ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The incorporation of 14C-labelled phenylalanine into proteins of the mitochondrial systems obtained from 48-h germinating seeds of Vigna sinensis (L.) Savi can be stimulated by polyuridylic acid [poly (U)] and depressed by rifampicin, which is, however, ineffective if poly (U) is allowed to interact with the incorporating system before the antibiotic has access to it.A system consisting of a mitochondrial S-100 fraction and ribosomes from the same source with other cofactors can bring about polymerization of phenylalanine.The incorporation of 14C-labelled uracil into RNA by the plant mitochondria is greatly dependent on the exogenous addition of adenine, guanine, cytosine and also on 5-phosphoribosyl-l-pyrophosphate (5-PRPP). It is greatly suppressed by rifampicin and ethidium bromide.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ethylene stimulated the activity of l-phenylalanine ammonia-lyase (PAL) in carrot (Daucus carota L.) tissues. It is also known to induce the formation of isochlorogenic acid. However, the induction patterns were different for isochlorogenic acid and PAL activity. Ethylene action seems to be indirect, as it did not affect the PAL activity of cell-free extracts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The occurrence of gibberellins and abscisic acid (ABA) in extracts of roots of Vicia faba was demonstrated by gas-liquid chromatography (GLC) of the methylated eluates from the relevant zones of thin-layer chromatograms (TLC) of purified extracts. Quantitative determination of the hormone contents in extracts from upper and lower halves of roots which had been kept in the horizontal position for 30 min indicated a redistribution of the hormones during the geotropic stimulation. Gibberellins whose methyl esters appeared at the retention time of methylated gibberellic acid (GA3), used as a standard, occurred in higher concentration in the upper than in the lower halves (ratio 2.08:1), whereas the concentration of ABA was highest in the lower halves (ratio 3.08:1). The ratio of the hormones in right and left halves of vertical roots was close to 1:1. Indoleacetic acid (IAA) and ABA were found to retard the elongation of roots of Vicia faba and Lepidium during the first 24 h. Additional experiments with Lepidium showed that this retardation occurs within the first hour after application. Low concentrations of GA3, when applied to germinating seeds just after the radicles had broken the seed coat, stimulated root elongation in Vicia faba within 24 h and in Lepidium within 36 h. When applied to Lepidium seedlings with 20 mm long roots, GA3 showed a stimulatory trend within the first 2 h, and distinct stimulation in the subsequent hours, particularly at the lowest concentrations, 0.01 and 0.001 mg/1. These results suggest the possibility of a participation of ABA and gibberellins (in addition to IAA) in the development of the positive geotropic curvature.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Kinetin delays the fading of cut rose (Rosa hyb. cv. Golden Wave) flower shoots exposed to water stress conditions. Using leafless flower shoots (i.e., a plant system devoid of stomates), we demonstrated that the main initial effect of kinetin was on increasing water uptake and petal growth. Later, kinetin slowed down processes associated with both senescence and stress (RNase activity and dry weight reduction), and maintained petal turgidity for an extended period.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Lea fage influences the level of activity and the decay rate of the enzymes nitrate reductase (NR: E.C. 1.6.6.1) and glucose-6-phosphate dehydrogenase (G6PD; E.C. 1.1.1.49) extracted with and without protein in the extraction media. Such influence was determined in three plant species: corn (Zea mays L.), oats (Arena sativa L.), and tobacco (Nicotiana tabacum L.). Leaves of different ages were obtained from plants of various ages, or by removal of leaf blades from different positions on a single shoot. NR activity (per g fresh weight) declined as leaves of these plant species became older, especially when extraction was effected with conventional media (i.e. without added protein). The instability of NR in these extracts increased as leaves became older. Decay of NR in vitro was exponential with time. Addition of protein [3 %(w/v) casein or bovine serum albumin] to extraction media markedly increased the level of NR activity and its stability, especially in older leaves of all three plant species. Addition of protein did not affect the level of G6PD extracted from corn leaf blades, but slightly enhanced its activity in extracts from the oldest leaf blade of oats. G6PD activity also declined as leaf blades of corn and oats became older.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Germination Heterogeneity of Rumex crispus L. seeds: Occurrence and Attempt at Interpretation. Rumex crispus L. seeds, harvested without taking into account localization of mother plants or seed position on single plants differ in their response to unfavourable conditions inductive of dormancy as a function of their weight. During induction, application of potassium or GA3 prevents or reduces the entry into dormancy, suggesting that the observed heterogeneity is due to nutritional variations of the seeds in relation to their position on the mother plant.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Kinetic studies of the uptake of 63Ni by cultures of the diatom Phaeodactylum tricornutum Bohlin revealed that the uptake capacity of the cells depended strongly on their metabolic state. Phosphate-starved cells gave saturation-type uptake curves and had low nickel-binding capacity. This was increased markedly by the addition of phosphate to the cultures. When nickel ions were added before or together with the phosphate, the increase in nickel-binding capacity of phosphate-starved cells failed to appear more or less completely. Uptake of phosphate and formation of polyphosphate by the cells were not affected by the addition of nickel to the growth medium. The phosphate dependent synthesis of the principle involved in nickel binding was induced 15–20 h after the addition of phosphate to starved cells. Whether phosphate was directly or indirectly involved in this process could not be established.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The use of chromatographic techniques coupled with mass spectrometry, infra-red analysis and nuclear magnetic resonance revealed that the amino acid phenylalanine might be responsible for a large proportion of the cell division activity of coconut milk as determined by the soybean bioassay. The observation that zeatin can be removed very readily by partitioning against ethyl acetate at alkaline pH values, cautions against inclusion of this method as a purification step for extracting cytokinins from plant extracts. Mass spectrometry revealed the presence of an unidentified cell division substance with a molecular ion of 279 and which co-chromatographed with zeatinriboside on Sephadex LH-20.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The rate of hydrolysis of fats during germination of peanuts decreased with the increase in the concentration of aflatoxins. Free-reducing sugars increased up to 96 h of germination, and thereafter their concentrations remained more or less constant. However, the rate of formation of free-reducing sugars decreased with increase in the concentration of aflatoxins. At all the stages of germination the rate of formation of sucrose decreased with increase in the concentration of aflatoxins. The aflatoxins stimulated the fixation of nitrogen during the preflowering stage, leading to an increase in the concentrations of soluble nitrogen in roots and protein in shoots: the maximum amount of total nitrogen fixed and that excreted into the soil was at a concentration of 2.5 μg/ml aflatoxins.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: When abscisic acid-2-C-14 (AbA-2-C-14), 1 μg in 5 μl 40% ethanol, is applied to the apical bud of light-grown pea seedlings, C-14 is translocated downwards only in very small amounts and does not enter the root. In contrast to this, C-14 from indoleacetic acid-C-14 (IAA-2-C-14) applied in the same manner is translocated to the root where it accumulates. When AbA-2-C-14 is injected to the stem tissue at the apical bud, more labelled material is transported downwards than after application to the surface. Application of AbA-2-C-14 to an expanded leaf results in considerable accumulation of C-14 in the growing apical parts and in the lateral roots.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The photo-induced cell division in single-celled protonemata of the fern Adiantum capillus-veneris was studied. When the protonemata were exposed to monochromatic light at 50 nm intervals between 350 and 750 nm, irradiations in the blue and near-ultraviolet regions effectively induced cell division, while wavelengths longer than 550 nm showed no such effect. As reciprocity between duration and intensity was observed within the range of incident energy used, the action spectrum for the frequency of the photo-induced cell divisions 24 h after irradiation was determined between 360 and 510 nm at 10 nm intervals. Furthermore, the previously known effect of phytochrome on the timing of the cell division was minimized by a short exposure to red light given immediately after the monochromatic irradiation. The resulting action spectra showed a peak in the neighborhood of 460 nm with shoulders and another peak in the near-ultraviolet region.