bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concentration Dependent Uptake of Copper by Barley Roots
Authors: VELTRUP WERNER 
Published: April 2006

AbstractThe time course of the uptake of copper by excised barley roots (Hordeum distichum L.) after 24 h shows other characteristics than after 2 h. A further investigation of the concentration dependent uptake of copper by intact roots and kinetic analysis demonstrates a biphasic pattern for 2 h uptake periods, and possibly monophasic behaviour for uptake periods of 20 min and 24 h.Plasmolysis data of cortex cells of barley roots indicate that concentrations above 80 μM Cu are unphysiological with regard to longer uptake periods.
Ethylene Accumulation in Flooded Plants
Authors: KAWASE MAKOTO 
Published: April 2006

AbstractEthylene concentration in sunflower (Helianthus annuus L.) cuttings increased 5‐fold within 6 h after submersion in distilled water and then declined. When only the basal half of the cutting was steeped in water, ethylene concentration was slightly over half the concentration of the completely submerged cutting. Ethylene concentration also increased when cuttings were wrapped with moist paper tissue. When wrapped with Saran transparent plastic film, ethylene concentration increased continuously for 12 h. When part of the stem of an intact plant was wrapped with Saran, ethylene also increased in that part of the stem. When wrapping was removed or submersion was discontinued, accumulated ethylene in the cuttings decreased, much faster from unwrapped cuttings than from previously submerged ones. During 3 h submersion, ethylene production rate in submerged cuttings was approximately 10% of that for the controls and over 97% ethylene escaped out of the control cuttings while only 22‐52% escaped from the submerged cuttings.Water content increased during submersion and decreased when submersion was discontinued. Water content did not change significantly during wrapping, but decreased when the cuttings were unwrapped. High water content in the submerged cuttings was apparently not related to the high ethylene concentration in the cuttings.Causes of ethylene increase in flooded plants were discussed and it was concluded that one of the first and major causes is the accumulation of ethylene in flooded portions of the plants due to the blockade of ethylene escape by water.
Activities of Various Peptidases in the Senescing Petals of Tulip
Authors: SOPANEN TUOMAS , CARFANTAN NICOLE 
Published: April 2006

AbstractThe hydrolysis of seven peptidase substrates by petal extracts of tulip (Tulipa sp. cv. Guillaume Tell) was assayed at four stages in the life cycle of the petals. During senescence pronounced increases from three‐ to sixfold took place in all the activities. At the same time the amount of soluble protein decreased about 75% and there was a simultaneous increase in free amino acids.The activity levels (on a dry weight basis) in the petals at the beginning of withering were rather similar to those present in normal leaves. Despite their different pH‐optima (5‐9), all the peptidases probably act in the mobilization of protein amino acids in the senescing petals.
Activities of Various Peptidases in the First Leaf of Wheat
Authors: SOPANEN TUOMAS , LAURIÈRE CHRISTIANE 
Published: April 2006

AbstractIn the first leaf of wheat (Triticum aestivum L. cv. Capelle) the content of soluble protein diminished to about 50% of the initial value between the 7th and the 19th day after sowing.In order to understand proteolysis in the leaves, the activities of several peptidases were measured in extracts from leaves at four different ages. The carboxypeptidase activities increased during the growth of the leaves, and then began to decrease. The activities of the alkaline peptidases increased, while that of the benzoyl‐DL‐arginine‐p‐nitroanilide (BAPA) hydrolysing enzyme decreased during the whole period studied. The “naphthylamidase” activities showed first a slow rise, but then leveled off. Two bands with naphthylamidase activity could be detected after disc electrophoresis.All the peptidases studied were present in the leaves at rather high concentrations. This indicates that they all may participate in the hydrolysis of leaf proteins into free amino acids.
Uptake and Effect of Abscisic Acid during Induction and Progress of Radicle Growth in Seeds of Chenopodium album
Authors: KARSSEN C. M. 
Published: April 2006

