bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth Regulators in Populus tremula IV. Apical Dominance and Suckering in Young Plants
Authors: ELIASSON LENNART 
Published: April 2006

AbstractExperiments with small plants of Populus tremula L. growing in solution culture indicate that polarly transported auxin is an important factor in the control of axillary bud growth. If the auxin supply from the growing apex is eliminated, the number of buds released is influenced by factors translocated in the transpiration stream from the roots. Suckers may be induced to develop from aspen roots, the age of which is six weeks or more. Removal of the growing apex and the axillary buds or stoppage of shoot growth by short day treatment were effective in inducing abundant suckering in small aspen plants. Some mature leaves had to be maintained, indicating the dependence of sucker formation on carbohydrate supply. These treatments are known to decrease auxin production in the shoots. Extraction and biological assay showed a decrease in the content of auxin in the roots as a consequence of removal of growing shoot parts. The results indicate that suckering in roots of intact aspen plants is prevented by auxin transported into the roots from growing shoot parts.
Adverse Effect of Shoot Growth on Root Growth in Rooted Cuttings of Aspen
Authors: ELIASSON LENNART 
Published: April 2006

AbstractIn experiments with rooted cuttings of aspen (Populus tremula L). with a small leaf area, it was found that the roots grew well as long as there was no shoot growth. The onset of shoot growth was followed by a period of decreased root growth. When the leaf area had increased sufficiently, root growth recovered. Decreasing the shoot growth by removal of growth points in the shoot or by short day treatment increased the fraction of photosynthesis products used for root growth, leading to increased root/shoot ratios. Competition between growing shoots and roots for carbohydrates formed in photosynthesis is considered to cause the effects noted and to be of importance for maintaining the balance between the root and shoot systems.
Frost Damage Resulting from Ice Crystal Formation in Seedlings of Spruce and Pine
Authors: CHRISTERSSON LARS 
Published: April 2006

AbstractThe influence of ice crystal formation in tissues of unhardened and hardened seedlings of Pinus silvestris L. and Picea abies (L.) Karst. was determined. An apparatus for this purpose was constructed.Unhardened seedlings of spruce collapsed completely as a result of ice crystal formation in their shoots, while unhardened seedlings of pine survived ice crystal formation with or without injury to the needles. After a hardening period of 4–5 weeks, seedlings of spruce and pine survived ice formation but injuries occurred in spruce. For pine, on the contrary, the temperature after ice formation had a decisive effect on the extent of the injuries. Observed injuries are discussed in terms of inter‐ and intracellular ice crystal formation.
Differential Transport of Boron in Tomato (Lycopersicon esculenlum Mill.)
Authors: BROWN J. C. , JONES W. E. 
Published: April 2006

AbstractTwo tomato cultivars, T3238 (B‐inefficient) and Rutgers (B‐efficient), were grown in solution cultures with increasing concentrations of B. Rutgers was about 15 times more efficient than T3238 in utilizing the B in the growth medium. Rutgers translocated more B to top leaves than the inefficient T3238. When plants developed B‐deficiency symptoms, there was no evidence of B redistribution between tissues. Reciprocal grafts of T3238 and Rutgers demonstrate root control of B transport.
The Relation Between the Phytylation and the 682 → 672 nin Shift in vivo of Chlorophyll a
Authors: AKOYUNOGLOU G. , MICHALOPOULOS G. 
Published: April 2006

AbstractThe rate of phytylation and the rate of the in vivo Chl682→ Chl672 nm shift of the newly formed chlorophyllide were examined after a brief illumination of dark‐grown Phaseolus vulgaris leaves at different stages of development. Both processes were found to be age dependent but independent of one another. The Chl682→ Chl672 nm shift process precedes that of phytylation. In addition, there is a linear relationship between tissue age and the delay time between the two processes, indicating that they are not identical, although they are almost parallel. There was no evidence obtained of a far‐red light effect on any of the two processes. Experiments done with freeze‐dried etiolated plant tissue showed the presence of PChl650 and PChl637 forms, which by illumination form Chl678. If a trace of water is added to the etiolated freeze‐dried tissue before illumination the PChl650 and PChl637 are transformed to the non‐phototransformable PCh650 form. Moreover, no shift of the Chl678 form is observed, unless a trace of water is added to the freeze‐dried tissue. These results are explained by a mechanism of structural rearrangement in the chloroplast after protochlorophyllide phototransformation leading into monomeric chlorophyllide units, which can then be phytylized.This explanation is substantiated by the results of experiments done with isolated protochlorophyllide‐holochrome: addition of 4M urea before or after illumination to the protochlorophyllide‐holochrome solution showed a PChl636→ PChl629 and Chl676→ Chl668 shift respectively.
The Effect of Growth Regulators and Cu2+ on the Activation of Amylopectin‐l,6‐glucosidase Activity in Pea Seedlings
Authors: VLODAWSKY LEA , HAREL E. , MAYER A. M. 
Published: April 2006

