bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Changes in Translocation of 14C from Different Age‐Classes of Needles on 20‐Year‐Old Scots Pine Trees (Pinus silvestris)
Authors: ERICSSON ANDERS
Published: April 2006

Needles of 20‐year‐old Scots pine trees (Pinus silvestris L.) were permitted to photoassimilate 14CO2 for 1 h on different dates during the growing season. The loss of radioactivity from current, 1‐year‐old, and 2‐year‐old needles was followed, and the translocation of photoassimilated 14CO2 from older needle age‐classes to the elongating new needles studied. The effects of good mineral and water supply on translocation were also considered.

In the spring, 1‐year‐old and 2‐year‐old needles accumulated 14C. These reserves, together with current photosynthate, were utilized when the trees started growing. The 1‐year‐old needles exported 14C to the current needles during the first weeks of elongation of the later, while no such translocation occurred from the 2‐year‐old needles. Removal of the 1‐year‐old needles resulted in translocation of assimilates from the 2‐year‐old needles to the current needles. The general pattern of translocation observed in the control trees was not changed when the trees were fertilized and irrigated.

The new needles started to export assimilates in the middle of July when the photosynthetic rate per needle was comparable with that of the older age‐classes. This occurred about 4 weeks after positive net photosynthesis was first measured for the current shoot. The current needles of trees with good nutrient and water supply seemed to become self‐sufficient in photoassimilates earlier than the current needles of the control trees.
Nitrogenase Activity Measurements in Intact Plants of Alnus incana
Authors: HUSS‐DANELL KERSTIN
Published: April 2006

A technique for C2H2‐reduction assay on intact plants of Alnus incana (L.) Moench was evaluated. Cloned plants were grown, in pots, on fine gravel. During assay only the pot was inserted into a Perspex incubation chamber of simple construction. The incubation volume was rather small, plants with various shoot heights could be used, and the shoot was not exposed to the C2H4 produced. Intact plants showed high and constant C2H2‐reduction rates during several hours of incubation. In comparison, excised nodulated roots conventionally incubated in test tubes showed low and decreasing rates, due to removal of the photo‐synthesizing shoot and injury to the root nodules when drawn from the pot. Repeated nitrogenase activity assays on the same intact individual plants did not affect growth. The technique thus proved useful in studies. where repeated nitrogenase activity measurements are important.
The in vivo response of corn mitochondria to Bipolaris (Helminthosporium) maydis (race T) toxin
Authors: MALONE CARL P. , MILLER RAYMOND J. , KOEPPE DAVID E.
Published: April 2006

The addition of 2‐deoxyglucose to tissue elicits an in vivo mitochondrial conformation response (contraction) that can be viewed ultrastructurally and is indicative of the phosphorylative capability of mitochondria. Utilizing this technique toxin from Bipolaris (Helminthosporium) maydis race T was found to penetrate leaf and root tissue of Texas male‐sterile cytoplasm corn (Zea mays L. W64A) only slowly, but once in cells the toxin had a rapid deleterious effect on mitochondrial function. It is concluded that B. maydis (race T) toxin has effects on in vivo mitochondria similar to those reported after in vitro experimentation and that mitochondria are a primary site of toxin action. These observations are followed by the suggestion that susceptibility or resistance to B. maydis (race T) is conferred in corn by a cytoplasmically inheritable character associated with mitochondria.
The Aetiology of Vascular Discoloration in Cassava Roots after Harvesting: Association with Water Loss from Wounds
Authors: MARRIOTT J. , BEEN B. O. , PERKINS C.
Published: April 2006

When root pieces of cassava, Manihot esculenta Crantz (cv. Yellow Heart or cv. Cuba Sweet), with an area of periderm removed or with a transverse cut uncovered, were held at low humidity and at 22°C, vascular discoloration consistently developed within 2 days. Vascular discoloration was prevented when injured pieces were stored at high humidity or when wounds were covered by a semi‐permeable film. When pieces were injured by removal of periderm, at high humidity the respiratory rate was unaltered but at low humidity an increase in respiratory rate occurred after 1 day. When pieces were injured by a transverse cut, at high humidity respiratory rate increased during the first day but decreased thereafter, whereas at low humidity the initial increase was followed by a further increase in respiratory rate after 2 days. It is suggested that vascular discoloration and a respiratory increase may occur in freshly harvested cassava roots as a result of stress produced locally by high rates of water loss at cuts and abrasions.
Cold Hardiness of Pine Needles and Apple Bark as Affected by Alteration of Day Length and Temperature
Authors: BERVAES J. C. A. M. , KETCHIE D. O. , KUIPER P. J. C.
Published: April 2006

Cold hardiness of pine needles and apple bark was determined in a series of experiments. Plants were exposed to 0°C and 20°C and exposed to day length conditions of 9 and 14 h. All 16 possible combinations were investigated by transfer of the plants from the original condition to each of the other conditions. In order to interpret the results, it was necessary to distinguish between a single and a dual environmental factor change. In pine plants at 20°C, a change in two factors decreased cold hardiness contrary to a single change in temperature or day length. In plants at 0°C, the effects of a change in day length and temperature were additive. Differences in pine and apple are discussed in relation to natural conditions and to geographical distribution. It is suggested that for increased hardiness shortening of day length should precede a low temperature regime and that reversal of this order may upset the signal system, resulting in dehardening.
Cytokinin Production by Tomato Root: Occurrence of Cytokinins in Staled Medium of Root Culture
Authors: KODA YASUNORI , OKAZAWA YOZO
Published: April 2006