AbstractIn the seeds of Chenopodium album L. visible phenomena preceding the final protrusion of the radicle enable a clear distinction between the induction and the progress of growth inside the covering structures. The light‐dependent induction of radicle growth is not inhibited by exogenously applied abscisic acid (ABA). Experiments with 1‐14C‐ABA ruled out a lack of penetration of the hormone.However, ABA does inhibit the growth of the radicle before final protrusion. This inhibition and the uptake of 1‐14C‐ABA are enhanced at lower pH values, indicating absorption of the undissociated molecule. The uptake of labeled hormone strongly increases during the growth of the radicle. This increase is not merely a reflection of extra water uptake.Seeds of different degrees of dormancy contain equallly low levels of endogenous ABA. Much higher levels of ABA in the seeds were obtained by exogenous application of the hormone but these levels stills do not prevent the breaking the dormancy by light. It is concluded that ABA has no function in the regulation of dormancy in C. album seeds.
Water Potential Components, Stomatal Function, and Liquid Phase Water Transport Resistances of Four Arctic and Alpine Species in Relation to Moisture Stress
Authors: JOHNSON DOUGLAS A. , CALDWELL MARTYN M. 
Published: April 2006

AbstractTranspiration measurements of two alpine tundra species, Deschampsia caespitosa and Geum rossii, and two arctic tundra species, Dupontia fischeri and Carex aquatilis, were conducted under varying atmospheric and soil moisture stress regimes to determine if the stomatal response to water stress may play a role in the local distributions of these species. Under low soil moisture stress, stomata of the species restricted typically to wet meadow areas, Deschampsia and Dupontia, did not exhibit closure until leaf water potential declined. However, when soil moisture stress was low and atmospheric stress increased, Geum and particularly Carex exhibited partial stomatal closure before leaf water potential dropped, suggesting a direct response of the stomata to the vapor pressure gradient between the leaf and the atmosphere. Lower liquid phase water transport resistance from the soil to the leaves may also reduce the development of leaf moisture stress in Geum. Furthermore, Geum and possibly Carex appeared to undergo less of a loss of leaf turgor when leaf water potential decreased. This response may serve to maintain leaf cell turgor and to abate the reduction in leaf enlargement.
L'induction du rythme endogène de sporulation chez Aspergillus niger: Rõles du rapport glucose/potassium et de micro‐éléments
Authors: JEREBZOFF S. , JEREBZOFF‐QUINTIN S. , LAMBERT E. 
Published: April 2006

AbstractIn Aspergillus niger Van Tieghem cultivated on a synthetic medium, the induction of an endogenous rhythm of sporulation and its perpetuation depend on the glucose K+ balance in the medium, an excess of one of them suppressing the oscillations. In its inducing effect on the rhythm K+ is partially replaced by Rb+, but not by Na+, Li+ or Cs+. While the glucose K+ balance is favourable for the manifestation of the rhythm, the addition of increasing levels of Na+, Li+ or Cs+ do not modify the period length. Nevertheless, at 0.3 M of Na+ or Li+ and 0.03 M of Cs+ rhythm disappears. The amplitude of oscillations depends on the level of the micro‐elements furnished, especially on Mn2+. EDTA (1 × 10−3M) inhibits the rhythm.
Endogenous Gibberellins and Growth of Tobacco Callus Cultures
Authors: LANCE BARBARA , REID DAVID M. , THORPE TREVOR A. 
Published: April 2006

AbstractTobacco callus grown under a range of conditions for different lengths of time contained various levels of gibberellin‐like substances. Culture conditions, viz: light versus darkness and the quantity of cytokinin in the medium, affected the amount of gibberellins found in the tissue. These culture conditions were also important in controlling growth rate of the callus and modified the ability of the tissue to respond to exogenous gibberellins. Furthermore, substances which are known to inhibit gibberellin biosynthesis and also thought to block gibberellin action in some cases, were found to reduce the rate of growth. These data support the idea that endogenous gibberellins may be important in the control of the normal growth of tobacco cells in culture.
Seasonal Changes in the Cytokinin Content of Ginkgo biloba Leaves
Authors: VAN STADEN J. 
Published: April 2006

AbstractDuring the course of the growing season Ginkgo biloba leaves undergo both quantitative and qualitative changes in their cytokinin content. In young expanding leaves the major cytokinins cochromatograph with zeatin and zeatin riboside. In mature and aging leaves most of the cytokinin activity was due to slow moving compounds (paper chromatography) which could be hydrolysed by β‐glucosidase. After hydrolysis the active compounds co‐chromatographed with zeatin and zeatin riboside respectively. This indicates that both zeatin glucoside and zeatin riboside glucoside are present in the mature leaves. It is suggested that these glucosides are formed when the xylem transported cytokinins are metabolized (inactivated) in the leaves.
Changes of Exponential Growth Rates in Relation to Differentiation of Geotrichum candidum in Submerged Culture
Authors: KIER I. , ALLERMANN K. , FLOTO F. , OLSEN J. , SORTKJAER O. 
Published: April 2006

