bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Nutrients and Light on Growth and Root Formation in Pisum sativum Cuttings
Authors: ELIASSON LENNART 
Published: April 2006

AbstractCuttings obtained from seedlings of Pisum sativum L. were rooted in water solution. Shoot growth continued after excision and shoot length increased considerably before roots emerged. Increase in dry weight was strongly dependent on light supply. Continued growth was dependent on supply of mineral nutrients to the rooting solution.Mineral nutrients had no or slight influence on the number of roots formed on cuttings from stock plants grown in fertilized soil, but the growth in length of the roots was dependent on the presence of calcium in the solution. Root formation was dependent on photosynthetic products formed after excision. No roots were formed on cuttings kept in the dark. The number of roots increased with increasing irradiance given to the leafy part of the cutting. At a low level of irradiance sucrose supply through the rooting medium increased the number of roots. Light given to the basal part of the cuttings had a strongly inhibitory effect on the number of roots formed. It is concluded that the carbohydrate level easily becomes a limiting factor for root formation in growing pea cuttings. Availability of mineral nutrients influences in the first place the growth of the shoots.
Diurnal and Seasonal Changes in Water Balance of Acer saccharum and Betula papyrifera
Authors: PEREIRA J. S. , KOZLOWSKI T. T. 
Published: April 2006

AbstractDiurnal and seasonal changes in plant water potential, leaf diffusion resistance, and stem radial changes of Acer saccharum and Betula papyrifera trees were studied in northern Wisconsin during the 1974 and 1975 growing seasons. Water potential decreased during the day, following relatively high values in the morning, and increased in the late afternoon and evening. Diurnal patterns and actual values of water potential varied with species, soil water availability, and factors influencing transpiration (e.g., solar radiation, vapor pressure deficit, and transpiration flux density). When plant water deficits were not severe, leaf resistance of both species was rather stable during the day. During severe droughts, however, leaf resistance increased (stomata closed) during the day when light intensity was high. Leaf resistance at high light intensity was higher in Acer than in Betula. Stomatal closure with decreasing light intensity varied between species and among Acer trees. Tree stems of both species shrank during the day, as internal water deficits developed, and they expanded as trees rehydrated during the night. Stems of Acer shrank more than those of Betula. The amount of daily stem shrinkage increased as the season progressed if the trees were not under severe water deficits. During severe droughts the amount of diurnal stem shrinkage decreased. Shrinkage of stems lagged behind water potential changes by 1 to 2 h in Acer and less than 1 h in Betula. The relationship between stem radius and leaf water potential was not constant throughout the growing season.
Regeneration of Mesophyll Protoplasts Isolated from Dihaploid Clones of Solanum tuberosum
Authors: BINDING H. , NEHLS R. , SCHIEDER O. , SOPORY S. K. , WENZEL G. 
Published: April 2006

AbstractProtoplasts have been isolated from leaves of shoot cultures of six dihaploid clones of Solanum tuberosum L. (2n = 2x = 24). In the KM medium (Kao and Michayluk 1975), sustained cell divisions were obtained in up to 50% of the plated protoplasts of four clones, whereas only a few divisions occurred in the other two clones. The first mitosis appeared 2–8 days after plating, dependent on the clones. In the clones showing sustained cell divisions, a protoplast titre of about 5 × 103 per ml turned out to be optimal. The culture conditions for protoplasts of one of the poorly growing clones, clone H2 140, have been improved using modified KM media, plating at a concentration of as high as 5 × 104 cells per ml, and subsequent diluting at intervals 5 days. The dilutions were carried out with media containing 0.25% agar. Up to 60% of the plated protoplasts underwent divisions within 10 days under these conditions. After about 15 days, the regenerants were transferred onto media inducing organogenesis. Shoots and roots were formed on modified media MS (Murashige and Skoog 1962) and B5 (Gamborg et al. 1968). Plants have been regenerated in four of the investigated clones. Countings of chromosomes revealed a satisfactory stability of the karyotype in shoot culture and protoplast regeneration.
The Effect of Abscisic Acid (ABA) on the Respiration and Uptake of Inorganic Phosphate by Potato Pith Discs
Authors: HEMBERG TORSTEN 
Published: April 2006

