bluuebunny/crossref_metadata_2025 huggingface dataset:
Responsivencess of Intact and Scarified Seeds of Barbarea vulgaris to Gibberellic Acid and Changes in Phytochrome
Authors: TAYLORSON R. B.
Published: April 2006

Either red light or millimolar levels of gibberellic acid promoted germination of seeds of yellow rocket (Barbarea vulgaris R. Br.), and their effects were generally additive. Buffering the substrate pH at 3.0, addition of 20 mM nitrate to the substrate, preliminary incubation at 10 or 30°C, and brief scarification of the seeds increased responsiveness of the seeds to gibberellic acid. Scarification increased several thousandfold the sensitivity of the seeds to gibberellic acid. Pretreatment of the seeds in darkness or far‐red light did not lower their responsiveness to gibberellic acid. These results suggest that uptake of gibberellic acid is a limiting factor in the stimulation of germination in intact seeds and that there is only a minimal requirement for active phytochrome to express gibberellic acid action.
The Presence of Cellulose in Heterocyst Envelopes of Blue‐Green Algae and its Role in Relation to Nitrogen Fixation
Authors: GRANHALL ULF
Published: April 2006

The present study gives evidence for the presence of cellulose in the heterocyst envelope of blue‐green algae by means of electron microscopy, cellulase treatments and specific staining and demonstrates the role of this cellulose for the protection of the heterocyst nitrogenase during acetylene reduction. Experiments with lysozyme and cellulase suggest that nitrogen fixation in heterocystous blue‐green algae under aerobic conditions is functionally effective only when an intimate relationship exists between vegetative cells and heterocysts and both cell types have intact wall structures.
Characterization of Sulphate Uptake in Anacystis nidulans
Authors: UTKILEN HANS CHRISTIAN , HELDAL MIKAL , KNUTSEN GJERT
Published: April 2006

Sulphate uptake in the blue‐green alga Anacystis nidulans appears based upon an active mechanism with a Km of 0.75 μM and Vmax of 0.7 pmol/min × 106 cells. Sulphate uptake is competitively inhibited by thiosulphate and sulphite. The sulphate uptake has a pH optimum at 8 and a temperature optimum at 40°C. By increasing the extracellular sulphate concentration from 0.1 to 10 μM the sulphate pool in Anacystis was altered from 8.3, 10−5M to 5.9, 10−4M.
Polar Lipids of Spinach (Spinacia oleracea) Roots
Authors: SUKHIJA P. S. , SITAL J. S. , RAHEJA R. K. , BHATIA I. S.
Published: April 2006

The polar lipid components in the roots of spinach (Spinacia oleracea) plant were identified as phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, monogalactosyl‐diglycerides, digalactosyldiglycerides, polygalactosyldiglycerides, sulpholipids and three unknown glycosides. Phospholipids constituted only 10% of the polar lipid fraction and 90% was of nonphosphatidic nature. This latter fraction was highly unsaturated and contained linoleic acid as the major fatty acid component.
Salinity and the Hydraulic Conductance of Roots
Authors: SHALHEVET JOSEPH , MAAS E. V. , HOFFMAN G. J. , OGATA GEN
Published: April 2006

The effect of salinity on hydraulic conductance of intact roots of tomato (Lycopersicon esculentum Mill.) and sunflower (Helianthus annuus L.) was determined in split‐root experiments using salinized nutrient solutions. Experiments were conducted in controlled climate chambers under two or three relative humidity levels and four solution osmotic potential levels.

The relationship between water flux through roots (Jv) and total water potential difference between the leaves and the root medium (Δψ) was linear, usually with a small intercept. Thus, the root hydraulic conductance (L) was not affected by salinity within the range of fluxes obtained in these experiments, with L= 0.036 mm h−1 bar−1 for tomato and L= 0.0167 mm h−1 bar−1 for sunflower. Our results agreed with theoretical analysis of coupled water and ion uptake.

From Cl− and Na+ uptake data, the reflection coefficient (o) for tomato roots was calculated as 0.956, which was compatible with the near‐zero intercept. A large intercept for sunflower could not be readily explained.

Relative humidity strongly affected root growth, with more rapid growth under low humidity conditions. Transpiration of sunflower plants was reduced by 20% when the relative humidity was increased from 34% to 84%, whereas transpiration in tomato was reduced 50%.
Effects of Water Stress and Abscisic Acid on Transpiration Regulation in Wheat
Authors: NORDIN ÅSA
Published: April 2006

The transpiration response to recurrent light periods was studied'n water‐stressed wheat seedlings. Seedlings were stressed by three methods: addition of mannitol to the root medium, root cooling and drving of the roots in air. All three methods induced almost equal effects on transpiration regulation during alternating dark and light intervals. Exogenous abscisic acid supplied to the shoots of excised plants had qualitatively the same effect as water stress.