AbstractGrowth and differentiation of the imperfect fungus Geotrichum candidum were followed in submerged cultures containing a simple synthetic glucose salt medium. Uptake of glucose, ammonium and oxygen from the medium were measured during the entire growth perod. In 0.1% glucose the fungus grows with one exponential growth phase until all the glucose has been consumed. The arthrospores are formed in the stationary phase. In 0.5% glucose the growth curve has two exponential growth phases, one with a doubling time of 1.8 h and a second one with a doubling time of 4.9 h. The second exponential growth phase, which starts when less than 15% of the glucose and less than 30% of the ammonium have been consumed, is shown to be the sporulation phase. During this growth phase the oxygen saturation in the culture remained constant at about 50%.
Control of Nutrient Solution pH with an Ion Exchange System: Effect on Soybean Nodulation
Authors: HARPER J. E. , NICHOLAS J. C. 
Published: April 2006

AbstractGrowth and nodulation response of soybean (Glycine max (L.) Merr.) to various single nitrogen sources in solution culture is confounded by unequal shifts in solution pH. A recirculating ion exchange system was designed in which a cation exchange resin (Amberlite IRC 50) was used to control the pH of solutions in which soybeans were grown. Nutrient solution pH levels were established at range extremes of 9.0 to 3.7 with 100% Ca2+ or H+ forms of resin, respectively. Intermediate pH levels were established by varying the ratio of Ca2+ to H+ forms of resin. The system is capable of maintaining pH within 0.5 to 0.9 units of the initial pH over a two‐week growth period of soybeans with either nitrate‐ or urea‐N sources. In the absence of the resin column, pH of the urea nutrient solution rapidly declined to less than pH 4 which resulted in depressed plant nodule development. The optimum pH range for nodule mass and N2 fixation (measured by acetylene reduction) was between 5.2 and 7.0 with urea nutrition. Both nitrate‐ and ammonium‐N sources were inhibitory to acetylene reduction in comparison with urea which allowed extensive nodule development and activity.
Relation entre réaction géotropique et évolution du statenchyme dans la racine d'Asperge
Authors: PERBAL GÉRALD , RIVIÈRE SIMONNE 
Published: April 2006

Abstract Relationship between the Geotropic Response and the Evolution of the Statenchyma in Roots of Asparagus officinalis. The evolution of the statenchyma in roots of Asparagus of ficinalis seedlings, grown in obscurity, was followed during the first 17 days. After 7 days of etiolation, a decrease of both the average diameter of the amyloplasts and the average number of these organelles was observed in the central root cap cells. If the seedlings were illuminated (with white light) from the 7th day, the average number of statoliths increased rapidly in the statocytes. The volume of these organelles undergoes the same variation in etiolated and in illuminated plants.The initial rate of curvature (Vi) of the roots (stimulated in a horizontal position) and the volume of amyloplasts (Vac) in their caps were analysed as a function of the time of germination in obscurity (from the 8th to the 17th day). It was found that Vi increased as a linear function of the logarithm of Vac, which confirms that the weight of the amyloplasts of the statocytes may play a role in the geotropic stimulation of the roots.
Transport and Distribution of 14CO2 Assimilate in Lolium perenne in Response to Varying Nitrogen Supply to Halves of a Divided Root System
Authors: BARTA A. L. 
Published: April 2006

AbstractThe movement of 14C assimilate from shoots to roots and its subsequent metabolism in the root of Lolium perenne L. was studied using variable N nutrition supplied to halves of a divided root system. Half of the N‐deficient root system was supplied with either high NO3‐N or high NH4‐N for 16 hours or 6 days before 14CO2 labeling of the shoots.The distribution of 14C in sugars, ethanol‐soluble nitrogen and organic acids in roots appeared to be related to the N content of the tissue. Supply of high NO3‐N for 6 days resulted in significant internal translocation of N into the low N supplied root half. Both root halves also had similar patterns of 14C distribution among soluble and insoluble metabolites. However, NH4‐N supply for 6 days did not result in a significant increase of N in the low N supplied roots, thus only the high NH4‐N supplied roots displayed stimulated sugar metabolism, similar to that in both root halves in the high NO3‐N supply treatment.Percent transport of 14C assimilates from shoot to root was influenced by form and level of N supplied to root halves. Root halves supplied with either high N source for 6 days accumulated greater amounts of 14C assimilate than the corresponding low N root half. However NH4‐N supply appeared to make roots stronger sinks since NH4 supply resulted in significantly greater 14C accumulation in both the high NH4 supplied and the low N root halves than did NO3‐N supply in corresponding root halves.The data suggest that factors other than root metabolism, such as N mediated metabolism in the shoot, may also influence the percent transport of assimilates to the root. Internal distribution of the incoming assimilate within the root system could be regulated by the metabolic activity or assimilate demand of the roots.
Barley Leaf Unfolding under Mixtures of Red and Blue Light
Authors: DEUTCH BENTE 
Published: April 2006