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Detached corn and sunflower leaves exposed to various concentrations of Cd, supplied as CdCl2, exhibit reduced photosynthesis and transpiration. The reduction is dependent on the concentration of CdCl2 solution and generally becomes more pronounced with time. In sunflower, net photosynthesis and transpiration are completely inhibited within 45 min after the introduction of 18 mM Cd. Within two hours net photosynthesis is reduced to 40% and 70% of maximum after the introduction of 9 and 4.5 mM Cd respectively. In corn the trend of photo-synthetic response to Cd is similar to that in sunflower except that the inhibition in corn is more pronounced at all treatment levels. A strong linear relationship between photosynthesis and transpiration inhibition is obtained in both species suggesting that Cd contamination induces stomatal closure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Sexual reproduction of many dermatophytes is easily induced in complex media such as soil plus keratin. In Arthroderma benhamiae this process could be initiated also in synthetic agar media. A number of carbon sources (glucose, fructose, galactose, mannose, maltose, lactose, sorbose, sucrose) had about the same stimulatory effect on reproduction, while xylose was inhibitory. Organic sulphur was not crucial for the process in contrast to the nitrogen supply. The nitrogen sources could be divided into four groups; I. very stimulatory (arginine, citrulline, isoleucine, leucine, ornithine, phenylalanine, proline, valine, glutathione); II. stimulatory (alanine, asparagine, lysine, serine); III. slightly stimulatory (aspartic acid, cysteine, glutamic acid, glycine, histidine, urea, NH4Cl, NH4-tartrate); IV. inhibitory (hydroxyproline, methionine, threonine, tryptophan). Synergistic effects were shown between some amino acids. Generally a combination between 5 g/l glucose and 300–400 mg/l nitrogen induced the largest number of cleistothecia, regardless of the nitrogen source used. The level varied between the sources, however. A C/N ratio of about 10 was optimal while a value above 20 gave no cleistothecia. The optimal temperature for the process was 30°C. Sexual reproduction occurred between pH 4.4 and 8.0 (final values). However, at a final pH above 7.2 the number of ascospores/cleistothecium was reduced.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Suspension cultures of Datura innoxia Mill, were successfully grown on a modified Murashige and Skoog medium with 2,4–D, NAA or BAP as growth substances, provided the micronutrient levels were reduced to 1/10. Normal amounts of micronutrients were toxic. Attempts to identify the toxic elements did not succeed.Cultures grew exponentially on a shaker at 27°C in the light. Their doubling times varied from 1.1 days on 2,4–D (10–6M) or NAA (10−5M)+ 1 g/1 casein hydrolysate to 2.7 days on BAP (3 × 10−7M) and 5.1 days on supraoptimal levels of 2,4-D (10−5M). Cultures grew on NH4+-N alone (from ammonium malate) or on NO3−-N alone. Dry weight yield was proportional to the amount of nitrate-N added (47 mg/mg N).Filtered suspension cultures containing single cells (plating cultures) could be grown in agar in petri dishes when NAA or 2,4-D were used as growth substances. Cells grew at densities above 500 units/ml in the agar. Most colonies grew from cell aggregates but division in single cells was observed. The highest plating efficiency was about 50% on 10−6 M 2,4-D + 1 g/1 casein hydrolysate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cell-free extracts of Rhizobium meliloti contain a soluble lactate dehydrogenase (LDH-EC 1.1.1.27.). This was purified 250-fold by ammonium sulfate precipitation and filtration on different Sephadex gels. This enzyme catalyses the reduction of pyruvate to lactate in the presence of NADH and for the first time we report its ability to reduce indole-3-pyruvic acid (IPyA) to indole-3-lactic acid (ILA). Optimal conditions for activity and Km values for both substrates were determined. In the presence of NAD the reverse reaction could be demonstrated with the aliphatic substrate (lactate), but under our conditions it was not possible to achieve the oxidation of ILA to IPyA. The role of this LDH in the indole metabolism is discussed and a general reaction scheme is suggested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Embryogenic callus was induced by culturing explants of pumpkin hypocotyls on Murashige-Skoog-medium with the addition of 3% glucose and one of the following growth substances (or combinations of them): β-indolylbutyric acid, 2,4-dichlorophenoxyacetic acid, β-indolylacetic acid, α-naphthyl-acetic acid, adenine (natural), kinetin, autoclaved water-melon sap and yeast extract (Difco). A large number of embryoids and adventive buds were produced. These were able to develop to normal plants.The 17 strains of embryogenic tissue obtained have maintained their embryogenic characteristics for more than 3 years. The induction of embryogenic callus in pumpkin seems to be strongly dependent on the genetic constitution of each individual plant.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Etiolated 6-day-old wheat (Triticum aestivum L. cv. Chris) seedlings were subjected to osmotic stress by an application of polyethylene glycol 12 h prior to the exposure to a continuous 72-h light period. The water potential of the primary leaf of stressed seedlings was between –9 and –14 bars throughout the light period.Stress impaired seedling growth, leaf unfolding, and the increase in leaf area. The imposed osmotic stress reduced total chlorophyll accumulation, particularly after 9 h light, suggesting that this is the approximate time period for the depletion of the protochlorophyll(ide) pool and the pool of an essential protochlorophyll(ide) precursor. The chlorophyll a/b ratio of extracts from stressed and non-stressed plants was the same during the 72-h greening period. Water deficit stress impaired carotenoid accumulation sooner than the impairment of chlorophyll production suggesting either a smaller carotenoid pool size of precursors or that the metabolic pathway of carotenoid synthesis was more sensitive to stress. Shifts from the usual plastid pigment absorbance maxima were not observed in these studies.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The exposure of red beet root tissue to ultraviolet (254 nm) at 2 × 106 erg × cm−2× min−1 (0.2 J × cm−2× min−1) causes release of betacyanin after a 20 minute induction period. Ultraviolet-photolysis is temperature-sensitive having a thermal threshold at about 10°C. Reduction in pigment release was effected by chlorides of Mg, Ca and Sr, but not by Li, Na or K. This effect was marked but not complete, even at 40 mM concentration.It is concluded that photolysis is indirect, and involves a lytic factor, possibly an oxidant, derived from an original photochemical product.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An acid ether-soluble, strongly growth-stimulating substance revealed by the Avena coleoptile straight-growth test in methanol extracts from bean seedlings (Phaseolus vulgaris L.) was identified as indol-3yl-aspartic acid (IAAsp). Points of agreement between synthetic IAAsp and the investigated growth stimulator were indicated by chromatographic behavior, elution volume in gel filtration, mobility in paper electrophoresis, “colour reaction” with DMCA reagent, ability to form indol-3yl-acetic acid (IAA) and aspartic acid after hydrolysis and, finally, biological activity in the Avena test. Furthermore, some experiments demonstrated the occurrence of an inhibitor in extracts from light-grown tissue. This masked the stimulation of IAAsp in the Avena test when the extracts had been chromatographed in isopropanol: NH3:H2 O. A comparison of the levels of IAAsp between green and etiolated tissue did not reveal any distinct difference, demonstrating that the IAA conjugate IAAsp does not participate in the regulation of the photomorphogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The abscisic acid content of the mature shoot tissue of vigorous Prunus avium, medium sized Prunus cerasus and dwarfing Prunus cerasus self (S) was estimated by spectropolarimetry and gas chromatography. There is no correlation between the levels of ABA found in the tissue and the dwarfing potential of the trees investigated. However, Prunus arium stem tissue shows the lowest sensitivity to ABA, whereas the explants of normal and dwarfing Prunus cerasus exhibit a stronger inhibition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Soybean (Glycine max (L.) Merr.) cultivars have been reported to range in tolerance to injury by 4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one (metribuzin), from tolerant (e.g.‘Bragg’) to susceptible (e.g.