bluuebunny/crossref_metadata_2025_split huggingface dataset:
TAXONOMY AND TAXIMETRICS OF STELLARIA MEDIA (L.) VILL., S. NEGLECTA WEIHE AND S. PALLIDA (DUMORT.) PIRÉ
Authors: WHITEHEAD F. H. , SINHA R. P. 
Published: May 2006

SummaryThree species of Stellaria (S. media, S. neglecta and S. pallida) have different ecological amplitudes, S. media is ubiquitous and S. pallida and S. neglecta have well‐defined and circumscribed ecological niches. They also differ in phenological behaviour and Cytology. In morphological attributes, the differences are less marked so tbat they have always presented difficulties in identification.The present paper is concerned with the morphometrical aspect of an integrated approach to the taxonomy of the Stellaria media complex. Twelve variables were used and data were collected from the floral parts of 253 British herbarium specimens. The data were employed in both canonical variate and principal component analyses utilizing a computer. The three species were shown by these methods to be quite distinct. Morphometrically, S. pallida was found to be clearly separable from the other two species. These latter, although separable, were found to have intergrading morphometric features. The characters seed length, seed weight, length of tubercles and pollen diameter were shown to be the most significant in discrimination and, therefore, suitable for the construction of a key to separate the three species.The advantages of canonical variate and principal component analyses in the future development of taxonomy are discussed.
THE APICAL MERISTEM OF FUCUS
Authors: MOSS BETTY 
Published: May 2006

SummaryStudies on young vegetative apices of Fucus show that after the large apical cell is differentiated it becomes surrounded by an extensive meristematic zone, the pro‐meristem. It is suggested that this is the main zone of cell division at the apex and that the apical cell itself rarely segments. But the apical cell is the main seat of control, for without it the apex shows no further growth. The size of the apical cell and of the pro‐meristem increases during growth of the vegetative branch. A new apical cell becomes associated with a portion of the pro‐meristem when forking of a branch occurs. Morphologically there is sudden change from vegetative to reproductive growth at an apex. Apical initials and a pro‐meristem function in a receptacle until all concept‐acles are laid down. Following conceptacle development there is a loss of meristematic activity at the apex, and after gamete discharge the tissues gradually disintegrate.
ANATOMY OF THE STIGMA AND STYLE OF SWEET POTATO
Authors: MARTIN F. W. , ORTIZ SONIA 
Published: May 2006

SummaryThe stigma and style are the sites where self‐incompatibility and hybrid sterility reactions occur in the sweet potato. The stigma is a highly branched structure covered with a specialized papillate epidermis which exudes a sticky fluid. The cells of the body of the stigma are arranged in gradually narrowing columns which conduct the pollen tubes from stigma to style. The style contains a central, uniform core of pollen‐tube conducting tissue. The junction of style and ovary provides a continuous but contorted pathway of conducting tissue which pollen tubes follow. The incompatibility reaction, which occurs at the stigmatic surface, is hypothesized to be due to interactions of substances in the pollen and in the stigmatic exudate. Sterility, on the other hand, may be due to pollen tube disorientation or failure at the stigma‐style junction and the style‐ovary junction, where passage may be mechanically more difficult.
THE DEVELOPMENT OF ORCHIS PURPURELLA IN ASYMBIOTIC AND INOCULATED CULTURES
Authors: HARVAIS G. , HADLEY G. 
Published: May 2006

SummaryIn asymbiotic cultures Orchis (Dactylorchis) purpurella seed germinated freely on deionized water agar and on defined and undefined media. Germination was enhanced by prolonged sterilization periods and high temperatures but was inhibited by light. Asymbiotic protocorms never attained the photosynthetic stage except on undefined media.Several Rhizoctonia solani strains enhanced seed germination at low temperatures. The further development of the relationship between host and endophyte varied with the strain; two pathogenic isolates from tomato and rice were strongly symbiotic to protocorms while other strains although stimulating growth ultimately became parasitic.Symbiosis was most stable at low temperatures but with any one strain there was a general pattern of infection in which nutrient depletion in the protocorm was often followed by parasitism. Drip feeding with carbohydrate delayed parasitism but in some conditions led to intense growth of the fungus. It is suggested that a careful balance of nutrients is important in the maintenance of a stable relationship between host and endophyte. The significance of this is discussed in relation to conditions in nature.
THE SIGNIFICANCE OF MYCORRHIZAL NODULES OF AGATHIS AUSTRALIS
Authors: MORRISON T. M. , ENGLISH D. A. 
Published: May 2006

