE OF LABILE P FROM SOIL
Authors: HAYMAN D. S. , MOSSE B. 
Published: May 2006

SummaryOnion plants were grown in a range of soils labeled with 32P. It was found that although the mycorrhizal plants had taken up more phosphorus and grown larger, the proportion of 32P to total P (specific activity) taken up by mycorrhizal and non‐mycorrhizal plants after 10 weeks was not significantly different. It is concluded that the mycorrhizal roots used the same source of labile phosphate but explored a greater volume of soil beyond the zone of phosphate depletion near the root surface. There was no indication that mycorrhizal roots had access to sources of phosphate different from those accessible to non‐mycorrhizal roots.The specific activity of NaHCO3‐extractable phosphorus differed considerably between the eight soils but the specific activity of absorbed phosphorus in the plants always corresponded closely to that of the soil in which they had grown.
RESPONSE OF ETIOPLASTS IN SITU AND IN ISOLATED SUSPENSIONS TO PRE‐ILLUMINATION WITH VARIOUS COMBINATIONS OF RED, FAR‐RED AND BLUE LIGHT
Authors: WELLBURN FLORENCE A. M. , WELLBURN A. R. 
Published: May 2006

SummaryA quantitative comparison has been made of the ultrastructural development taking place in the light and in darkness between plastids in intact etiolated tissue and in suspensions of etioplasts, which have been given various pre‐treatments of red, far‐red and blue light. Plastid development in situ and in suspensions is enhanced by pre‐illumination with red light and this enhancement can be reversed by following red light with far‐red light. The reverse is also true; pre‐illumination with far‐red light inhibits development and this inhibition is abolished and replaced by enhancement by following far‐red light with red light. Blue light of short duration has no effect on the early stages of ultrastructural development in plastids.It is concluded that a phytochrome‐mediated mechanism is present either inside the plastid or on the plastid envelopes.
UPTAKE OF PICLORAM BY EUCALYPT LEAF DISCS
Authors: SANDS R. , BACHELARD E. P. 
Published: May 2006

SummaryUptake of picloram by upper and lower surfaces of Eucalyptus viminalis juvenile leaves in light and dark, and measurements of stomatal resistances, were consistent with a major role of stomata in uptake.Uptake of picloram and stomatal resistances of E. viminalis and E. polyanthemos leaf discs measured under varying experimental conditions also suggested a major role for stomata in uptake. This is discussed in terms of leaf surface characteristics and wettability.Some premises on which arguments denying stomatal penetration of herbicides are based are examined, and concluded to be false.
THE ULTRASTRUCTURE OF LICHENS V. HYDROTHYRIA VENOSA, A FRESHWATER LICHEN
Authors: JACOBS J. B. , AHMADJIAN V. 
Published: May 2006

SummaryThe fine structure of the aquatic lichen Hydrothyria venosa was investigated from collections made in the summer and fall. The phycobiont lacked plastoglobuli in the summer but did contain them in the fall. Polyglucoside granules, structures not found previously in lichenized blue‐green algae, were present in the phycobiont. The mycobiont lacked ellipsoidal bodies, structures that have been found in almost all previously studied lichen fungi.
OBSERVATIONS ON THE SWOLLEN LATERAL ROOTS OF THE CYPERACEAE
Authors: DA VIES JAMES , BRIARTY LEWIS G. , RIELEY JOHN O. 
Published: May 2006

SummaryA swollen and markedly hairy type of lateral root in the Cyperaceae is described which closely resembles the proteoid roots of certain Proteaceae. In both cases the existence of some biological causal agent outside the root tissue is indicated and the young swollen laterals of Carex flacca, examined with light and electron microscopy, exhibited no endophytes. These roots form extensive mats in the surface soil and the idea is advanced that they may play some particular role in the absorption of nutrients.
LONG‐RANGE TRANSMISSION OF TREE POLLEN TO SHETLAND
Authors: TYLDESLEY J. B. 
Published: May 2006