‘Coker 102’ and ‘Semmes’). ‘Bragg,’‘Coker 102’, and ‘Semmes’ soybeans were grown in sand subirrigated with nutrient solution containing labelled (14C-carbonyl metribuzin) and nonlabelled metribuzin to determine cultivar variability in absorption, translocation, and metabolism of metribuzin. Plants were periodically harvested, autoradiographed, and radioactivity in tissue extracts quantified. Data indicated that all 3 cultivars readily absorbed and translocated metribuzin. However, ‘Bragg’ tissues accumulated greater quantities of metribuzin metabolites than the other two cultivars. The major 14C-containing metabolite in ‘Semmes’ and ‘Coker’ roots and stems was 6-tert-butyl-as-triazine-3-5-(2H,4H)-dione, whereas the major 14C-metabolite isolated from‘Bragg’ roots and stems was a glucose conjugate. Results indicated that differential-intraspecific responses to metribuzin may result from differential capacities for herbicide detoxification by conjugation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The oscillatory transpiration of 6 days old Avena plants was investigated with respect to the water potential of the root medium. The desired water potential was obtained by means of mannitol solutions.When the water potential was lowered (“mannitol step”), the amplitude of the oscillations decreased. Below –3.0 bars no oscillations persisted. A detailed study was made of the phase changes of the oscillations caused by a short time decrease of the water potential of the root medium (“mannitol pulse”). The duration of these short term treatments was either 9.0, 3.0 or J.5 min.The experimental results are discussed on the basis of an electric analogue previously presented in the literature. Published simulations based on the model were in clear contrast to the present experimental results as well as to earlier results in the literature. However, simulations in the present paper showed that the model could explain the experimental results if suitable parameter values were chosen.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: On dispersal the seed of Acer platanoides contained a dormant embryo, from which dormancy could be removed by chilling but not by hormone application. Dormany was deep in the embryonic axis, particularly in the radicle, but less so in the cotyledons. Under the storage conditions employed the dormancy pattern was modified so that during the subsequent incubation at 20°C, cotyledon expansion of isolated embryos from stored fruits was more rapid than that of isolated embryos from newly dispersed fruits. In addition, the dormancy of isolated embryos from fruits stored for several weeks could be broken by incubation in kinetin. It was concluded that embryo dormany in this seed can be divided into two phases, an initial phase when the embryo responds to chilling but not to cytokinins, and a later phase when cytokinins also become effective. The relationship between this transition and the apparent gradual reduction in the depth of embryo dormancy during storage is also discussed.The chilling period necessary for dormancy breaking was reduced by kinetin and to a lesser extent by gibberellin, indicating a close relationship between the concentrations of these hormones and the chilling requirement.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Water uptake of root systems of Phaseolus vulgaris was measured in a Scholander pressure cylinder at a constant pressure. Water uptake rises gradually till a steady state is reached after 15 to 60 minutes. This time course can be described as a transport process with the property of a self-induction. The latter was not affected by temperature. It is concluded that the property of self-induction is located in the cytoplasm or at the interface between cytoplasm and plasmalemma of the endodermal cells. It is suggested that cytoplasmic streaming controls the time course of water transport.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This study continues the investigations previously conducted as laboratory experiments. The results from the present study confirm our earlier observations made on alder seedlings concerning the effect of water stress, temperature and light on the net uptake of CO2.A variable that we could call the physiological water stress is proposed as a measure of the intrinsic factor of photosynthesis during and after drought. A physiological water stress builds up and discharges slowly and interacts strongly with temperature. Our model for the effects of physiological water stress, temperature, and light intensity explains satisfactorily the net uptake of CO2 in birch in the field. Thus, our earlier results concerning the effects of physiological water stress on photosynthesis are not artifacts generated by the unnatural laboratory environment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Kinetic studies of a microsomal, dithiotreitol treated, homogenate from sugar beet roots led to the following conclusions about its ATPase activity: (1) MgATP in complex appears to be the primary substrate for the reaction. The reciprocal equilibrium constant for the binding to the enzyme is estimated to be approximately 0.2 × 10−3M. (2) Free ATP acts as a competitive inhibitor of the MgATP. The binding constant is about twice as high as for MgATP. Consequently the enzyme has less affinity for ATP than for MgATP. (3) Free Mg2+ has little influence on the velocity, as the binding affinity of the enzyme for Mg2+ is almost negligible.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nitrite and nitrate uptake by wheat (Triticum vulgare) from 0.5 mM potassium solutions both showed an apparent induction pattern characterized by a slow initial rate followed by an accelerated rate. The accelerated phase was more rapid for nitrate uptake, was initiated earlier, and was seriously restricted by the presence of equimolar nitrite. The accelerated phase of nitrite uptake was restricted by nitrate to a lesser extent. The two anions seem not to be absorbed by identical mechanisms.Ammonium pretreatments or prior growth with ammonium had relatively little influence on the pattern of nitrite uptake. However, prior growth with nitrate eliminated the slow initial phase and induced development of the accelerated phase of nitrite uptake. A beneficial effect was noted after 3 h nitrate pretreatment and full development had occurred by 12 h nitrate pretreatment. The evidence suggests that a small amount of tissue nitrite, which could be supplied either by absorption or by nitrate reduction, was specifically required for induction of the accelerated phase of nitrite uptake.Cycloheximide (2 μg ml−1) seriously restricted development of the accelerated phase of nitrite uptake, but its effect was not as severe when it was added after the accelerated phase had been induced by prior exposure to nitrite or nitrate. However, translocation of 15N from the absorbed nitrite was sharply decreased under the latter conditions, indicating a difference in sensitivity of the uptake and translocation processes to cycloheximide.Potassium uptake was greater from KNO3 than from KNO2 and in both instances it was enhanced during the early stages of the accelerated phase of anion uptake. Moreover, addition of NaNO3 to KNO2 substantially increased potassium uptake. A coupling between anion and potassium uptake was therefore evident, but the coupling was not obligatory because the accelerated phase of nitrite uptake could occur in absence of rapid potassium uptake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of fluoride on respiration of plant tissue and mitochondria were investigated. Fumigation of young soybean plants (Glycine max Merr. cv. Hawkeye) with 9–12 μg × m−3 HF caused a stimulation of respiration at about 2 days of treatment followed by inhibition 2 days later. Mitochondria isolated from the stimulated tissue had higher respiration rates, greater ATPase activity, and lower P/O ratios, while in mitochondria from inhibited tissue, all three were reduced.Treatment of etiolated soybean hypocotyl sections in Hoagland's solution containing KF for 3 to 10 h only resulted in inhibition of respiration. Mitochondria isolated from this tissue elicited increased respiration rates with malate as substrate and inhibited respiration with succinate. With both substrates respiratory control and ADP/O ratios were decreased.Direct treatment of mitochondria from the etiolated soybean hypocotyl tissue with fluoride resulted in inhibition of state 3 respiration and lower ADP/O ratios with the substrates succinate, malate, and NADH.Fluoride was also found to increase the amount of osmotically induced swelling and cause a more rapid leakage of protein with mitochondria isolated from etiolated corn shoots (Zea mays L. cv. Golden Cross Bantam).The results are discussed with respect to possible effects of fluoride on mitochondrial membranes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: DNA synthesis, mitosis and ploidy of dividing cells were studied during 30 h after wounding around wounds inoculated with Agrobacterium tumefaciens, around sterile wounds and in control stems of Vicia faba. DNA synthesis was examined by counting nuclei labelled with 3H-thymidine in slides in which mitoses had been counted and analyzed before autoradiography.The main results were that around inoculated wounds, DNA synthesis and the number of mitoses showed a peak between 12 and 22.5 h. Both types of wounding induced mitoses, many of them polyploid (DNA content higher than 4C), both in the pith and the cortex, whereas in the control stems only diploid mitoses, mostly in the stelar area, were seen. The first polyploid (8C) mitoses around the inoculated wounds took place at 12 h and at 15.5 h 32C mitoses were seen; around the sterile wounds the first 8C divisions occurred at 26 h. The frequency of polyploid mitoses and their degree of ploidy continued to be considerably higher around the crown gall than around the control wounds. When a cell with a higher than 4C content is induced to divide, the 12 chromosomes, as a rule, consist of four, eight, 16 or 32 chromatids, instead of the normal two.The early division of highly polyploid cells around the inoculated wounds is obviously caused by growth factors which are known to be produced by the bacteria. It appears possible that this ability to synthesize excessive amounts of growth factors is subsequently transferred to the host cells through bacterial DNA.