bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NOTE ON A LATE‐WEICHSELIAN SPLACHNUM CAPSULE FROM SCOTLAND
Authors: CONOLLY A. P. , DICKSON J. H. 
Published: May 2006

SummaryA single capsule of the coprophilous genus Splachnum is reported from deposits of Late‐Weichselian (Late‐glacial) age in Berwickshire. Other Quaternary records of moss sporophytes are briefly discussed.
A RADIOCARBON‐DATED POLLEN DIAGRAM FROM NORTH‐WEST SCOTLAND
Authors: MOAR N. T. 
Published: May 2006

SummaryA series of radiocarbon dates from critical levels in a pollen diagram from a site near Scourie, Sutherlandshire, proves the recorded events to be much younger than the trend of the pollen curves would suggest. Evidence of pine forest growing in the area during the late Atlantic and Sub‐boreal confirms earlier observations that these forests persisted in north‐west Scotland later than in many other parts of the British Isles. The extremely slow rate of accumulation between about 420 cm and 455 cm, 1320 years, implies a break in deposition, but there is no biostratigraphic or lithostratigraphic evidence of this.
THE GROWTH OF PEA LEAVES IN RELATION TO INTERNODE GROWTH AS AFFECTED BY GIBBERELLIC ACID AND B‐9
Authors: SPRENT JANET I. 
Published: May 2006

SummaryThe effects of gibherellic acid (GA) and N‐dimethylaminosuccinamic acid (B‐9) on leaf growth in several pea cultivars have heen investigated. The relationships hetween the growth of a leaf and its suhtending internode were examined. A general inverse relationship hetween growth of the two organs was found in untreated and GA‐treated plants, and in B‐9‐treated plants grown at low light intensities. At high light intensities B‐9 was inhihitory to hoth leaf and internode growth.
ASPECTS OF STALING IN LIQUID CULTURES OF FUNGI
Authors: ROBINSON P. M. 
Published: May 2006

SummaryCriteria for assessing staling in liquid cultures of fungi are examined and assays based on the germinative capacity of culture filtrates are considered unsuitable for interpreting the capacity of the same filtrates to support mycelial growth. The interrelationships of nutrient level and growth inhibitors in staling systems are emphasized. The possible importance of both labile and stable metabolites is discussed in relation to staling phenomena.
APICAL MERISTEMS AND GROWTH CONTROL IN HIMANTHALIA ELONGATA (S. F. GRAY)
Authors: MOSS BETTY 
Published: May 2006

SummaryThe young plant shows considerable internal differentiation before an apical meristem is organized. Once formed, the apical cell segments slowly. It is triangular in transverse section and segments cut off from its three sides are actively meristematic and soon build up an extensive meristem which enlarges and functions throughout the vegetative phase of the plant's development. Experiments have shown that the apical cell is the main seat of growth control and if it is destroyed another apical cell cannot be regenerated to take over this role. Division of the apical cell followed by division of the whole meristem into two, marks the end of vegetative growth and, the onset of reproduction. Successive divisions of the meristem follow and each new meristem becomes the tip of a fertile branch or receptacle. Eventually meristematic activity at the apices declines and this decline is associated with the termination of conceptacle initiation. As the entire vegetative meristem is used up in reproductive growth, there is no meristem left to continue vegetative grovrth after gamete discharge. Hence reproduction terminates the life span of Himanthalia.
CONCERNING THE MORPHOLOGY OF ISOLATED PLANT CUTICLES
Authors: LANGE R. T. 
Published: May 2006

SummaryThe morphological basis of cuticle analysis is discussed. A résumé is provided of the categories of microrelief occurring on the inner and outer surfaces of isolated plant cuticles. This is illustrated with photographs obtained by electron‐scanning microscopy. Some existing interpretations of cuticle morphology are called into question.
THE OVULE AS AN INDICATOR OF EVOLUTIONARY STATUS IN ANGIOSPERMS
Authors: SPORNE KENNETH R. 
Published: May 2006

