bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ammonium and Potassium Uptake by Citrus Roots
Authors: HASSAN M. M. , VAN HAI TANG 
Published: April 2006

AbstractMultiphasic kinetics were indicated for uptake of ammonium and potassium by intact cirtrus seedlings as measured by a continuous flow technique. Uptake at low concentration, below 10−3M, was biphasis. The patterns for ammonium uptake by 60‐day‐old and 180‐day‐old seedlings were similar, but the rates of uptake per g dry weight of root were greater for the younger plants.
Mineral Requirements for Growth and Callus Initiation of Tissue Explants Excised from Mature Coconut Palms (Cocos nucifera) and Cultured in vitro
Authors: EEUWENS C. J. 
Published: April 2006

AbstractGrowth of stem, leaf, and inflorescence explants from mature coconut (Cocos nucifera L.) palms on a new mineral formulation (Y3) was superior to that on the minerals of White, Heller, or Murashige and Skoog. Cell division in the upper part of cultured explants gave rise to a layer of white callus within a month.The effects of omitting entirely or altering the concentration of individual elements in the Y3 formulation were investigated. It was concluded that growth on White's and Heller's minerals was seriously limited by deficiencies in macro‐elements, i.e. nitrogen (particularly ammonium), potassium and phosphorus, as well as micro‐elements, i.e. iron, iodine and molybdenum. The Murashige and Skoog formulation, on the other hand, was deficient only in certain micro‐elements (particularly iodine).
Interactions between Abscisic Acid, Gibberellins and Cytokinins in Grand Rapids Lettuce Seeds Germination
Authors: POGGI‐PELLEGRIN MARIE‐CHRISTINE , BULARD CAMILLE 
Published: April 2006

AbstractExperiments with Grand Rapids lettuce seeds (Lactuca sativa L.) maintained in darkness or irradiated with red light have shown that the inhibition of germination induced by low concentrations of ABA (2, 4, 6 μM) could be overcome by gibberellins (GA3 or GA4). The same results were obtained, although to a lesser extent, under the influence of two out of the four cytokinins tested (K and BAP) for seeds maintained in darkness.To suppress the block induced by higher concentrations of ABA (for example 8 μM), it was necessary to apply a cytokinin (K, BAP, Z or 2iP) and a gibberellin (GA4 or GA3) simultaneously, or a cytokinin following a red light treatment.Experiments conducted in darkness in which ABA (8 μM) was applied together with a cytokinin (BAP) and a gibberellin (GA4) showed that the gibberellin and the cytokinin played similar roles towards each other and towards ABA.
Matric Bound Water of Water Tissue from Succulents
Authors: WIEBE H. H. , AL‐SAADI H. A. 
Published: April 2006

AbstractMatric bound water was measured as water retained by frozen and thawed tissue after desorption on a pressure membrane filter under 20 bars nitrogen gas pressure. Central water‐storage tissue and peripheral chlorenchyma from leaves or stems of 15 taxonomically diverse non‐halophytic succulent species were investigated. Matric bound water as a per cent of the dry weight averaged higher in water storage than in chlorenchyma tissue but lower than values reported for many mesophytic leaves. Matric bound water as a proportion of the total water held, however, was lower in water tissues. Osmotic potentials were generally high (solute contents low). It is concluded that matric or osmotic forces cannot account, in any unique way, for the high water content of water tissues. This appears to depend, instead, on the enormous ability of the thin‐walled cells to take up available water and expand.
Characterization and Regulatory Properties of Glucose‐6‐Phosphate Dehydrogenase from Black Gram (Phaseolus mungo)
Authors: ASHIHARA HIROSHI , KOMAMINE ATSUSHI 
Published: April 2006

AbstractGlucose‐6‐phosphate dehydrogenase (E.C. 1.1.1.49) was partially purified by fractionation with ammonium sulfate and phosphocellulose chromatography. The Km value for glucose‐6‐phosphate is 1.6 × 10−4 and 6.3 × 10−4M at low (1.0–6.0 × 10−4M) and high (6.0–30.0 × 10−4M) concentrations of the substrate, respectively. The Km value for NADP+ is 1.4 × 10−5M.The enzyme is inhibited by NADPH, 5‐phosphoribosyl‐1‐pyrophosphate, and ATP, and it is activated by Mg2+, and Mn2+. In the presence of NADPH, the plot of activity vs. NADP+ concentration gave a sigmoidal curve. Inhibition of 5‐phosphoribosyl‐1‐pyrophosphate and ATP is reversed by Mg2+ or a high pH.It is suggested that black gram glucose‐6‐phosphate dehydrogenase is a regulatory enzyme of the pentose phosphate pathway.
Variation du taux d'acide abscissique chez deux variétés de poiriers, la Passe‐Crassane et la Doyenne du Comice, en fonction de l'induction de la parthénocarpie par l'acide gibbérellique
Authors: LAFFRAY D. , DUPIN J. F. , PAULET P. 
Published: April 2006