AbstractNo evidence could be obtained for hormonal control of amylopectin‐l,6‐glucosidase activity in germinating peas for the first 72 hours of germination. The embryonic axis did not stimulate the appearance of enzyme activity. The autolytic system which releases amylopectin‐l,6‐glucosidase activity from the particulate fraction, in which it originates, was studied in greater detail. Using Cu2+ ions to inhibit a proteolytic enzyme in vivo, it was shown that enzyme activation can occur in the zymogen‐like granules without liberation of the enzyme into the soluble cell fraction. Activity so formed is labile. Some of the data on proteolytic enzymes in peas is discussed and an attempt made to interpret the liberation of amylopectin‐l,6‐glucosidase in peas on the basis of the involvement of at least two distinct proteolytic enzymes.
Growth of Avocado Fruit Callus and Its Relation to Exogenous and Endogenous Cytokinins
Authors: BLUMENFELD A. , GAZIT S. 
Published: April 2006

AbstractCallus derived from avocado cotyledons and mesocarp was grown in tissue culture. Cytokinins in nutrient media were vital for the growth of mesocarp callus but not for the growth of cotyledonous callus. It was found that cotyledonous callus synthesized Cytokinins.
Photosynthetic Rates, Gross Patterns of Carbon Dioxide Assimilation and Activities of Ribulose Diphosphate Carboxylase in Marine Algae Grown at Different Temperatures
Authors: MORRIS IAN , FARRELL K. 
Published: April 2006

AbstractStudies of the marine green flagellate Dunaliella tertiolecta have confirmed and extended previous observations of Steemann Nielsen and his colleagues. Algae, grown at 12°C, assimilated carbon dioxide under light‐saturated conditions more rapidly than did those grown at 20°C; for both, the assimilation rate being higher at 20°C than at 12°C. Cells grown at the lower temperature contained higher concentrations of soluble protein, higher activities of ribulose diphosphate carboxylase and showed an enhanced relative rate of protein synthesis during the photosynthetic assimilation of carbon dioxide. This appears to represent true adaptation since it allowed the growth rate at 12°C to be almost the same as that at 20°C.Studies of the marine diatom Phaeodactylum tricornutum have not revealed the same picture of temperature adaptation. Cultures grown at 5°C had significantly higher rates of photosynthesis than did those grown at 10°C, but the same was not true when algae grown at 10°C were compared with those grown at 20°C. In this organism, growth at the lower temperatures reduced its ability to photosynthesize at 20°C. Cells grown at the lower temperatures contained more protein than did those grown at 20°C; this was particularly marked in cells growing at 5°C, a temperature which reduced the growth rate. The relative rate of protein synthesis was higher in Phaeodactylum grown at lower temperatures; but this difference was most marked when the measurements were made at 20°C.
Translocation of Photosynthates in Tall and Dwarf Varieties of Pea, Pisum sativum
Authors: LOVELL PETER H. 
Published: April 2006

AbstractQuantitative studies of the translocation of radiocarbon from a young expanded leaf of two tall varieties (Improved Pilot and Thomas Laxton) and two dwarf varieties (Little Marvel and Meteor) of Pisum sativum showed that 40 to 45 per cent of the radiocarbon was exported from the 14CO2 treated leaf after 24 hours in all four varieties. Although substantial export to the upper shoot always occurred it was more marked in the two tall varieties. Pre‐treatment with GA did not affect total fixation but increased total export from the 14CO2 treated leaf in cv. Meteor and decreased it in cv. Improved Pilot. GA had no effect on the translocation pattern in the tall plants but modified that of the dwarf plants to correspond to that found in the tall varieties.
The Effect of Some Inhibitory Sugars upon the Content of Adenosine Triphosphate in Wheat Roots
Authors: STENLID GÖRAN 
Published: April 2006