Cytokinins were released into the medium by cultures of excised tomato (Lycopersicon esculentum Mill.) root tips. A large portion was directly released from the proximal cut‐end of the roots. The most active substance was found to co‐chromatograph with zeatin riboside in both paper and Sephadex column chromatographies. The cytokinin activity after 7 days of growth was found about eight times higher in the medium as compared with that in the root tissues. When freshly excised root tips were subcultured throughout eight passages, the accumulation of cytokinin in the medium of each passage was approximately the same. These results show that the root tip is a main site of cytokinin synthesis.
Tissue Culture of Cassava on Chemically Defined Media
Authors: PARKE DONNA
Published: April 2006

Defined media that promote the initiation and undifferentiated growth of callus derived from stem explants of four cultivars of cassava, Manihot esculenta Crantz, are described. Growth rates and yields of cassava callus after 4 weeks of culture are shown to be comparable to those of callus of Nicotiana tabacum L. cv. Wisconsin No. 38. Nitrogen sources of ammonium nitrate or of ammonium chloride plus succinate supported growth of all four cultivars. Sucrose was superior to glucose as a carbon source. The cassava cultivars differed in their response to increasing concentrations of sucrose between 0.5% (w/v) and 3%, two of them increasing in dry matter with increasing sucrose concentrations of up to 3%. When cultured in the light on defined media that contained higher ratios of cytokinin to auxin, callus of the latter two cultivars turned green. Roots but not shoots differentiated from the callus of all cultivars. The influence of hormone concentrations, sucrose level, and nitrogen source on greening and root formation is summarized.
Low Pressure and Ethylene in Lettuce Seed Germination
Authors: RUDNICKI RYSZARD M. , BRAUN JOSEPH W. , KHAN ANWAR A.
Published: April 2006

The extent and manner of ethylene involvement in germination of lettuce (Lactuca Sativa L. cv. Mesa 659) seed at a moderate temperature (20°C) were investigated. Inhibition of germination at low pressure of 150 mmHg in an oxygen flow‐through system was alleviated to a marked extent by ethylene. Carbon dioxide was ineffective by itself but caused further alleviation of inhibition in presence of ethylene and oxygen. Other seed treatments which partially alleviated the inhibition caused by low pressure included soaking in 10μM of fusicoccin and a prior treatment with acetone. Of the two ethylene adsorbents used, Purafil was more effective in inhibiting germination in a closed container. Although the ethylene biosynthesis inhibitor, 8‐hydroxyquinoline (1.0 mM). showed no effect on ethylene production, it markedly inhibited germination and the effect was partially reversed by ethylene and GA3. An ethoxy analog of rhizobitoxine, on the other hand, had little or no effect on germination but strongly inhibited the ethylene production. Although no causal relation of ethylene to germination was established, the evidence presented here implicates ethylene, together with other gases, in the regulation of germination.
High Yield Isolation of Nuclei from Plant Protoplasts
Authors: ZUILY‐FODIL Y. , PASSAQUET C. , ESNAULT R.
Published: April 2006

Nuclei were isolated from protoplasts obtained from Parthenocissus tricuspidata Crown Gall callus tissues. The effect of various isolation procedures, detergent or ultrasonication, on yield and quality of nuclei was studied. A standard procedure, based on the use of 5 × 10−3% Triton × 100 — 6% PVP — 20% glycerol, may be carried out in 30 min and gives 80 to 90% yield of nuclei in which RNA polymerase activity is retained.
Mouvements nycthéméraux foliaires chez le Cassia fasciculata inversé dans le champ de la pesanteur
Authors: GAILLOCHET JACKY
Published: April 2006

Nyctinastic movements of leaves of Cassia fasciculata inversed in the field of gravity.

Plants of Cassia fasciculata Michx, were grown under controlled conditions with a diurnal rhythm of 14 h light and 10 h dark. The nyctinastic movements performed by the leaves were observed by time lapse photography, on plants inverted in the field of gravity and compared to those recorded on plants remaining in natural position. The movements were observed on leaves from which the petiolar gland has been removed as well as on leaves in which it has been preserved.

In plants inverted in the field of gravity, the leaflet movements were not disturbed but the petiolar ones were opposite to those observed on plants in natural position and smaller in amplitude (52 and 15 degrees difference between maximum and minimum positions respectively). This was not influenced by the removal of the petiolar gland. Inverting plants greatly shortened duration of closing and time spent maximally closed while increasing both duration of opening and time spent maximally opened. Removal of the petiolar gland did not influence the opening‐closing schedule of the plants in normal position but in inverted plants it caused marked changes in this schedule.

These results are discussed in connection with what is known about IAA. K+ and amyloplasts and their role in causing changes in pulvinus turgor.
Quantum Requirements of Photosynthetic Electron Transport In Sitka Spruce from Different Light Environments
Authors: LEWANDOWSKA M. , JARVIS P. G.
Published: April 2006

Quantum requirements of photosynthetic electron transport have been measured in shoots of Picea sitchensis (Bong.) Carr. (Sitka spruce) from different levels in a forest canopy and in shoots from plants grown in contrasting light environments in controlled environment chambers. Neutral density filters were used to obtain very low photon flux densities. The light absorbed by the chloroplast suspensions was calculated from measurements of the transmittance of the suspensions. The shoots from the top of the forest canopy (“sun” shoots) had lower quantum requirements for photosystems I and II than the shoots from the bottom of the forest canopy (“shade” shoots). High light grown plants and “sun” shoots had higher rates of electron transport at light saturation than low light grown plants and “shade” shoots. Thus a higher potential for electron transport was found to exist in “sun” shoots than in “shade” shoots at both high and low photon flux densities.
Sterols in Germinating Seeds and Developing seedlings of Longleaf Pine, Pinus palustris
Authors: Van VU Cu , BIGGS Robert H.
Published: April 2006

