bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Deleterious Concentrations of Copper on the Growth of Chlorella pyrenoidosa
Authors: Nielsen E. Steemann , Kamp‐Nielsen Lars
Published: April 2006

The effect of deleterious concentrations of ionic Cu on the growth of Chlorella pyrenoidosa has been studied. An earlier paper showed a distinct effect of the same concentrations on the photosynthesis of the alga. Several substances, e.g. Fe and citric acid counteract the effect of Cu. In media ordinarily used for growing unicellular algae the influence of Cu is relatively slight due to the extraordinarily large concentrations. of Fe. At a concentration of 6 μg/I Fe – near to that in nature –even one μg/I Cu significantly decreases the growth during the first 24 hours. Cu is adsorbed to the negative charges on micelles of Fe(OH)3 created in the alkaline medium. Citric acid is readily assimilated by Chlorella and thus counteracts the influence of Cu for only relatively short period.

Cell concentration is of decisive importance for the deleterious influence of Cu on growth. The effect of a certain Cu concentration stops at a certain concentration of of the algae regardless of whether the experiment is started at this cell concentration or this concentration is attained during the experiment. This is due to the binding of Cu by the organic matter of cell walls and slime envelopes.

H+ ions compete with Cu both when combining with the organic matter in the cell walls and when occupying the active sites of the cell membranes. The latter explains the fact that the influence of Cu is only slight at pH 5 compared with that at pH 8.

At a Cu‐concentration where no growth of algae can take place, the algae are by no means killed. After being transferred to an ordinary medium the algae start to grow again.

The influence of Cu depends on the division stage of the algae. If the initial steps of cell division have taken place, the cell continues to divide.
Mechanism of Zinc Uptake in Bean (Phaseolus vulgaris) Tissues
Authors: Rathore V. S. , Wittwer S. H. , Jyung W. H. , Bajaj Y. P. S. , Adams M. W.
Published: April 2006

Uptake of micronutrient zinc by intact leaves, enzymically isolated leaf cells, leaf disks, excised roots, and stem‐callus tissue of two field bean cultivars 'Saginaw’ and ‘Sanilac’) was studied using radio‐isotope tracer technique. Radio‐phosphorus absorption by these tissues was also followed under comparable experimental conditions. A rapid absorption of the micronutrient and strong dependency on external zinc concentration and pH were revealed. Absorption of zinc was not inhibited by respiratory inhibitors (dinitrophenol, azide, cyanide, and amytal), and was not light or temperature dependent. Q10 values for zinc uptake ranged between 1 and 1.2. Uptake of phosphate, on the other hand, was temperature and light dependent and drastically reduced by the presence of metabolic inhibitors.

Differences in responses to respiratory inhibitors, temperature, pH, light and darkness, and kinetic data, strongly suggest that zinc uptake in bean tissues occurs primarily by a passive mechanism, involving possibly a physical or physiochemical binding of the micronutrient ions to the cell wall and free space components, and a passive diffusion into the interior of the cell.
Effects of Pyrocatechol on Some Metabolic Processes of Mature Sugar Beet (Beta vulgaris) Plants
Authors: Singh B. , Wort D. J.
Published: April 2006

Pyrocatechol (PC), 10‐2M, was applied to the foliage of mature plants of sugar beet (Beta vulgaris L.). Its effect on the activity of nitrate reductase, transaminase, invertase, phosphatases, sucrose synthetase, sucrose phosphate synthetase, and UDPG‐pyrophosphorylase were determined 7, 14, and 21 days after treatment. Significant reductions in the activity of nitrate reductase, transaminase, invertase, and phosphatases (including phenyl phosphatase, glucose‐1‐, glucose‐6‐, fructose‐6‐phosphatase, and adenosine triphosphatase) in the treated plants occurred. On the other hand, activities of the enzymes of sucrose biosynthesis, uridine, diphosphate glucose pyrophosphorylase (UDPG‐pyrophosphorylase), sucrose synthetase, and sucrose phosphate synthetase were significantly stimulated by the application of pyrocatechol. The results suggest that the growth inhibition following the application of PC to sugar beet plants may stem in part from an amino acid stress resulting from a PC‐induced decrement in nitrate reductase and transaminase activity. Its application also creates an enzymatic condition favorable for sucrose biosynthesis and storage.
Germination et culture aseptique de Thlaspi sylvestre Jord. subsp. calaminare (Lej.) Maly
Authors: Méalotte R. , Ramaut J. L.
Published: April 2006