AbstractAbscisic acid (ABA) stimulates the oxygen uptake and inhibits the uptake of inorganic phosphate of discs of potato pith. It is assumed that ABA acts as an uncoupler of the oxydative phosphorylation in agreement with what was shown earlier for β inhibitor from resting potato peelings. The effect is probably not directly related to growth phenomena.
Cytokinin Activity in Lupinus albus
Authors: DAVEY J. E. , VAN STADEN J. 
Published: April 2006

AbstractThe cytokinin content of the root exudate and leaves of fruiting white lupin plants (Lupinus albus L.) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence. Up to 8 weeks after anthesis the level of cytokinins in the root exudate increased. However, at 10 weeks after anthesis insufficient sap was produced for analysis. Cytokinins co‐eluting with zeatin and zeatin riboside were detected in the root exudate after fractionation on Sephadex LH‐20. The cytokinin levels in the mature leaves steadily increased up to 8 weeks after anthesis and thereafter remained relatively constant. Three peaks of activity, co‐eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in the leaf extracts. The level of glucoside cytokinins in the leaves was high at 8 and 10 weeks after anthesis. Paper chromatography of extracts of fruits collected at 2 weeks after anthesis indicated that as fruit development proceeded there was a build up of cytokinin in this region of the plant. It is suggested that, in the white lupin, the cytokinins translocated to the shoot are accumulated in the leaves and in the fruits and that it is only later when there is a considerable decrease in sap (10 weeks after anthesis) production that a decreasing supply of cytokinins leads to shoot senescence.
Cytokinin Activity in Lupinus albus
Authors: DAVEY J. E. , VAN STADEN J. 
Published: April 2006

AbstractThe cytokinins in the pod wall and seeds of the white lupin (Lupinus albus L.) were investigated at 4, 6 and 8 weeks after anthesis. The level of cytokinin in the pod walls increased up to 8 weeks after anthesis, but then declined at 10 weeks. Fractionation on Sephadex LH‐20 shows that during the early stages of pod development cytokinin activity was associated mainly with substances co‐eluting with zeatin and zeatin riboside. However, in the later stages of pod wall growth an increase in activity was noted not only in these cytokinins but also in the cytokinins co‐eluting with the glucoside cytokinins. The level of cytokinin activity in the seeds decreased over the 10‐week experimental period. After fractionation on Sephadex LH‐20 four peaks of cytokinin activity were recorded in extracts of 6‐week‐old seeds. Two of these peaks co‐eluted with zeatin and zeatin riboside. The remaining peaks co‐eluted with the nucleotide and glucoside cytokinins. Only two peaks of activity co‐eluting with zeatin and zeatin riboside on Sephadex LH‐20 were recorded in 10‐week‐old seeds. Dihydrozeatin and its riboside also appear to be present in the seeds extracts. The significance of the quantitative and qualitative changes in the cytokinins of the seeds and pod walls is discussed.
Inter‐organ Control of Greening in Etiolated Cucumber Cotyledons
Authors: DEI MITSURU 
Published: April 2006

AbstractInter‐organ control of greening in etiolated cucumber (Cucumis sativus L. cv. Aonagajibae) cotyledons was investigated. Four‐ or six‐day‐old excised or intact etiolated cucumber cotyledons were illuminated under aerobic conditions. Excised cotyledons without hypocotyl hooks produced chlorophyll without a prolonged lag phase and the rate of chlorophyll formation was not depressed if they were illuminated immediately after excision. If the excised cotyledons were incubated in the dark before illumination, chlorophyll accumulation at the end of 6 h of continuous illumination was remarkably lowered as the dark period lengthened, especially in 6‐day‐old cotyledons. The rapid loss of chlorophyll‐forming capacity of excised cotyledons during dark preincubation suggests a stimulatory effect of hypocotyls on the greening in cotyledons. The treatment of excised cotyledons with bleeding sap in the dark for 18 h resulted in the promotion of chlorophyll formation during subsequent continuous illumination. Partial fractionation of bleeding sap with organic solvents and paper chromatography indicates that the active substances showed the same behavior as cytokinins. These facts add weight to the hypothesis that cytokinins from roots flow into cotyledons and stimulate greening.
Changes in Malate Content and in Enzymes Involved in Dark CO2 Fixation during Growth of Acer pseudoplatanus Cells in Suspension Culture
Authors: VANDERHOVEN C. , ZRŸUD J.‐P. 
Published: April 2006