Sterols in germinating embryos and young seedlings of longleaf pine (Pinus palustris Mill.) were identified and quantities determined for different periods after germination. Sterol analyses were performed by gas‐liquid chromatography (GLC) and verified by combination of GLC‐mass spectrometry. Campesterol and β‐sitosterol were two major sterols which accounted for most of the sterol composition while stigmasterol was present in very small amounts. No cholesterol was revealed by GLC‐mass spectrometry although there was a minor peak appearing on the sterol gas‐liquid chromatograms with a retention time close to that of authentic cholesterol. By fractionation, three different forms of sterols were obtained: steryl esters, steryl glycosides, and free sterols. The sterols were mainly found in the esterified fraction, while steryl glycosides and free sterols only made up a small portion of the total sterol value. The total sterol content in general increased during seedling development, and this increase reflected mainly a change in steryl esters. The low levels of both free and glycosidic sterols remained nearly unchanged throughout the experimental germination period.
The Role of Lipids and Proteins in the Mechanism of Latex Vessel Plugging in Hevea brasiliensis
Authors: SHERIEF P. M. , SETHURAJ M. R.
Published: April 2006

The phospholipid content of the bottom fraction of latex as well as the neutral lipids of rubber particles were determined in thirty‐one clonal mother trees of RRII clones of Hevea brasiliensis Muell. Arg. Ratios between cationic proteins and anionic proteins in the B‐sera, which is the sera contained in the lutoid particles in latex, obtained from clones RRIM‐501, PB 6/9, RRII‐105 and Tjir‐l were determined by electrophoresis. The influence of these factors on plugging index (a measure of the magnitude of latex vessel plugging) was investigated. Lutoid instability, as indicated by bursting index, is negatively ocrrelated with the phospholipid content of the bottom fraction of latex. The neutral lipid content of rubber particles is positively correlated with the colloidal stability of latex. The latex vessel plugging during latex flow is found to be negatively correlated with both the lutoid stability and the neutral lipids in the rubber particle. A high ratio of cationic and anionic proteins in B‐serum may also enhance the process of plugging.
Sporulation and the Macromolecular Composition of the Mycelium and Arthrospores of Geotrichum candidum
Authors: ALLERMANN K. , FLOTO F. , OLSEN J. , SORTKJær O. , KIER I.
Published: April 2006

In submerged culture the mycelium of Geotrichum candidum breaks into fragments (arthrospores) which are either cylindrical or ellipsoidal in shape; the proportion of each spore type depends upon the glucose concentration in the medium. Above 0.2% glucose the ellipsoidal type prevails, whereas the cylindrical type is more abundant at lower glucose concentrations. The cylindrical spores and the mycelium have a very similar macromolecular composition, but the ellipsoidal spores have less RNA and protein and more carbohydrate than the mycelium.
The Promotive Effect of Purine and Pyrimidine Bases in Rooting Hypocotyl Cuttings of Phaseolus mungo in Relation to Auxin and Nutrition
Authors: BHATTACHARYA SHEILA , BHATTACHARYA N. C. , NANDA K. K.
Published: April 2006

Exogenously supplied nitrogenous bases in combination with IAA + sucrose hastened the formation of roots on hypocotyl cuttings of Phaseolus mungo L. cv. G31. While purine and pyrimidine bases had little effect when used alone, together with IAA or sucrose they increased the number of roots and the effect was even more pronounced in combination with (IAA + sucrose). By contrast, guanine inhibited rooting completely in higher concentrations even in combination with (IAA + sucrose), and cuttings died within 48–72 h.
Thymidine Phosphorylation in Arachis hypogaea by Combined Activities of Adenosine Triphosphate Phosphohydrolase and Nucleoside Phosphotransferase
Authors: MULLIN BETH C. , FITES ROGER C.
Published: April 2006

Extracts from hypocotyls of germinating peanuts (Arachis hypogaea L.) stimulated the formation of thymidine monophosphate from thymidine and adenosine triphosphate in the presence of magnesium ions. Such extracts were incapable of incorporating isotopic phosphorus from gamma‐labelled adenosine triphosphate into thymidine during the synthesis of thymidine monophosphate but were competent in transferring phosphorus from alpha‐labelled adenosine triphosphate to thymidine. The apparent thymidine kinase activity thus appeared to result from the combined activities of an adenosine triphosphatase (adenosine triphosphate pyrophosphohydrolase, E. C. 3.6.1.3) and a nucleoside phosphotransferase (E. C. 2.7.1.77). The latter two enzymes could be largely separated by using DEAE‐Sephadex chromatography.
Membrane ATPase Activity of Barley Roots and Potassium Uptake by Isolated Stele and Cortex
Authors: NASSERY H. , VALAMANESH A.
Published: April 2006

Uptake of potassium ions by isolated stelar tissues of barley from 0.5 and 10 mM K+ was respectively 13 and 3.6% of that of the cortical tissues. 0.1 mM H2PO4, LO mM ATP and 10 mM Ca(NO3)2 did not increase the potassium uptake of either stele or cortex during 5 h of uptake period.

