bluuebunny/crossref_metadata_2025 huggingface dataset:
PROBLEMS OF INTERPRETING THE RELATIONSHIP BETWEEN THE AMOUNTS OF LEAD AND ZINC IN PLANTS AND SOIL ON METALLIFEROUS WASTES
Authors: BARRY S. A. S. , CLARK S. C.
Published: May 2006

The lead and zinc contents of shoot material of Agrostis tennis, Festuca ovina and Minuartia verna and of the soil in which they were growing at an abandoned lead‐mining area on Grassington Moor, Yorkshire, England were determined. The relationship between the zinc contents of shoot material and soil was broadly linear. There was little increase, however, in the lead content of the shoot material over the range 500‐20000 μg g−1 lead in the soil. Above this value the lead content of the shoot material increased markedly. There were large differences between samples in the metal contents of the shoot material collected from soils having the same metal contents. Possible reasons for this variation are discussed and specific suggestions for future comparative work are made.
SOME NEW PALAEOBOTANICAL RECORDS FOR THE BRITISH IPSWICHIAN INTERGLACIAL
Authors: HALL ALLAN
Published: May 2006

Details are given of four interesting new palaeobotanical records from an Ipswichian (last) Interglacial site in the East Midlands of England. The taxa are considered in the context of the site, and a brief review is presented of their Tertiary and Pleistocene history and present ecology, with some discussion of the phytogeographical implications.
LEAF RESISTANCES IN DIFFERENT POPULATIONS OF SESLERIA CAERULEA (L.) ARD.
Authors: LLOYD N. D. H. , WOOLHOUSE H. W.
Published: May 2006

Six races of Sesleria caerulea from widely separated parts of the geographical range of the species exhibited different rates of photosynthesis and transpiration when grown under standard conditions. These can be traced to various attributes of the stomatal apparatus. The stomata differ in frequency, size and the depth to which they are sunk below the epidermal surface in the different races, but quantitative consideration of these parameters leads to the conclusion that the apertures to which the stomata can open, an attribute which correlates with the depth to which they are sunk, determines the maximum rates of photosynthesis and transpiration. Evidence is presented to suggest that, although this complex of stomatal modifications may be interpreted as representing xerophytic adaptations, they may have evolved not so much for conservation of water per se, but to conserve the energy balance of the leaves, thereby reducing evaporative heat loss and so maintaining leaf temperature. A leaf temperature of 1–2°C above ambient may increase the rate of photosynthesis by 10–20% in the range from 10–20°C.
THE OCCURRENCE OF SOME ACID PHOSPHATASES AND DEHYDROGENASES IN THE VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUSMOSSEAE
Authors: MACDONALD R. M. , LEWIS M.
Published: May 2006

The occurrence of acid phosphatase, glutamate dehydrogenase, succinate dehydrogenase, glyceraldehyde‐3‐phosphate dehydrogenase, glucose‐6‐phosphate dehydrogenase and NADH and NADPH diaphorases in Glomus mosseae (yellow vacuolate Endogone spore type) was demonstrated cytochemically. Acid phosphatase was found in lysing and growing fungal structures. It was inferred that the fungus possesses an Embden‐Meyerhof‐Parnas system, a tricarboxylic acid cycle and a hexose monophosphate shunt.
STUDIES ON MUCORALEAN MYCOPARASITES
Authors: CURTIS F. C. , EVANS G. H. , LILLIS V. , LEWIS D. H. , COOKE R. C.
Published: May 2006

The effects of nine species of Piptocephalis de Bary on the growth of four host fungi were studied. Depending on temperature and the mycoparasite‐host combination, host growth was either unaffected, inhibited or stimulated, In addition, mycoparasite‐induced abnormal morphology in the host often resulted. Hypotheses are presented to explain these phenomena and to act as a basis for investigations into the physiology of mycoparasitism.
WHOLE PLANT STUDIES ON PHOTOSYNTHESIS AND ACETYLENE REDUCTION IN ALNUS GLUTINOSA
Authors: GORDON J. C. , WHEELER C. T.
Published: May 2006

Rates of photosynthesis and acetylene reduction by whole plants were measured on (a) twelve Alnus glutinosa clones and (b) A. glutinosa seedlings grown in low and high irradiances. Both genetic and environmental manipulation of photosynthetic rates produced concomitant changes in rates of acetylene reduction. For the clonal material, growing under closely similar environmental conditions, mean rate of net photosynthesis was significantly positively correlated with both the mean fresh weight of nodules formed per plant and with the mean rate of acetylene reduction.
DINOFLAGELLATE CYSTS IN THE PLANKTON
Authors: REID PHILIP C.
Published: May 2006

The geographical and seasonal occurrences of dinoflagellate cysts at a depth of 10 m in the North Atlantic and North Sea are described from samples taken by the Continuous Plankton Recorder between June 1973 and December 1975. A special study was made of the large cyst of Polykrikos schwartzii Bütschli in the autumn of 1973 when CPR samples were supplemented by vertical sampling in the upper 500 m with a Longhurst‐Hardy Plankton Recorder at Ocean Weather Station, INDIA.