We have studied the action of different zinc concentrations (10, 50 and 100 mg/l) on the germination of Thlaspi seeds and on the seedlings obtained from them when grown on water containing the same zinc concentrations.

It appears that the 10 mg/l zinc concentration enhances slightly the percentage germination and that the 50 mg/l concentration is the optimum one for the growth of the seedlings. Therefore it seems that the normal growth of a plant growing on a “calamine soil” demands a given quantity of zinc, the optimum being in the neighbourhood of 50 mg/l.
Selectivity and Ion Transport in Excised Bean Hypocotyls
Authors: Waisel Y. , Neumann Ruth , Kuller Z.
Published: April 2006

Ion transport and ion selectivity in bean hypocotyl slices were investigated. The transport mechanism is practically independent of temperature and in short term experiments appears to be non‐metabolic.

Selectivity may be attributed either to specific adsorption sites or to the properties of the diffusion barrier. The fact that with a physical transport mechanism selectivity is observed only under physiological temperature conditions hints that a flexible barrier (plasmalemma?) rather than fixed adsorption sites should be regarded as governing the process.
Root Growth Inhibition by Siduron and Its Relief by Kinetin
Authors: Splittstoesser Walter E. , Hopen Herbert J.
Published: April 2006

The growth of crabgrass (Digitaria ssp.) and barley (Hordeum vulgare) seedlings was susceptible to injury by siduron (1‐2(methylcyclohexyl)‐3‐phenylurea). In both species, root growth was inhibited more than shoot growth and if a functional root system was developed before coming into contact with siduron the plant survived.

Kinetin partially overcame the effect of siduron on root growth and increased root length and the number of cells undergoing mitosis per root tip. The effect of siduron seems specific to cell division.
Conversion of Various Substrates to Ethylene by Flowers
Authors: Phan Chon‐Tǒcn
Published: April 2006

The emanation of Petunia (Petunia hybrida) flowers fed with various substrates has been found to be a mixture of at least four gaseous components, one of which being ethylene. The relative proportions of these gases change with the substrate, which therefore means that the compounds generally accepted as ethylene precursors are not all converted primarily into ethylene.
Colony Size of Tuberolachnus salignus (Gmelin) in Relation to Mass Transport of 14C‐labelled Assimilates from the Leaves in Willow
Authors: Peel A. J. , Ho L. C.
Published: April 2006

Willow cuttings were used in which u narrow, longitudinal strip of bark was removed commencing from the base of the leafy shoot. Aphid colonies of different sizes were then sited on the stem either side of the strip, 10 cm below the base of the shoot. The leaves were allowed to assimilate 14CO2, and the dry weight and total activity of the honeydew from each colony was measured over a given period of time.

It was found that not only did the total activity from the large colony exceed that of the small colony, but that the specific activity of the honeydew from the large colony was higher than that from the small colony. This has been taken as evidence that neighbouring pierced sieve tubes do not act independently of each other; mutual interference occurs. Increasing the distance between pierced sieve elements by dispersing the members of the large colony over a greater area of stem, did not apparently reduce interference effects.