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 42K and 14C (U)-glucose uptake by foliar discs of maize (Zea mays L.) and pelargonium (Pelargonium zonale L.) is inhibited by dimethyl sulfoxide (DMSO) at concentrations of 5 and 10%. This effect increases with the duration of the absorption and appears with varied concentrations in K or glucose. In most cases, this inhibitory effect is less with aged discs than with freshly cut discs. Besides, the DMSO (10%) enhances the exsorption of 42K by foliar discs of maize. The effects of DMSO and two osmotic agents, mannitol and polyethylene glycol 1000, on the uptake and water content of discs are compared. It seems that the effect of DMSO on the uptake is not only an osmotic effect. It may also be related to other actions of this substance in affecting an active uptake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Phaseolus vulgaris L. plants were grown in two naturally lighted, outdoor controlled environment plant growth chambers. The approach velocity to the plant growing zone was 75 cm s−1 in one chamber and 225 cm s−1 in the other. The lower air velocity represents the presently considered maximum permissible air velocity in controlled environment plant growth chambers. The humidity in both chambers was near saturation. After three weeks' growth in these chambers, there were no significant differences in fresh or dry weights of the plants or any parts thereof. The high air velocity reduced the transpiration rate as predicted by energy budget considerations and significantly lowered the average leaf temperature of the crop by three degrees. The data strongly support the hypothesis that the maximum permissible air velocity in controlled environment plant growth chambers can be raised considerably if the humidity is maintained high.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Sugar beet leaf homogenate contains Mg2+-stimulated ATPase activity with the highest specific activity in the 25,000–30,000 ×g-fraction. This fraction also has (Na++ K+)-activated ATPase activity. Both activities have two pH optima, one stable at pH 7.9 and one variable at lower pH. When optimal conditions of Na+ and K+ were tested with 64 combinations of these ions, at least two mountains of activity were revealed.The (Na++ K+)-ATPase had a high specificity for ATP. It had lost about 50% of its original activity after 56 days of storage at −85°C. The activity drop was most pronounced at high ionic concentrations in the test medium.The (Na++ K+)-ATPase shows four peaks of activity when tested at constant ionic strength. The idea is put forward that the four peaks reflect two ATPases, one in the tonoplast and one in the plasmalemma, which undergo conformational changes in relation to the ionic milieu.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: <list xml:id="l1" style="custom">1In a mendelian (sr3) and an uniparental (sr35) streptomycin resistant mutant of Chlamydomonas reinhardi the influence of streptomycin on protein synthesis on the chloroplast and cytoplasmic ribosomes was investigated in vitro. Hetero-, mixo- and phototrophic agar cultures and heterotrophic liquid cultures were used.2Protein synthesis on the cytoplasmic ribosomes, measured by the activity of glyceraldehyde-3-phosphate: NADP dehydrogenase (EC 1.2.1.9), was not inhibited, but rather stimulated by streptomycin.3Protein synthesis on the chloroplast ribosomes of sr3, measured by the activity of ribulose-1,5-diphosphate carboxylase (EC 4.1.1.39), was greatly inhibited by streptomycin, especially in hetero- and mixotrophic cultures. In sr35 the chloroplast ribosomes were resistant to streptomycin.4Heterotrophically grown cultures of sr3 and of a streptomycin-sensitive strain are yellow in the presence of streptomycin and form no or only reduced thylakoids on solid media. But 70-S organelle-ribosomes are present in a normal amount.5The relationship between chloroplast protein synthesis and thylakoid formation is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 30 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The postulate that single roots of Zea mays transport their absorbed phosphorus nonuniformly to the leaves was tested. Plants were grown under growth chamber conditions for three to four weeks in nutrient solution. At this stage of growth a series of plants was placed into a system in which two roots on each plant were allowed to absorb either 33P or 32P from uptake solutions for time intervals of up to 24 hours. Plants subsequently were harvested such that each leaf was partitioned into samples containing tissue from one side or the other of the midrib. All samples were assayed for 33P and 32P and the results were expressed as the amount of total P transported into different plant parts from a single root.Nonuniform P accumulation in the leaves occurred and different patterns of accumulation, dependent on the type of root chosen for uptake were observed. Nearly uniform P accumulation occurred between one side and the other of a given leaf when transport was from radicle roots. In marked contrast, transport from adventitious roots resulted in an alternating pattern of accumulation between one side and the other of each successive leaf up the stem. The seminal root system supplied more P to the older leaves than did the adventitious root system. The nature of these nonuniform P transport patterns is attributed to the vascular organization between roots and leaves.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 30 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The composition and amount of carotenoid pigments were determined in etiolated seedling leaves of 6 barley (Hordeum vulgare L.) mutants, comprising 1 xantha and 5 tigrina mutants. All mutants had on a mole basis approximately the same content of carotenoids as the wild type.The mutants xan-u21, tig-n32, and tig-33 contained significantly higher amounts of carotenes than the wild type, ranging from 32 to 68% of the total carotenoid content as compared to the 4–8% found in the wild type. In the mutants tig-b23 and tig-o34, only a slight increase in the amount of carotenes was notable. The carotene content and composition in tig-d12 was indistinguishable from that of the wild type.The carotenes extracted from xan-u21, tig-b23, tig-n32, tig-33, and tig-o34 were characterized by adsorption chromatography and spectrophotometry. Mutant xan-u21 is in the dark blocked in β-carotene synthesis, and accumulates the aliphatic polyenes: phytofluene, proneurosporene, poly-cis-lycopenes, neo-lycopene and lycopene. The other four mutants synthesize β-carotene, but accumulate in addition various higher saturated carotenes, the main components being ζ-carotene in tig-b23, a lycopenic pigment in tig-n32 and tig-33, and lycopene in tig-o34.Accumulation of higher saturated carotenes appears correlated with specific aberrations of the membrane structure in plastids. The regulation of carotene and protochlorophyllide syntheses in etioplasts are closely linked as shown by the single gene mutants which affect both pathways. However, several mutants have been identified which cause defects in protochlorophyllide synthesis only.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Half melting temperature (Tm) of DNA prepared from the nuclear fraction of vegetatively growing cells of Spirogyra was 86°C in the standard saline-citrate solution and 68°C in the dilute saline-citrate solution, and the major Tm values of soluble chromatin were 68°C and 78–80°C in the dilute saline-citrate solution. The Tm value of DNA prepared from the nuclear fractions of conjugating and zygote cells was 88°C in the standard saline-citrate solution and 70°C in the dilute saline-citrate solution, and the major Tm values of soluble chromatin were 72°C, 78–80°C, and 84°C in the dilute saline-citrate solution. The Tm values of DNA prepared from cells arrested at different stages of the life cycle of Spirogyra were raised by combining with different fractions of histones. The results agreed with an altered structure of the nucleoprotein complex during the life cycle of Spirogyra.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Effects of ethylene on the elongation of bean (Phaseolus vulgaris) embryonic axes and hypocotyls, and of cocklebur (Xanthium pennsylvanicum) hypocotyls were studied. In the bean axes, exogenous ethylene was promotive in stimulating longitudinal growth during the early germination period, but thereafter it turned inhibitive. This transition of the ethylene action is likely involved in the appearance of newly differentiated tissues in the hypocotyl, which are negatively sensitive to the gas. The ethylene stimulated elongation of the axes was hardly affected by light or by the presence of the cotyledons. In the bean hypocotyl segment unit, elongation was stimulated by ethylene in its limited zone, when the concentration of ethylene and the exposure times to ethylene were adequate (0.3 to 30 μl/l, 6 to 8 h): Elongation in the much younger region near to the elbow was inhibited by ethylene treatment, whereas the treatment of the upper region of the shank with ethylene finally resulted in significantly increased growth as compared to the untreated controls. In the continuing presence of ethylene over 3 days, the elongation of every region was retarded markedly and radial growth was induced in most regions of the shank from just below the elbow. These ethylene responses occurred independently of red light irradiation, but the ethylene promotion of elongation was lost by shortening the segment height, by removing the hook portion from the segment unit, or with its natural disappearance as a result of ageing. Fundamentally, similar effects of ethylene was observed in cocklebur hypocotyls.