Only ten isolated records of cysts were made in the western Atlantic. All others occurred to the east of 30° W in both oceanic and neritic waters and especially in the shallow waters of the North Sea. Cysts were found in the spring plankton but were most abundant in the autumn. They have been recorded down to 500 m but occur most frequently in the top 30 m of the water column. Large aggregations of cysts in bottom sediments probably reflect concentration over many years since they cannot be explained by the low numbers found in the plankton. Generally, the distribution of cysts in the plankton is reflected in bottom sediments but concentrations in sediments may be outside the centres of production, implying movement by currents or sediment transport.
DEMOGRAPHY VERSUS PLANT GROWTH ANALYSIS
Authors: HUNT RODERICK
Published: May 2006

This paper discusses a recent extension of demographic techniques into a field more conventionally dealt with by plant growth analysis. It concludes that the two approaches are complementary.
STUDIES IN THE VEGETATIONAL HISTORY OF MID‐WALES
Authors: MOORE P. D.
Published: May 2006

Stratigraphic and pollen evidence is presented from a mire site on the eastern side of the main Cambrian watershed of central Wales. A complex basin contains Late Devensian lake sediments overlain by Flandrian organic detritus muds. Organic lake muds were replaced by swamp and carr vegetation on the north and west of the site, but the south‐east basin continued as a lake until relatively recent times (the last 200 years). Final colonization of the lake was by a floating raft of Carex rostrata, Menyanthes trifoliata and Sphagnum cuspidatum, on which the present sphagnum‐dominated vegetatiiin has developed. Such schwingmoor mire types are uncommon in Britain and this is a particularly good example.

Pollen analysis of the Flandrian lake sediments provides information concerning vegetational history. Interesting early Flandrian records are of Hippophäe rhamnoides. Linum bienne and Fumaria. Pinus sylvestris has low pollen levels in the early Flandrian, unlike many western sites. It is suggested that sites having high values may have Pinus as a local mire colonist. The Ulmus decline is very marked and is accompanied by evidence of cultivation. This is the first evidence of cereal growing in early Neolithic times in Central Wales. Higher in the profile Cannabis saliva assumes importance, possibly as a result of Iron Age/Roman cultivation.
AMYLASE ENZYMES ISOLATED FROM INCUBATED DE‐EMBRYONATED MAIZE KERNELS
Authors: GOLDSTEIN L. D. , JENNINGS P. H.
Published: May 2006

An enzyme extract prepared from incubated, de‐embryonated maize (Zea mays L.) kernels was resolved into three major amylase activities by ion‐exchange chromatography using DEAE‐cellulose. These activities, designated peak I, II and III in order of their elution, were further analysed utilizing isoelectric focusing. The pi values of peaks I and II were found to be 4.55 and 4.95 respectively. The activity contained in peak III was separated into two isoelectric components with pI's of 4.30 and 5.05. Each of the four isoelectric forms showed distinct electrophoretic properties on polyacrylamide gels. Peak I contained (β‐amylase on the basis of its inactivation by 10−5M HgCl2, lack of protection against heat inactivation by added Ca2+, stable activity after dialysis against 10−2 M EDTA, and its sole reaction product with starch being identified as maltose. Peak II activity appeared to be an a‐amylase as determined by its reaction products with starch and its stabilization against heat inactivation by added Ca2+, however, it was inactivated by HgCl2 treatment and dialysis against EDTA. The two isoelectric components of peak III were also characterized as a‐amylase using the same criteria, with the 5.05 component being more sensitive to HgCl2 inactivation than the 4.30 component. All four isoelectric forms exhibited broad pH activity profiles.
GENECOLOGICAL STUDIES OF SALT TOLERANCE IN GROUNDSEL (SENECIO VULGARIS L.) WITH PARTICULAR REFERENCE TO ROADSIDE HABITATS
Authors: BRIGGS D.
Published: May 2006

Salt contamination of soils has been studied in a range of habitat types of groundsel (Senecio vulgaris L.). Evidence suggests that roadsides salted in winter and areas around salt dumps have high mean values of exchangeable sodium; lower values have been found for coastal areas, and inland sites not known to be salted.

Salt tolerance tests‐both in Petri‐dish experiments and in soils irrigated with different salt solutions‐suggest that topodemes from sites subject to salting are, in general, more salt tolerant than those from non‐salted areas. This apparently simple relationship is critically examined. Genecological implications of salt tolerance patterns are fully discussed.
PROTANDRY AND THE SEQUENCE OF FLOWER OPENING IN THE ONION (ALLIUM CEP A L.)
Authors: CURRAH LESLEY , OCKENDON D. J.
Published: May 2006

To assess the importance of protandry in promoting outbreeding in onions, detailed observations were made of the sequence of flower opening in onion umbels. Six stages of flower development were defined, covering the period from flower opening to withering of the style. Regular counts were made in the 1976 season of the total number of flowers at each stage during the flowering of twenty‐nine umbels representing four cultivars and six inbred lines. The pattern of flowering was similar in all cases, although the number of flowers per head varied from 126 to 681. At first the number of flowers opening was small, but rapidly increased, giving a peak, which lasted for a mean of 4–10 days. During the middle of the peak flowering period the maximum number of flowers open at one time was often more than 50% of the total flowers on the head. A particular flower could not easily be pollinated with its own pollen because the stigma did not become receptive until about 2–3 days after the anthers had started to dehisce. Protandry was not considered to be effective in preventing pollination between flowers on a single umbel because there was abundant pollen available from the time the first stigmas became receptive, almost until the end of flowering. Other factors which may account for high out‐crossing rates in onions are discussed.
COMPARATIVE ASPECTS OF PHOTOSYNTHESIS, PHOTORESPIRATION AND TRANSPIRATION IN FOUR SPECIES OF THE CYPERACEAE FROM THE RELICT FLORA OF TEESDALE, NORTHERN ENGLAND
Authors: LLOYD N. D. H. , WOOLHOUSE H. W.
Published: May 2006