AbstractThe content of adenosine triphosphate (ATP) in roots of ‐wheat (Triticum aestivum L.) was determined with the fire‐fly‐luciferase method. The content is decreased by D‐mannose, which inhibits root growth, respiration and chloride uptake. In intact seedlings the inhibition of root growth is relieved by other sugars and also by the flavanone naringenin and by 2,4‐dinitrophenol. This reversal is combined with an increased content of ATP.The inhibition of chloride uptake by mannose in excised roots is reversed by some other sugars (including D‐galactose which is in itself inhibitory to root growth), and also in this case the ATP content is increased. Naringenin and dinitrophenol do not relieve the inhibition of chloride uptake caused by mannose. Nor do they increase the content of ATP in this case.The primary effect of mannose seems to be inhibition of glycolysis whereas the effect upon root growth is secondary. Galactose, which also inhibits root growth, does not inhibit respiration or reduce the ATP content and the primary effect of galactose (and also of 2‐deoxy‐D‐glucose and 2‐deoxy‐D‐galactose) seems to be on the synthesis of cell wall substances.
Transport and Degradation of Auxin in Relation to Geotropism in Roots of Phaseolus vulgaris
Authors: IVERSEN TOR‐HENNING , AASHEIM TORBJØRN , PEDERSEN KNUT 
Published: April 2006

AbstractThe movement of auxin in Phaseolus vulgaris roots has been examined after injection of IAA−3H into the basal root/hypocotyl region of intact, dark‐grown seedlings. Only a portion of the applied IAA−3H was transported unchanged to the root tip. The major part of the chromatographed, labelled compounds translocated to the roots was indole‐3‐acetylaspartic acid (IAAsp) and an unidentified compound running near the front in isopropanol, ammonia, water.The velocity of the auxin transport (7.2 mm per hour) was calculated from scintillation countings of methanol extracts from serial sections of the root. An accumulation of radioactive compounds in the extreme root tip, was observed 5 h after the injection of IAA.The influence of exogenous IAA on the geotropical behaviour of the bean seedling roots was examined. Pretreated roots were stimulated for 5 min in the horizontal position and then rotated parallel to the horizontal axis of the klinostat for 60 or 90 min. The resulting geotropic curvature of IAA‐injected and control roots showed significantly different patterns of development. When the stimulation was started 5 h after application of the auxin, the geotropic curvature became larger in roots of the injected plants than in the controls. If, however, the translocation period was extended to 20 h the geotropic curvature was significantly smaller in the roots of the injected plants. The auxin injection did not significally affect the rate of root elongation.The change in geotropical behaviour of the roots is interpreted as a result of the influence of the conversion products of the applied IAA on the geotropical responsiveness.
The Interaction of pH and Aeration in CI Uptake by Barley Roots
Authors: JACOBSON L. , COOPER B. R. , VOLZ M. G. 
Published: April 2006

AbstractThe uptake of Cl by excised roots of barley (Hordeum vulgare L.) from KC1 solution maintained at high pH was markedly reduced by high rates of aeration, whereas K uptake was scarcely affected. Aeration rate had relatively minor effects at low pH. The effect of high aeration rate at pH 9 could be overcome by the use of buffered solutions. In unbuffered solutions the H resulting from the excess cation uptake together with that produced from respiratory CO2 was sufficient to materially reduce the pH of the solution. The reduction in pH favored the uptake of Cl which is adversely affected by high pH. The effect of aeration rate could be explained in terms of root induced pH changes and film diffusion involving the solution film adjacent to the root surface.
Protein Metabolism of Allium Radicle Tips during Germination
Authors: MALLERY CHARLES H. 
Published: April 2006