SummaryTree pollen was found in the air at Lerwick, Shetland in May and June 1970 and April and May 1971. The predominant species were birch and pine, and peak concentrations (daily mean) of 20 and 30 grains m‐3 respectively, were recorded. Trajectories on surface meteorological charts give good agreement of the catch with likely source areas in Scandinavia and Britain. Possible applications and extensions of the work are mentioned briefly.
THE UPTAKE OF METAL IONS BY LICHENS: A MODIFIED ION‐EXCHANGE PROCESS
Authors: PUCKETT K. J. , NIEBOER E. , GORZYNSKI M. J. , RICHARDSON D. H. S. 
Published: May 2006

SUMMARYHeavy metal ions were absorbed by lichens to different degrees in laboratory experiments. The relative capacities for uptake from solutions containing a single metal ion were Fe, Cu>Ni>Pb>Co>Zn. Competitive uptake studies revealed the selectivity sequence Fe>Pb>Cu>Ni, Zn>Co. The sequences are in accord with a cation uptake mechanism involving ion exchange modified by metal‐complex formation. Correlations between laboratory studies and the metal content of lichens growing in the vicinity of a smelter are discussed.
THE DEVELOPMENT AND FINE STRUCTURE OF THE ASCUS APEX AND ITS ROLE DURING SPORE DISCHARGE IN XYLARIA LONGIPES
Authors: BECKETT A. , CRAWFORD R. M. 
Published: May 2006

SUMMARYThe development and structure of the ascus apex of Xylaria longipes were studied by light and electron microscopy. An apical body (Spitzenkörper) and vesicle system were associated with a localized thickening of the ascus wall to form an apical ring. On completion of the apical ring, the vesicles dispersed but the apical body remained, together with a dense ‘plug’ within the ring. Breakdown of the apical body and ‘plug’ was followed by the formation of fibrous material which linked the ascospores to the inside of the apical ring. Ascus dehiscence was accompanied by the complete eversion of the apical ring.
STRUCTURAL AND PHYSIOLOGICAL STUDIES ON THE PARASITIC RED ALGA HOLMSELLA
Authors: EVANS L. V. , CALLOW J. A. , CALLOW MAUREEN E. 
Published: May 2006

SUMMARYA study has been made of the structural and physiological relationship between the autotrophic red alga, Gracilaria verrucosa, and the parasitic, chloroplast‐free, red alga, Holmsella pachyderma. By means of 14C‐labelling experiments, the major product of photosynthesis in the Gracilaria was found to be the alcohol glycoside, floridoside. Chromatography and autoradiography showed that 14C was transferred to Holmsella and accumulated there as floridoside, mannitol and starch. This transfer probably occurred through endophytic filaments which arise from the base of the parasite and penetrate between the cells of the Gracilaria.
NITROGEN FIXATION BY LICHENS IN SCOTLAND
Authors: HITCH C. J. B. , STEWART W. D. P. 
Published: May 2006

SUMMARYOf thirty‐six species of metabolically active lichens taken mainly from Scottish coastal habitats, eight showed a capacity to reduce acetylene to ethylene. These were species of Collema Web., Lichina C. Ag., Peltigera Willd. and Placopsis Nyl. and all contained a blue‐green alga as the primary or secondary phycobiont. Acetylene reduction rates were sometimes high in the field and showed marked diurnal and seasonal variations. Nitrogenase activity was higher in vegetative than in fruiting thalli of Peltigera rufescens, and in P. canina was higher nearer the apices of the thalli than in older parts. Of the environmental factors affecting fixation, desiccation was the most important, temperature was less important and the lichens, while requiring light, could continue to fix nitrogen in the dark for up to 18 hours (Lichina confinis) and 26 hours (Peltigera rufescens). The average percentage nitrogen contents of nitrogen‐fixing lichens (2·20%) was significantly higher than the non‐nitrogen‐fixing lichens (0·83%). The maximum and mean rates of nitrogen fixation by P. rufescens were 38·1 and 4·1 μg N (mg N)‐1 day‐1 respectively. The corresponding values for Lichina confinis were 29·4 and 0·4.
LICHEN PHYSIOLOGY XIII. EFFECTS OF REWETTING DRY LICHENS
Authors: SMITH D. C. , Molesworth SUSAN 
Published: May 2006