SummaryExperiments using excised nodules of kauri showed that vesicular‐arbuscular mycorrhizal infection markedly stimulated phosphate absorption by these organs. Small but significant fixation of nitrogen was also noted in excised nodules, whether mycorrhizal or not.
SURGICAL INVESTIGATION OF THE ROLE OF IAA AND GA IN THE ELONGATION OF‘METEOR’PEA INTERNODES
Authors: ARNEY S. E. , MANCINELLI P. A. 
Published: May 2006

SummaryThe elongation of the second internode of Meteor pea seedlings and the relationship of this elongation to cell division and cell elongation in the epidermis and cortex has been determined after treatment with either IAA or GA or both together, and in combination with decapitation, and removal of the first or second leaves either separately or together. The cells from the side of the internode subtending the second leaf are consistently longer than on the other side, and this effect is intensified by application of GA and abolished by application of IAA. Decapitation and defoliation together abolish the usual stimulation of cell elongation by GA. It is concluded that the results are in harmony with the hypothesis that the cell elongating effect of GA is the result of an increased production of auxin in the apical regions and young leaves.
THE MECHANISM OF SPORANGIAL DISCHARGE IN PYTHIUM MIDDLETONII
Authors: WEBSTER J. , DENNIS C. 
Published: May 2006

SummaryMethods are described for inducing zoospore formation in Pythium middletonii. Stages in the discharge of the sporangial contents into the vesicle have been followed by means of a sequence of photomicrographs. The mechanism of sporangial emptying is discussed. Photomicrographs at various stages of zoosporangial discharge have been measured to give estimates of sporangial and vesicle volumes. Shrinkage in sporangial volume by about 46% and increase in cytoplasmic volume of about 58% presumably caused by water uptake, occur during discharge. During movement of cytoplasm from the sporangium into the vesicle the residual cytoplasm assumes a spherical shape, and it is suggested that surface energy is responsible for the emptying of the sporangium. This hypothesis is supported by photomicrographic evidence showing that separation of the cytoplasm from the sporangium wall does not occur until the vesicle diameter is almost equal to that of the shrunken sporangium. It is further postulated that the liquid surrounding the cytoplasm in the vesicle must exert a higher surface tension than water. The difficulties of alternative hypotheses are discussed.
POLYPHENOL OXIDASE ACTIVITY AND THE METABOLISM OF GLYCINE BY POTATO TUBER SLICES
Authors: ABUKHARMA D. A. , WOOLHOUSE H. W. 
Published: May 2006

SummaryGlycine and catechol when added separately to both fresh and washed potato‐tuber slices stimulated their oxygen uptake and CO2 production. Glycine and catechol added together produced an additive stimulation of the respiration of fresh tuber‐slices but gave no stimulation of respiration by washed slices. The inhibitory effect of 3,4‐dichlorophenyl serine on the oxidation of glycine by unwashed slices suggests that this step in the degradation was probably mediated by polyphenol oxidase.
ELECTRICAL POTENTIAL MEASUREMENTS, ION PUMPS AND ROOT EXUDATION—A COMMENT AND A MODEL EXPLAINING CATION SELECTIVITY BY THE ROOT
Authors: JENNINGS D. H. 
Published: May 2006

SummaryThe value of measurements of the electrical potential difference between the external solution and the xylem sap for determining the presence or absence of an active ion flux in a root is discussed. It can be shown that the presence of an ion pump within the cells of the root is by no means incompatible with electrochemical equilibrium between the exuding sap and the external solution. A model is proposed for an exuding root of which the important features are a sodium pump at the tonoplast and the absence of any role for the endodermis. This model is shown to explain many experimental facts of which detailed consideration is given to the selective effect of the root on the cation composition of the exudate and the effect of an induced water flow through the root in reducing this selectivity.
CARBOHYDRATE TRANSLOCATION IN ORCHID MYCORRHIZAS
Authors: SMITH SARAH E. 
Published: May 2006