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Uniform 1- or 2-year-old rooted cuttings of 3 Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, clones were grown under natural conditions in containers from July 1, 1971 to February 15, 1972. At 2-week intervals, plants from this natural temperature and daylength environment were moved into controlled, long day (LD-18 h) and short day (SD-9 h) environments to measure the intensity of bud dormancy from its inception to termination based on number of days to bud break and percentage of expanding buds on a given date. Growth responses to bud scale removal were also helpful in describing the degree and nature of bud dormancy. The cessation of initiatory activity at the bud apex, reflected in the needle number of the subsequent growth flush, corresponded to a September peak of bud dormancy based on the number of days to bud break in the LD environment. Similarly, the cold requirement for breaking bud dormancy was measurable in the SD environment. The use of such rest intensity indices is illustrated in the close relationship established between bud dormancy development and stem cutting rooting ability.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Internodal segments from 6-weeks-old rape plants (Brassica napus L. cv. Zephyr) were induced to differentiate in vitro producing shoots or shoots and roots on synthetic nutrient medium under controlled conditions. Benzyladenine (BA) alone (5 × 10−6 M) induced multiple shoot formation on all stem explants. Roots were induced on shoots when recultured on nutrient medium supplemented with auxins such as naphthalene-acetic acid (NAA) or indoleacetic acid (1AA) or when planted in vermiculite. Complete plant formation was obtained when NAA (2 × 1−6, 5 × 10−6 and 10−5 M) was employed in conjunction with BA at 5 × 10−6M. At higher concentrations (10−5M) NAA retards the shoot development while 1AA suppresses it totally. Lower levels of auxins along with the cytokinin did not retard or inhibit shoot differentiation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: T3238fer (Fe-inefficient) and T3238FER (Fe-efficient) tomato plants differ in their ability to utilize Fe and therefore can be used as test genotypes to locate sites of Fe uptake or to characterize changes that occur in roots in response to Fe stress (Fe deficiency). T3238fer does not respond to Fe stress. Release of hydrogen ions and reduction of Fe3+ to Fe2+ are two primary responses of T3238FER roots to Fe stress. Fe reduction sites were predominately in the young lateral roots, and between the regions of root elongation and maturation of the primary root. The use of BDPS (bathophenanthrolinedisulfonate) to trap Fe2+ did not affect the release of H+ ions or reduction by T3238FER roots. BPDS did not decrease Fe uptake until it exceeded the Fe concentration in the nutrient solution. A sevenfold increase in BPDS caused a threefold decrease in Fe taken up by the plant. Fe3+ is reduced to Fe2+ at root sites accessible to BPDS. Adding Zn decreased the response to Fe stress.Iron stress initiates the development of lateral roots, and we propose that most Fe enters the plant through these roots. The iron moves through protoxylem into the metaxylem of the primary root and then to the top of the plant as Fe citrate. Root environmental factors that are competitive or inhibit Fe-stress response, or genotypes that fail to respond to Fe stress, contribute to the development of Fe deficiency in plants.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The agglutinating effects of Concanavalin A (Con A) on protoplasts isolated from cell suspensions of Daucus carota were studied. Con A was shown to agglutinate the plant protoplasts in a manner similar to the way some animal cells are agglutinated. The agglutination process is dependent on the Concanavalin A concentration, protoplast density, treatment time, the temperature, and the membrane condition, α-D-Methylgluco-pyranosid completely inhibited Con A induced agglutination. The results are discussed in relation to membrane structure and morphology.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Detached cotyledons of Sinapis alba rooted readily in water in petri dishes in the light. The addition of (6 × 10−2M) galactose, mannose or 2-deoxy-D-glucose to the culture medium proved toxic to cotyledon growth. Of the other sugars tested that were not toxic, sucrose was the most inhibitory to root formation and increased petiolar yellowing to the greatest extent. Glucose was more inhibitory than fructose which in turn increased petiolar yellowing more than methyl-D-glucose.Sucrose, glucose, or fructose at 6 × 10−2M in the culture medium gave rise to very substantial increases in the cotyledon petiole of reducing sugar and starch with smaller increases in sucrose. Methyl-D-glucose had much less effect on internal sugar levels. It was found that the higher the internal level of glucose the more rapid the rate and final extent of petiolar yellowing. In general, the degree of petiolar yellowing was inversely related to the ability of the cotyledon to root. Methyl-D-glucose differed from the other sugars in that it delayed and reduced root formation but had very little effect on petiolar yellowing.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Recovery from desiccation by Tortula ruralis (Hedw.) Gaertn., Meyer and Scherb was accompanied by an immediate, rapid increase in respiration (measured as oxygen uptake) at 25.5°C or 3.5°C. The respiratory burst was greater on rehydration of moss which had been rapidly desiccated over silica gel than that which had been more slowly desiccated in atmospheres of high relative humidity. No respiration was observed in dry moss. Dried moss which had been placed in liquid nitrogen resumed respiration on rewarming and rehydration but moss which had been frozen in the hydrated state respired to a lesser extent and showed signs of freeze damage. In the initial stages of slow drying a slight increase in respiration was noted, followed by a gradual decrease as drought became more severe.In contrast to observations made on many higher plants under drought stress, this moss did not exhibit any changes in its starch and sugar content during or following desiccation, nor were there any changes in free proline levels. Using (1-14C)-glucose and (6-14C)-glucose, the relative activities of the Embden–Meyerhof–Parnas and pentose phosphate pathways in hydrated and rehydrated moss were determined, as were the activities of specific enzymes involved in these pathways. An increased activity of the Embden–Meyerhof–Parnas pathway of glucose oxidation on rehydration of Tortula was observed. The possible significance of this latter observation is outlined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The various methods for chlorophyll determination, found in the literature, may give chlorophyll values differing by as much as 20%. Not only the choice of solvent and equations but also the routines and conditions for processing of samples can be large sources of errors.In the present paper some recommendations are given concerning sampling and storage of plant material, extraction and determination of chlorophylls.A simple and fast method for chlorophyll determinations is described and recommended as a suitable method for most ecological and eco-physiological investigations in which chlorophylls are determined. The principle of the method is that the total amount of chlorophylls is determined in a colorimeter calibrated for chlorophyll measurements. Results from a prototype of the “Chlorophyllometer” are presented and compared with spectrophotometric determinations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tobacco plants (Nicotiana tabacum cv. Burley 21) were cultured in the greenhouse to the 18-leaf stage. The apical meristem was removed and subsequent axillary bud growth was removed by hand (controls) or axillary bud development was inhibited by application of maleic hydrazide. Compared with the controls, maleic hydrazide treated plants had a decreased stem diameter and stem weight, but an increased leaf weight and leaf weight/area. Plant height and leaf area were the same for both treatments. Maleic hydrazide inhibited translocation of 14C from a single leaf exposed to 14CO2. Respiration was greater than in the controls three days after application of maleic hydrazide, but 9 and 14 days after application there were no differences in respiration between the two treatments. Maleic hydrazide did not affect photosynthetic activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Preharvest applications of N6-benzyladenine and gibberellic acid caused a lowering of respiratory rates and a transient reversal in the color changes normally associated with the postharvest ripening of apricot fruits (Prunus armeniaca L.) Light transmission at 589 and 657 nm were used to detect color change. A physiological and metabolic link is implied by the close temporal coincidence of both the reversal in color change and the reversal in respiratory rate that occurs at the climacteric minimum. Postharvest treatments with the same phytohormones had generally similar but much less pronounced effects.