SUMMARYTwo distinct phenomena occur when water is added to air‐dry lichens: (1) an immediate non‐metabolic release of a substantial volume of gas containing 75–80% CO2; and (2) a rapid rise in respiration to rates well above control values. This excess respiration (‘resaturation respiration’) persisted for about 9 hours in Peltigera polydactyla and about 2 in Xanthoria aureola and was, unlike basal respiration, azide‐ and cyanide‐sensitive. When the mannitol content of Peltigera discs had been doubled by feeding glucose before drying, the initial rate of subsequent resaturation respiration was correspondingly much higher. Cycles of wetting and drying caused progressive reductions both in mannitol content and resaturation respiration. In Peltigera, resaturation respiration occurred if the water content of discs had fallen below approximately 40% of maximum. Xanthoria aureola, which grows in drier habitats than Peltigera polydactyla, was much more tolerant of cycles of wetting and drying and showed much less intense resaturation respiration.
POST‐FERTILIZATION DEVELOPMENT IN INDOTRISTICHA RAMOSISSIMA (WIGHT) VAN ROYEN
Authors: MUKKADA ANTONY J. , CHOPRA R. N. 
Published: May 2006

SUMMARYIn Indotristicha ramosissima (Wight) van Royen there is normal syngamy. However, the polar nucleus is not fertilized so that a primary endosperm nucleus is not formed. Consequently, there is no endosperm in the seed. The post‐fertilization dissolution of the nucellar cells below the embryo sac results in the formation of a pseudo‐embryo sac into which the growing pro‐embryo penetrates. The first division of the zygote is transverse and the development of the embryo conforms to the Solanad type. The embryo possesses a large, coenocytic haustorial cell which disorganizes by the time the embryo is fully differentiated. The integuments and the ovary wall are rich in starch deposits which disappear during maturation. In the mature seed, the outermost layer of the outer integument becomes mucilaginous. The cells of the inner epidermis of the ovary wall become binucleate and occasionally multinucleate.
CALCULATION OF THE PRIMARY TRAJECTORIES OF PLUMED SEEDS IN STEADY WINDS WITH VARIABLE CONVECTION
Authors: BURROWS F. M. 
Published: May 2006

SUMMARYThe aerial paths described by plumed seeds shed from motionless plants and moving in steady horizontal winds with vertical convection currents are discussed and formulae established for calculating them both roughly and fairly accurately. Most of the formulae are simple and of practical use to botanists. Example calculations show the effect of release height, convection velocity, and the terminal velocity of fall of the seed in still air, and the various trajectory shapes concocted can be used to account for seed behaviour as observed and reported in the literature. It is also shown how, under certain conditions, some approximate calculations can be very much in error.
POLLEN ANALYSIS AND RADIOCARBON DATING OF A PEAT ON SLIEVE GALLION, CO. TYRONE, N. IRELAND
Authors: PILCHER J. R. 
Published: May 2006

SUMMARYA radiocarbon dated pollen diagram is presented from 430 m altitude on Slieve Gallion, Co. Tyrone, N. Ireland. Deposits of reedswamp peat overlain by blanket peat cover the period c. 8000 B.C.* to the present. Total tree‐pollen remains mostly below 60% of total pollen throughout the Post‐glacial indicating more open conditions than are found in the lowlands. Lack of herb pollen suggests areas of bare rock on the mountain top before c. 7650 B.C. The early Post‐glacial juniper period is estimated to have lasted 300–400 years. Hazel expands rapidly at c. 7050 B.C. and oak and elm appear at c. 6800 B.C. Elm expands some 800 years before the oak. The arrival of alder is dated to c. 5000 B.C. and its expansion to about 4250 B.C. An elm decline is shown dating from just after 3000 B.C. and a decline of pine pollen at c. 2000 B.C. in common with other sites in this area.
SYSTEMATIC DISTRIBUTION OF RIBITOL IN THE FUNGI
Authors: PFYFFER GABY E. , RAST DORA M. 
Published: May 2006