AbstractThe content of abscisic acid in the developing fruits of two cultivars of pear (Pyrus communis L.) was determined by UV spectrophotometry and by a colorimetric method based on the possibility of the lactone corresponding to abscisic acid to give a purple colour when sodium hydroxide is added. The young fruits were harvested either from trees treated with gibberellic acid (GA3), for the purpose of inducing parthenocarpy, or from untreated trees.High levels of abscisic acid were associated with abortion and abscission of young fruits (June drop). There was little difference between fruits of GA3‐treated and untreated trees of the cultivar Passe‐Crassane. In the other cultivar, ‘Doyenne du Comice’, the level of abscisic acid in the fruits of GA3‐treated trees was about twice as high as in control fruits and seemed to be directly related to the number of fruits per tree.
The Interaction of Human Serum with the Plant Hormone Indole‐3‐Acetic Acid
Authors: HILDEN JØRGEN , RøNNIKE FOLKE , SCHOU HENNING 
Published: April 2006

AbstractIt is well known that human serum inhibits the longitudinal root growth in Lupinus albus L and Triticum sativum Lam. This inhibitory effect has been ascribed to the IAA content in human serum, which unfortunately has never been measured quantitatively. Experiments are presented in which Triticum roots are grown in media with pooled human serum and varying concentrations of IAA. In the presence of 10−5M p‐chlorophenoxy‐isobutyric acid (PCIB) and serum, minute IAA additions promoted the growth. This feature hardly could be expected were the serum inhibition in itself an IAA effect. In view of this finding, renewed but unsuccessful attempts were made to demonstrate a similar promotion in media without serum. To explain the observed response curves, it must be further assumed that serum components bind IAA reversibly. In experiments without PCIB in the medium the response curves were similar at a lower level of growth, except that no growth promotion by IAA was discernible. It is concluded, that the inhibiting effect of human serum on the growth of plant roots is not due to free IAA, although IAA in all probability occurs in that fluid.
Nitrogenase Activity in Relation to Intracellular Organisms in Sphagnum Mosses
Authors: GRANHALL ULF , HOFSTEN ANGELICA V. 
Published: April 2006

AbstractElectron microscopic studies of Sphagnum lindbergii (Schimp.) and S. riparium (Ångstr.) have revealed the presence of intracellular organisms such as blue‐green algae, green algae, bacteria and fungi.Nitrogenase activities of these Sphagnum mosses were found to be related mainly to the presence of intracellular Nostoc filaments. The appearance of nitrogen‐fixing blue‐green algae within bryophytes is thus not restricted to liverworts. The association is likely to be of ecological importance as it seems to occur in very acid habitats generally lacking blue‐green algae.Possible interrelations between the moss, the blue‐green algae and different types of bacteria are discussed.
Photoperiod and Temperature Interactions in Growth and Flowering of Strawberry
Authors: HEIDE OLA M. 
Published: April 2006

AbstractGrowth and flowering of strawberry cultivars were studied in controlled environments. Early cultivars adapted to marginal growing areas in Scandinavia initiated flower buds in all photoperiods including continuous light at temperatures of 12 and 18°C. At 24°C they remained vegetative in photoperiods above 14 or 16 h. The later cultivars ‘Senga Sengana’ and ‘Abundance’ did not initiate flower buds in 24‐h photoperiods at any of these temperatures. Their critical photoperiod changed from above 16 h at 12°C to about 14 and 13 h at 18 and 24°C, respectively. It is concluded that at high latitudes temperature is as important as photoperiod in controlling flowering in the strawberry.Stolon formation, petiole elongation, and leaf area growth were stimulated by high temperature and long days, usually with optima at 16 h and 18°C for petiole elongation and 16 h and 24°C for stolon formation. Although growth and flowering responses in general were opposite, the results indicate that they are to some extent independent. The photoperiodic growth responses were mainly of morphogenetic nature. Dry weight of stem and leaves was little influenced by photoperiod when the irradiance was kept constant.
Kinetics of Freezing Damage in Apple Bark and Pine Needles
Authors: BERVAES J. C. A. M. , KETCHIE D. O. , KUIPER P. J. C. 
Published: April 2006