The results are explained in relation to the magnitude of the contributory length (Peel and Wealherley 1962), of individual sieve tubes pierced by the large, as opposed to the small colony.
Cytokinin Content of Pea Seeds during their Growth and Development
Authors: Burrows W. J. , Carr D. J.
Published: April 2006

Seed development in Pisum arvense L. cv. New Zealand Maple has been studied in relation to changes in level of total endogenous cytokinins. Growth of both the whole seed and the embryo is diauxic, having two phases of active growth separated by a lag period. The two maxima in the growth rates of the whole seed and the embryo occur about the 23rd and 31st days after anthesis. The lag period occurs between days 26 and 28. Cell division is thought to have ceased prior to day 19 and the changes in total cytokinin content in pea seeds after this time are believed to be largely independent of cell division. The three maxima in the cylokinin content per gm. fresh weight of seed and per seed were found to be coincident with the maximum volume of endosperm per seed and the two maxima in the growth rates of the whole seed and the embryo.
Growth of Boletus variegatus in Surface and Shake Cultures
Authors: Pedersen T. A. , Lindeberg Göusta
Published: April 2006

A method of growing the mycelium of Boletus variegatus Fr. (Suillus variegatus Kuntze) in shake cultures is described. The growth curves of the fungus in stationary surface cultures and shaken submerged cultures have been compared. Growth in stationary cultures comprised (1) an acceleration phase, characterized by an approximately linear cube root plot, (2) a linear phase of constant increase of dry weight per day, and (3) a deceleration phase. In the shake cultures, two growth periods, both characterized by linear cube root plots, were observed. The growth rate constant was higher for the first than for the second period. During the second period, enlarged rounded cells with dense contents but normal cell walls were formed. The carbon source was exhausted and growth stopped after nine days in the agitated cultures and after about three weeks in the stationary ones. The economic coefficient for glucose utilization was higher in the agitated than in the stationary cultures.
A Definition of Optimum Nutrient Requirements in Birch Seedlings. I.
Authors: Ingestad Torsten
Published: April 2006

The aim of the investigation was to find a method of growing birch seedlings with a constant optimum nutrient status. The studies in this paper have indicated important factors in such a growth method which must be comprised in a definition of nutrient requirements. The optimum nutrient proportions in the seedlings and the optimum total concentration in the solution must be known. Special attention must be paid to the ratio between NH4+ and NO3−in the solution and in the uptake. The amounts of nutrients taken up at optimum nutrition can be followed by measurement of pH and conductivity. Thus, the nutrients consumed may be replaced by titrations which may be automated by standard equipment. The nutrient proportions to be added are determined by the optimum internal proportions. It is not necessary to change the nutrient solution even if the volume is relatively small in relation to plant mass. There was no evidence of effects of accumulation of root exudates or infections. By using the system described, it is possible to attain considerably greater fresh and dry matter production in birch seedlings than when an optimum conventional solution is used.
Effects of Benzyladenine on Bean Leaf Senescence and the Translocation of 14C‐Assimilates
Authors: Fletcher R. A. , Hofstra G. , Adedipe N. O.
Published: April 2006

Treating primary leaves of bean plants with benzyladenine (BA) greatly increased the retention of photosynthetic assimilates in the treated leaves. Within 24 hours of treatment, the BA treated primary leaves retained 70 % of their assimilates and maintained this high level throughout the period studied. In contrast, the primary leaves of control plants retained 30 % at week 2, increased retention to 80 % between week 4 and 5 and dropped to 50 % during senescence at week 6. When the trifoliate leaves of 5 week old plants were fed 14CO2, less than 1 % of the total activity was recovered from the BA treated leaves. It is concluded that the retardation of leaf senescence by BA on intact plants is not due to mobilization of metabolites from other plant parts, but is associated with a high retention of photosynthates.
Differential Responses to Environmental Conditions by Fungal Cells Sensitized by Heat Shock or UV Irradiation
Authors: Fries Nils
Published: April 2006