Summary

Populations of two continental‐northern species, Carex ericetorum Poll, and Eriophonim latifolium Hoppe and two arctic‐alpine species, Kobresia simpliduscula (Wahlenb.) Mackenzie and Carex capillaris L., from the flora of Teesdale were grown under controlled conditions and their rates of photosynthesis, photorespiration and transpiration were measured in an open gas‐analysis system over the leaf temperature range 5 to 30 °C over a range of irradiances. The maximum rates and the temperature optima for photosynthesis were similar for all the species. The rates of photosynthesis at low temperature and the light saturation characteristics of C. ericetorum and E. latifolium were significantly different from those of K. simpliciuscula and C. capillaris. The differences are discussed in relation to the habitats in which these species usually occur.
LEGUMIN OF PISUM SATIVUM AND VICIA FABA
Authors: CROY R. R. D. , DERBYSHIRE E. , KRISHNA T. G. , BOULTER D.
Published: May 2006

Summary

The legumins of Pisum and Vicia have been compared and the proteins have been shown to differ in molecular weight, subunit molecular weights and amino acid composition. Legumin of Pisum however has a similar disulphide bridged subunit construction to that of Vicia and consists of basic (pI's greater than 7) and acidic subunits (pI's less than 7). Of the two molecules, Pisum legumin was shown to be more acidic at pH values of neutral and above. The protein from Pisum has all the antigenic determinants of Vicia legumin and one or more determinant groups in addition.

Tryptic peptide maps indicate that legumin is an homologous protein in Vicia and Pisum.
MECHANISMS FOR UREA UPTAKE BY THE DIATOM PHAEODACTYLUM TRICORNUTUM: THE UPTAKE OF THIOUREA
Authors: REES T. A. V. , SYRETT P. J.
Published: May 2006

Summary

Thiourea inhibited competitively the uptake of urea by urea‐grown cells of Phaeodactylum with a Kt of 180 μM. Urea‐grown cells also absorbed and accumulated thiourea. Uptake of thiourea resembled that of urea in that (i) uptake by ammonium‐grown cells was slow, (ii) uptake was much increased by a period of nitrogen starvation, (iii) uptake was stimulated by light and (iv) at low substrate concentrations uptake was inhibited almost completely by 0.1 mM CCCP (carbonyl cyanide m‐chlorophenylhydrazone). It is concluded that thiourea and urea are taken up by the same active mechanism. With nitrogen‐depleted cells, the relationship between rate of thiourea uptake and thiourea concentration was hyperbolic with a half‐saturation constant of 170± 33 μM and a Vmaxof 580 nmol thiourea 108 cells−1 h−1. This half‐saturation constant is about 200 times greater than the value for urea uptake by nitrogen‐depleted cells although the Vmaxvalue is about the same. The relationship between passive and active uptake is discussed. Because of the low affinity of the active uptake mechanism for thiourea, passive uptake is quantitatively important at low thiourea concentrations; this is particularly so with nitrogen‐replete cells in which the capacity of the active mechanism is less well developed. As much of the urea taken up by Phaeodactylum remains in the cells as free urea, it is preferable to study the urea uptake mechanism by measuring the uptake of urea directly. In contrast, organisms like Chlorella metabolize [14C]urea rapidly and conclusions may be ambiguous if measurement of 14C within the cells is used as a measure of uptake. With Chlorella, it may be preferable to use the analogue, (14C)thiourea, to study the uptake mechanism and, in this organism, the difference in affinities of the active uptake mechanism for urea and thiourea is not so great as it is in Phaeodactylum.
THE APOPLASTIC CONDUCTION OF WATER IN POLYTRICHUM JUNIPERINUM WILLD. GAMETOPHYTES
Authors: TRACHTENBERG S. , ZAMSKI E.
Published: May 2006

Summary

Apoplastic water movement on the electron microscopic level was studied by means of PbS particles produced in situ after exposing gametophytes which were immersed in Pb‐EDTA to H2S. The presence of PbS particles in the tissue is used to evaluate the apoplastic conduction of water. All cell walls of all the tissues appear to conduct water. The heavy mass of cell‐wall material contributes to the radial conduction of water to the hadrom. Absorption of water through the aerial surface of the gametophyte is more efficient than through the rhizome.
COBALT AND NITROGEN FIXATION IN LUPINUS ANGUSTIFOLIUS L. I. GROWTH, NITROGEN CONCENTRATIONS AND COBALT DISTRIBUTION
Authors: ROBSON A. D. , DILWORTH M. J. , CHATEL D. L.
Published: May 2006

Summary

Cobalt application markedly increased the growth of and nitrogen concentrations in tops of Lupinus angustifolius irrespective of inoculation with an effective strain of Rhizobium. Cobalt‐deficient plants produced a greater weight of lateral nodules and total nodule weight than cobalt‐adequate plants. Cobalt‐sufficient plants produced more crown nodule weight than cobalt‐deficient plants.

Cobalt concentrations were higher in roots and nodules than in tops irrespective of cobalt application. In plant tops cobalt concentrations in young leaves were considerably lower than those in old leaves at both cobalt levels. Cobalt concentrations and contents increased in old leaves throughout the experiment.

Under cobalt deficiency cobalt appeared to be preferentially distributed to nodules. Six weeks after sowing cobalt contents of nodules of cobalt‐deficient plants were similar to those in whole tops. By contrast at this time cobalt contents of nodules of cobalt‐adequate plants were only approximately one‐third those of whole tops.
COBALT AND NITROGEN FIXATION IN LUPINUS ANGUSTIFOLIUS L. II. NODULE FORMATION AND FUNCTION
Authors: DILWORTH M. J. , ROBSON A. D. , CHATEL D. L.
Published: May 2006

Summary

The effects of cobalt deficiency on nodule formation and function in sweet lupin (Lupinus angustifotius L. cv. Unicrop) were studied in cobalt‐deficient Lancelin sand in the glasshouse.