AbstractThe time course of freezing damage in pine needles and in bark of apple trees was followed at different subzero temperatures. From these data the killing rate by freezing was determined for trees which differed in degree of cold hardiness.The activation energy of the killing reaction was also calculated. The killing rate was lowest in cold‐acclimated trees, but the activation energy of the killing reaction was very high indicating a high degree of structured water in the cells. Non‐acclimated trees showed uniform low values of the activation energy of the killing reaction at all subzero temperatures studied.It is suggested that intracellular supercooling could be a part of the mechanism of frost protection in cold‐acclimated apple trees within the – 30 to – 20°C range, but not in the –20 to –10°C range.
Phytoluminography: Imaging Plants by Delayed Light Emission
Authors: SUNDBOM E. , BJÖRN L. O. 
Published: April 2006

AbstractIt is demonstrated that photographic images of plants can be produced in the absence of external illumination using an image intensifier. The image is produced by the weak delayed light emission (afterglow) from photosynthetically active chloroplasts.We propose the use of such “phytoluminographs’ for the study and diagnosis at an early stage of disturbances due to parasites, mineral deficiency, herbicides, frost etc.
The Spectral Response of Light Dependent Chlorophyll b Formation
Authors: VIRGIN HEMMING 
Published: April 2006

AbstractDark grown seedlings of barley will obtain a high ratio chlorophyll a/chlorophyll b when exposed to intermittent light (1 min of incandescent light or one electronic flash every hour). Such material has been exposed to monochromatic light of different wavelengths for 1 h. The ratio a/b gets a minimum in light of 670 nm, indicating the highest rate of chlorophyll b formation at this wavelength. The possibility is discussed that the light absorber (and also precursor) could be a short‐lived chlorophyll a form, existing prior to the forms in the Shibata‐shift. Chlorophyll b formation in darkness is discussed from the findings that the rate of formation of chlorophyll b is higher in intermittent light than it should be, calculated from the rate in continuous light, where the saturation intensity is rather low.
The Role of Abscisic Acid in Flower Abscission of Lupinus luteus
Authors: PORTER N. G. 
Published: April 2006

AbstractThe role of abscisic acid in the control of flower abscission in Lupinus luteus L. was examined. Using a modified extraction and purification technique, endogenous abscisic acid levels in the upper flowers of an inflorescence were found to increase markedly some days before abscission could be detected. When abscisic acid was injected into flower‐bearing nodes or fed via the roots, no increase in the abscission rate was obtained at any position in the flowerhead. Application of abscisic acid to only the leaves resulted in a marked increase in flower abscission. The role of abscisic acid per se as a primary controlling factor of flower abscission in yellow lupin is questioned.
Site of in vivo Regulation of Tree Stem Elongation by Bark‐Banded Morphactins
Authors: NEUMANN PETER M. , BACKHAUS RALPH , DOSS ROBERT P. , SACHS ROY M. 
Published: April 2006

AbstractMorphactin ester applied as a bark band to stems of Monterey pine seedlings (Pinus radiata D. Don) at first stimulated and then inhibited the rate of stem elongation over a 20‐day period. The inhibition was caused by a direct action of morphactin on the shoot rather than by indirect action on the root system. 14C labelled morphactin applied to the bark accumulated in the shoot apices and the amount accumulated could be related to the inhibition of growth. More than 70% of labelled material isolated from roots and shoot apices was in the form of a metabolite similar to the carboxylic acid derivative of the morphactin ester. A preparation of 14C labelled acid derivative applied to the bark was translocated to the shoot apex and to the roots and inhibited stem elongation.
Phytochrome Control of Longitudinal Growth and Phytochrome Synthesis in Maize Seedlings
Authors: DUKE STEPHEN O. , NAYLOR AUBREY W. , WICKLIFF JAMES L. 
Published: April 2006

AbstractThe active, far‐red light absorbing, form of phytochrome was found to inhibit growth and phytochrome levels in the mesocotyl and coleoptile of 4‐ to 5.5‐day‐old seedlings of Zea mays L. Short, low‐irradiance red or far‐red light treatments were used to produce different proportions of active phytochrome at the end of highdirradiance white‐light periods, which left different levels of total phytochrome in the plants. After light treatments which left relatively high levels of spectrophotometrically assayable phytochrome in the seedlings, apparent phytochrome synthesis in the subsequent dark period was low regardless of the proportions of each form of the pigment present at the beginning of the dark period. In light treatments producing relatively low levels of assayable phytochrome, levels of apparent phytochrome synthesis in both red and far‐red treatments and differences between apparent synthesis in red and far‐red treatments were maximal. No simple correlation was found between growth and apparent phytochrome synthesis. However, growth and total phytochrome levels were positively correlated in both organs. Using a subtractive method of correlation, in which only phytochrome effects were plotted, strong linear relationships between phytochrome levels or longitudinal growth and Pfr levels were found in those light treatments leaving greater than 8% of dark control levels of phytochrome in the tissues. Using this technique non‐linear, inverse relationships between Pfr and apparent phytochrome synthesis was found, indicating that modes of phytochrome control over phytochrome synthesis and growth differ. Our results are consistent with the view that in vivo assays of “bulk’ phytochrome reflect levels and states of the physiologically active phytochrome fraction under our experimental conditions in maize.
Photoautotrophic Growth and Photosynthesis in Cell Suspension Cultures of Chenopodium rubrum
Authors: HÜSEMANN WOLFGANG , BARZ WOLFGANG 
Published: April 2006