AbstractIt has been reported in some cases that an increase in pCO2 stimulates growth in diluted cell suspension cultures. Experiments have been designed to study the pattern of dark CO2 fixation in sycamore cells grown in liquid suspension and to correlate this pattern with the culture growth phases. Comparisons were made between enzymatic activities, CO2 incorporation, malic acid content during lag, logarithmic and stationary phases of growth. Malic enzyme (NADP‐dependent) was at its maximum activity during early logarithmic growth phase, when biosynthetic capacities were at the highest. Phosphoenolpyruvate‐carboxylase activity was strongly correlated with the ability of cells to fix CO2. Malic acid content decreased soon after transfer of the cells to a new medium and increased at the onset of stationary phase. Under optimal conditions, the CO2 incorporation pattern did not change during growth, with an almost identical incorporation in the basic (amino acids) and acidic (organic acids) fractions. These observations have been discussed in relation to a possible effect of increased pCO2 in the cell environment.
Senescence‐Related Changes in the Lipid Transition Temperature of Microsomal Membranes from Algae
Authors: THOMPSON J. E. , MAYFIELD C. I. , INNISS W. E. , BUTLER D. E. , KRUUV J. 
Published: April 2006

AbstractThe phase behaviour of smooth microsomal membranes from senescing cultures ofScenedesmus quadricaudahas been examined by wide‐angle x‐ray diffraction. The algae were grown in Bristol's medium at 22°C under continuous illumination. The transition temperature, taken to be the highest temperature at which crystalline (gel) phase lipid can be detected, increased with culture age from a low of 0°C for young cultures to a high of about 70°C for 140‐day‐old cultures. This indicates that for young cultures the membrane lipid is entirely liquid‐crystalline (fluid) at physiological temperatures, but as the cultures age portions of the lipid become crystalline. The increase in transition temperature showed a close temporal correlation with loss of chlorophyll and loss of protein per g dry weight, and can thus be construed as an index of senescence. The unsaturated to saturated fatty acid ratio of the membrane lipid, while fluctuating with culture age, did not show any consistent trend that could be related to the change in transition temperature. Thus the formation of gel phase lipid does not appear to be due to a change in fatty acid saturation.
Application of the Entropy‐Enthalpy Relationship in Water Transport through Plant Roots
Authors: KUIPER F. , KUIPER P. J. C. 
Published: April 2006

AbstractWater transport through plant roots is determined by a single layer of cells, so that water passes through a plasmamembrane‐cytoplasm‐plasmamembrane system. The water transport shows an exponential relationship with temperature in two phases with an abrupt transition. The Arrhenius activation parameters log A and E are calculated for the two phases of water transport below and above the transition temperature. Between log A and E two linear and parallel relationships are observed, one for each phase of water transport. The difference of log A between these two relationships is a measure for a change in entropy in cell water structure at the transition temperature. The change in entropy was small (13.4 J · mol−1· K−1) in comparison to the difference in activation energy E for water transport above and below the transition temperature. The role of the plasmamembrane and cytoplasm in determining the cell water structure is discussed.
The Antiranspirant Effect of Acetylsalcylic Acid on Phaseolus vulgaris
Authors: LARQUÉ‐SAAVEDRA A. 
Published: April 2006

AbstractA series of experiments were carried out in order to elucidate whether acetylsalicylic acid (ASA) fed via petioles to beans could affect transpiration rate. In comparison with the water control it was found that a 10−3M ASA reduces transpiration as much as 43%, a reduction equivalent to 5 × 10−5M abscisic acid (ABA). Preliminary kinetics on the ABA, ASA and the water control on transpiration rate are presented and the results discussed.
The Uptake of Cytokinins by Protoplasts and Root Sections of Brassica campestris
Authors: DEKHUIJZEN H. M. , BOSSEN M. E. , VONK C. R. 
Published: April 2006

AbstractThe effect of cytokinins was studied on the incorporation of 14C‐labelled precursors into the nucleic acid fraction of protoplasts isolated from callus or roots of Brassica campestris. Protoplasts from callus and roots took up 14C‐uridine from the incubation medium and incorporated this precursor into the ribonucleic acid fraction during the experimental period of 16 h. Low concentrations of kinetin (10−8‐5 × 10−6M) did not stimulate the incorporation, and kinetin inhibited this process at higher concentrations (5 × 10−5M). This result led to an investigation on the uptake of cytokinins by protoplasts of roots. In contrast to a rapid uptake of radio‐actively labelled adenine and uridine. protoplasts from roots took up only small amounts of labelled kinetin. zeatin, zeatin riboside and zeatin nucleotides from the incubation medium.Root sections took up far more adenine and kinetin than protoplasts from roots. The ratio between the amount of kinetin taken up and applied was much higher for the sections than for protoplasts, indicating that intact root cells took up kinetin far more rapidly than protoplasts. It is suggested that the plasmalemma and cell wall play an essential role in the uptake of cytokinins or that the differences in the uptake rates are related to differences between the rates of metabolism of cytokinins in root sections and in protoplasts.
Effect of Storage in Darkness and in Light on the Content of Membrane Lipids of Potato Tubers
Authors: LILJENBERG CONNY , SANDELIUS ANNA STINA , SELSTAM EVA 
Published: April 2006