Bacteroid densities in cobalt‐deficient nodules were lower than in normal nodules. Recovery from cobalt deficiency in inoculated treatments was associated with increases in bacteroid density and cobalt accumulation in lateral nodules. Such changes did not occur in treatments infected with rhizobia from the soil.

Acetylene‐reducing activity of cobalt‐deficient plants was not initiated until plants were nearly 6 weeks old, at which time cobalt‐treated plants were at their peak of activity. Specific activities of cobalt‐deficient nodules remained very low even when nitrogenase did develop. Their large mass of nodules allowed cobalt‐deficient plants to reach 20 to 50 % of the normal activity per plant, but specific activities were only 5 to 13 % of peak activities in cobalt‐treated nodules.

Nodule bacteroid content and leghaemoglobin content were linearly related to cobalamin content, each with a single relationship. Plotting acetylene‐reducing activity against cobalamin content or leghaemoglobin content generated two different linear response curves in each case; the slopes of the lines were different, depending on the presence or absence of cobalt. It is suggested that there may be a function in N, fixation in legume nodules for a non‐cobalamin form of cobalt.
FAVOLASCHIA DYBOWSKYANA (SINGER) SINGER (APHYLLOPHORALES), A NEW ORCHID MYCORRHIZAL FUNGUS FROM TROPICAL AFRICA
Authors: JONSSON L. , NYLUND J. E.
Published: May 2006

Summary

Mycorrhiza of the ptyophagous type was formed by Favolaschia dybowskyana (Singer) Singer in axenic culture with protocorms of the terrestrial Japanese orchid, Bletilla striata (Thunb.) Rchb. f. The growth of inoculated protocorms was much greater than uninoculated material, which was unable to develop on cellulose agar. The growth rate of the inoculated material on this medium was almost the same as that of material in sterile culture on full nutrient medium. Infected Bletilla material was studied by light and transmission electron microscopy and information obtained, together with previously published data, support a non‐specific relationship between the symbionts.
VITAMINS AND NITROGEN REQUIREMENTS OF ORCHIS LAXIFLORA LAMK.
Authors: MEAD J. W. , BULARD C.
Published: May 2006

Summary

Orchis laxiflora Lamk. grown from seeds in asymbiotic cultures has a special need for thiamine which is necessary for its development; riboflavin though it has a favourable influence on germination is unable to replace it.

The requirement of this orchid for a nitrogen source can be satisfied with casamino acids; no mineral nitrogen source can play the same role, but in presence of the organic source, the addition of ammonium nitrogen is an improving factor while nitric nitrogen is unfavourable.
THE ULTRASTRUCTURE OF POLLEN‐GRAIN DEVELOPMENT IN THE OLIVE(OLEA EUROPAEA). 2. SECRETION BY THE TAPETAL CELLS*
Authors: PACINI E. , JUNIPER B. E.
Published: May 2006

Summary

The parietal tapetal cells in the olive can, through their greater ribosome density, be distinguished from the pollen mother cells by about the leptotene stage. The organelles of these two cell types remain similar up to the tetrad stage. At this stage the tapetal and microspore cytoplasm are separated by four walls; the tapetal cell wall, the pollen mother cell wall, the tetrad callosic wall and the primexine. Microtubules are prominent against the radial walls of the tapetal cells. The cytoplasm of the tapetal cells is orientated around a central vacuole in a form suggesting cyclosis. Cytoplasmic vesicles generated from various sources within the tapetal cytoplasm appear to migrate towards the plasmalemma adjacent to the loculus or adjacent to the intercellular spaces. These vesicles, which are of at least three different types, fuse with the plasmalemma, apparently to discharge their contents.

The points of contact between the plasmalemma of the tapetal cells and the exine sculptures leave a transitory layer, the ‘tapetal printing’, on the pollen surface. Fibrillar material, probably protein, accumulates in the tapetal intercellular spaces and eventually comes to rest on the pollen poral surfaces. Granular electron dense bodies also accumulate in the tapetal intercellular spaces and finally come to lie between the pollen bacula. Orbicules are also produced by the tapetal cells and, at maturity, cluster around the degenerate lipoidal mass which is the final state of the tapetal cells.
THE ORIGIN OF POLLEN IN LAKE SEDIMENTS: AN ENCLOSED LAKE COMPARED WITH ONE RECEIVING INFLOW STREAMS
Authors: PENNINGTON WINIFRED
Published: May 2006

Summary

The contribution from inflow streams to pollen in lake sediments was examined by comparison of percentage and absolute pollen data from sediment cores taken from two small lakes (5 and 10 h) within the same lowland region of south Cumbria; one in an enclosed basin (a large interdrumlin hollow) and the other receiving streams. The vegetation histories of the last 7000 years, interpreted from percentage pollen analysis, were similar. Calculated rates of annual influx of pollen to the sediments were at all times lower in the enclosed basin; in it they agreed with present deposition into pollen traps from respectively forest, incompletely vegetated land, and grassland. These rates are accepted as estimates of the amount of pollen per unit area which annually reaches a small lake by deposition from the air. Differences between these rates and those to the open lake, for each successive vegetation type, give estimates of the contribution from streams to sediments of the open lake. This contribution constituted < 50 % of the total during the forest period and increased to > 80 % at the horizon of extensive forest clearance.

In the open lake, parallel changes in pollen and geochemistry at this clearance horizon show that the source of increased pollen influx lay in organic soils (mor); distribution of the tracer pollen Ilex shows that these soils must have formed on this catchment after initial disturbance of primary forest, and thereafter constituted a source of pollen of ages older than the time of deposition in the lake. Disruption of the vegetation cover on this catchment by deforestation and ploughing appears to have increased permanently the rate at which streams transported sediment, including pollen, to the lake. Only in the enclosed lake do rates of pollen influx remain in equilibrium with vegetation changes recorded in the percentage data. In this lake, with a similar history of changing land use, there is no perturbation of rates of annual pollen influx.