AbstractA method is described for growing cell suspension cultures of Chenopodium rubrum photoautotrophically for prolonged periods of time. By using a two‐tier culture vessel the growth medium with the cells was separated from the CO2 reservoir. Definite CO2 concentrations were established by a K2CO3/KHCO3 buffer. Photoautotrophic growth in C. rubrum cell suspension cultures was correlated with the CO2 level. At 0.5% CO2 the cell cultures contained 68 μg chlorophyll/g fresh weight and showed an increase in fresh weight of about 80% in 18 days. At 1% CO2 an increase in fresh weight of 165% in 18 days was observed. The chlorophyll content rose up to 84 μg/g fresh weight.The photoautotrophic growth was also greatly influenced by the 2,4‐D content of the medium. Cell growth was enhanced by lowering the auxin concentration. Best growth was attained (210% increase in fresh weight) at 10−8M 2,4‐D.The photosynthetic activity of the cells was measured by the light dependent 14CO2 incorporation. At 0.5% CO2 the cell suspensions assimilated about 100 μmol CO2/mg chlorophyll × h. In the presence of 1% CO2 the light driven assimilation was raised up to 185 μmol CO2/mg chlorophyll × h. In both cases, the dark incorporation of CO2 was merely 1.8% of the values obtained in light.
Peroxidases in Relation to Removal of Dormancy and Germination of Apple Embryos
Authors: THÉVENOT CLAUDINE , GASPAR THOMAS , LEWAK STANISLAW , CÔME DANIEL 
Published: April 2006

AbstractThe changes in germination, peroxidase activity and isoperoxidase spectrum have been studied in apple embryos at 5°C (stratification) and at 20°C in the presence or absence of seed coats. The embryo dormancy is progressively released at 5°C, but not at 20°C. The peroxidase activity in embryos covered with seed coats is very low at 5°C as well as at 20°C which corresponds to a restricted number of isoenzymes. In isolated embryos the peroxidase activity increases significantly. This is due to an increase in both the number and the activity of the isoperoxidases and it is more pronounced at 20°C than at 5°C.The obtained results suggest that the soluble peroxidases are not involved in the process of the release of embryo dormancy. The variations observed are attributed to the growth process following germination, which can occur even at low temperature.
Metabolisme du γ‐aminobutyrate chez Agaricus bisporus III. La succinate‐semialdehyde:NAD(P)+ oxydoreductase
Authors: BALDY PIERRETTE 
Published: April 2006

AbstractMetabolism of γ‐Aminobutyrate in Agaricus bisporus. III. The Succinate‐Semialdehyde: NAD (P)+ Oxidoreductase.The succinate‐semialdehyde:NAD(P)+ oxidoreductase (E.C. 1.2.1.16) is responsible for the second step in the catabolism of γ‐aminobutyrate: the irreversible enzymatic conversion of succinic semialdehyde (SSA) to succinate. Succinate semialdehyde dehydrogenase was extracted from mitochondrial fraction of fruit‐bodies of Agaricus bisporus Lge. The mitochondrial pellet was sonicated and centrifuged at 110,000 g; the supernatant obtained was designated the “crude extract”. The enzyme was extremely unstable on storage, unless 1 mM EDTA and 20% glycerol were added.Kinetic studies were carried out at 30°C, and the formation of NADH or NADPH was followed by measuring increase of absorbance at 340 nm with a spectrophotometer. The dehydrogenase was completely inactive when the reaction was run in the absence of thiol and was more active with NAD+ than with NADP+. In the “crude extract” the activity with NADP+ had a pH optimum between 8.6 and 9.1 and the Km values for SSA and NADP+ were 2.0 × 10−4M and 1.4 × 10−4M respectively. The pH optimum with NAD+ was found between 8.6 and 8.8 and the Km value for SSA is 4.8 × 10−4M and for NAD+ 2.0 × 10−3M. With NAD+, the kinetic values (pH, Km) of the “crude extract” chromatographed on hydroxylapatite were unchanged. Inhibition by thiamine pyrophosphate (TPP) was uncompetitive with respect to NAD+, those by malate, ATP, ADP and NADPH non‐competitive and that by NADH competitive. These results and the fact that activity with NAD+ was lost more slowly than with NADP+ indicate the possibility of at least two mitochondrial succinate‐semialdehyde dehydrogenases, even though the activities of this enzyme assayed with NAD+ and NADP+ respectively were not able to be separated from each other by hydroxylapatite column chromatography.Some speculations on the metabolic regulation of this dehydrogenase and considerations on the significance of these results in the physiology of respiration in Agaricus bisporus Lge are given.
The Influence of a Strong Reducing Agent upon the Initiation of Callus from the Germinating Seedlings of Gossypium barbadense
Authors: KATTERMAN FRANK R. H. , WILLIAMS M. DALE , CLAY WILLARD F. 
Published: April 2006