Water stress and ABA increased the time lapse between light‐on and the onset of transpiration increase and lowered the amplitude of transpiration increase in light. Weak light introduced before strong light shortened the delay times.
On the Relation Between the Effects of Auxin on Growth, pH and Potassium Transport
Authors: ILAN I. , SHAPIRA S.
Published: April 2006

The relation between the effects of auxin on growth, pH and potassium transport in hypocotyl segments of Helianthus annuus was studied. In a solution containing 20 mM Na2SO4 auxin‐induced growth was accompanied by an auxin‐induced pH drop in the medium. (NH4)2SO4, at the same concentration, brought about an almost complete abolishment of the effect of auxin on the pH. The magnitude of auxin‐induced growth was, however, only slightly reduced. This result does not confirm the hypothesis according to which the action of auxin on growth is a result of its effect on the pH.

In a solution containing 2 mM sodium phosphate buffer an inhibitory action of IAA on the release of potassium from the tissue was observed. Addition of 20 mM Na2SO4 to the medium brought about a complete abolishment of this effect. The magnitude of auxin induced pH drop was, however, similar in the two treatments. It was concluded that, although under suitable experimental conditions, a close relationship may exist between the effects of auxin on pH on K+ transport, the coupling between the two phenomena is not obligatory.
Seasonal Effects in the Hormonal Control of Growth in the Submerged Aquatic Macrophyte Ceratophyllum demersum
Authors: BEST ELLY (P. H.) , SOEKARJO R.
Published: April 2006

The season dependent changes in growth response to treatment with auxin or gibberellin were studied in the aquatic macrophyte Ceratophyllum demersum.

Control plants show, under experimental conditions, a maximum growth in length in February. In the same period most of the lateral buds appear. Growth of the lateral buds occurs later.

IAA causes a stimulation of growth in length from late November or December until February, in concentrations of 10−9M and 10−6M. There is almost no stimulation of lateral bud formation by IAA, only a slight increase from late November until December occurs by the lowest concentrations used. The highest concentration used, 10−4M, is in most cases supraoptimal for lateral bud formation; only when plants become dormant (August), this high dose may stimulate the process.

GA3, in concentrations of 10−9, 10−6 or 10−4M, exhibits a dose dependent increase of the response with respect to growth in length and lateral bud formation. The response occurs earlier than that for IAA: already early in November, or December, until February.

Growth of the lateral buds may show only a slight stimulation by IAA as well as GA in winter. From February until April all GA concentrations used could cause a small increase of the growth of sprouts. In the case of IAA, however, only the lowest concentration could cause a small increase.
Physiology of Polyploid Plants: Water Balance in Autotetraploid and Diploid Tomato under Low and High Salinity
Authors: TAL M. , GARDI I.
Published: April 2006

Diploid and autotetraploid plants of the cultivated tomato Lycopersicon esculentum cv. Lukullus (Luk) were studied under low and high salinity. Polyploids had a higher water content than diploid plants. Water content in both plant types decreased under salinity, the decrease being smaller in the polyploid plants. Dry weight of whole young plants decreased in both diploid and polyploid plants under salinity, the decrease being smaller in the latter. Transpiration of whole plants, grown in control solution, was lower in polyploid than in diploid plants and decreased more under salinity in the latter. Rate of change of water loss of detached drying leaves was similar in diploid and polyploid plants. Leaves of control diploid plants, however, lost more water per unit leaf area during the phase of stomatal closure apparently due to higher stomatal density. Polyploid plants had fewer but more open stomata per unit leaf area, under both control and saline conditions. Root pressure, determined only under control conditions, seemed to be higher in polyploid plants. No difference in Cl− concentration per unit leaf dry weight was found between diploid and polyploid plants grown in either control or NaCl solution.
Effects of Flavonoids on the Polar Transport of Auxins
Authors: STENLID GöRAN
Published: April 2006

The effect of some flavonoids on the polar transport of auxins was investigated in hypocotyl sections of dark grown seedlings of cucumber, Cucumis sativus L., by means of 14C labelled auxins. In experiments of 4–6 h duration quercitrin, morin, dihydroquercetin, naringin, sulfuretin and ferulic acid increased the polarity of the transport of indol‐3yl‐acetic acid (stimulation of basipetal, inhibition of acropetal transport). Naringenin, genistein and pinobanksin, on the other hand, decreased the polarity of this transport. For NAA no increase in the polarity of the transport could be observed, but all the substances tested inhibited the basipetal transport. There was no simple correlation between the effects on the polar transport and the effects on IAA oxidase.
Nitrate Reductase Activity in Calcifugous and Calcicolous Tomatoes as Affected by Iron Stress
Authors: BROWN JOHN C. , JONES WILLIAM E.
Published: April 2006