AbstractAs an initial step in the study of the molecular events surrounding the establishment of a mature root apex, analyses of the early germinative growth of the Allium radicle were undertaken. Changes in the level and pattern of the soluble proteins were investigated by polyacrylamide gel disc electrophoresis and Joyce‐Loebl densitometry. Histochemical studies revealed the presence of protein bodies in the terminal mm of the Allium radicle. These bodies underwent depletion and breakdown during germination.The results of the electrophoretic fractionation of the soluble proteins during germination showed that there was not a proliferation of protein components but, rather, a considerable change in the concentration of existing protein fractions. Several fractions, assumed to be components of the reserve or storage proteins, showed a quantitative depletion correlated in time with the loss of the protein bodies.Quantification of the soluble proteins during germination showed a 32% decrease per radicle tip over a 67‐hour period, but when expressed on a per cell basis a 32% increase was noted. A dramatic increase in protein synthesis, as measured by 3H‐leucine incorporation, was initiated after 36 hours' exposure to germinative conditions, that is, at the beginning of radicle protrusion.A time‐ordered sequence of events was noted for the depletion of the protein bodies and their assumed reserve components, suggesting their ultimate utilization in new protein synthesis.
The Role of Light in the Interrelated Processes of Morphogenesis and Photosynthesis in the Fern Gametophyte
Authors: DONAHER D. J. , PARTANEN C. R. 
Published: April 2006

AbstractThe interrelationship of photosynthesis and photomorphogenesis in the gametophyte of the fern Pteridium aquilinum was examined in detail. High energy red light produces filamentous gametophytes composed of greatly elongated cells. Blue light of equal energy produces normal cordate gametophytes composed of isodiametric cells. The assimilative rates of the two forms are identical during the initial stages of development. However, the filamentous gametophytes eventually exhibit a decline in assimilation not matched by their normal counterparts.Although this decrease in assimilation of gametophytes exposed to red light may be traced to a decrease in the photo‐synthetic rate due to a decrease in chlorophyll synthesis, these events occur subsequent to the establishment of the filamentous mode of growth and are therefore a result, not a cause, of filamentous development.Gametophyte assimilation is also impeded under low energy blue light, due to a reduction in the photosynthetic rate at this low energy; and the initial filamentous stage, in which the cells remain normally isodiametric, is not exceeded. The addition of extra exogenous sucrose restores the capacity for growth and normal cordate prothalli result.It may therefore be concluded that the ultimate form of the gametophyte is under the control of a photoreceptor that is sensitive to blue light, and activated at a relatively low energy level. Red light at any level is ineffective in promoting normal cordate development, but is effective in supporting growth through vigorous photosynthesis, yielding a filament composed of greatly elongated cells. The eventual photosynthetic decline of the filamentous form is due directly to this particular growth mode.Low energy blue light is sufficient to effect form (the cells remain isodiametric), but insufficient to provide the necessary energy for growth through vigorous photosynthesis. Therefore, in order for the gametophyte to reach maturity it must be supplied with light energy that not only satisfies the requirement for form but the requirement for growth as well. The implications of these requirements are discussed in the text.
A Cotyledonary Inhibitor of Root Nodulation in Pisum sativum
Authors: PHILLIPS DONALD A. 
Published: April 2006

AbstractRoot nodule formation was studied in 11‐day‐old seedlings of Pisum sativum L. cv. Alaska, which were inoculated with Rhizobium leguminosarum at the time of planting. On intact plants an identical nodulation pattern was observed in the lateral roots attached to the two xylem strands connected to the cotyledons. When one cotyledon was removed before germination, however, a highly significant increase in nodultion was observed on the lateral roots attached to the xylem strand which no longer was connected to a cotyledon. Excision of one cotyledon also caused an alteration in the radial location of root nodules on the primary root. Under these conditions there was a distinct promotion of nodular proliferations in the root cortex opposite the primary phloem poles. The fact that removal of one cotyledon increased nodulation on the lateral roots but had no effect on the rhizobial infection of lateral root hairs suggested that a cotyledonary inhibitor acts at a step between the infection process and the appearance of a macroscopic nodule. The data were interpreted in terms of an inhibitor of cortical cell division which is translocated from the cotyledons to the developing root via the phloem.
Periodic Nocturnal Stomatal Opening of Citrus in a Steady Environment
Authors: EHRLER WILLIAM L. 
Published: April 2006