The absolute pollen data for Tilia cordata in the enclosed lake confirm for this site the distribution history suggested for this species by Pigott and Huntley (1978).
THE PAST AND PRESENT VEGETATION OF THE CAENLOCHAN NATIONAL NATURE RESERVE, SCOTLAND. I. PRESENT VEGETATION
Authors: HUNTLEY B.
Published: May 2006

Summary

The geology, climate and soils of the Caenlochan N.N.R. are briefly described. The flora is discussed and the results of a primary phytosociological survey are described. One hundred and ninety‐three relevés were collected from uniform stands of vegetation and analysed using phytosociological techniques. Thirty‐four noda are delimited: 9 of them are heath types, 3 are bogs, 9 are grasslands, 4 represent various types of cliff‐ledges and 9 are mires, springs, rills and wet flushes. The floristics and ecology of the noda are briefly discussed.

The ecological and floristic interrelationships among the noda are discussed. An ordination of the noda using constancy data is used to illustrate these relationships and to identify the principal habitat gradients. Soil base‐status and soil moisture are seen to be of primary importance but the secondary importance of land‐use history in determining the present vegetation is also emphasized.
THE TRANSLOCATION OF 32P IN TWO SUBMERGED AQUATIC ANGIOSPERM SPECIES
Authors: WELSH R. P. H. , DENNY P.
Published: May 2006

Summary

The translocation of phosphorus as 32P was investigated in two species of rooted, submerged, aquatic angiosperm, Potamogeton pectinatus and Potamogeton crispus. Experiments were conducted in two forms of partition apparatus for periods of either 1 to 48 h or 6 to 10 days. The apparatus used for the shorter‐term experiments incorporated three compartments so that possible isotope leakage through seals could be critically distinguished from plant excretion. Results of autoradiography and of radioactive counting provide evidence for a circulation of 32P in these plants akin to that described for terrestrial plants but with slower rates of movement. Quantitative differences in rates and amounts of 2P transport in the two species are discussed in relation to their anatomy and ecological distribution. There was no evidence of excretion of isotope, following transport, in the experiments conducted.
THE EFFECT OF DIFFERENT INORGANIC NITROGEN SOURCES AND PLANT AGE ON THE COMPOSITION OF BLEEDING SAP OF PHASEOLUS VULGARIS
Authors: THOMAS R. J. , FELLER U. , ERISMANN K. H.
Published: May 2006

Summary

The composition of the bleeding sap N of Phaseolus vulgaris varied with the inorganic nitrogen source fed to the plant but was not changed by a fourfold difference in external nitrate concentration. Highest sap N concentration and fastest growth were observed in ammonium nitrate grown plants. With nitrate grown plants 60 % of the total sap N was inorganic nitrate‐N and 40 % organic‐N whereas with ammonium nitrate grown plants nitrate contributed 30 % to the total N and organic‐N 70 %. Virtually all of the N in the sap of ammonium grown plants was organic‐N. Allantoic acid was the major individual reduced N compound in the bleeding sap of plants fed with nitrate, ammonium or ammonium nitrate. During the development of the plant from seedling to mature plant with ripened pods, the concentration of N in the bleeding sap of nitrate grown plants decreased sharply initially and then gradually during pod formation; it increased again when the pods had ripened. Nitrate reductase activity of leaf extracts was correlated with nitrate content of bleeding sap and was not much affected by increases in reduced N compounds in the sap.
SORBITOL, A COMPATIBLE OSMOTIC SOLUTE IN PLANTAGO MARITIMA
Authors: AHMAD I. , LARHER F. , STEWART G. R.
Published: May 2006

Summary

Plantago maritima grown under saline conditions accumulates large quantities of sodium chloride. Salinity reduces tissue potassium, calcium and magnesium contents. Several enzymes from P. maritima are shown to be salt‐sensitive. In contrast to many other higher plant halophytes, P. maritima shows no accumulation of either amino acids or methylated onium compounds. High levels of the polyhydric alcohol sorbitol are however accumulated under saline conditions. The possible role of sorbitol as a compatible cytoplasmic solute is discussed.
1THE EFFECT OF GALACTOSE ON THE GROWTH OF LEMNA
Authors: DeKOCK P. C. , CHESHIRE M. V. , MUNDIE C. M. , INKSON R. H. E.
Published: May 2006

Summary

Solutions of 0·1% galactose were toxic to Lemna gibba in axenic culture. The toxicity was counteracted by glucose and exacerbated by ethanol. Plants showing toxicity accumulated large amounts of starch and showed a mineral analysis typical of ageing fronds.

Radioactively labelled galactose was readily transformed to glucose by plants in toxic conditions. The distribution of activity suggests only a slight impairment of cellulose synthesis. Although hormonal disturbances are probably involved, the fact that galactose is toxic to both plants and animals suggests that a more fundamental aspect of metabolism is involved.
WINTER FIXATION OF NITROGEN IN SCOTCH BROOM (CYTISUS SCOPARIUS L.)
Authors: WHEELER C. T. , PERRY D. A. , HELGERSON O. , GORDON J. C.
Published: May 2006

Summary

The retention of green lateral branches by Scotch Broom allows nitrogen fixation to continue during mild winters. Tolerance of low soil temperatures is suggested to be a major factor contributing to the occurrence of winter nitrogen fixation.
THE EFFECTS OF BISULPHITE AND SULPHATE UPON PHOTOSYNTHESIS IN SPHAGNUM
Authors: FERGUSON P. , LEE J. A.
Published: May 2006