Cells of the ascomycele Ophiostoma multianulatum were sensitized to the supra‐optimal temperature of 30°C either by heat shock or by UV irradiation. At this incubation temperature the death rate of the heat‐shocked cells was higher than that of the irradiated cells. This difference was increased if hydrolysed casein was added to the incubation medium. The heat‐shocked cells were also killed faster at 30°C, if nitrogen instead of air was bubbled through the cell suspension. Heat shock, in contrast to UV irradiation, strongly increased the sensitivity to a high concentration of sodium chloride.
Evolution de I'amidon et des sucres solubles chez des feuilles isoléaes d' Aster tripolium et de Cochlearia tniglica. Action du NaCI Par
Authors: Binet P.
Published: April 2006

Starch and soluble sugars in leaves of Aster tripolium L. and Cochlearia angliea L. Effect of NaCI. ‐ The limbs or foliar disks of Aster tripolium L. and Cochlearia anglica L. synthelize starch when exposed to light at 25°C, and in the presence of glucose or saceharose together with 0.25 to 0.61 % of NaCI.
Changes in the Activity of Certain Enzymes of Acer pseudoplatanus L. Cells at four Stages of Growth in Suspension Culture
Authors: Kaarina Simola Liisa , Sopanen Tuomas
Published: April 2006

The activities of twelve enzymes were studied in Acer psendoplatanum L. cells grown in suspension cultures for 6, 12, 19 and 22 days. The enzyme activities of cells (6 and 12 days) in the phase of rapid cell division were rather different from that of cells in the stationary phase (19, 22 days). The activity of aldolasc was highest at the first two stages of growth, when the amount of RNA and protein per cell was highest, and after this decreased steeply. The curves of specific activities of several phosphatases (glucosc‐6‐phosphatasc, α‐glycerophosphatase, acid phosphatase and ATPase) and ribonuclease were almost the reverse of the curve of aldolase, showing a minimum in 12‐day‐old cells and a maximum in cells 19 and 22 days old. The activity of peroxidase was also high in ageing cells. Glutamate: oxaloacetate transaminase and aminopeptidases (leucine and alanine) had synchronous maxima (6 and 19 days) of specific activity but the activity of aminopeptidases decreased gradually during ageing of the suspension, if the enzyme activities are calculated per 107 cells. Glutamate: pyruvate transaminasc activity was very low and no dcoxyribonuclease activity could be detected.
Influence of Auxin on Young's Modulus in Stems and Roots of Pisum and the Theory of Changing the Modulus in Tissues
Authors: Burströum H. G. , Uhrströum Inger , Olausson B.
Published: April 2006

The effect of auxin on elastic extensibility has been investigated by means of the resonance frequency melhod in Pisum, sativum. The time lag for the decrease in Young's modulus E, caused by IAA, was between 2 and 3 minutes in etiolated stem internodes. The time lag for growth was about 7 minutes. The measurements of E in root segments were only qualitative owing to the structural characteristics; IAA decreases E in roots as it does in stems, but only in the region where IAA is assumed to enhance elongation. The connexion between elastic modulus and growth is discussed with reference to other investigations. The assumption has been made that a decrease in elastic modulus indicates a change in the cell wall which in some way is conducive to growth (induction of elongation). The theoretical possibilities of changing E have been discussed with reference to the formula for water fluxes. Both a change in a cell wall properly and a change in the cytoplasmic permeability are able to cause a change in E in the same way as auxin does. An early action of auxin must be located in the cell‐wall‐plasmalemma region.
The Starch Statolith Hypothesis and the Optimum Angle of Geotropic Stimulation
Authors: IVERSEN TOR‐HENNING , LARSEN POUL
Published: April 2006