SummaryThe soluble sugars of uninfected regions of Dactylorchis purpurella were found to be glucose, fructose and sucrose. Mycelium of three mycorrhizal fungi, isolated from this orchid, was found to contain glucose and trehalose. Two of the fungi also contained mannitol. Mycorrhizal seedlings of D. purpurella contained carbohydrates contributed by both orchid and fungal partners.The incorporation of 14C into mycorrhizal seedlings was followed, after [14C]glucose had been supplied to infective hyphae some distance from the seedlings. 14C incorporation into soluble and insoluble materials continued throughout the 7‐day experimental period. The results were consistent with the hypothesis that a carbohydrate, possibly trehalose, is translocated by the fungal hyphae into the seedlings. The fungal sugar, trehalose, was the first to become labelled, and the proportion of label in this sugar declined as 14C was incorporated into other carbohydrates, notably sucrose. As sucrose was not found in fungal mycelium, movement of a 14C‐labelled compound from internal fungal hyphae to orchid cells must have taken place.
ONTOGENY AND CYTOCHEMISTRY OF THE CHALAZAL PROLIFERATING CELLS OF CAPSELLA BURSA‐PASTORIS (L.) MEDIC.
Authors: POLLOCK E. G. , JENSEN W. A. 
Published: May 2006

SummaryThis paper describes the ontogenic development and cytochemistry of a group of cells which proliferate from the chalaza of the ovule of Capsella bursa‐pastoris. These cells arise from nucellar tissue in the chalaza at the time of embryo development and develop a consistent morphology which seems to protrude into the embryo sac. Azure B staining and intensity of incorporation of nucleic acid precursors indicates a high rate of activity of these cells up to the time that the embryo is in the heart stage. They then begin to disintegrate quickly with but a few cells remaining in the mature seed. The evidence suggests that they may play a physiological role in early embryo development.
MOVEMENT OF GROWTH REGULATORS IN PLANTS
Authors: McCREADY C. C. , JACOBS W. P. 
Published: May 2006

SummaryThis paper describes the effects on auxin transport of treatments which changed the rate of elongation of the transporting tissues. The inclusion of mannitol in blocks of agar gel applied to each end of segments cut from petioles of Phaseolus vulgaris L. reduced elongation of the segments. This treatment also increased basipetal movement of 2,4‐dichlorophenoxyacetic acid (2,4‐D) from donor blocks through the segments into receiver blocks and decreased net acropetal movement, so that the polarity of 2,4‐D transport was raised, Gibberellic acid applied in the donor blocks promoted elongation but decreased the basipetal movement of 2,4‐D and increased its net acropetal movement, so that the polarity of 2,4‐D transport was lowered. It is concluded that polar transport of this auxin is not dependent on elongation of the transporting tissues.
PHOTOSYNTHESIS AND RESPIRATION IN RELATION TO LEAF AGE IN PERILLA FRUTESCENS (L.) BRITT
Authors: HARDWICK K. , WOOD M. , WOOLHOUSE H. W. 
Published: May 2006

SummaryThe rate of photosynthesis in the third pair of leaves of Perilla frutescens declined gradually from the time of completion of expansion of the leaves until approximately I week from abscission when there was a more rapid decrease. The decrease in rate of photosynthesis first became apparent in the parts of the lamina proximal to the petiole and gradually extended to the more distal regions. The rate of respiration of the leaf remained approximately constant until I week from abscission when there was a transient rise prior to the final decrease in rate, The gradual decline in photosynthesis was accompanied by a similar decline in the RNA and protein content of the leaf although the chlorophyll content did not change during this period. Measurements of photosynthesis by means of 14CO2 incorporation showed a similar pattern of change and further revealed that the rate of incorporation of label into protein declined more rapidly than did the total protein content, The data are interpreted as suggesting the cessation of synthesis of proteins essential for photosynthesis rather than an increased rate of proteolysis as the cause of the senescence changes.
STUDIES OF THE POST‐GLACIAL HISTORY OF BRITISH VEGETATION
Authors: GODWIN H. 
Published: May 2006

SummaryTwo boreholes in the organic deposits of Old Buckenham Mere, Norfolk show that accumulation began in the Late‐Glacial period. The rich pollen flora from two boreholes shows great similarities with that of three other Late‐Glacial sites in the region, and differs from that of the Late‐Weichselian at Colney Heath mainly in the prevalence of tree birches. Above a depositional hiatus shown to correspond with most of pollen Zones V, VI and Vila, borehole 2 has 7 m of uniform organic muds to which a conjectural timescale has been applied. Thus the detailed pollen diagrams can be correlated with pre‐historic and historic events from early Neolithic to the present day. For this period the diagrams yield evidence of the changing kind and intensity of forest exploitation and destruction, and particularly the great extension of arable cultivation in Anglo‐Saxon times. The re‐expansion of many Late‐Glacial plants as weeds and ruderals is evident and analysis of the changing frequencies of trees and shrubs accords with explanations in terms of anthropogenic rather than climatic effects. There is now remarkable continuity of evidence of the character of East Anglican vegetation from Full‐Weichselian time to the present day.
A LARGE CAPACITY HAND‐OPERATED PEATO SAMPLER
Authors: SMITH A. G. , PILCHER J. R. , SINGH G. 
Published: May 2006