SUMMARYThe polyol fractions of the fruit bodies of 12 basidiomycetes and the vegetative mycelia of more than 30 species representing all major classes of fungi were isolated, tested by gas chromatography for the presence of ribitol and found to be free of this compound – with the exception of Mortierella rammaniana, Actinomucor elegans, Mucor miehei and Zygorhynckus moelleri. Using preparative paper chromatography, ribitol was isolated from M. miehei in a yield of about 0·3 % of the mycelial dry wt and its identity confirmed by IR spectroscopy and determination of melting point. The present survey, together with the reported occurrence of ribitol in only two other species, Puccinia graminis f.sp. tritici and Candida polymorpha, shows this polyol to be a rare fungal component that appears to be distributed randomly within the Eumycetes. Clustering of ribitol within the Mucorales can, however, not be overlooked.
THE HOST‐PARASITE RELATIONSHIP BETWEEN ZIZANIA CADUCIFLORA TURCZ. AND USTILAGO ESCULENTA P. HENN. II. USTILAGO ESCULENTA IN CULTURE
Authors: CHAN YUK‐SIM , THROWER L. B. 
Published: May 2006

SUMMARYWith the exception of dikaryotization, the complete life‐cycle of Ustilago esculenta occurred on potato dextrose agar in culture. In liquid synthetic media, the maximum dry wt of sporidia was reached in 7 days at 27°C compared with 20 days for mycelium. The sporidia were hetero‐trophic for thiamine but not for biotin; the mycelium required neither vitamin. Mannitol supported the best growth of sporidia but only poor growth of mycelium; both stages grew well on fructose, glucose and sucrose. At suitable dilutions, an aqueous extract from culms of the host plant supported growth of sporidia and mycelium that was similar, or superior, to that on synthetic media. The implications of these results for the host‐parasite combination are discussed.
THE HOST‐PARASITE RELATIONSHIP BETWEEN ZIZANIA CADUCIFLORA TURCZ. AND USTILAGO ESCULENT A P. HENN. III. CARBOHYDRATE METABOLISM OF U. ESCULENTA AND THE HOST‐PARASITE COMBINATION
Authors: CHAN YUK‐SIM , THROWER L. B. 
Published: May 2006

SUMMARYSporogenous hyphae and teliospores of Ustilago esculenta, collected from swollen culms of Zizania caduciflora, contained mannitol as the principal carbohydrate, together with erythritol and trehalose in trace amounts. In vitro experiments with labelled sugars showed that both sporidia and mycelium of U. esculenta incorporated fructose and glucose to a similar degree, yielding mannitol as the principal endogenous carbohydrate, erythritol and five amino acids including alanine and arginine. Sucrose was the main translocated sugar in the leaf but the principal sugars in the culms were fructose and glucose. Fructans of high mol. wt were not abundant in the culms but low mol. wt fructans (including fructose) may be important in the metabolism of the culms; the content of such fructans was highest in the non‐sporulating culms. A scheme is proposed for the metabolism of carbohydrates in the formation of gau sun.
THE DEVELOPMENTAL HISTORY OF SCRAGH BOG, CO. WESTMEATH AND THE VEGETATIONAL HISTORY OF ITS HINTERLAND
Authors: O'CONNELL M. 
Published: May 2006