When roots of cress seedlings (Lepidium sativum L.) are stimulated for 10 min at an angle of 135° (i.e. the root tips are pointing obliquely upward), the resulting geotropic curvatures become larger than after 10 min stimulation at 45°. This well‐known behavior has been explained by the better conditions for statoliths, initially located in the floor end of the statocytes, to slide along the cell walls when root tips are pointing upward at 135° than when pointing downward at 45°. Accepting this explanation, one would predict the optimum angle of stimulation to be near 45° when roots had first been kept inverted long enough for their statoliths to accumulate in the opposite end of each functional statocyte. This prediction has been verified in experiments with cress seedlings which were first kept inverted for 16 min, then stimulated for 10 min at given angles, and subsequently rotated parallel to the horizontal axis of the klinostat at 2 rpm. Under these conditions, roots stimulated at 45° curve faster during a 20 to 30 min period on the klinostat than roots stimulated at 135°, but thereafter they stop curving. Roots stimulated at 135°, on the other hand, although initially curving slower than those at 45°, continue curving for at least a whole hour, and attain larger curvatures than the others after 40 min. The optimum shifts from near 45° to near 135° during the course of the klinostat rotation. The behavior of normal and pre‐invertcd roots is interpreted as the result of at least two effects: (1) a stimulation due to the movement of amyloplasts, which is enhanced if these are allowed to slide along the cell walls, and (2) a modification of the development of the resulting curvatures by tonic effects, which are inhibitory between stimulation angles 0° and 90°, and absent or enhancing between 90° and 180°.
De novo Synthesis of Polyglucans by a Phosphorylase Isoenzyme in Algae
Authors: FREDRICK JEROME F.
Published: April 2006

The α2 phosphorylase isoenzyme of Oscillatoria princeps, Rhodymenia pertusa and Chlorella pyrcnoidosa has been found to be capable of the synthesis of amylose‐like polyglucans without the necessity for addition of primers. This enzyme differs in this respect from the a1 isoenzyme of blue‐green and green algae. The a2 enzyme appears to be a glyco‐protein and synthesis of linear polyglucans appears to occur by the apposition of glucosyl residues from glucose‐1‐phos‐phate directly to the glycosyl moiety of its molecule.
Investigations of the Geotropic Curvature of the Avena Coleoptile
Authors: JOHNSSON ANDERS
Published: April 2006

The geotropic reaction in Avena coleoptiles is studied as a function of the stimulation time. The direction of the stimulation with respect to the vascular bundles must be defined when studying geotropic responses.

It is found that the threshold time to evoke geotropic response is less than half a minute, i.e., at least ten times lower than the presentation time usually reported in the literature. An extrapolation procedure can be used to give a so‐called extrapolated presentation time tb, which is intimately related to the logarithmic part of the geotropic response curve and has a physical meaning in the reciprocity rule.

The problem of the duration of the true threshold time for stimulation with 1 g is discussed.

An experiment indicates that it is not necessary for mass particles (“statoliths”) to settle on the lateral cell wall in order to start the geotropic reaction chain.

The slope of the logarithmic part of the geotropic response curve is independent of the transverse force applied to the coleoptiles. Support is given to the view that the slope is determined by the number of sedimenting mass particles.
A New Tomato Mutant Inefficient in the Transport of Iron
Authors: BROWN J. C. , CHANEY R. L. , AMBLER J. E.
Published: April 2006

An Fe‐inefficient tomato mutant, T3238fe (Lycopersicon esculentum) was identified by growing the plants in solution cultures containing different concentrations of FeHEDTA. Approach grafts of T3238Fe (Fe‐efficient) top on T3238fe rootstock and vice versa, located the cause of Fe inefficiency in T3238fe roots. The T3238Fe tomato takes up more Fe than T3238fe and it responds favorably to Fe‐stress by releasing hydrogen ions from its roots, increasing reduction of Fe3+ to Fe2+ at its roots, and increasing the citrate concentration in its roots. T3238fe showed very little response to Fe stress; it was unable to absorb and transport adequate Fe from PeEDDHA to support growth.
The Contribution of Photosynthesis to Chlorophyll Formation in Etiolated Mung Bean Leaves
Authors: DODGE A. D. , ALEXANDER D. J. , BLACKWOOD G. C.
Published: April 2006