SummaryThe crassinucellate ovule has long been regarded as more primitive among angiosperms than the tenuinucellate. Support for this view is provided by thirteen highly significant statistical correlations between the crassinucellate condition and other dicotyledon characters, both floral and vegetative. This character is therefore included among a total of twenty‐two characters believed to be of use in assessing evolutionary status. The ‘advancement indices’ of dicotyledon families are re‐calculated, using the most recently available facts. While the most primitive families are among the Magnoliales, there are also some very primitive ones among the Myrtiflorae, Violates, Geraniales, Rosales, Guttiferales and Fagales.It is concluded that the ancestral type of ovule in angiosperms was crassinucellate with three envelopes (two integuments and an aril) each of which received a vascular supply.
EFFECT OF LIGHT INTENSITY AND CO2 ON APPARENT PHOTOSYNTHESIS AND ITS RELATIONSHIP WITH LEAF ANATOMY IN GENOTYPES OF LOLIUM PERENNE L.
Authors: WILSON D. , COOPER J. P. 
Published: May 2006

SummaryA manometric technique was used to examine the effect of light intensity and CO2 on the relative photosynthetic activity of ten contrasting Lolium genotypes grown in a common environment. Relationships between leaf anatomy and photosynthesis were examined. At a given CO2 concentration, apparent photosynthesis increased with increasing light intensity until ‘light saturation’was reached. The saturating light intensity increased with increasing CO2 concentration. There were significant differences in photosynthetic rate between genotypes where light or CO2 respectively were limiting, but the relative order of the genotypes differed in these two cases. There was also independent variation in response to increasing CO2 to very high concentrations. At approximately 300 ppm CO2 and at light saturation, apparent photosynthesis was negatively correlated with mesophyll cell size. The most efficient leaves under these conditions were smaller and thinner than the less efficient. When light was limiting, apparent photosynthesis was not related to any anatomical feature. There was no indication of a stomatal effect under any conditions. The association between light‐saturated photosynthesis and mesophyll cell size was similar to that between cell size and the estimated cell surface: volume ratio.
APPARENT PHOTOSYNTHESIS AND LEAF CHARACTERS IN RELATION TO LEAF POSITION AND AGE, AMONG CONTRASTING LOLIUM GENOTYPES
Authors: WILSON D. , COOPER J. P. 
Published: May 2006

SummaryThe effect of leaf position, specific leaf weight and chlorophyll on light‐saturated apparent photosynthesis, and their relationships with leaf mesophyll, among contrasting Lolium genotypes are described. Within a range of up to four fully expanded leaves on a tiller, the lower (older) leaves had greater photosynthetic activity than the upper (younger). For any particular leaf, maximum photosynthesis was attained prior to full expansion. These effects were closely related to differences in mesophyll cell size. A wide range in leaf chlorophyll levels exhibited by Lolium mutants was not associated with differences in apparent photosynthesis. Specific leaf weight and chlorophyll content were greater in thin leaves with small mesophyll cells than in thick leaves with large cells. Chlorophyll content was not associated with differences in photosynthesis in limiting light (500 ft‐candles).
THE DIURNAL FLUCTUATION IN NITROGEN FIXATION IN THE NODULES OF ALNUS GLUTINOSA AND MYRICA GALE
Authors: WHEELER C. T. 
Published: May 2006

SummaryMaximal rates of nitrogen fixation in the root nodules of first‐year plants of Alnus glutinosa and Myrica gale growing under natural illumination but at nearly constant temperature were found by the acetylene assay to be attained about midday. The nitrogen content of the sap exuding from the stumps of decapitated plants and the level of soluble nitrogen in the nodules were also highest close to midday, the same being true of the rate of respiration in detached nodules.The hypothesis that in view of these findings the midday period must be that of maximum ingress of photosynthates into the nodules is not reflected in analyses of gross carbohydrate levels in the nodules at different times of day.
INFLUENCE OF HERBICIDES ON THE COMPETITIVE ABILITY OF FUNGI TO COLONIZE PLANT TISSUES
Authors: WILKINSON VALERIE , LUCAS R. L. 
Published: May 2006

SummaryExperiments show that the presence of herbicide residues in plant remains may be a potent factor determining the outcome of competition between saprophytic fungi colonizing such substrates. Pairs of fungi were induced to compete with each other for a substrate both in the presence and in the absence of herbicides. In all cases the outcome of competition for a substrate incorporating the herbicide was different from that for the substrate alone. Paraquat sprayed on to potato haulm altered the outcome of competition between Trichoderma viride and Fusarium culmorum in favour of F. culmorum and the same herbicide on wheat chaff suppressed Rhizopus stolonifer in favour of Aspergillus niger. Treatment of leaves of Raphanus raphanistrum with MCPA altered the outcome of competition between Fenicillium notatum and Aspergillus niger in favour of A. niger.
NITROGEN METABOLISM IN LICHENS
Authors: MILLBANK J. W. , KERSHAW K. A. 
Published: May 2006