AbstractBarley leaf unfolding is stimulated by mixed red and blue light. However, the stimulation from mixed light is attenuated when compared with the stimulation from red light alone, particularly for low intensities of the mixed light and for short irradiation times. For higher light intensity mixtures of red and blue light and for longer irradiation times, the blue light enhances the stimulation from red light and vice versa. This supports the assumption that the blue light effect in this case is also mediated by the phytochrome system. Furthermore the present findings point to the possibility of competitive reactions caused by red and blue light in the excitation of phytochrome.
The Effect of Gamma‐Irradiation on Lettuce Seedling Elongation
Authors: YEALY LYNN P. , STONE BENJAMIN P. 
Published: April 2006

AbstractThis study was initiated to determine the effects of gamma‐irradiation on lettuce hypocotyl elongation and ribosomal RNA synthesis relative to gibberellic acid and 5‐fluorouracil treatment. Exposure of seeds to gamma‐irradiation inhibited hypocotyl elongation of seedlings grown in continuous light and darkness. The presence of 5‐fluorouracil in the incubation medium significantly retarded hypocotyl elongation; however, gibberellic acid was stimulatory to elongation in seedlings grown from irradiated and un‐irradiated seeds. The synthesis of ribosomal RNA was selectively depressed by 5‐fluorouracil while gibberellic acid stimulated incorporation of 3H‐uridine into ribosomal and transfer RNA. The observed response implies that ionizing radiation is effective in decreasing the synthesis of ribosomal and transfer RNA which is correlated with lettuce hypocotyl elongation.
Influence of Gibberellic Acid on Growth and Endogenous Auxin Level in Epicotyl and Hypocotyl Tissues of Normal and Dwarf Bean Plants
Authors: JINDAL KRISHAN KUMAR , HEMBERG TORSTEN 
Published: April 2006

AbstractApplication of gibberellic acid to the apex of dwarf bean plants (cv. Alabaster) stimulated the elongation growth of epicotyl and hypocotyl but showed no significant effect on elongation growth in a normal cultivar (‘Blue Lake’). Gibberellin‐treatment of dwarf plants was characterized by about twofold increase in the level of endogenous auxin. Maximum increase in IAA level was observed after 48 h of GA treatment. There was less increase in IAA content in normal bean plants. — Gibberellin treatment to excised epicotyl and hypocotyl sections of either dwarf or normal cultivar showed no effect on elongation growth. However, a considerable increase in the auxin level was observed in the sections of the dwarf cultivar. The maximum effect occurred with only 1 h incubation in basal medium containing gibberellin. — The indolo‐α‐pyrone spectro‐fluoremetric method for IAA determination was used.
Attachment of Rhizobium to Legume Roots as the Basis for Specific Interactions
Authors: CHEN ANN‐PING T. , PHILLIPS DONALD A. 
Published: April 2006

AbstractExperiments were conducted to elucidate the basis of the observation that different strains of Rhizobium infect particular legumes. Rhizobia specific for a variety of legumes were grown with 13PO2−4 and exposed to pea roots (Pisum sativum L.), R. leguminosarum 128C53, which nodulates pea, did not attach to the roots in greater numbers than those strains of rhizobia incapable of infecting pea roots. A complex of R. leguminosarum 128C53 conjugated to a fluorochrome‐labeled antibody exhibited a striking attachment to the tips of pea root hairs, where infection normally occurs, but this fluorescent complex also bound to the root hairs of Canavalia en siformis DC., Lupinus polyphyllus Lindl., Trifolium pratense L., and Medicago sativa L., which are not infected by this bacterium. A reproducible, quantitative technique developed for studying interactions between fluorochrome‐labeled lectins and rhizobia revealed no relationship between lectin‐Rhizobium interactions and the capacity to infect a plant. The data are interpreted as suggesting that simple attachment of Rhizobium to a legume root is not the basis of host‐symbiont specificity in this system.
Fluxes of Na+, Rb+ and Cl‐ Ions in Excised Roots of Sugar Beet Seedlings
Authors: SZYNKIER K. , KYLIN A. 
Published: April 2006