Chlorophyll formation in seven day old etiolated mung bean leaves was inhibited by CMU. The inhibition was reversed by feeding sucrose, or by leaving the cotyledons attached to the leaves. Photosynthesis appeared to contribute substrates for further chloroplast development soon after its commencement. When sucrose was fed in the presence of CMU at a range of light intensities, there was a distinct light induced promotion of chlorophyll formation at light intensities of 500–2000 lux. Treatment of the leaves with salicyl‐aldoxime, an inhibitor of cyclic photophosphorylation indicated that this process could play an important part in chloroplast development.
Control of Tryptophan Biosynthesis in Plant Tissue Cultures: Lack of Repression of Anthranilate and Tryptophan Synthetases by Tryptophan
Authors: WIDHOLM JACK M.
Published: April 2006

Tobacco (cv. Xanthi and cv. Wisconsin 38), rice, carrot, tomato, and soybean tissue cultures were grown in liquid media containing L‐tryptophan. The addition of tryptophan increased the cellular tryptophan levels greatly (12–2500 fold), but did not lower appreciably the levels of two tryptophan biosynthetic enzymes, anthranilate synthetase and tryptophan synthetase. However, the addition of 50 μM tryptophan to the crude enzyme extract completely inhibited the anthranilate synthetase activity while 1 mM tryptophan inhibited the tryptophan synthetase activity by only 10–20°/o. This information indicates that tryptophan biosynthesis is controlled by the feedback inhibition of anthranilate synthetase by tryptophan and not by repression of enzyme synthesis.

All of the species had significant enzyme levels. Anthranilate synthetase activity could not be detected in extracts from cells grown on tryptophan unless the extracts were first passed through two G‐25 Sephadex columns with a short 30 °C warming step in between, a procedure shown to remove an inhibitor of the enzyme.
Changes in Indoleacetic Acid Oxidase Activity Associated with Plant Water Potential
Authors: DARBYSHIRE B.
Published: April 2006

The effect of plant water potential on the activity of indoleacetic acid oxidase was examined. It was found that with increasing plant water deficit the activity of indoleacetic acid oxidase increased. Higher activies of this enzyme are known to be associated with older tissues and lower endogenous auxin levels. It is suggested that while water stress may adversely affect a variety of physiological processes, increases in the activity of indoleacetic acid oxidase may provide plants with a drought adaption mechanism.
Phytochrome Effects in Night‐break Illuminations on Flowering of Chrysanthemum
Authors: KADMAN‐ZAHAVI AVISHAG , YAHEL HERUT
Published: April 2006

The inhibition of flowering in chrysanthemum by cyclic or continuous illuminations in the middle of the night was studied with mixed red/far red (incandescent) and pure red light at different intensities. Although cyclic lighting greatly enhanced the flower‐inhibitory capacity of mixed red/far red light, no such effect was obtained with pure red light. It is argued that the “dark reversion” hypothesis is not adequate to explain the differential effectiveness of cyclic lighting. A possible mechanism is suggested by which mixed red/far red light may produce more Pfr by interrupted than by uninterrupted illuminations.

Contribution from The Volcani Institute of Agricultural Research, Bet‐Dagan, Israel. 1970 Series No. 1826‐E.
Light, Seed Coat and Gibberellic Acid in Relation to the Amylase Activity in Germinating Scots Pine Seeds (Pinus silvestris)
Authors: NYMAN BENGT
Published: April 2006

The amylolytic activity in homogenates from both embryos and endosperms of Scots pine seeds depends on the presence of α‐amylase. The activity of this enzyme has been studied in relation to the light factor during the first 24 hours of the germination process. No positive correlations have been found between the observed activities and earlier observed enhancement of the starch degradation in light. The endosperm activities have been shown to be affected both by the presence of an intact coat and the presence of the embryo. The embryo influence could not be restored by gibberellic acid. The results have been discussed in relation to the physiology of gibberellin and ethylene.