A time‐course incubation for histological demonstration of the ATPase activity of the plasmalemma and tonoplast of the matured sections of the roots demonstrated a greater activity for the cortical than the stelar tissue. In the stelar parenchyma cells, the plasma lemma showed a higher activity than the tonoplast. These results, which support the “leakiness hypothesis” of the stele, are discussed in relation to the proposed mechanisms of radial ion transport in roots.
Effects of pH on Georeaction and Elongation of Maize Root Segments
Authors: GABELLA MAURO , PILET PAUL EMILE
Published: April 2006

The pH effect was analysed in relation to the georeaction and the elongation of apical maize root segments. Two kinds of citrate‐disodium phosphate buffers were used for pretreatment and application on the fresh cut section of the segments. Both reactions to gravity and to growth seem to be more affected by the buffer components than by the proton concentration. Such results were confirmed by the comparison of several buffers.
Temperature and Light Requirements for the Sprouting of Chilled and Unchilled Tubers of the Purple Nutsedge, Cyperus rotundus
Authors: SHAMSI S. R. A. , AL‐ALI F. A. , HUSSAIN S. M.
Published: April 2006

Mature and immature tubers of purple nutsedge (Cyperus rotundus L.) chilled at 0°C in dry and wet conditions, were sprouted along with fresh, unchilled tubers over a range of temperatures (10°C‐45°C) in light and darkness. Fresh immature tubers showed a high sprouting percentage at all temperatures between 20°C and 40°C, while the mature ones did so only at 30°C and 35°C. Chilling of dry tubers stimulated early sprouting and increased the maximum sprouting percentage of both the mature and immature tubers. Dry chilling also lowered the limit of favourable temperatures to 15°C in the case of mature tubers. Chilling of wet tubers had a depressing effect and no sprouting occurred below 30°C.

At all temperatures, light apparently favoured the sprouting of both the mature and immature tubers (except mature wet‐chilled ones at 35°C and 40°C). Immature tubers showed relatively higher sprouting percentage than the mature ones, both in light and darkness. Alteration of temperature requirements due to dry and wet chilling of the tubers is regarded as significant and functional in relation to the ecology of the species.
Chlorophyll Destruction in Lemon Fruit by Light and 2′,4’Dichloro 1‐Cyanoethane‐sulphonanilide
Authors: HALL A. E. , COGGINS C. W.
Published: April 2006

Chlorophyll content decreased when excised lemon fruits were exposed to light. A quantitative model for the photodestruction of chlorophyll exhibited reasonable agreement with data on in vivo destruction of chlorophyll. Photodestruction of chlorophyll was enhanced by treating fruit with 2′,4′‐dichloro‐l‐cyanoethane‐sulphonanilide (R33417). Measurable enhancement of chlorophyll destruction was observed with concentrations of R33417 as low as 10 μg/l. Maximum activity was achieved at approximately 600 μg/1. R33417 treatment enhanced photodestruction of chlorophyll to a greater extent at higher photon flux densities.
Light and Branch Formation in the Alga Vaucheria dichotoma (Xanthophyceae)
Authors: ÅBERG HÅKAN
Published: April 2006

Branches of Vaucheria dichotoma (L.) Ag. were induced in two ways: by cutting, which led to a branch in the wound area and by exposure to light.

Blue and red light were most active in branch formation. The light intensity dependence and the action spectrum of branch formation showed patterns similar to those of photosynthesis. Photosynthetic involvement was also indicated by the DCMU inhibition of branch formation. Elongation‐branching studies at different photoperiods showed that branching was increased by the presence of more photosynthetic light than was necessary for elongation.

It may be concluded that photosynthesis exerted the main control of the branch formation of V. dichotoma. However, the action spectrum of branch formation showed a higher efficiency in blue light than would be expected from the action spectrum of photosynthesis. It is therefore possible that apart from the main induction via the photosynthetic pigments, other blue light sensitive pigments may have a regulatory effect.

Far‐red light treatment of filaments pre‐exposed to 8‐h and 16‐h light periods did not affect branch formation. Spectrophotometrical detection of phytochrome was not successful. This may indicate that there is no participation of phytochrome in branch formation.

I am indebted to Dr. Lisbeth Fries for her interest. I also wish to thank Prof. Lars Olof Björn and his friendly staff at the Institute of Plant Physiology at the University of Lund, where some of the experiments were carried out. I am grateful to AB Tomaso Minori for revising the English test and to Miss Inga‐Britt Jansson for typing it.

The investigation was supported financially by a grant to Dr. Lisbeth Fries from the Swedish National Science Research Council.
Inhibition of Etiolation in Spirogyra by Phytochrome
Authors: VIRGIN HEMMING I.
Published: April 2006

Cells of Spirogyra filaments grown in darkness become longer than light grown cells. This elongation can be prevented by a few minutes of red light given with intervals of 24 h under the dark period. Far‐red light given after the red light pulse counteracts the red light effect. Cells which have finished their elongation in light do not elongate further in darkness. Along with the cell elongation the chloroplasts become less spirally wound and ultimately shortened to straight bands.
The Aetiology of Vascular Discoloration in Cassava Roots after Harvesting: Development of Endogenous Resistance in Stored Roots
Authors: MARRIOTT J. , BEEN B. O. , PERKINS C.
Published: April 2006