Summary

The effect of various concentrations of HSO3‐ and SO42‐ on photosynthetic oxygen evolution in Sphagnum spp. was studied. Almost instantaneous reductions induced by HSO3‐, the magnitude of which increased with concentration, were not reversed by additions of HCO3‐. SO32‐ had no effect on oxygen evolution. The effect of HSO3‐ was markedly pH‐dependent, being much greater at lower pH. 14CO2 uptake was less sensitive to HSO3‐ than O2 evolution; low HSO3‐ concentrations enhanced 14CO2 fixation but never increased O2 evolution. 14CO2 fixation in the dark was also inhibited by 0·1 mM HSO3‐ but enhanced by lower concentrations. The results are discussed in relation to known mechanisms of sulphite toxicity and to effects of sulphite upon growth of Sphagnum spp.
A NOTE ON AERATION AND AERENCHYMA IN THE RHIZOME OF BRACKEN (PTERIDIUM AQUILINUM (L.) KUHN VAR. AQUILINUM)
Authors: WATT A. S.
Published: May 2006

Summary

The tissues involved in the aeration of the bracken [Pteridium aquilinum (L.) Kuhn var. aquilinum] rhizome are briefly described and functionally tested. The aerenchyma functions only until maturation of the rhizome.

In experiments with blocks of Gault Clay placed in a sandy soil the clay is penetrated by the rhizome without change in its diameter. The roots, however, are reduced in number, thickness and in length (max. 3 cm) to a degree regarded as inadequate for the maintenance of a plant wholly in clay.
ON THE THEORY OF EXPLOSIVELY DISPERSED SEEDS: A CORRECTION
Authors: SWAINE M. D. , DAKUBU T. , BEER T.
Published: May 2006

Summary

Attention is drawn to an error in two earlier papers on seed dispersal (Beer and Swaine, 1977; Swaine and Beer, 1977). The correction of the error leads to quantitative changes in the earlier results which do not substantially affect the biological conclusions drawn.
POLLEN DIAGRAMS FROM NORTHUMBERLAND
Authors: DAVIES G. , TURNER J.
Published: May 2006

Summary

Pollen diagrams from four sites in Northumberland have been produced in order to study the impact of prehistoric man on the vegetation of the region since Neolithic times. The major vegetational changes have been radiocarbon dated at Fellend, Steng and Camp Hill Mosses, but not at Broad Moss.

There is evidence at all four sites for small temporary clearances in the woodlands during the Bronze Age and also during the pre‐Roman Iron Age. These clearances were mainly for grazing and their frequency at a site accords well with the archaeological evidence for settlement.

All the diagrams show a major clearance of forest, primarily for pasture, dated at Fellend and Steng Mosses to the time of the Roman occupation of the north‐east of England. At Camp Hill this clearance gave a late medieval date, but there is good reason for suspecting the sample may have been contaminated with 14C‐rich carbon. Regeneration of forest occurred some one to two hundred years after the withdrawal of the Romans. This has also been observed on diagrams from neighbouring counties, and indicates a post‐Roman period of economic stability.

There was a further extensive clearance, dated at Fellend and Steng Mosses to the time of the Scandinavian settlement, and the diagrams show a late medieval recession in farming and a regeneration of woodland before the present landscape was created.

Rates of peat accumulation were estimated from the radiocarbon dates at Fellend Moss, where it increased in late medieval times, and at Steng Moss, where it did so in the late Bronze Age.
SILICA DISTRIBUTION IN EQUISETUM HYEMALE VAR. AFFINE L. (ENGELM) IN RELATION TO THE NEGATIVE GEOTROPIC RESPONSE
Authors: SRINIVASAN J. , DAYANANDAN P. , KAUFMAN P. B.
Published: May 2006

Summary

In young growing Equisetum shoots silica deposition proceeds basipetally in the internodes. The surface of the mature internode, including the stomata, becomes encrusted with silica. Only young shoots with active intercalary meristems and very little silica deposition show a negative geotropic response. As the internodes mature, the difference in silica deposition between intercalary meristem and upper part diminishes so that the failure of mature internodes to respond geotropically is most likely due to significant silica deposition in the once active intercalary meristem sites.

Initiation of negative geotropic curvature in young Equisetum shoots takes 36 to 48 h, and six to nine internodes are involved. Control of the geotropic response is auxin‐mediated as shown by experiments with the auxin transport inhibitors, triiodobenzoic acid (TIBA) and methyl‐2‐chloro‐9‐hydroxy fluorene (CFM, a morphactin). The former partially inhibited the response while the latter completely inhibited curvature.
ULTRASTRUCTURAL ASPECTS OF ENDOMYCORRHIZA IN THE ERICACEAE
Authors: BONFANTE‐FASOLO P. , GIANINAZZI‐PEARSON V.
Published: May 2006

Summary

The ultrastructural organization of endomycorrhizal hair roots of Calluna vulgaris has been studied in naturally infected plants by scanning and electron microscopy. Heavy fungal infection is present in, and limited to, cells of the root cortex. All intracellular hyphae have simple septa and associated Woronin bodies, characteristic of ascomycetous fungi. Penetrating hyphae are surrounded by a layer of inner host wall material. The host plasmalemma invaginates to surround the individual intracellular hyphae and it is separated from them by an interfacial matrix of varying thickness. No evidence of lysis or digestion of the intracellular hyphae by the host plant has been observed.
LICHEN METABOLISM
Authors: COWAN D. A. , GREEN T. G. A. , WILSON A. T.
Published: May 2006