The author wishes to express his thanks to the Swedish Natural Science Research Council for financial support and to Miss Brigitte Thierbach for skilful, technical assistance.
Indole‐3‐acetic Acid Levels and the Role of Indole‐3‐acetic Acid Oxidase in the Normal Root and Club‐root of Cabbage
Authors: RAA JAN
Published: April 2006

The auxin content of club‐root (Plasmodiophora brassicae Wor.) is 50–100 times higher than that of normal cabbage root. The importance of this difference in the disease development is discussed. Both normal root and club‐root of cabbage contain allosteric IAA oxidase and IAA oxidase with ordinary kinetic properties. In normal cabbage root the allosteric one is associated with cell fractions sedimenting at 20,000 × g and 105,000 × g, in club‐root it remains in the supernatant after 105,000 × g centrifugation. IAA oxidase with conventional kinetic properties is present in both these tissues in the cell fraction sedimenting at 10,000 × g, which contains mainly cell wall fragments. It is concluded that IAA oxidase is not primarily involved in regulation of the endogenous IAA level.
Uptake and Incorporation of 14C‐labelled Maleic Hydrazide into the Roots of Salix viminalis
Authors: COUPLAND D. , PEEL A. J.
Published: April 2006

Labelled maleic hydrazide (MH) was shown to be accumulated preferentially into the root‐tips of young Willow roots by radiochemical analysis. A large proportion of the activity incorporated into the cell constituents was associated with RNA. MH was also bound in some way to the cell wall material. The greatest proportion of the activity was easily removed from the root tissue and thus probably occurred free within the cytoplasm and free‐space.

The incorporation of MH into RNA and its subsequent effects on cell metabolism via abnormal protein and enzyme synthesis is given as an explanation of the mode of action of MH.
Effects of Benzyladenine on Photosynthesis, Growth and Senescence of the Bean Plant
Authors: ADEDIPE N. O. , HUNT L. A. , FLETCHER R. A.
Published: April 2006

The net photosynthetic rate of attached primary bean leaves treated with benzyladenine (BA) decreased from 35 nano‐grams carbon dioxide per square centimetre and second (ng cm−2 s−1) at week 2 to 17 ng cm−2 s−1 at week 4, and thereafter increased to 24 at week 6. By contrast the net photo‐synthetic rate of the water‐treated leaves decreased to 4–5 ng cm−2 s−1 at weeks 5 and 6. The stomatal resistance was not markedly affected by BA treatment.

The BA‐treated primary leaves had higher dry and specific weights, and the chlorophyll and carotenoid contents were greater than for the water controls. The pigment content of the BA‐treated leaves steadily increased from week 2 to 6, whereas in the water controls it remained constant till week 4 and thereafter decreased.

It is concluded that retardation of leaf senescence by BA is assoclatcd with a mnintenance of photosynthetic activity.
Infrared Energy as a Factor in Controlled Environments
Authors: PALLAS J. E. , MICHEL B. E.
Published: April 2006

The proportion of visible to infrared radiation varies in different growth chambers. Whether this might affect leaf temperature and plant growth was investigated in chambers with equal visible radiation. In one chamber infrared energy was half the total, while in two chambers it was 75% of the total. Photoperiods were 14 hours and day and night temperatures 25° and 20°C, respectively. Warm weather species tested were Zea mays, Phaseolus vulgaris, Gossypium hirsutum, Glycine max, and Sorghum vulgare.

High infrared did not increase the leaf temperatures of Sorghum vulgare, but growth was better than under low infrared. In the other 4 species, slightly higher leaf temperatures were observed, but growth was not significantly increased by high infrared. Of the cool weather species, Pisum sativum L. (Alaska and Wando) and Vicia faba L., grew less; Avena saliva L. grew equally; and Brassica oleracea L. var. capitata grew better in high infrared. Leaf temperatures of these cool weather species were generally below ambient and were not appreciably affected by the proportion of infrared. The CO2 was uncontrolled in one high infrared chamber and was 400 μl CO2 liter or more. Except for G. max and P. vulgaris, the growth of the warm weather species was not significantly affected; however, all cool weather species grew best in this chamber. A sparing effect from infrared damage is induced by high CO2.
The Effect of Fruiting upon Transpiration Rate and Stomatal Opening in Apple Leaves
Authors: HANSEN POUL
Published: April 2006