Calcicolous plants are generally more Fe‐efficient than calcifugous plants, because they respond to Fe stress by releasing H‐ions and “reductants” from their roots that causes Fe to become available. The objective of our study was to determine if differential response to Fe stress in calcicolous and calcifugous varieties affects nitrate reductase activity. T3238FER (Fe‐efficient) and T3238fer (Fe‐inefficient) tomato (Lycopersicon esculentum Mill.) cultivars were grown in nutrient solutions supplied with N as NH4+‐N plus NO3−‐N, and as NO3−‐N only. The chemical reactions induced by Fe stress concomitantly increased nitrate reductase activity in roots and tops of calcicolous, but not in calcifugous tomato. This nitrate reductase activity decreased, however, when Fe was made available to the plants. When Fe stress was eliminated by adding Fe, nitrate reductase activity was comparable in the two cultivars.
Free and Protein‐bound β‐Amylases of Barley Grain. Characterization by Two‐dimensional Immunoelectrophoresis
Authors: HEJGAARD J.
Published: April 2006

The β‐amylases of ungerminated barley (Hordeum distichum L. cv. Emir) were characterized by two‐dimensional immunoelectrophoretic techniques in order to elucidate the structure and physiological importance of the latent β‐amylase present in cereal grains. Two water‐soluble forms with partial immunochemical identity were detected. One of the enzyme forms was found to consist of aggregates between β‐amylase and an immunochemically distinct non‐active protein. Both β‐amylase and the protein could be released from the aggregates with β‐mercaptoethanol and, to some extent, with papain. β‐Mercaptoethanol increased the extractability of β‐amylase and of the non‐active protein. The aggregated form of β‐amylase was found to predominate in extracts made in the presence of papain. Possible functions of the non‐enzymatic protein in formation of latent β‐amylase is discussed.
Effect of Zinc Nutrition on Photosynthesis and Carbonic Anhydrase Activity in Cotton
Authors: OHKI K.
Published: April 2006

Photosynthesis, respiration, carbonic anhydrase activity and chlorophyll concentrations were correlated with zinc nutrition in cotton (Gossypium hirsutum L.). The critical zinc level during early plant growth was 13 μg/g dry weight in recently matured leaves (blade three). Photosynthesis and chlorophyll concentration required a minimum Zn of 13 and 14 μg/g dry weight, respectively, in blade three for maximum activity and synthesis. Respiration was not influenced by zinc status. Carbonic anhydrase activity increased curvilinearly as zinc status improved from deficiency to adequacy.
Descriptive Physiology and Biochemistry of the Abnormally Ripening Tomato Fruit (Lycopersicon esculentum) cv. Snowball
Authors: MIZRAHI YOSEF , DOSTAL HERBERT C. , CHERRY JOE H.
Published: April 2006

The relationships between different parameters of fruit ripening have been studied in tomato, Lycopersicon esculentum Mill. cv. Snowball. Chlorophyll degradation, fruit softening, polygalacturonase activity, titratable acids, and the rates of CO2 and ethylene evolution followed a normal pattern during ripening. However, fruits detached before reaching 100% development did not develop any red color and remained yellow‐white. Some fruits allowed to ripen on the plants developed a pale color with a normal pigment profile as scanned in an aceton/hexan extraction. Ethephon or propylene, applied to fruits, did not change these parameters but hastened the initiation of ripening.
Correlative Bud Inhibition and Abscisic Acid in Acer pseudoplatanus and Syringa vulgaris
Authors: DORFFLING KARL
Published: April 2006

Growing shoots of Acer pseudoplatanus and Syringa vulgairs were decapitated and defoliated (“treated”) in June 1972–1975. During the 2–3 weeks after treatment the contents of abscisic acid (ABA) in the out‐growing lateral buds at the upper‐most node as well as in the petiole stumps and nodes were determined by means of gas‐liquid chromatography. The concentration of ABA in lateral buds of intact shoots, calculated on a fresh weight basis, varied greatly from year but was consistently several times higher than in petioles and nodes. Defoliation and decapitation caused out‐growth of the lateral buds. This was accompanied by a sharp decrease in the ABA concentration, which finally reached the level of petiole tissue. The concentration of ABA in controls (“untreated”) decreased also, but to a smaller extent, and remained higher than in petioles. In petioles and nodes of treated as well as of untreated shoots, the ABA concentration did not change. The absolute amount of ABA in the buds of treated shoots after 2–3 weeks varied greatly, but was apparently not different from the amount in buds of untreated controls or in buds at the beginning of the experiment. Therefore, the decrease of the ABA concentration was mainly due to fresh weight increase. The results are discussed in relation to a possible role of ABA in correlative bud inhibition.
Concentration Dependent Uptake of Copper by Barley Roots
Authors: VELTRUP WERNER
Published: April 2006

The 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

Ethylene 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

The 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

In 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

In 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

Transpiration 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

In 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

Tobacco 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

During 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

Growth 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

Growth 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

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

The 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

Barley 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

This 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

Application 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

Experiments 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

Uptake 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

Seven‐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

Embryogenesis 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

Breakdown 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

In 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.
Ammonium and Potassium Uptake by Citrus Roots
Authors: HASSAN M. M. , VAN HAI TANG
Published: April 2006

Multiphasic 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

Growth 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

Experiments 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

Matric 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

Glucose‐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

The 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

It 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

Electron 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

Growth 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.