SummaryNitrogen fixation has been demonstrated to occur in the cephalodia of the lichen Peltigera aphthosa which contain a species of Nostoc. The rate of fixation is very high in comparison with the maximum rates for N. muscorum under optimum culture conditions. Virtually all of the nitrogen fixed is secreted to the lichen thallus at a rate equal to the rate of fixation. The possible control mechanisms of this secretion are discussed.
OBSERVATIONS ON THE NITROGEN METABOLISM OF PROTOTHECA KRÜGER
Authors: CASSELTON P. J. , STACEY J. L. 
Published: May 2006

SummaryFour strains of the putative apochlorotic algal genus Prototheca Krüger (P. chlorelloides, P. moriformis, P. portoricensis and P. zopfii), could utilize either ammonium sulphate or adenine as sole nitrogen source for growth but neither potassium nitrate nor sodium nitrite could be utilized. P. zopfii could also utilize the purines hypoxanthine and guanine, and both P. zopfii and P. chlorelloides could utilize a wide range of l‐ and d‐amino acids as sole nitrogen sources for growth in media containing glucose. P. zopfii and P. chlorelloides behave similarly to one another in the experiments and may, therefore, not be separate species, while P. moriformis and P. portoricensis behaved differently from them and from each other.Cell‐free extracts of P. zopfii had transaminase and nicotinamide adenine dinucleotide phosphate (NADP) dependent glutamate dehydrogenase activities. An attempt to show that ammonium assimilation involves a coupling between the NADP glutamate dehydrogenase and the oxidative pentose phosphate pathway was complicated by the fact that uptake of exogenously supplied glucose was inhibited during ammonium assimilation. The production of [14C] carbon dioxide from [1‐14C] glucose was inhibited less than both the uptake of glucose and the production of [14C] carbon dixoide from [6‐14C] glucose, suggesting that the oxidative pentose phosphate pathway provides the reduced coenzyme for ammonium assimilation.
SEASONAL AND DIURNAL EXPANSION AND CONTRACTION OF PINUS BANKSIANA AND PICEA GLAUCA CONES*
Authors: CHANEY W. R. , KOZLOWSKI T. T. 
Published: May 2006

SummaryChanges in diameter of intact first‐year Picea glauca and second‐year Pinus banksiana cones were continuously monitored during two growing seasons. Early in their development the cones made intermittent increases in diameter. Cones expanded during the evening and night while vapour pressure deficit of air was decreasing or low, and did not change in diameter during the daytime when vapour pressure deficit was high. In a mid‐stage of development, reversible diurnal shrinkage and expansion of cones occurred and these fluctuations were inversely correlated with vapour pressure deficit. Late in the development of P. banksiana cones, many rapid daytime fluctuations in diameter were recorded. Maturing cones of Picea glauca decreased in diameter in a step‐like manner. Diurnal shrinkage of maturing cones occurred when the vapour pressure deficit was increasing or high and no appreciable change in diameter occurred when vapour pressure deficit was low.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: YOUNIS M. E. 
Published: May 2006

SummaryStrawberry leaves were fed with [14C] glucose either in water or in iodoacetate. The latter considerably increased the 14CO2 output and the permeability of the plasmalemma and the tonoplast as is evident from the increased leakage from the free and inner spaces of leaves. The time required to wash out the free space was most probably of the order of 10 minutes after which time the activity diffusing out was considered to come from the inner space.The magnitude of leakage of sugars was much higher in iodoacetate than in water. The rate of leakage of sugars was dependent on their content in the inner space.The results were thought to indicate that iodoacetate increased the accessibility in the metaholic region of substrates and enzymes normally not saturated with their substrates and so the increased respiration could be explained on this basis.
EFFECT OF SELECTION FOR MESOPHYLL CELL SIZE ON GROWTH AND ASSIMILATION IN LOLIUM PERENNE L.
Authors: WILSON D. , COOPER J. P. 
Published: May 2006