SummaryA sampler is described that will take 12 cm cores, 1.5 m long, from peat and compacted organic lake sediments. The sampler tube has a longitudinal slit to obviate compression and is provided with a plastic liner. The sampler is driven by lever chain‐hoists. For insertion, the hoists are attached to basal members of a scaffold‐pole rig secured to the deposit by long pins.
THE INFLUENCE OF DIURNAL TEMPERATURE FLUCTUATIONS ON THE GROWTH OF FUNGI
Authors: BURGESS L. W. , GRIFFIN D. M. 
Published: May 2006

SummaryA theoretical relationship is developed relating growth of a fungus during one cycle of a diurnal temperature fluctuation to the growth at relevant constant temperatures. The theory involves the assumption that the growth‐rate of the fungus at a given temperature in the cycle is unaffected by its previous temperature experience. Growth of Gibberelta zeae, Cochliobolus sativus and C. spicifer was measured at each of sixteen diurnal temperature regimes differing in median temperature and amplitude. The measured growth was compared with the expected growth. In general, the analysis supports the derived theoretical relationship. In some instances, growth at a fluctuating temperature is greater than or less than that at the corresponding median and the difference is anticipated, and explained, by the theory.
THE NUTRITIONAL REQUIREMENTS OF EXCISED ROOTS OF THREE GENOTYPES OF ARABIDOPSIS THALIANA (L) HEYNH.
Authors: NEALES T. F. 
Published: May 2006

SummaryMethods are described for the culture of excised roots of Arabidopsis thaliana. Cultures of the roots of three genotypes (EST, PI and 1018/6) were established. The genotypes PI and 1018/6 each differ from the wild‐type, EST, by a single gene mutation. It is shown that there are differences between the excised roots of the three genotypes in growth rate and in the requirement for the vitamins, thiamin and biotin. The vitamin requirements of the excised roots largely reflect those of intact plants, as established by Langridge. However, roots of the genotype PI responded to thiamin and biotin, whilst whole plants of this strain respond only to biotin.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J. , KHAN M. A. A. 
Published: May 2006

SummaryIn eleven experiments with apples and potatoes phosphoenolpyruvate decreased during anoxia in nine experiments. The data were thus, in general, in accord with the ‘localization’ theory of the Pasteur effect.Of the eleven experiments, only two showed the decrease in glucose‐6‐phosphate and increase in fructose diphosphate in anoxia which are accepted as evidence that the ‘activation/inactivation’ theory is operating. The data were thus, in general, not in accord with the ‘activation/inactivation’ theory of the Pasteur effect.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J. 
Published: May 2006

SummaryThe contents of glucosc‐6‐phosphate, fructose diphosphate, 3‐phosphoglycerate and phos‐phoenolpyruvate were substantially unchanged during the ‘climacteric’ rise in CO2 output in apples. The mechanism of the ‘climacteric’ increase in respiration in apples thus appears to differ from that in bananas.
THE ONSET OF PHOTOPHOSPHORYLATION IN CHLOROPLASTS ISOLATED FROM DEVELOPING BEAN LEAVES
Authors: GYLDENHOLM A. O. , WHATLEY F. R. 
Published: May 2006

SummaryPhotophosphorylation has been achieved in isolated chloroplasts of Phaseolus, without inhibition, by the addition of bovine serum albumin. Cyclic and non‐cyclic photophosphorylation and four partial reactions of photosynthetic phosphorylation were studied in the system with chloroplasts of different ages. There seems to be evidence for a correlation between a minimum structural complexity of the chloroplast and the ability to carry out the reactions studied.
STUDIES IN THE RESPIRATORY AND CARBOHYDRATE METABOLISM OF PLANT TISSUES
Authors: BARKER J. 
Published: May 2006