AbstractIn a steady environment, leaf stomates of sour orange (Citrus aurantium L.) remained closed in the dark, whereas those of rough lemon (Citrus jambhiri Lush) underwent several 20‐minute periods of pronounced opening at intervals of 60–85 minutes. Peak nocturnal opening occurred about 10 minutes after the cycle began, as shown by a change in leaf diffusion resistance from 60 s cm−1 (closed) to 2 s cmminus;1 (open). This minimal leaf resistance equals that obtainable in rough lemon in strong illumination (26 kilolux).The transitory stomatal opening detected by leaf resistance measurements was corroborated by measurements of leaf temperature and leaf thickness. During nocturnal opening, leaf temperature was 2°C below the value representing non‐cycling periods. Also, minimal leaf thickness coincided with maximal stomatal opening.The triggering mechanism for nocturnal stomatal opening appears to originate within the plant, since the environmental factors of air temperature, humidity, carbon dioxide concentration, and substrate (aerated water culture) were held steady.
Lipids in Cruciferae IX. The Effect of Growth Temperature and Stage of Development on the Fatty Acid Composition of Leaves, Siliques and Seeds of “Zero‐erucic‐acid” Breeding Lines of Brassica napus
Authors: APPELQVIST LARS‐ÁRKE 
Published: April 2006

AbstractTwo breeding lines of “zero‐erucic‐acid” rapeseed (Brassica napus) were grown in climate chambers at a constant night temperature (12°C) and constant photoperiod (16 hours) but with different day temperatures (15, 20 and 25°C). Samples of leaves, siliques and immature seeds were analysed for total fatty acid pattern. The content of different acyl lipids and the fatty acid pattern of these lipids were also determined in some of the samples by use of preparative TLC followed by GLC of the fatty acids. The mature seeds produced by ten plants of each selection in each climate were analysed separately for total fatty acid composition.Mono‐ and digalactosyl diglycerides (MGDG, DGDG) were the predominant acyl lipids in leaves and siliques. In developing seeds they also were more abundant than the phospholipids, but in this case the neutral lipids, mainly triacylglycerols, contained about 95% of the total fatty acids. Large variations were found in the fatty acid composition of monogalactosyl diglyceride and digalactosyl diglyceride, isolated from leaves, siliques and immature seeds. The palmitic acid content of leaf MGDG was about 15 %, atypically high for MGDG from photosynthetic tissue. The linolenic acid content of the MGDG was about 45 %, 30 % and 10 % in the leaf, silique and seed tissues respectively. A hexadecatrienoic acid (16: 3) was found almost exclusively in the MGDG samples of leaves, siliques and immature seeds (about 25 %, 10 % and 3 % 16:3 respectively). The lipids of siliques — mainly photosynthetising tissue — were different from those of leaves and had especially high contents of stearic acid (6–12 % in the different lipids).For all lipid classes studied, leaves grown at the lowest day temperature had a slightly lower oleic and higher linolenic acid content than those grown at the highest temperature.On the other hand, increasing the day temperature caused a decreased level of oleic, an increased level of linoleic and an essentially unchanged level of linolenic acids in the mature seeds from both selections.
Tissue Tensions during Cell Elongation in Wheat Roots and a Comparison with Contractile Roots
Authors: BURSTRÖM H. G. 
Published: April 2006

AbstractA study has been made of tissue tensions in growing Triticum roots. After the initial phase of elongation with both a lateral and an exponential longitudinal growth, the tissues are under strong longitudinal stress. Plasmolysis in situ or splitting of the root in the pericyclic region causes an increase in length of the perivascular part. Freed from the stele the perivascular part contracts on plasmolysis. During the following only longitudinal growth, the stress decreases under decreased root diameter. When elongation has ceased, the root in situ contracts on plasmolysis. It is suggested that during radial growth longitudinal stresses are built up, which are released when the stele catches up with the growth of the cortex. The similarity to conditions in contractile roots of Arum (Lamant and Heller 1967) is pointed out. A difference is found in the polarity of growth and thus in the mode of release of the stresses. The cause of the tensions and methodical difficulties are discussed.
Effects of Indole‐3‐acetic Acid and Gibberellin on Synchronous Cultures of Chlorella fusca
Authors: LIEN TORLEIV , PETTERSEN RUNE , KNUTSEN GJERT 
Published: April 2006

AbstractThe applicability of synchronous cultures of Chlorella fusca as a reproducible experimental system for the study of growth regulators has been investigated using indole‐3‐acetic acid (IAA) and gibberellin.

None of these compounds stimulated growth or sporulation.
IAA inhibited growth and sporulation at concentrations higher than 6 × 10−5M, the effect increasing with increasing acidity. Gibberellin had no effect.