SummaryDivergent selection for mesophyll cell size (mean cross‐sectional area) was made within a population of ‘Veya’ perennial ryegrass. Selection for small mesophyll cells generally resulted in smaller mesophyll cells, heavier seed, and greater yield of shoot dry matter than selection for large cells. Between the third and fifth leaf stage, families from parents with small cells exhibited greater net assimilation rate and lower leaf area ratio than those from parents with large cells. Rate of light‐saturated photosynthesis of young leaves was negatively related to cell size in the F1 generation.Greater shoot dry matter in the small, compared with the large, cell selections was accounted for in terms of greater initial seed reserves (heavier seed) and also greater net assimilation rate at some stage prior to full expansion of the third leaf. It was concluded that mesophyll cell size is a useful criterion for selecting for light‐saturated photosynthesis in Lolium perenne.
SPORE SIZE IN THE GENUS EQUTSETUM
Authors: DUCKETT JEFFREY G. 
Published: May 2006

SummaryNo trace of morphological heterospory has been found in the genus Equisetum. Reports that sex may be altered by environmental conditions indicates that it is not determined by genotypic or physiological properties of the spores. Spore size is extremely dependent on viability, maturity and mounting medium, but within each species all the viable spores are spherical, bright green and vary little in size. Slight subgeneric differences exist in spore size but there is great overlap between all species rendering the spores of little use taxonomically. Colourless abortive spores are found in the two hybrids E.×moorei and E.×trachyodon and also in E. telmateia and E. palustre var. polystachyum. Of common occurrence in E. hyemale, E. ramosissimum and E. laevigatum are small, discoloured, misshapen spores which will not germinate. Considerations of the phenology of these species in relation to experiments on storage of ripe cones indicate that these spores were at one time mature and viable but had subsequently died. In E. variegatum and E. scirpoides large variations were observed between cones, in spore size and germination. This was due to the ripe cones containing variable proportions of mature and immature spores.
THE NOCTURNAL BEHAVIOUR OF XEROPHYTES GROWN UNDER ARID CONDITIONS
Authors: GINDEL I. 
Published: May 2006

SummaryStomatal apertures of seventy‐eight species of xerophytes grown under arid conditions were greater at night than during the day. Most stomata were closed during the day, and especially during the hottest period. Many stomata opened at night, especially in the presence of dew or mist. Nocturnal opening did not occur at low relative humidities.
THE EFFECT OF NITROGEN SUPPLY ON TRANSPIRATION AND STOMATAL BEHAVIOUR OF BEANS (PHASEOLUS VULGARIS L.) *
Authors: SHIMSHI DANIEL 
Published: May 2006

SummaryThe effect of nitrogen supply on the transpiration rate and stomatal opening of potted bean plants was studied in a series of experiments. The transpiration rates of N‐supplied plants were higher than those of N‐deficient plants when soil moisture was relatively high; as soil moisture approached the wilting range, the transpiration rates of N‐supplied plants dropped to below those of N‐deficient plants. In spite of the marked differences in transpiration rates, as influenced by soil moisture and nitrogen supply, the stomata appeared closed. By coating the upper or lower surfaces of the leaves with a vapour‐impervious compound it was shown that stomatal apertures below the limit of microscopic resolution control the rate of transpiration. Under conditions that encourage stomatal opening (covering the plants with transparent plastic bags), the stomata of the N‐deficient plants opened to a lesser degree than those of N‐supplied plants. There was some evidence that when stomata were visibly open, transpiration rates were regulated by the degree of plant hydration rather than by the degree of stomatal opening. It is concluded that N‐deficient plants fail to open their stomata as widely and to close them as tightly as N‐supplied plants.
THE ULTRAVIOLET ABSORPTION PROFILE OF STIGMATIC EXTRACTS
Authors: MARTIN FRANKLIN W. 
Published: May 2006

SummaryUltraviolet absorption profiles were examined of alcoholic extracts of stigmatic surfaces of forty‐four species. The extracts of species showed characteristic absorption peaks, and batho‐chromic shifts on the addition of NaOH. In many cases the peaks corresponded to those of simple phenolic compounds or their derivatives. The possible use of the absorption profile as a taxonomic tool is discussed.
EFFECTS OF COTYLEDON AND HYPOCOTYL PHOTOSYNTHESIS ON GROWTH OF YOUNG PINE SEEDLINGS *
Authors: SASAKI S. , KOZLOWSKI T. T. 
Published: May 2006