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Wheat seedlings were subjected to heat shock for 2 min at 45°C. The seedlings were then incubated at 25°C or higher temperatures (usually 35°C). At 25°C the root tips survived the heat shock, but not at temperatures above 34°C, unless they had been pretreated with ethanol or kinetin, After 1 h in ethanol and after more than 15 h in kinetin the root meristem survived a high incubation temperature after the heat shock. Immediately after heat treatment the glyceride content in treated root tips was higher than in untreated roots. The same was observed after heat treatment of root tips pretreated in ethanol and kinetin. The content of ether extractable lipids was not changed by the heat shock.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pea plants were grown at different irradiances for eleven days. At this stage they were used for cuttings. The irradiance during the rooting period (155 mW · dm−2) was the same in all the experiments, Cuttings from stock plants cultivated at the weakest irradiance obtained the highest number of roots, and the poorest rooting appeared in cuttings from stock plants grown at the highest irradiance. The results indicate that the nutritional status of the stock plant is an important factor for root formation in the cutting. Light may influence the production of inhibitors which directly or indirectly affect root formation. The possible role of carbohydrates and growth promoters in the process of root formation is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Volatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine (Pseudocallyma alliacium), avocado (Persea americana) and haole-koa (Leucaena glauca) release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vaporpressure temperature relationship for mercury. Mercury can be trapped in nitric-perchloric acid digestion fluid, or n-hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole-koa also contain extractable mercury but volatility declines in the series n-hexane (90%) > methanol (50%) > water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media. Gas chromatographic analysis shows that the volatile compound is not dimethyl mercury.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A NAD specific proline-dehydrogenase was found in pumpkin (Cucurbita moschata Poir. cv. Dickinson Field) which oxidized proline to Δ1-pyrroline-5-carboxylate. NADP did not substitute for NAD and L-proline-methyl-ester and thiazolidine-4-carboxylate were substrates in the reaction, at a rate of 107% and 33% respectively, of the rate with L-proline. Pumpkin cotyledons contained the bulk of the enzyme activity with 90% of the activity being in the soluble fraction. Proline-dehydrogenase, which was not treated at high temperature, was stable at –10°C for 4 months in the presence of high ammonium sulfate concentration. The Michaelis constant for NAD was 2.2 mM and for L-proline was 2.5 mM. At 5 mM NADP, a 40% non-competitive inhibition of proline-dehydrogenase was obtained, while 50 μM NADP was sufficient to induce 20% inhibition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Adenosine triphosphatase activity of tobacco leaf chloroplasts in the dark was measured, using leaves of different age as determined by the position of the leaves along the stem. The activity of the chloroplast preparations strongly decreased with age, regardless of the addition of Mg2+ or Ca2+. Opposite effects of Mg2+ and Ca2+ on the activity of the chloroplasts were noted in experiments where different ratios of Mg2+/Ca2+ were applied. They were related to the age of the leaves, Ca2+ strongly stimulated the activity of the preparations from old leaves but was practically without effect in young, just expanded leaves. Mg2+ slightly stimulated the activity from old leaves while it invariably inhibited the hydrolytic activity of preparations from young leaves.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Following a single inductive short day, cytokinin activity in extracts of leaf laminae, buds and root exudate of Xanthium strumarium L. (as measured by the soybean callus bioassay) declined to between 10 and 25% of the level detected under long-day conditions. Additional inductive cycles, up to five, produced little further change. Cytokinin activity of petiole extracts fluctuated and did not decline to the same extent as that of leaf laminae, buds or exudate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Spray applications of 1000 mg/l (2-chloroethyl)phosphonic acid (CEPA) five times, at weekly intervals, during November and early December induced heavy flowering in ringed and nonringed juvenile mango seedlings. The treated plants produced flower buds which opened by the end of December, while the control and ringed seedlings produced only a new flush of vegetative growth. The results show that CEPA could be profitably used for early evaluation of hybrid seedlings in mango breeding programme.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Model-experiments to determine the quantitative yield in purification of cytokinin extracts have been performed with kinetin, isopentenyladenine and zeatin and with their ribosides. When these substances in water solution of pH 3 are shaken three times with equal volumes of ethyl acetate, most of the kinetin and isopentenyladenine and their ribosides go over to the ethyl acetate phases. Zeatin and its riboside stay in the water phase. The unsuitability of using ethyl acetate to purify cytokinin extracts is pointed out.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nutrient requirements of callus tissues previously obtained from Vigna sinensis hypocotyl segments were investigated on modified White's (Miller and Skoog) and Murashige and Skoog's media containing 1 mg/1 of each of 2,4-D and kinetin, 2% sucrose and 1% agar. Yields of tissues on the latter medium were 3 times more than the former. After studying various organic and inorganic nutrients, two synthetic media have been developed for callus cultures. The above modified White's medium further supplemented with 2% sucrose, and 500 mg/1 of urea or asparagine was suitable for a compact callus with a dry-to-fresh-weight ratio around 8% and on this the tissues grew 15- to 17-fold in 5 weeks. Similarly the Murashige and Skoog's medium further enriched with 2% sucrose, 400 mg/1 of urea or a mixture of aspartic acid (750 mg/1), glutamic acid (250 mg/1), asparagine (250 mg/1) and arginine (250 mg/1), was apt for a friable callus with a dry to fresh weight ratio of 3 to 4% and it promoted a 45- to 50-fold increase in growth in 5 weeks.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Examination of the effect of CO2-concentration and time of day on the content of malic acid, citric acid, aconitic acid, isocitric acid, succinic acid and fumaric acid in tomato leaves, revealed that the total content of these acids will rise with the CO2-concentration up to 0.10 vol% CO2. In the morning up to 0.22 vol% CO2 was needed for optimal effect.Samples of leaves picked at 1 a.m. showed the lowest content of these acids. At 9 a.m. the content had increased, and at 4 p.m. the increase was considerable. The content of malic and citric acid constituted 36 and 34% of the total acid content. In the afternoon and the night the aconitic acid represented 14% and in the morning 20% of the total acid content. Isocitric acid, fumaric acid and succinic acid occurred only in relatively small concentrations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Agrostis palustris turfs cut weekly at 1.3 cm were subjected to successive four-week periods with day-night temperature regimes of 20–10, 25–15, 30–20, 35–25 and 40–30°C. Plants grown at 40–30°C exhibited a growth character distinctly different from those grown at 20–10°C. They were more upright and bristle-like in growth habit. The percentage dry weight of leaf blade tissue increased 67% and weight per unit area increased 53% between 20–10 and 40–30°C. Reduced leaf blade width was noted first at 30–20°C while leaf blade length reduction first occurred at 35–25°C. Weekly yields were significantly reduced at the supraoptimal temperature regimes of 35–25 and 40–30°C. Chlorophyll content was lowest at 20–10 and 40–30°C, the lowest and highest temperature regimes studied. Shoot density appeared to decrease under the 35–25°C regime, but no dead plants were observed. The apparent decrease in shoot density was attributed to the upright growth habit. Density decreased at 40–30°C upon death of individual plants. A community of grass plants maintained as a turf was found to change in form quite rapidly in response to temperature.