SUMMARYStratigraphical, macrofossil and pollen analytical studies on the sediments of Scragh Bog, a small fen in central Ireland, are described.The Flandrian pollen diagram is divided into local pollen assemblage zones which in turn are related to the zones of Mitchell (1956). The Ulmus‐Quercus‐Alnus assemblage zone of the Atlantic period is proposed as a regional assemblage for base‐rich areas in Ireland as distinct from the Alnus‐Quercus‐Pinus regional assemblage of Jessen (1949). The changes associated with the Elm decline are considered in detail.The subfossil records, which are not abundant, include Acrocladium giganteum and Sphagnum contortum from the Late‐glacial and Antitrichia curtipendula and Isothecium myosuroides, both probably from zone VIIIa.The depositional processes in the basin and the vegetational history of the hinterland are reconstructed. The nature of Landnam and the possibility of in situ survival of the present‐day fen communities are discussed.
EFFECTS OF PHENYLACETIC ACID ON ABAXIAL AND ADAXIAL STOMATAL MOVEMENTS AND ITS INTERACTION WITH ABSCISIC ACID
Authors: PEMADASA M. A. 
Published: May 2006

SUMMARYThe effects of varying concentrations of phenylacetic acid (PAA), alone and in combination with abscisic acid (ABA), on abaxial and adaxial stomatal movements were examined on isolated epidermis of Commelina communis. Increasing PAA concentration progressively suppressed abaxial opening, while up to 5 mol m−3 PAA produced remarkably wide adaxial apertures but higher concentrations caused closure; the stomatal K.+ changed accordingly. PAA, like the K+ ionophore benzo‐18‐crown‐6, showed strong antagonistic interactions with ABA. The results are interpreted by postulating that PAA, like benzo‐18‐crown‐6, increases the membrane permeability to K+. The normal abaxial permeability allows a net K+ gain required for opening, but the PAA‐induced increase in permeability causes a net K+ loss leading to closure, because the efflux down a concentration gradient outweighs the influx coupled with proton extrusion. In contrast, the normal K+ content is much less in adaxial than in abaxial guard cells, clear evidence of an inherent restriction to K+ fluxes; this is attributed to restricted membrane permeability to K+, which PAA is postulated to alleviate progressively with increasing concentration. Thus, an increase in permeability up to a critical limit favours a net K+ gain and promotes opening, but any further increase leads to a net K+ loss and causes closure, as in abaxial guard cells. This interpretation is substantiated by both the progressive reduction of PAA‐induced closure with increasing KC1 in the medium and the close similarity of the effects of PAA and benzo‐18‐crown‐6, alone and in antagonism with ABA, on abaxial and adaxial stomata.
ABSCISIC ACID EFFECTS ON SPORE GERMINATION AND PROTONEMAL GROWTH IN THE FERN,MOHRIA CAFFRORUM
Authors: CHIA SHIH‐GEE E. , RAGHAVAN V. 
Published: May 2006

SUMMARYThe effects of abscisic acid (ABA) and its interaction with gibberellic acid (GA), indoleacetic acid (IAA) and kinetin on the germination of spores and growth of protonemata of the fern,Mohria caffrorumSw. were studied. ABA did not affect the initial divisions of the spore protoplast leading to the formation of rhizoid and protonema, but inhibited the subsequent elongation of the latter. The apparent reversal of ABA‐induced inhibition of protonemal elongation by GA appears to be due to an overall growth promotion by GA, rather than due to its interaction with ABA. On the other hand, both IAA and kinetin, which by themselves did not promote protonemal growth, reversed to some extent the inhibitory effect of ABA on the growth of the protonema.
THE INOCULATION OF WHITE CLOVER WITH MYCORRHIZAL FUNGI IN UNSTERILE HILL SOILS
Authors: RANGELEY A. , DAFT M. J. , NEWBOULD P. 
Published: May 2006