AbstractHard compact calluses were initiated from the cotyledons of germinating cotton seedlings (Gossypium barbadense L.) by use of a strong reducing agent (dithiothreitol) and a higher than normal concentration of an auxin, naphthalene‐acetic acid. Dithiothreitol was superior to other compounds such as ascorbic acid and polyvinyl‐pyrrolidone in preventing a toxic brown coloration of the initiated callus. After eight to ten subculturings, some of the hard callus tissues (c. 2 to 3%) proliferated into larger and faster growing cells.
Determination of Prenylquinones in Green Photosynthetically Active Moss and Liver Moss Tissues
Authors: LICHTENTHALER HARTMUT K. , KARUNEN PIRJO , GRUMBACH KARL H. 
Published: April 2006

AbstractThe prenylquinone composition of two species of mosses (Polytrichum formosum Hedw., Sphagnum acutifolium Ehrh.) and two species of liver mosses (Lunularia cruciata (L.) Dum., Pellia epiphylla (L.) Cord.) was determined and compared with the chlorophyll content and the photosynthetic activity of the intact moss and liver moss tissues.

Green moss and liver moss tissues possess in principle the same prenylquinone composition as higher plants with plastoquinone‐9, α‐tocopherol, α‐tocoquinone and the phylloquinone K1 as main components. On a chlorophyll basis the lipoquinone levels are lower than in higher plants. Differences among the individual mosses as well as within one species only occur in the quantitative levels of the chloroplast prenylquinones, but there are no differences between musci and liver mosses.
There are differences in the maximal fluorescence of liver mosses and mosses. The variable fluorescence in turn, which is a measure of in vivo photosynthetic activity, is very similar for all examined species of mosses and liver mosses (values from 0.7 to 1.0) but somewhat lower than in leaf pieces of higher plants. DCMU blocks the variable fluorescence and the concomitant oxygen evolution in all mosses and liver mosses.
From the lower prenylquinone levels and the low values for the variable fluorescence it is concluded that mosses and liver mosses exhibit on a chlorophyll basis fewer reaction centres and electron transport chains than chloroplasts of higher plants.
Photosynthetic Response to Water Stress in Phaseolus vulgaris
Authors: O'TOOLE J. C. , OZBUN J. L. , WALLACE D. H. 
Published: April 2006

AbstractWater stressed Phaseolus vulgaris L. plants were monitored to detect the relationships between net photosynthesis, transpiration, boundary layer plus stomatal resistance, mesophyll resistance, CO2 compensation point, ribulose, 1,5‐diphosphate carboxylase activity and leaf water potential.At full expansion, the first trifoliate leaves of greenhouse grown bean plants were subjected to water stress by withholding irrigation. Gas exchange and enzyme activity of the central trifoliolate leaflets were monitored as leaf water potential decreased.Although increased stomatal resistance appeared to be the primary causal factor of reduced net photosynthesis, increased mesophyll resistance and decreased ribulose 1,5‐diphosphate carboxylase activity further documented the role of non‐stomatal factors.
Rise in the Ratio Heavy to Light Extractable Ribosomal RNA during Sprouting of Birdcherry Buds
Authors: EKELUND R. 
Published: April 2006

AbstractUsing the diethyl pyrocarbonate method, nucleic acids have been extracted from buds of European bird‐cherry (Prunus padus L.) in different developmental stages and analysed by sucrose gradient centrifugation. The ratio heavy to light ribosomal RNA was about I in extracts from dormant and non‐dormant but slowly growing buds. In extracts from sprouting buds the ratio was about 1.7. This increase probably reflects an increased extractability of heavy ribosomal RNA and may depend on a change of ribosomal structure during sprouting.