AbstractThe lipid composition of tubers from the potato varieties Bintje and Desirée was investigated during storage. Storage in total dark ness after harvest gave only small changes in the amounts of triglycerides. monogalactosyl diglycerides and digalactosyl digtycerides. Storage in light resulted in changes in these lipids and in their fatty acid composition. The absolute amount and the relative content of linolenic acid in the galactolipids increased. A simultaneous and equivalent decrease in the percentage of linoleic acid took place without any marked percentage changes in the other major fatty acids. The light induced changes of the lipids, which occur simultaneously with greening of the tuber, are discussed and related to the development of thylakoid membrane systems in the plastids.
Accelerated Nitrate Uptake in Wheat Seedlings: Effects of Ammonium and Nitrite Pretreatments and of 6‐Methylpurine and Puromycin
Authors: TOMPKINS GARY A. , JACKSON WILLIAM A. , VOLK RICHARD J. 
Published: April 2006

AbstractThe experiments reported herein had two objectives. One was to determine if the slow rate of nitrate uptake which occurs upon initial exposure of nitrogen‐depleted wheat (Triticum vulgare cv. Knox) plants to nitrate was the result of insufficient reduced nitrogen. The second was to determine the impact of restrictions in ribonucleic acid or protein synthesis on both nitrate uptake and nitrate reduction.Pretreatments of 14‐day‐old seedlings for a few hours in ammonium or nitrite did not result in an enhancement of the initial slow rate of nitrate uptake. Growth for two additional weeks in ammonium also failed to eliminate the induction period. The evidence indicates that the presence of nitrate, rather than a product of its reduction, was required to initiate development of the accelerated rate of nitrate uptake.Puromycin (400 μg ml−1) and 6‐methylpurine (0.5 mM) prevented development of the accelerated phase of nitrate uptake. With both compounds, the relative restriction of nitrate uptake was greater than that of nitrate reduction as revealed by incorporation of 15N from labeled nitrate into reduced forms. The proportion of reduction which occurred in the root system under the imposed treatments could not be delineated precisely, preventing an unequivocal determination of the extent to which the two processes are coupled in the root system. The data nevertheless indicate nitrate reduction was closely associated with nitrate uptake.Accumulation of nitrate in the shoots was markedly restricted in presence of 6 methylpurine. This effect most likely was a result of a severe restriction in the translocation of nitrate into the xylem, rather than an increase in the reduction rate in the shoots.
Effects of Ca2+ and Temperature on Potassium Uptake along Roots of Wheat, Rice and Cucumber
Authors: ZSOLDOS FERENC , KARVALY BÉLA 
Published: April 2006

AbstractThe differences in K+ uptake of different segments of excised roots of two thermophilic plants (rice, Oryza sativa L. cv. Dunghan Shali and cucumber, Cucumis sativus L. cv. Csemege Fürtös) and a non‐thermophilic plant (wheat, Triticum aestivum L. cv. Aurora) were investigated in the presence and absence of Ca2+, at 0 and 25°C, using radiotracer K+(86Rb+) technique. The K+ uptake exhibited different temperature‐ and Ca2+‐dependent distributions along the root axis for the different species studied. In the case of rice and cucumber an extraordinarily large K+ uptake occurred in the apical root portion at 0°C if Ca2+ was omitted. The presence of Ca2+ diminished this anomaly. For wheat normal K+ uptake patterns were observed under similar conditions. At 25°C Ca2+‐stimulated K+ uptake may appear in each root segment, depending upon species and composition of the uptake solution. The results indicate that there may be considerable differences in the compositions of the cell walls and membranes of root cells of thermophilic and non‐thermophilic plants, and in their ion‐exchange properties, especially in the apical region.
Interaction du photopériodisme et des effets de la zéatine, du saccharose et de ľeau dans la floraison du Chenopodium polyspermum
Authors: SOTTA BRUNO 
Published: April 2006