The susceptibility of cassava roots, Manihot esculenta Crantz, to vascular discoloration beneath two types of injury site, transverse cuts and periderm injuries, was compared for freshly harvested and stored roots. Susceptibility beneath transverse cuts changed rapidly, so that roots stored at ambient temperature for 5–9 days were largely resistant to vascular discoloration beneath this type of injury. Susceptibility to localized deterioration beneath periderm injuries changed more slowly, but significant decreases were observed in roots stored at ambient temperature for 10–16 days. Changes in susceptibility were observed in all cultivars tested, seven in Colombia and one in Jamaica. These changes were retarded but not prevented by storage at 2°C and by storage in sealed polyethylene bags. Pruning plants 1 to 3 weeks prior to harvesting, which has been shown to reduce the rate of post‐harvest deterioration of roots, was also found to reduce the susceptibility of roots to vascular discoloration beneath injuries made immediately after harvesting. Water loss through injuries caused a respiratory response as well as vascular discoloration. This respiratory response was as large in stored (resistant) roots as in freshly harvested (susceptible) ones. The potential of cassava roots to develop endogenous resistance to vascular discoloration either before or after harvesting is discussed in relation to the problems of storage of harvested cassava roots.
Abscisic Acid Inhibition of Kinetin Nucleotide Formation in Germinating Lettuce Seeds
Authors: MIERNYK J. A.
Published: April 2006

Imbibing ‘Grand Rapids’ lettuce (Lactuca saliva L.) seeds take up 14C‐kinetin, and metabolize this cytokinin to the 5′‐nucleotide. The identity of the labeled nucleotide in seed extracts was verified by Sephadex LH‐20 column chromatography, paper and thin layer chromatography, and high voltage paper electrophoresis.

Incubations with kinetin in the presence of abscisic acid lead to an apparent specific inhibition of kinetin nucleotide formation. ABA has no effect on kinetin uptake, and does not inhibit kinetin nucleotide synthesis in vitro by a cell‐free preparation from lettuce seeds. Additionally, ABA does not inhibit adenylate synthesis from exogenously supplied adenine. These results represent a specific cytokinin‐ABA interaction, which might play a significant role in the hormonal regulation of lettuce seed germination.
Cytokinins and Senescence in Lemon Leaves
Authors: ILAN I. , GOREN R.
Published: April 2006

The effect of leaf age on cytokinin level was studied in Citrus limon (L.) Burm. f. cv. Eureca. It was found that mature 1‐year‐old leaves and senescing 2‐year‐old leaves contained considerably more cytokinins than young 3‐month‐old leaves. No consistent distinct decrease in cytokinin activity was revealed when the leaf passed from the mature to the senescing state. It was concluded that the results cannot be regarded as supporting the hypothesis that leaf senescence is brought about, at least partially, by a decrease in the level of its cytokinins.
Abscisic Acid and Gibberellic Acid Contents in Ripening Barley Seeds
Authors: SŁOMIŃSKI B. , REJOWSKI A. , NOWAK J.
Published: April 2006

The ABA and GA3 contents were investigated in barley seeds during maturation and after harvest. The highest amount of ABA was found in milk and wax ripeness – 13 ng and 11 ng per seed respectively. The level decreased during the later stages of maturation and during release of dormancy and was 1 ng per seed 6 weeks after harvest.

The content of gibberellic acid decreased in a similar way but in an earlier stage of maturation. The determined amounts of GA3 were: 0.4, 0.1, 0.03 and about 0.05 ng per seed respectively, in milk, wax and full ripeness and after harvest.

The results of quantitative determination, obtained with the GLC method, corresponded to the growth effects in the test of the first leaf of oat.
Translocation of 14C‐Assimilates in Roses
Authors: MOR YORAM , HALEVY ABRAHAM H.
Published: April 2006

Movement of 14C‐assimilates from young and mature leaves to young rose shoots (Rosa hybrida cv. Marimba) was examined in two developmental stages.

In the first stage after bud breaking the young shoot, especially its tip, depends for its supply of assimilates mainly on the mature foliage. At this stage young leaves are powerful sinks and retain 97% of their own photosynthates. The translocated 3% move mainly to the roots. At a later stage, just after the appearance of the flower bud, most of the leaves on the shoot become a source. The upper leaves supply assimilates to the flower bud and to the upper part of the stem. The 14C‐assimilates from the lower leaves move in two directions, the larger part being directed downward.
Effects of Kinetin on Transpiration Rate and Abscisic Acid Content of Water Stressed Young Wheat Plants
Authors: BENGTSON CURT , FALK STIG OLOF , LARSSON STIG
Published: April 2006

Effects of kinetin on transpiration rate and abscisic acid content were determined. Leaves from 9‐day‐old wheat plants (Triticum aestivum L. cv. Weibull's Starke II) were used. —Transpiration rate decreased in excised leaves put in water, but it was maintained at a higher rate when kinetin was supplied. When excised leaves were water stressed by air‐drying for 1 h, addition of kinetin resulted in a considerable stimulation of transpiration rate. The effect reached its maximum after 15 h and this level remained relatively unchanged for at least 10 h. Intact seedlings which were stressed before leaf excision, showed only a slight stimulation of kinetin on transpiration rate. — Abscisic acid content slowly increased up to three‐fold in 2 days in excised leaves put in water. In excised and water‐stressed leaves the abscisic acid content was reduced during the first 24 h and then increased. As the leaves were fully turgid, the increase could not have been caused by water stress. However, both in stressed and unstressed leaves kinetin addition reduced the increase in abscisic acid content. — It is suggested that the stimulation by kinetin on transpiration rate in excised and water stressed leaves was mainly due to the combined effect of (1) a reduction in the activity of endogenous cytokinins, (2) kinetin acting as a ‘substitute’ for the inactivated cytokinins but exerting a stronger effect on transpiration than the endogenous cytokinins, and (3) the ‘extra’ reduction in abscisic acid content caused by the kinetin treatment. Furthermore, the results indicate that changes in cytokinins might be partly responsible for the aftereffect on transpiration.
Promotion of Flowering in the Pinaceae by Gibberellins
Authors: ROSS STEPHEN D. , GREENWOOD MICHAEL S.
Published: April 2006