SummaryTransferring potatoes, peas and strawberry leaves from 10 to 1° C produced initial increases in the contents of glucose‐6‐phosphate and fructose‐6‐phosphate and, in some experiments, the amounts of fructose diphosphate and of dihydroxyacetonephosphate. In contrast the contents of 3‐phosphoglycerate and of phosphoenolpyruvate decreased at 1° C. The above changes in phosphate esters appeared not to affect the rate of respiration.
CHANGES IN THE ENZYME ACTIVITY OF SOLUBLE PROTEIN FRACTIONS IN THE COURSE OF FOLIAR SENESCENCE IN PERILLA FRUTESCENS (L.) BRITT.
Authors: KANNANGARA C. G. , WOOLHOUSE H. W. 
Published: May 2006

SummarySeparation of the soluble proteins from leaves of Perilla by means of gel filtration on a Sephadex Groo column yielded two protein bands with molecular weights of approximately 400,000 and 23,000, which appear to correspond to the well‐known Fraction I and Fraction II proteins respectively. The amount of Fraction I protein in the leaves decreased progressively from the time that the leaves became fully expanded whilst the amount of Fraction II protein decreased only in the later stages of senescence. Aleasurements of the activity of several enzymes in successive 4 ml fractions from the column showed that each occupied a different peak position within the two main protein fractions. Fach of the enzymes assayed showed a different pattern of change in the course of senescence of the leaves. These changes in protein content and enzyme activity are discussed in relation to earlier observations on the physiological functioning of senescing leaves of Perilla.
STUDIES ON THE α‐l‐ARABINOFURANOSIDASE OF PHYTOPHTHORA PALMIVORA (BUTL.) BUTL.
Authors: AKINREFON O. A. 
Published: May 2006

SummaryThe properties of the extra‐cellular enzyme, α‐l‐arabinofuranosidase, produced by Phytophthora palrmivora was studied in some detail. The optimum pH for the enzyme activity was 4.0, a level which is typical of the host plant tissues. Activity was stable over a considerable range of pH (2.0–8.0) depending on the length of time of e.Kposure to this condition. The optimum temperature was 50° C, higher than that recorded for its production. The activity was thermostable between 10 and 50° C; thermal inactivation was recorded at 70° C. The data from the Q10 values indicated that thermal inactivation beyond 60° C might be due to the denaturation of the enzyme protein.The molecular weight determination indicated that the enzyme existed in two major molecular units of 63, 100 and 15, 850, respectively.The enzyme activity was proportional to the log enzyme concentration. The enzyme was highly specific for its substrate; the average Km value was 0.65 mM. The activity was inhibited by arabinogalactan competitively, the Ki value being 5.83 mM. The activity was enhanced by the presence of calcium arabonate tetrahydrate. The activation was due to Ca2+. Plant metabolic analogues affected enzyme activity; L‐arabinose was the most inhibitory sugar, and L‐glutamine the most inhibitory amino acid. Oxidized phenolics were more potent than the unoxidized forms.The possible role of the enzyme in plant pathogenesis was discussed.
THE INFLUENCE OF ROOT PRUNING ON THE GROWTH AND TRANSPIRATION OF WHEAT UNDER DIFFERENT SOIL MOISTURE CONDITIONS
Authors: ANDREWS ROSALIE E. , NEWMAN E. I. 
Published: May 2006

SummaryTwo similar experiments were conducted with winter wheat growing in pots of soil. Plants about 5 weeks old were placed in a growth chamber under constant conditions. On half of the plants 60% of the roots were cut at their origins; thus the root density was altered, but not the volume of soil. Half of these pruned pots and half of the unpruned were maintained at field capacity. The remainder were allowed to dry out to somewhat drier than —15 bars soil matric potential (this took 8 and 13 days in the two experiments), and the plants were then harvested. In the dry treatment root pruning did not reduce growth. There is some indication that root pruning increased growth in the dry treatment and reduced it in the wet; but this is not conclusive. When the mean of wet and dry treatments together is considered, root pruning had no detectable effect on either root or shoot growth. In the wet treatments root pruning reduced transpiration by about 25–30%. In the dry treatments as the soil dried out the relative difference in transpiration rate between pruned and unpruned plants decreased. This result differs from a previous expectation that root density would have more effect on transpiration in dry soil than in wet.
LOW‐POWER ELECTRON MICROSCOPY OF THE ROOT CAP REGION OF EUCALYPT MYCORRHIZAS
Authors: CHILVERS G. A. 
Published: May 2006

SummaryLow‐power electron micrographs of a eucalypt mycorrhiza are presented which show how root cap cells are progressively decomposed by invasion of fungal hyphae. The development of tannin‐like deposits in cells of the root cap and epidermis is discussed briefly.