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Agrostis palustris sods were grown sequentially in a controlled environment chamber at 20–10, 25–15, 30–20, 35–25, and 40–30°C day-night temperature regimes. Leaves grown at 40–30°C contained 53% more ethanol soluble and 51% more water soluble carbohydrate than those grown at the 4 lower temperature regimes. The increase in ethanol and water soluble carbohydrate in leaves at 40–30°C could not be attributed to a blockage in translocation of photoassimilate to lower plants parts based on quantitative carbohydrate analyses on stem and stolon tissue.Manometric measurements of photosynthesis indicated that leaf blades grown at the five temperature regimes exhibited different rate capabilities when tested under non-limiting light and carbon dioxide levels. Oxygen evolution increased directly with temperature from 20 to 40°C and was 8 to 11 fold greater than the rate of carbon dioxide evolution. Both quantitative and qualitative differences in the photosynthetic rate were postulated in the leaf blade tissue tested. The quantitative difference was attributed to a possible difference in the number of cells per unit area and their size. The qualitative difference was attributed to greater thermal stability of leaf proteins when plants were grown at supraoptimal temperatures.Manometric respiratory rate studies did not indicate similar differences in temperature response in leaf blade tissue grown at the five temperature regimes. The cause of decreased shoot growth at supraoptimal temperatures could not be attributed to decreased and limiting C-6 carbohydrate synthesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ATP pool of growing fungal mycelia, particularly Fomes annosus, has been determined. The ATP level varied during the different growth phases and correlated with the variations in the economic coefficient. Common uncouplers (at concentrations similar to those used in mitochondrial tests) decreased the ATP pool very rapidly. The size of the pool often fell 50–80% before the O2 uptake decreased below that of the control and was accompanied by an increasing exudation of inorganic phosphate. Phenolic compounds added to the medium stimulated the lacease activity, generally in combination with a decrease in the ATP level.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Lipid composition of whole roots of wheat (Triticum vulgare Vill. cv. Svenno Spring Wheat) and oat (Avena sativa L. cv. Brighton) and of cell wall fractions, mitochondrial fractions and microsomal fractions of these roots were studied. Lipid composition depended upon the level of mineral nutrition. In wheat total phospholipids, phosphatidyl choline and sulfolipid content was highest in the roots grown at the higher salt concentration, while the reverse was true for oat roots. In both species glycolipid and sterol content was lower in the high salt roots, at the same time as higher proportions of them were built into the microsomal fraction. Phosphatidyl choline content of the wheat root membrane fractions increased with the salt level, while the opposite occurred in the oat roots.The phosphatidyl choline content may be correlated with the (Ca2+, Mg2+)-stimulated ATPase activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Intact, 14-day-old nitrogen-depleted wheat (Triticum vulgare cv. Blueboy) seedlings were exposed to solutions of 0.5 mM KNO2, 0.05 mM CaSO4 and 1 mM sodium 2-[N-morpholino]-ethanesulfonate, pH 6.1. Nitrite uptake was determined from depletion of the ambient solution or from incorporation of 15N in the tissue. An initial nitrite uptake shoulder was followed by a relatively slow uptake rate which subsequently increased to a substantially greater rate. This accelerated phase was maintained through 24 h. Nitrite accumulated to a slight extent in the root tissues during the first few hours but declined to low values when the accelerated rate was fully developed, indicating an increase in nitrite reductase activity paralleling the increase in nitrite uptake capacity. About 50% of the nitrogen absorbed as nitrite was translocated to the shoots by 9–12 h.Development of the accelerated nitrite uptake rate was restricted in excised roots, in intact plants kept in darkness, by 400 μg puromycin ml−1 and by 1 mM L-ethionine. When puromycin and L-ethionine were added after the accelerated phase had been initiated, their effects were not as detrimental as when they were added at first exposure to KNO2. The two inhibitors restricted translocation more than uptake. The data indicate an involvement of protein synthesis and a requirement for movement of a substance from shoots to roots for maximal development of the accelerated nitrite uptake phase. A requirement for protein synthesis in the transport of soluble organic nitrogen from roots to shoots is also suggested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Morphogenesis has been induced in excised organs and callus tissue cultures obtained from various parts of the seedling and mature plants of pimpernel (Anagallis arvensis). Vigorously growing cell cultures capable of being periodically subcultured have been established in liquid as well as on the agar-solidified Murashige and Skoog's medium supplemented with 2,4-D (0.1 mg/1) + kinetin (0.1 mg/l) + coconut milk (10%). The callus tissue obtained from excised hypocotyl segments is white, soft, friable and fast growing, and has been subcultured over a period of two years without showing any sign of decline in growth. The optimum conditions for growth are at pH 5.9, temperature 27°C, and with 4% sucrose as the carbon source. Under appropriate nutritional supply these cultures can be manipulated to induce rhizogenesis in the suspension cultures, and buds and “embryo-like” structures on agar-solidified media.The excised leaves, hypocotyl and stem segments regenerate buds. Of the cytokinins used, 6-(y,y-dimethylallylamino)-purine proved to be the best for the number of cultures producing buds, as well as for the number of buds per culture. Anatomical studies revealed that buds arise from the epidermal and subepidermal layers of leaves and hypocotyl; these buds form shoots which eventually develop into plantlets.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of exogenously supplied NAA and BA on the shoot and root formation in isolated petiole segments of Begonia×cheimantha was determined in vitro on a modified White medium at a constant temperature of 24°C. The best development of normally appearing plants was obtained on media containing 0.01 mg × 1−1 of NAA and 0.5 to 1.0 mg × 1−1 of BA. Lower concentrations of BA yielded no shoots, higher concentrations promoted shoot formation, but the shoots were abnormal with malformed leaves. Lower concentrations of NAA resulted in poorer survival rate and no roots, with higher concentrations of NAA many roots developed, but these were thickened and their longitudinal growth inhibited. Temperature proved to be of utmost importance for the induction of shoot formation. Thus significantly fewer shoots were formed at the higher temperature (25°C) than at lower temperatures (15 to 20°C). Temperature immediately after initial transfer was of greatest importance: 25°C, during the first week followed by low temperature, produced very few shoots.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The mechanism of ABA-induced callus formation was studied in sterile bud cultures of Citrus [Citrus sinensis (L.) Osbeck] on defined media. ABA was found to promote callus formation in the abscission zone between the petiole and the branch while inhibiting bud growth. The promoting effect of ABA was dependent on the physiological state of the shoot from which buds were excised, and on the size of the explant. Callus formation was highest in autumn and summer (i.e. younger) buds, and lowest in older buds excised from previous summer flush.GA was only slightly active in promoting callus formation when applied separately, but showed a highly synergistic effect when applied with ABA: maximal callus formation was attained at a combination of 10−5M ABA and 10−6 MGA in the medium. Subcultures of ABA-induced callus revealed that ABA inhibited the growth of isolated subcultured callus, while IAA and kinetin, and especially GA, promoted its rapid proliferation. A general decrease in protein synthesis was found in the abscission zone during the first 5 days of induction, while total protein content changed only slightly.The results suggest that ABA-induced callus formation in Citrus bud explants is a multiphasic phenomenon involving, at least, two stages: (1) activation of certain cells in the abscission zone by ABA, resulting in the formation of callus layers, and (2) subsequent proliferation of the callus tissue, which is dependent on the hormonal balance in the explant. This growth-promoting effect of ABA seems to be a general phenomenon in explants exposing a cut-surface.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: When seedlings of Pharbitis nil are presented with an inductive dark period at varying times, they show a circadian fluctuation in the number of flower buds initiated. This study determines if this fluctuation is due to the plant's perception, at the time of the inductive dark period, of either a rhythmic, external, environmental stimulus or of an endogenous rhythm.Using experimental designs in which the time of planting, the time of seedling emergence from the soil, and the time at which the presentation of an inductive dark period are varied, this fluctuation in flower bud formation is shown to be due to an endogenous rhythm initiated or synchronized by some event associated with the emergence of the seedlings from the soil. The results are inconsistent with the hypothesis that the plants are responding to rhythmic external stimuli.