Gibberellins (GAs) were effective in promoting flowering in sexually mature (45‐year‐old scions) grafts of loblolly pine (Pinus taeda L.). Seed‐cone production was increased 12‐fold in field‐grown, grafted ramets by bi‐weekly, May‐September applications of 500 μg per branch of GA4/7. Gibberellin A3 was equally effective at 500 μg but not at 100 μg per branch, while GA5 was ineffective at either concentration. A second study using potted, less‐sexually mature (8‐to 10‐year‐old scions) grafts gave a reduced level of seed cones in response to GAs. However, even on these younger grafts GA4/7 was a significant promotive treatment, GA3 being considerably less effective. Branch girdling, tested as an adjunct treatment, was ineffective. It is now apparent that exogenous applications of GA4/7 are effective on a number of Pinaceae species, and their use to promote earlier and more abundant flowering in breeding orchards of grafted ramets for at least two species, loblolly pine and Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] is practical.
Effect of Gibberellic Acid and Monophenols on Flowering of lmpatiens balsamina in Relation to the Number of Inductive and Non‐inductive Photoperiodic Cycles
Authors: SOOD VINI , NANDA K. K.
Published: April 2006

A single treatment of plants with GA3 (gibberellic acid) is not adequate to cause induction under LD (long day: 24‐h photo‐period) condition, but its effect is added to the sub‐threshold induction caused by one SD (short day: 8‐h photoperiod) cycle. Floral bud initiation is hastened, and the number of floral buds and flowers per flowering plant increases in plants receiving a single treatment with the combination GA3+ SA (salicylic acid) accompanying a single SD cycle. However, the increase on 10 replicate basis is more marked in plants receiving three treatments with the combination GA3+β‐N (β‐naphthol) and five treatments with the combination GA3+ SA accompanying six and 10 SD cycles, respectively. The number of floral buds and flowers decreases with an increase hi the number of SD cycles, but it is higher in plants treated with GA3, SA or GA3+β‐N than in the water‐treated controls. — Under long days, treatment of plants with the combinations GA3+ SA or GA3+β‐N accelerates the initiation as well as increases the number of floral buds. While a minimum of five treatments with GA3 or of 25 with SA or β‐N alone is needed for floral bud initiation under a 24‐h photoperiod, three treatments are adequate to induce floral buds with the combination GA3+ SA or GA3+β‐N under continuous illumination. Ten or more treatments with these combinations under a 24‐h photoperiod produce more flowers than the same treatments under an 8‐h photoperiod.
Influence of Growth Regulators on Root and Shoot Initiation from Flax Meristem‐Tips and Hypocotyls in vitro
Authors: LANE W. DAVID
Published: April 2006

Hypocotyl sections and isolated meristem‐tips from 7‐ to 10‐day‐old seedlings of flax were cultured on a Murashige and Skoog (1962) medium. The optimum concentrations of naphthaleneacetic acid (NAA) and benzyladenine (BA) were determined for shoot and root initiation from hypocotyls. Meristem‐tip cultures differentiated shoots and roots in response to these concentrations. The frequency and yield of shoots, promoted by BA, decreased if NAA or gibberellic acid (GA3) was included in the medium. At high NAA concentration GA3 and BA inhibited root initiation. Morphological development of cultures differed depending on the growth regulators in the medium.
Effects of Fertilization and Irrigation on the Seasonal Changes of Carbohydrate Reserves in Different Age‐Classes of Needle on 20‐Year‐Old Scots Pine Trees (Pinus silvestris)
Authors: ERICSSON ANDERS
Published: April 2006

The effects of fertilization, irrigation or both on the seasonal changes of starch and soluble carbohydrates (glucose, fructose, myo‐inositol, pinitol and sucrose) in needles of 20‐year‐old Scots pine trees (Pinus silvestris L.) were studied during three consecutive years. The starch content of the mature needles increased during spring and early summer to about 25% of dry weight. Neither fertilization nor irrigation affected the general pattern of starch accumulation during the spring. The starch reserves were mobilized when the shoot started to grow. Starch content decreased more rapidly in needles from fertilized than in those from unfertilized trees. The current needles from the control trees accumulated starch while they were still growing. The current needles of the fertilized trees did so to a lesser extent. The amount of starch was closely correlated to the air temperature and to the growth rate. Large amounts were found at low temperatures and low growth rates.

The concentrations of soluble carbohydrates showed the well‐known seasonal variation, with the highest value during the winter. The levels of sugars were nearly similar, irrespective of fertilization. An exception was sucrose, which was found in small quantities in needles from fertilized plots. Small amounts of sucrose were also found in growing current needles.

The results are discussed in relation to growth limitation by assimilate availability and indicate that the ‘sink demand’ is the limiting factor.
Plant Regeneration from Mesophyll Protoplasts of Several Nicotiana Species
Authors: BOURGIN JEAN‐PIERRE , CHUPEAU YVES , MISSONIER CLAUDINE
Published: April 2006

In a search for model systems in plant cell genetics studies mesophyll protoplasts from eleven species of Nicotiana with low chromosome number (N. acuminata, N. alata, N. glauca, N. glutinosa, N. langsdorffii, N. longiflora, N. otophora, N. paniculata, N. plumbaginifolia, N. suaveolens, N. sylvestris) were shown to divide in a liquid culture medium. Plants were recovered from calli originating from protoplasts of all these species except N. glutinosa.
Evidence for Naturally Occurring Inhibitors of Archegonial Differentiation in Lygodium japonicum
Authors: TAKENO KIYOTOSHI , FURUYA MASAKI , YAMANE HISAKAZU , TAKAHASHI NOBUTAKA
Published: April 2006

Archegonial differentiation in prothallia of Lygodium japonicum was inhibited when the filtrate of conditioned medium or the extracts of prothallia with organic solvents were added to the medium. By varying the timing of treatment with the methanol extract, archegonial differentiation was shown to start at least 4 days before microscopically detectable change. The inhibitory effect of methanol extract was nullified by transferring the treated plants to a fresh medium omitting the methanol extract, so that the archegonial formation became discernible 6 days after the transfer.