Summary

Metabolic studies were carried out on two lichen species (Ramalina celastri and Peltigera polydactyla) using 3HHO(g) and 14CO2. Incubations in the presence and absence of light at 100 % r.h. resulted in 3H and 14C labelling of a variety of compounds. Tritium fixation during darkness was determined quantitatively as 4.1 and 8.2 % of ‘light’ labelling (for P. polydactyla and R. celastri, respectively), and was localized predominantly in polyols, alanine, glutamic acid, glutamine, aspartic acid and γ‐amino butyric acid. Under similar experimental conditions, only trace amounts of 14C were found in sugar alcohols, whereas amino acids were substantially labelled. The dissimilarity between 3H and 14C labelling patterns has led to the conclusion that polyols synthesized in the absence of photosynthesis must be derived from other stored substrates within the thallus. The role of tricarboxylic acid (TCA) cycle‐related amino acids in lichen metabolism, and some potential synthetic modes of the unusual amino acid, γ‐amino butyric acid, are discussed.
INTERNAL FACTORS CONTROLLING THE RATE OF EVAPORATION FROM FRONDS OF SOME INTERTIDAL ALGAE
Authors: JONES HAMLYN G. , NORTON T. A.
Published: May 2006

Summary

Factors controlling the rate of desiccation of single algal fronds were investigated using a diffusion porometer. Three species were compared—Laminaria digitata, Fucus serratus and Fucus spiralis. In all species the turgid thalli had a very high surface conductance (equivalent to a low resistance) to water loss. The rate of evaporation would therefore be controlled mainly by the environment, especially by the magnitude of the transfer resistance across the boundary layer. As the tissue of all species dried, the apparent surface conductance fell, though the conductance at any relative water content tended to be in the order Laminaria F. serratus F. spiralis. The more rapid the rate of desiccation, the lower was the surface conductance at any particular water content. This sensitivity to evaporation rate was much more pronounced in F. serratus than in the other two species and was less apparent in tissue stored for longer periods. An important factor contributing to water conservation in all three species was the shrinkage of tissue as water was lost, causing reduction of evaporating surface. The time taken for tissue of the three species to reach any given relative water content, when exposed to a particular environment, would be largely determined by the amount of water per unit area, which in saturated tissue, was highest in Laminaria, followed by F. serratus and then F. spiralis. The mechanism causing the lowered surface conductance was investigated using wet filter paper with or without the addition of mucilage or alginate gels.
THE USE OF SEED ISOENZYMES AS AN AID TO THE BREEDING OF FIELD BEANS (VICIA FABA L.)
Authors: GATES P. , BOULTER D.
Published: May 2006

Summary

A rapid and economical method has been developed for identifying inbred lines and detecting crossing between them. It employs non‐specific esterase and glutamate‐oxaloacetate transaminase isoenzyme patterns of cotyledon extracts, separated by electrophoresis on acrylamide gels. Isoenzyme patterns were genotype‐specific and stable from plants grown in a range of environmental conditions. The potential value of these isoenzymes as markers for genotype identification and measurement of outcrossing is illustrated and discussed in relation to the breeding of field beans.
MEMBRANE BOUND INCLUSIONS IN EPIDERMAL PLASTIDS OF DEVELOPING SESAME LEAVES AND COTYLEDONS
Authors: PLATT‐ALOIA K. A. , THOMSON W. W.
Published: May 2006

Summary

Epidermal plastids of young sesame leaves and cotyledons contain amorphous membrane bound inclusions similar to those found in the mesophyll. However, unlike the mesophyll inclusions which disappear during chloroplast development, those in epidermal plastids persist, even in fully mature leaves where a limited grana fretwork system develops.

The limiting membrane of the inclusion is apparently continuous with both the tubular complex of light grown tissues and the prolamellar body of etiolated tissues as well as with the granal and integranal membranes. These associations, as well as a decrease in staining density of the inclusion with maturation, are interpreted as indications of a precursor‐product relationship of the inclusion and a grana fretwork.

The coexistence of both grana and the (presumably) proteinaceous inclusion manifest the multifunctional capacity of plastids.
GROWTH AND INVERTASE ACTIVITY OF SUGAR BEET CALLUS
Authors: Mohammad A. M. S. , Collin H. A.
Published: May 2006

Summary

The nutrient requirements and cultural conditions for the initiation of sugar beet callus from the variety Kawe AA were established so that on a basic Murashige and Skoog nutrient medium containing 1‐0 mg l−1 kinetin, 1‐0 mg l−1 2,4‐D‐(2,4‐dichlorophenoxyacetic acid) and 4% sucrose a fast growing callus was produced. When the subculture period exceeded 3 weeks, the callus and medium became heavily pigmented. At 1.0 mg l−1 kinetin and 0.05 mg 1−1 2, 4‐D, root and shoot production were initiated and the plantlets were eventually isolated. Analysis of the invertase in callus showed both acid and alkaline invertase in the soluble and insoluble fraction. During a subculture the acid invertase activity remained constant but the alkaline invertase increased. There was no effect on the activity of increasing the concentration of sucrose in the medium. The pattern of invertase activity was similar to that found in other tissue cultures and dissimilar to that in intact plants where sugar accumulation was a notable feature.
NITRATE REDUCTASE ACTIVITY IN WHEAT (TRITICUM AESTIVUM L.) I. DISTRIBUTION THROUGHOUT THE LEAVES
Authors: HALLAM R. , BLACKWOOD G. C.
Published: May 2006

Summary

The distribution of nitrate reductase activity, as measured in vivo in the leaves of some spring wheats, was recorded. In plants grown under controlled conditions the highest activity was found in the youngest ligule emergent leaf. The acropetal part of this leaf had the highest level of activity until the leaf began to senesce. Changes in nitrate reductase activity in response to nitrate concentration in the nutrient solutions were also most pronounced in this tissue. Nitrate reductase activity in the basipetal part of the youngest ligule emergent leaf of two wheat varieties, grown at a range of nitrate levels, was followed throughout development. With a given variety the optimal nitrate concentration for development of enzyme activity was the same as that for growth, but this concentration differed between varieties.
NITRATE REDUCTASE ACTIVITY IN WHEAT (TRITICUM AESTIVUM L.) II. THE CORRELATION WITH YIELD
Authors: BLACKWOOD G. C. , HALLAM R.
Published: May 2006