SummaryThe importance of light to development of Pinus resinosa seedlings for a short time following seed germination was studied. Treatment of seedlings with photosynthesis‐inhibiting herbicides (monuron and atrazine) partially inhibited cotyledon expansion. Expansion of primary needles was light‐dependent since darkness stopped it. When young seedlings were exposed to 14CO2 in the light, some of the label accumulated in root tips and primary needles, and some was retained in cotyledons and hypocotyls for at least 3 weeks. Although measurable photosynthesis occurred in both cotyledons and green hypocotyl tissues, the rates were much higher in cotyledons. In intact seedlings, expansion of primary needles was not significantly influenced by exposure of hypocotyls to light but in those from which cotyledons had been removed, exposure of hypocotyls to light did affect their expansion. Thus green hypocotyl tissues appeared to be important for expansion of primary needles only in the absence of photosynthesis in the cotyledons. Some growth of cotyledons, radicles and hypocotyls also depended on current photosynthate in addition to megagametophyte reserves.
PLASTID DEVELOPMENT IN PRIMARY LEAVES OF PHASEOLUS VULGARIS
Authors: BRADBEER J. W. 
Published: May 2006

SummaryOn illumination 14‐day old dark‐grown beans showed initial lags in (i) cell growth, (ii) chlorophyll synthesis, (iii) increases in the activities of some chloroplast enzymes of the primary leaves and (iv) translocation of material to these leaves. In contrast there was no lag in the increase of leaf protein and in the rise of the activities of some enzymes which are common to cytoplasm and chloroplasts.
A POLLEN DIAGRAM FROM LAKE EURAMOO, NORTH‐EAST QUEENSLAND, AUSTRALIA
Authors: KERSHAW A. P. 
Published: May 2006

SummaryPollen analysis of organic sediments from a crater lake in north‐east Queensland provides a vegetation record from 10,000 B.P. to the present day. An initial sclerophyll vegetation was succeeded by rain forest about 7600 B.P., probably under increasing effective precipitation. Rain forest then persisted to the present day changing progressively from a ‘warm temperate’ to a ‘dry subtropical’ kind, almost certainly as a result of an increase in temperature.
GLYCEROL UTILIZATION IN SEEDS OF CORYLUS AVELLANA (L)
Authors: STOBART A. K. , PINFIELD N. J. 
Published: May 2006

SummaryThe distribution of radioactivity from [14C]glycerol in the cotyledons and embryonic axes of hazel seeds pre‐treated either with gibberellin or water for various periods has been investigated. The cotyledons of both gibberellin and water prereated seeds utilized considerable quantities of [14C]glycerol. In the cotyledons, gibberellin prereatment induced an increased percentage incorporation of radioactivity into sucrose but percentage incorporation of 14C in polar lipid and released CO2 gave higher values after pre‐treatment with water. The increase in gluconeogenesis in cotyledons from gibberellin pre‐treated seeds was accompanied by an increase in lipase activity. In the embryonic axes gibberellin pre‐treatment resulted in increases in percentage incorporation of 14C into both polar lipid and respired CO2.The results indicate that gibberellin stimulates the following processes in the cotyledons during the first 8 days of germination: a diversion of glycerol away from the TCA cycle and into carbohydrates, an increase in lipase activity, presumably resulting in a rise in production of endogenous glycerol and an increased rate of membrane dissolution. In the embryonic axes, over the same period, gibberellin appears to stimulate a more rapid respiration of glycerol and increased production of lipid membranes.
HYBRIDIZATION IN TARAXACUM
Authors: RICHARDS A. J. 
Published: May 2006

SummaryResults of hybridization experiments between twenty‐six species of Taraxacum (nine of which are sexual) are reported. Most crosses set good seed. The chief barriers to interspecific hybridization seem to be absence of sexuality, absence of pollen and restitutional pollen. There is no evidence of seed‐incompatibility. Taxonomically remote hybrids set less good seed than near interspecific hybrids.Hybrids are intermediate in character and usually more vigorous than the parents. The progeny of diploid sexual males are fertile, diploid and sexual, those of triploid agamospermous males are mostly near‐diploid, fertile and sexual, but some are facultatively agamospermous triploids.The existence of several intraspecific character differences is noted in some sexual species and the nature of character inheritance is noted in interspecific hybrids.The nature of hybrids in the field is discussed and examples of hybrid populations reported. The scarcity of reports of hybrids is noted and reasons for this are discussed.