The inhibitory activity was stable in both acidic and basic solutions at room temperature, and was partially lost by boiling at pH 3 or 11 for 30 min. The inhibitor, which could be retrieved from the filtrate and the methanol extract, was fractionated into the neutral ethyl acetate fraction, but was not found in the acidic ethyl acetate fraction and in the aqueous residue. At least two active zones were separated on thin layer chromatograms of the ethyl acetate extracts from the filtrate and the methanol extract, and the relative flow‐rates of each active zone from these two sources were very similar. The evidence described above indicates that specific inhibitors of archegonial differentiation may be produced in the tissue of prothallia of Lygodium and eventually be secreted to the medium.
Uptake of Nitrate by Mutants of Arabidopsis thaliana, Disturbed in Uptake or Reduction of Nitrate
Authors: DODDEMA HENK , OTTEN H.
Published: April 2006

Wildtype and nitrate reductase‐less mutant B 25 of Arabidopsis thaliana (L.) Heynh. were grown on a nutrient solution with NH4NO3 as the nitrogen source. Uptake of nitrate was determined with a continuous method in which the decrease of the absorbance at 210 nm of the the ambient solution was measured. The uptake rate, plotted against concentration, deviated in the low concentration range from the standard Michaelis‐Menten curve and appeared to follow the first tract of a sigmoid curve, indicating positive cooperativity kinetics. Starvation of the plants for nitrate during a few days resulted in an increased capacity (Vmax) and affinity (decreased Km) of nitrate uptake. After prolonged starvation the uptake capacity decreased again. The highest rates of uptake were reached after 2–3days' starvation for the wildtype and after 1–2 days' starvation for mutant B 25. Soluble carbohydrates were not correlated with nitrate uptake rates. Malate was accumulated during nitrate starvation, resulting in an inverse relation between malate and nitrate content of the plants. Certain amino acids, like l‐serine and l‐arginine were shown to inhibit nitrate uptake. Based on these, and previous results, a model was proposed for the regulation of nitrate uptake, which includes allosteric regulation of the nitrate carrier by nitrate and amino acids.
Mineral Nutrient Requirements of Pinus silvestris and Picea abies Seedlings
Authors: INGESTAD TORSTEN
Published: April 2006

The mineral nutrient requirements of Pinus silvestris L. and Picea abies Karst. were studied according to previously published methods applied to a series of various plant species. The optimum nutrient proportions are similar to those of Vaccinium, with a lower relative potassium requirement than birch and other broad‐leaf species. Various ratios between ammonium and nitrate nitrogen were about equally efficient except for a minor growth reduction with pure nitrate, which gave a comparatively low nitrogen content and a high cation/nitrogen ratio. The rate of ammonium uptake was much higher than that of nitrate when both sources were supplied. The required total concentration in the nutrient solution for maximum growth is lower in pine than in spruce, but both fall within the low salt range. Both species, especially pine, are sensitive to high salt concentrations. Although pine and spruce grow on the same type of soils as Vaccinium— leached soils with low base saturation – accumulation of calcium or other cations is not as pronounced as in Vaccinium, especially not in pine. The results are compared with results from similar experiments with a series of other conifers. All the conifers have more flexible cation uptake mechanisms than Vaccinium but the results indicate tendencies to accumulation of anions, nitrate and phosphate. Recommended fertilizer compositions for forest fertilization and nurseries are discussed.
The Influence of pH on the Cadmium‐Repressed Growth of the Alga Coelastrum proboscideum
Authors: MüLLER KLAUS W. , PAYER HANS‐D.
Published: April 2006

The inhibition of growth by different concentrations of CdCl2 in the range 4,5 × 10−7 to 5.6 × 10−7M was studied in the green alga Coelastrum proboscideum Bohlin in inorganic media at pH 4.3, 5.3 and 6.2. The factorial destgn of the experiments was evaluated as an analysis of 22 factors. Below pH 4.0 and above pH 6.5 growth was depressed without adding Cd. Cd concentrations exceeding 5.6 × 10−8M reduced algal growth significantly with a 50% inhibition at 5.6 × 10−7M Cd. The Cd concentration of 5.6 × 10−7M was less toxic at pH 6.2 than at pH 5.3 and 4.3, thus revealing a negative interaction between protons and Cd.
Hormonal Regulation of Ca2+ Stimulated K+ Influx and Ca2+, K+‐ ATPase in Rice Roots: in vivo and in vitro Effects of Auxins and Reconstitution of the ATPase
Authors: ERDEL LÁSZLÓ , TÓTH ILDIKÓ , ZSOLDOS FERENC
Published: April 2006

The role of natural and synthetic auxins in regulation of ion transport and ATPase activity was studied in rice roots (Oryza sativa L. cv. Dunghan Shah). In vivo treatment of seedlings with 2,4‐dichlorophenoxyacetic acid at 2 × 10−6M for a short period enhanced subsequent Ca2+ stimulated K+ influx and ATPase activity, while a longer treatment diminished both K+ influx and ATPase activity. Indoleacetic acid at 10−10–10−8M induced ATPase activity. In in vitro experiments both 2,4‐dichloro phenoxyacetic acid and indoleacetic acid (10−10–10−8M) stimulated Ca2+, K+‐ATPase activity of a plasmalemma rich micro somal fraction from the roots.