AbstractUptake and fluxes of sodium, rubidium (instead of potassium), and chloride ions in segments of 3‐week‐old sugar beet roots were studied. Radioactive 22Na, 86Rb and 36Cl were used for labelling of the ions. Compartmental analysis was used to obtain the fluxes and concentrations in the cell compartments. The passive or active character of the movements was examined by the Ussing‐Teorell equation and compared with electropotential measurements.In the case of sodium, net flux was in the outward direction over both tonoplast and plasmalemma, but the active components were directed away from the cytoplasm. Potassium was close to equilibrium. Chloride was actively transported from the medium to the cytoplasm, and — contrary to observations in other systems — from the vacuole to the cytoplasm. This unusual situation may be caused by a loss of sugar, both by lowering the energy supply and by formation of organic acids.
Stomatal Response of Citrus jambhiri to Water Stress and Humidity
Authors: KAUFMANN MERRILL R. , LEVY YOSEPH 
Published: April 2006

AbstractSeven‐month‐old rough lemon (Citrus jambhiri Lush.) seedlings were subjected to high‐ and low‐humidity treatments (vapor pressure deficits of 8.0 and 19.6 mbar) for 3 weeks. Half of each group was well supplied with water and half was subjected to a series of three drying cycles in which xylem pressure potential fell to below −25 bar. The relationship between leaf conductance and xylem pressure potential was similar during each drying phase and was unaffected by atmospheric humidity. Several days elapsed after rewatering before normal stomatal opening occurred. When all the plants were subsequently kept well watered, leaf conductances decreased as the leaf‐to‐air vapor pressure difference was increased. However, the conductances of previously stressed plants were lower than those of unstressed plants, and consequently previously stressed plants had lower transpiration rates.
Embryogenesis and Differentiation in Nigella sativa Leaf Callus in vitro
Authors: BANERJEE SABITA , GUPTA SUKUMAR 
Published: April 2006

AbstractEmbryogenesis occurred in Nigella sativa L. (Fam. Ranunculaceae) leaf callus tissue when coconut milk was replaced from the Murashige and Skoog's (MS) medium by casein hydrolysate. On MS + IAA (0.5 mg/l) + casein hydrolysate (100 and 500 mg/l) medium, tissue gained a capacity of growing embryoids for a pro‐longed culture period. At a concentration of 1000 mg/l casein hydrolysate suppressed the differentiating capacity after the fifth subculture. 2.4‐D and kinetin had inhibitory effects on morphogenesis. Histology of the differentiated tissue revealed that the origin of roots, shoot buds and leaves were from groups of meristematic cells whereas embryoids were initiated by the repeated division of a single cell.
Respiration and Utilization of Storage Materials in Wild and Cultivated Pea Seeds during Germination
Authors: MARBACH IRITH , MAYER A. M. 
Published: April 2006

AbstractBreakdown of storage materials, oxygen uptake, respiratory control and ADP/O ratios in the cotyledons of the garden pea P. sativum and in the wild pea P. elatius were compared. Starch and protein degradation was slower in P. elatius than in P. sativum. Embryo growth began later in the wild pea. However, in the garden pea the mitochondria were uncoupled after about 48 h of germination, while in P. elatius the ability to carry out oxidative phosphorylation was maintained for 4 days. The respiratory control ratio was higher in the wild pea at all stages of germination and a steady level of oxygen uptake was maintained in the cotyledons for at least 3 days.The findings are discussed in relation to the ecological requirements for germination in the two species.
The Effect of Single and Repeated Gibberellic Acid Treatment on Internode Number and Length in Dwarf Peas
Authors: SPIKER STEVEN , MASHKAS AMINA , YUNIS MUAZZAZ 
Published: April 2006

AbstractIn long‐term experiments comparing the results of single and repeated treatment of dwarf peas with gibberellic acid, both once‐treated and weekly‐treated plants formed more internodes than control plants. The initial high rate of internode formation in the once‐treated peas dropped rapidly reaching that of control plants three weeks after treatment. Weekly‐treated plants maintained a higher rate of internode formation.The ratio of internode lengths of once‐treated plants to control plants was high (over 3) for the internodes which were elongating during or shortly after the single treatment but dropped rapidly and approached unity in later‐developed internodes. The ratio of internode lengths of weekly‐treated plants to control plants continued to be high throughout the experiment.