Abstract Interaction of photoperiodism and zeatin, sucrose and water effects on the flowering of Chenopodium polyspermum Root removal in Chenopodium polyspermum, a quatitative short‐day plant, enhances flowering under non‐inductive conditions. Presence of roots may be mimicked by zeatin applications on buds. Induction of flowering by short days may be counteracted by applications of zeatin, and appearance of flowers depends on the balance between number of inductive short days and zeatin quantity applied. Sucrose added in the culture medium or applied on buds acts as zeatin. Applications of water on buds may also delay flowering. These results show the plurifactorial regulation of the floral development of this plant. The relations between the non‐specificity of the induction and the specificity of the morphogenetic response are discussed.
Uptake of Nitrate by Mutants of Arabidopsis thaliana, Disturbed in Uptake or Reduction of Nitrate
Authors: DODDEMA HENK , HOFSTRA J. J. , FEENSTRA W. J. 
Published: April 2006

AbstractA study of nitrate and chlorate uptake by Arabidopsis thaliana was made with a wildtype and two mutant types, both mutants having been selected by resistance to high chlorate concentrations. All plants were grown on a nutrient solution with nitrate and/or ammonium as the nitrogen source. Uptake was determined from depletion in the ambient solution. Nitrate and chlorate were able to induce their own uptake mechanisms. Plants grown on ammonium nitrate showed a higher subsequent uptake rate of nitrate and chlorate than plants grown on ammonium alone.Mutant B25, which has no nitrate reductase activity, showed higher rates of nitrate and chlorate uptake than the wildtype, when both types were grown on ammonium nitrate. Therefore, the uptake of nitrate is not dependent on the presence of nitrate reductase. Nitrate has a stimulating effect on nitrate and chlorate uptake, whereas some product of nitrate and ammonium assimilation inhibits uptake of both ions by negative feedback. Mutant B 1, which was supposed to have a low chlorate uptake rate, also has disturbed uptake characteristics for nitrate.
Effect of Benzyladenine on DNA, RNA, Protein, and Chlorophyll Contents in Intact Bean Leaves: Differential Responses to Benzyladenine According to Leaf Age
Authors: NAITO KUNIHIKO , TSUJI HIDEO , HATAKEYAMA ISAO 
Published: April 2006

AbstractBenzyladenine (BA) was applied to intact bean (Phaseolus vulgaris) leaves at different stages of their growth. Changes in the amounts of cellular constituents resulting from the different treatments were followed and compared. RNA, protein, and chlorophyll contents, dry weight, fresh weight, and leaf area per single leaf continued increasing when leaves were treated with BA from an early stage, whereas in untreated leaves all these values levelled off or declined with advancing age. Besides these changes, BA treatment induced an increase in the DNA content. Changes in RNA content was more remarkable in response to application or deprival of BA treatment than the corresponding ones in protein and chlorophyll contents. The pattern of response to BA varied greatly according to the age at which the leaf received the treatment. As leaves aged, they lost the ability to increase their area and fresh weight in response to BA. However, continuous treatment with BA from an early stage kept the leaves young and able to respond.
Rapid Effects of Abscisic Acid on Ion Uptake in Sunflower Roots
Authors: ERLANDSSON GUNVOR , PETTERSSON SUNE , SVENSSON SVEN‐BÖRJE 
Published: April 2006

AbstractShort‐term effects of ABA, ABA + kinetin and kinetin on ion (86Rb‐potassium and phosphate) and water uptake in sunflower plants (Helianthus annuus var. californicus) were examined with a continuous‐recording technique. Ion uptake in the roots and transport to the shoots were also investigated by conventional tracer uptake experiments and by sap bleeding experiments with excised roots.After addition of 5 × 10−6‐4 × 10−5M ABA to the root medium there was an immediate decrease (30–70%) in the rate of ion uptake which lasted 30–70 min. The rate of water uptake was not significantly affected as measured with this method. Ion transport to the shoots and to the bleeding sap of excised roots was decreased by ABA. ABA‐induced inhibition of ion uptake was abolished by the presence of kinetin, and uptake was slightly stimulated by 2 × 10−5M kinetin alone. We suggest that concentration gradients of ABA or rapid changes in the ABA‐kinetin balance in the roots affect ion uptake and transport.