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Procedures were devised for purification of the cytokinins in the milk of mature coconuts (Cocos nucifera fruits). One cytokinin isolated in crystalline form was unequivocally identified as 9-β-D-ribofuranosylzeatin. This compound appeared to account for a large proportion of the cytokinin activity in n-butanol extracts of coconut milk. The activity which was not extracted by n-butanol was largely due to unidentified compounds which could be partially purified by adsorption onto and elution from charcoal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The activities of trypsin inhibitors and Aspergillus-proteinase inhibitors have been assayed in barley embryos germinating in different conditions.The Aspergillus-proteinase inhibitor activity increased about 20-fold during 6 days at 20°C both in separated embryos germinating on nutrient agar and in the embryos of undissected grains germinating on agar with or without mineral salts. Significant inhibitor activity was also present in root tips at later stages of vegetative growth. Whether any changes occurred in the molecular weight distribution of the inhibitors present in the seedlings was studied by gel filtration on Sephadex G-75; only minor changes were observed.The trypsin inhibitor activity per seedling remained roughly constant in all cultures. In gel filtration experiments all the activity appeared to be due to the inhibitor species present in resting embryos.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 32 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Auxin was applied to the upper part of the cuttings, which were both decapitated and disbudded on the same day. The applied auxin was removed by redecapitating the cuttings at different time intervals. In a second experiment, auxin was applied either to the upper or lower part of the decapitated and disbudded cuttings at different time intervals.In cuttings, which were redecapitated after 1 and 2 days, the root formation was reduced considerably. The redecapitation after 3 days had no adverse effect on the root formation. Cuttings treated with auxin at different time intervals showed a weaker root promotion on days 0 and 1 than on the subsequent days.The results emphasize the fact that auxin is active only during the first part of the root initiation phase. A continuous flow of auxin for a period of the first 3 days during the root initiation is of overriding importance. There appears to be at least two different stages of the root initiation phase, (ia) auxin active stage, and (ib) auxin inactive stage. The results also seem to indicate that some other factors, in addition to auxin, are active during the first stage of the root initiation phase.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A sharp decline in water potential of petal tissue associated with wilting of cut rose flowers is described. Such a decline did not develop in senescing intact flowers. A circadian rhythm in water absorption by cut flowers was observed.The decline in fresh weight observed in the last phase of the vase life of cut flowers occurred earlier in a short-lived cultivar than in a longer-lived one. A decline in potential conductivity to water was observed with time in stems of cut roses. Concomitantly cellulase activity increased after cutting. Flowers held in cellulase solution wilted earlier than the controls. However, no difference was found in these two parameters between two cultivars differing in their longevity. The difference in longevity between the two cultivars was large especially under conditions promoting high transpiration rates, and was narrowed when flowers were either held in mild conditions, or the leaves were stripped off.Although stomates were equally open in intact flowers of the two cultivars, in cut flower shoots of the short-lived cultivar stomates were more widely open. In accordance transpiration rates were higher, and wilting occurred earlier in the short-lived cultivar than in the long-lived one. It is concluded that the earlier wilting of cut flowers of the short-lived cultivar is mainly due to lower ability to close stomates in response to water stress conditions, and not to earlier formation of vascular blockage.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The possibility that symptoms of flooding damage in plants are primarily caused by an accumulation of ethylene was investigated using pot-grown sunflower (Helianthus annuus) plants.When plants were flooded to the basal pairs of leaves, ethylene in roots and stems below the water line began to increase. This coincided with the start of hypocotyl hypertrophy and new root formation in hypocotyls, which continued for 14-16 days. There were highly significant correlations between ethylene concentration and number of roots and hypocotyl diameter.After approximately 4 days of flooding, ethylene concentrations in stems between nodes for the 1st and 3rd basal pairs of leaves started to increase, coinciding with initiation of chlorophyll breakdown and epinasty of the 2nd basal pairs of leaves. Thus, there were correlations between ethylene concentration and chlorophyll breakdown and epinasty. The lower the leaves, the more chlorophyll breakdown among 1st, 2nd, 3rd, and 4th basal pairs of leaves. The longer the flooding, the more severe the flooding damage; and even when returned to normal condition, plants flooded longer than 3 days were not able to recover from flooding damage.A gas chromatographic study revealed that Ethephon was absorbed by roots and decomposed to ethylene in the plant. Damage symptoms caused by soil application of Ethephon, such as reduced stem height, chlorophyll breakdown, epinasty of the 2nd basal pairs of leaves, and hypocotyl hypertrophy, were almost identical with those caused by soil flooding treatment.Microscopic studies revealed that radially enlarged cells and increased intercellular spaces in the cortex were the major contribution to the increased hypocotyl diameter in both flooded and Ethephon-treated plants.It is concluded that the increase in ethylene concentration in flooded plants is largely, although not exclusively, responsible for flooding damage symptoms.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The purpose of this study was to analyze the nature of the interaction between gibberellic acid (GA3) and abscisic acid (ABA) in the regulation of growth in excised Avena (oat) stem segments. Growth, compared to sucrose controls, was inhibited by ABA in the range of 10−4 to 10−6M. GA3-promoted growth was also inhibited by ABA in the same concentration range. A Lineweaver-Burk analysis of the interaction between GA3 and ABA indicated that ABA acts in a non-competitive fashion with GA3. This same result was obtained previously with GA3-indoleacetic acid (IAA) and GA3-kinetin interactions with Avena stem sections. Our results indicate that ABA can inhibit GA3-promoted growth within physiological concentrations, and that it is probably acting at a different physiological site from that for GA3.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of abscisic acid on plant growth and survival during water deprivation was studied in barley and wheat seedlings. Under conditions of both limited and ample water supply, treatment with abscisic acid greatly reduced transpiration and, in addition, suppressed root growth. In water-deprived seedlings, abscisic acid increased the total dry matter, reflecting improved efficiency in water-use. In addition, the growth period and survival of water-deprived seedlings were markedly prolonged. In field trials, however, abscisic acid had no significant effect on waterdeprived seedlings. Possible reasons for this lack of response are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The incorporation of 14C-labelled phenylalanine into proteins of mitochondria prepared from 48-h germinating seeds of Vigna sinensis (L.) Savi can be stimulated by gibberellic acid (GA3), kinetin and polyuridylic acid [poly(U)]. The incorporation is sensitive to various metabolic inhibitors which include rifampicin, actinomycin D, ethidium bromide, kanamycin, 5-azauracil, 8-azaadenine, and rotenone. They were used to study the effect of GA3 and kinetin on the sequential steps in protein synthesis (DNA -> RNA -> protein), which are variously affected by the inhibitors. The inhibitory effect of actinomycin D on the incorporation can be reversed by GA3 and kinetin, which implies that these two plant hormones act at the transcription level. With ethidium bromide the effect of hormones is not so convincing, though the trend is towards some release of inhibition. The plant hormones have apparently no effect on the incorporation sensitive to other inhibitors studied.GA3 and kinetin can also stimulate the normal and polyadeny-lic acid [poly(A)]-directed incorporation of 14C-labelled lysine into proteins by a mitochondria! preparation, lndole-3-acetic acid and 2,4-dichlorophenoxyacetic acid can only stimulate the normal synthesis, which is not further stepped up by poly (A). The polynucleotide even seems to depress the action of IAA. This anomaly has been discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 31 (1974), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Low-temperature (77°K) fluorescence and absorption spectra have been determined for whole cells and photosystem I particles of Anacystis nidulans grown in iron-supplied or iron-deficient inorganic media. Iron deficiency induces a decrease of F720 relative to F685 and F695 in the fluorescence spectra of both whole cells and photosystem I particles. This change is correlated to a reduction of preferentially the long wavelength absorbing fraction of chlorophyll a. The relative fluorescence intensity at 755 nm is increased by iron deficiency. No significant effects of culture-age are found in the ratio between the three fluorescence bands (F685: F695: F720) of iron-supplied A. nidulans.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005