Summary

Changes in nitrate reductase activity in response to nitrogen treatment were measured in vivo in the basipetal part of the youngest ligule emergent leaf of wheat plants during early development. The relationship between these measurements and grain yield is reported for some spring wheats grown in a growth room and some field‐grown winter wheats. In both situations the c correlation of a linear regression of yield parameters and single measurements of nitrate reductase was found to be significant. Where split dressings of nitrogen were applied the seasonal mean nitrate reductase activity correlated well with yield.
FACTORS AFFECTING NITRATE REDUCTASE ACTIVITY IN SYNCHRONOUS CULTURES OF CHLORELLA*
Authors: Griffiths D. J.
Published: May 2006

Summary

In synchronous cultures of Chlorella emersonii and C. vulgaris (Brannon No. 1 strain), growing on an inorganic medium in a light/dark regime, nitrate reductase (NR) activity increases rapidly during the early stages of the light period and declines in the dark. Evidence is presented that the increase in NR activity requires photosynthesis and involves synthesis of enzyme protein. The two strains tested differ in the extent of dependence of their NR activity upon photosynthesis, the difference being related to their relative ability to undergo a fully heterotrophic mode of nutrition on a glucose medium in the dark. The effect of glucose, oxygen supply and of two inhibitors of phosphorylation upon the rate of decline in NR activity in the dark is reported.
THE CARBOHYDRATES OF THE LEAFY LIVERWORT, PLAGIOCH ILAASPLENIOIDES (L.) DUM.
Authors: Suleiman A. A. A. , Bacon J. , Christie A. , Lewis D. H.
Published: May 2006

Summary

The soluble carbohydrates of both Plagiochila asplenioides var. asplenioides and var. major consist of volemitol and a volemitol derivative, sucrose and a series of sucrosyl‐fructans and mannitol. Glucose, fructose and trehalose are present in trace amounts. Quantitatively, volemitol is the single most abundant compound but this is exceeded by total fructan. Starch is only a minor component and the neutral insoluble fraction consists of galactose, arabinose (major components), glucose, xylose and mannose (intermediate quantities) and fucose and rhamnose (minor components). Only starch and sucrose are depleted when tissue is kept in the dark overnight. Results are discussed in relation to the soluble composition of bryophytes in general.
LICHEN METABOLISM. 1. THE USE OF TRITIUM LABELLED WATER IN STUDIES OF ANHYDROBIOTIC METABOLISM IN RAMALINA CELASTRI AND PELTIGERA POLYDACTYLA
Authors: COWAN D. A. , GREEN T. G. A. , WILSON A. T.
Published: May 2006

Summary

A new radiochemical technique has been applied to a study of anhydrobiotic metabolism in the lichen species, Ramalina celastri (Sprengel) Krog & Swinsc. and Peltigera polydactyla (Neck.) Hoffm. Specimens were incubated in known atmospheric humidities of THO vapour which were found to equilibrate with cellular H2O within 5 days. This method has proved effective in a study of a wide range of in vivo metabolic processes occurring at both high and low cellular water contents.

Qualitative and quantitative estimations of the 3H labelling of water soluble cell constituents (ammo acids, organic acids, sugars, sugar phosphates, and sugar alcohols), neutral and polar lipids, water soluble macromolecules, and insoluble cell residues have shown that diverse metabolic systems have significantly different levels of resistance to desiccation. Tricarboxylic acid cycle reactions and related amino acid interconversions were shown to be relatively desiccation resistant, whereas Calvin cycle metabolism appeared to be highly sensitive, a conclusion supported by 14CO8 tracer experiments. Conversely, the synthesis of sugar alcohols was found to be active beyond the limit of photosynthetic metabolism. Neither lipid nor macromolecular synthesis was shown to occur to a significant degree in either lichen in the desiccated state.

It is proposed that the syntheses of amino acids and sugar alcohols at low cellular saturation levels are important physiological processes. Amino acid synthesis results in the accumulation of an available store of stable intermediates, ready to feed into the T.C.A. cycle by trans‐amination or deamination on rehydration of the lichen. Sugar alcohol metabolism assists in the maintenance of a high sugar alcohol concentration to act as a physiological buffer during extreme dehydration.
STUDIES ON AEROBIOLOGY‐ATMOSPHERIC FUNGAL SPORES
Authors: BHATI H. S. , GAUR R. D.
Published: May 2006

Summary

A survey of atmospheric fungal spores was carried out at Modinagar, situated in the western part of Uttar Pradesh (India). The site for the study represents a rural and semi‐industrial area. The incidence of the fungal spores in the air was studied by the simultaneous exposure of adhesive coated slides for 24 h and petri dishes containing culture media for 5 min daily all the year round (August 1975 to July 1976). The slides exhibited a preponderance of spores of: Alternaria; Beltrania; Cladosporium; Curvularia; Epicoccum; Fusarium; Helminthosporium; Nigrospora; Prathroda.; rust spores; smut spores; small round spores (spp. of Aspergillus, Penicillium, Mucor, Rhizopus), Thielaviopsis. Species of Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Verticillium and Thielaviopsis showed excellent growth on exposed culture media dishes. Several other types of spores were also found in comparatively low numbers. The seasonal and monthly variation of these air‐borne fungi were studied qualitatively and quantitatively.