SUMMARYThe response of two cultivars of white clover (Aberystwyth S184 and New Zealand Grasslands Huia), grown under laboratory and field conditions, to inoculation with two endophytes (Glomus mosseae L1 and Glomus etunicatus) was investigated in two hill soils with various amounts of added phosphate.In the experiment with the deep peat soil in the laboratory, inoculation with either endophyte increased infection from 2% to up to 70%, the increase being less the higher the amount of added P. Shoot growth of white clover was significantly increased (P≤ 0.05) by inoculation at the 0 and 20 kg P ha−1 level and decreased at the highest level of added P (200 kg P ha−1). Both endophytes produced similar effects. With the brown earth soil, total infection of roots with indigenous endophytes ranged from 30 to 50 % and this was significantly (P≤ 0.05) increased by inoculation only at 40 kg P ha−1. However, the introduced coarse endophytes had replaced between a quarter and a half of the predominantly fine indigenous endophyte at each level of added P. This change of endophyte was without significant effect on dry wt of shoots and roots although there was a general trend for inoculation, and with Glomus etunicatus more than with Glomus mosseae LI, to increase shoot and root dry wt. Inoculation also tended to increase the P content of shoots and roots but this was statistically significant only at 40 kg P ha−1.In the field experiment with the deep peat soil, inoculation with Giomus mosseae L1 doubled the amount of infected root from 18 to 42% but there was no effect on shoot growth or the concentration of P. With the brown earth soil, although the amount of infection was not increased, the introduced coarse endophytes had become established in the roots but no effect on shoot growth was observed in the year of sowing. However, in the first harvest year, in the presence of 40 kg P ha−1, clover inoculated with Glomus etunicatus produced double the amount of dry shoot per hectare produced by uninoculated plants and 75% greater than that produced with Glomus mosseae L1.These observations encourage the view that inoculation with mycorrhizal fungi of white clover for improved hill pastures might have a practical role if the responses could be made more predictable. It is concluded that further work is justified to understand the ecology of mycorrhizal fungi in hill pastures and how the symbiosis functions, to select suitable endophytes and to develop methods of inoculation appropriate for use in routine field practice.
COMPETITIVE RELATIONSHIPS BETWEEN ATRAZINE RESISTANT AND SUSCEPTIBLE POPULATIONS OF AMARANTHUS RETROFLEXUS AND A. POWELLII FROM SOUTHERN ONTARIO
Authors: WEAVER S.E. , WARWICK S. I. 
Published: May 2006

SUMMARYThe relative competitive abilities of atrazine resistant and susceptible populations of Amaranthus retroflexus and Amaranthus powellii were compared in a greenhouse experiment using a de Wit replacement series. Both inter and intraspecific differences in competitive ability were apparent when the populations were grown in two‐way combinations of varying proportions but constant overall density. Within both species, the susceptible population had a greater competitive ability with respect to biomass and seed production than the resistant population. The susceptible population of Amaranthus powellii was more competitive than either the susceptible or resistant populations of Amaranthus retroflexus. The resistant population of Amaranthus powellii was more competitive than the resistant population of Amaranthus retroflexus but appeared to have a competitive ability equal to that of the susceptible population of Amaranthus retroflexus.
ANATOMICAL VARIATION IN FIRST LEAVES OF NINE TRITUCUM GENOTYPES, AND ITS RELATIONSHIP TO PHOTOSYNTHETIC CAPACITY
Authors: JELLINGS ANITA J. , LEECH RACHEL M. 
Published: May 2006

SummaryThe variation in over 20 leaf characters including morphological, anatomical and cellular features have been examined in nine Triticum genotypes at three levels of ploidy. The characters included transectional leaf area, leaf width, distance between vascular bundles, volume occupied by each cell type, cell size and number, and chloroplast size and number. Analysis of these characters showed that the major components of the variation were related to the ploidy level and the genotype of the species and cultivars examined. The measured characters most strongly influenced by ploidy level were cell size, chloroplast number and leaf thickness. Genetic variation accounted for the variation in all other measured characters. The interaction of genetic variation with the major effects attributable to ploidy level creates a characteristic anatomical ‘fingerprint’ for each genotype.The observation that photosynthetic capacity is negatively correlated with the ratio of mesophyll cell size to nuclear genome size, and with no other character, is discussed.