Acetone extracted ATPase preparations lost their activity. The enzyme regained its activity and its sensitivity towards ions (Ca2++ K+) when reconstituted with phosphatidyl choline. Addition of auxins also indicated that the presence of the lipid was necessary in the interaction between the ATPase and auxins. Auxins and ions probably interact with the intact ATPase lipoprotein complex, which may possess a receptor site for the auxins, possibly as a sub unit.
Effect of Continous Light on CO2 Fixation and Chloroplast Structure of the Mosses Pleurozium schreberi and Ceratodon purpureus
Authors: ARO EAV MARI , VALANNE NIINA
Published: April 2006

When the mosses Pleurozium schreberi (Brid.) Mitt, and Ceratodon purpureus (Hedw) Brid. were exposed for 4 week to either continuous or rhythmie light of 75 or 150 μE m−2 s−1, the photosynthetic rate, calculated on the basis of chlorophyll and of dry weight, was lower in the moss plants exposed to continuous light. RUBP‐carboxylase activity was lower in these plants, too. On the other hand more starch was accumulated in the chloroplasts in continuous than in rhythmic light. Neither moss species showed any differences in the dark respiration rates. The chlorophyll content was lower in continuous light, especially at the higher intensity; but Chi a/Chl b ratio showed little change compared with that in rhythmic light. The reduction of chlorophyll did not affect the two chlorophyll protein complexes equally; the percentage of chlorophyll associated with CP I decreased, while that associated with CP II showed liltle change. The decrease in CP I chlorophyll appeared to be due to the partial destruction of stroma thylakoids: the size or the grana increased in continuous light. Many of the effects of continuous light in these mosses resembled those observed in higher plants in the early phases of senescence.
Photophosphorylation and Ultrastructural Development in Pinus nigra Chloroplasts, Grown under Different Spectral Composition of Light
Authors: TYSZKIEWICZ E. , NICOLIČ D. , POPOVIČ R. , SARIČ M.
Published: April 2006

Developed pine seedlings synthesize chlorophyll in darkness. Their photosystem II reducing capacity is very low. The development of chloroplast structure and of photophosphorylation ability has been studied in plastids isolated from Pinus nigra (var. austriaca) developed for 14 days under different spectral compositions of light as compared with chloroplasts isolated from seedlings grown under white light or in darkness. Chloroplast structure was studied by electron microscopy. Cyclic and non‐cyclic photophosphorylation were studied under white light. The spectral bands which are efficient for the development of granal structures are different from those needed to make photosystem II functional: red light makes photosystem II functional but does not permit the formation of granal structure, and under yellow light the granal structure develops but photosystem II is not fully functional. Orange light alone fulfils both these purposes. The spectral band around 650 nm seems effective in making the photosystem II functional.
Solute Uptake of Acer pseudoplatanus Cell Suspensions during Recovery from Gas Shock
Authors: THOIRON BERNARD , THOIRON ARLETTE , GUIEL JEANNE LE , LüTTGE ULRICH , THELLIER MICHEL
Published: April 2006

When the ambient atmosphere of Acer pseudoplatanus cells in suspension culture is rapidly changed by opening the culture flasks and gently stirring (‘mild gas‐shock’) or by filtering and suspending in new medium (‘strong gas‐shock’), drastic modifications of the rates of leucine, methionine, glucose, adenine, sulphate and phosphate uptake are observed. Following the gas‐shock, rates of uptake rapidly decrease within a few minutes. Subsequently the rates increase again to the intial level within several hours. The uptake of potassium, which is known to be passively distributed between the medium and the interior of many plant cells, at least at high external concentrations, is apparently independent of gas‐shock.

The shock and recovery kinetics are similar for all solutes investigated (except K+), in particular for different solutes studied in double labelling experiments with the same batch of cells. At the maximum of the after‐effect of shock, i.e. at minimum rates of uptake, uptake shows a highly reduced dependence on temperatures. Gas‐shock probably inactivates, denatures, structurally alters or releases membrane macromolecules engaged in transport. These molecules are then re‐synthesized and re‐incorporated into the membrane during recovery.
Effects of pH Changes on Ion and 2,4‐D Uptake of Wheat Roots
Authors: ZSOLDOS FERENC , HAUNOLD ERNST
Published: April 2006

The quantitative relationships between pH‐dependent ion and 2,4‐D uptake in winter wheat seedlings (Triticum aestivum L. cv. Yubileynaya 50) have been investigated. The movement of various ions (potassium, phosphate, nitrate and ammonium) and 2,4‐D across the root membranes was monitored with radioactive and stable isotope tracer methods. It was found that the H+ ion concentration of the absorption solution strongly influences the 2,4‐D uptake of the roots. Simultaneously, the 2,4‐D uptake stimulates secretion of H+ into the absorption solution, that is, a H+ efflux can accompany the uptake of 2,4‐D. This finding is consistent with the acid secretion theory of auxin and fusicoccin action. At pH 4 the 2,4‐D uptake was much higher than at pH 6, thereby inhibiting the ion uptake and increasing the phytotoxicity in the plant. The results indicate that 2,4‐D enters the root cells rapidly at the lower pH, mostly as undissociated molecules. With reference to the 2,4‐D concentration in the roots at pH 4, a possible transport mechanism of the auxin herbicide is briefly discussed.