The uptake of water by apple trees (Malus × domestica‘Golden Delicious’) was measured in a pot experiment and was found to be much greater in apple trees carrying many fruits than in comparable specimens without fruits. The main reason seemed to be differences in the transpiration rates of the leaves. This was corroborated by microscopic investigations which showed a higher degree of stomatal opening in the fruiting trees. In some cases minor reductions in water uptake per tree were caused by reducing the supplies of potassium and nitrogen.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A.
Published: April 2006

A venacin, the resistance factor in oat roots against Ophio‐bolus graminis var. graminis, and a related triterpeneglycoside, aescin, induced a rapid release of K+ from mycelia of Opbio‐bolus graminis and Neurospora crassa, suspended in phosphate buffer. N. crassa also released Mg2+ whereas no outflux of Mg2+ was found from O. graminis.

The inhibitors induced a release of inorganic phosphate into acetate buffer from Neurospora crassa. The amount of inorganic phosphate in the mycelia decreased when O. graminis and N. crassa were treated with the inhibitors in phosphate buffer. In other media the inhibitors had weak or no effects on the ion contents of the mycelia.

The effect of aescin was low in Aspergillus niger and nil in Pythium irregulare. However, high amounts of K+, Mg2+, and phosphate ions were lost to the medium when the mycelium of P. irregulare, washed with distilled water, was suspended in different buffers. The ions lost were reabsorbed during the experimental period. The leakage of ions indicates that the plasma membrane of the growth sensitive fungi is severely affected by the inhibitors, while a corresponding effect on the growth insensitive fungi does not take place.
Influence des racines sur le développement végétatif ou floral des bourgeons cotylédonaires chez le Scrofularia arguta: role possible des cytokinines
Authors: MIGINIAC EMILE
Published: April 2006

Influence of roots on the vegetative or floral development of cotyledonary buds of Scrofularia arguta Sol.: A possible cytokinin role. This study shows that the presence of “nonabsorbing roots” insures a vegetative development of cotyledonary buds cultured in vitro whereas buds growing without roots produce flowers early. In the same way, roots suppress floral expression of axillary meristems of the same cotyledonary buds and induce these buds to vegetative functioning. Various trophic modifications in the culture medium are ineffective on non‐rooted buds as also are gibberellin As and adenine. On the contrary, several cytokinins (kinetin, benzyladenine and zeatin) exert the same influence as roots. These results suggest that roots regulate meristematic functioning through cytokinins.
Changes in the Cytokinins of Radish Roots during Maturation
Authors: RADIN J. W. , LOOMIS R. S.
Published: April 2006

The cytokinins of developing radish roots were extracted, partially purified, and separated by thin‐layer chromatography into three distinct bands of activity. One band was identified chromatographically as zeatin ribonucleotide and another was indistinguishable from a mixture of zeatin and zeatin ribonucleoside. The third band was not identified, but it was not a derivative of zeatin or of isopentenyladenine.

The unidentified cytokinin had physiological properties quite different from those of the zeatin derivatives. The zeatin‐based cytokinins increased in radish roots with the onset of cambial activity, and reapplication of these cytokinins to cultured primary roots stimulated cambial activity. The unidentified cytokinin became abundant only after extensive secondary thickening had occurred, and it was localized almost entirely in the xylem. It did not stimulate cambial activity in cultured roots. The evidence indicates that zeatin and its derivatives regulate cambial activity in radish, and that the unidentified cytokinin may be synthesized in the roots and transported to the shoot.
Photosynthetic Uptake of Free CO2, by the Roots of Lobelia dortmanna
Authors: WIUM‐ANDERSEN S.
Published: April 2006

Lobelia dortmanna L. is probably unable to utilize HCO3−and uses only free CO2 for photosynthesis as shown by the Winkler method. A 14C technique was used to show that if CO2 is added to the water around roots, photosynthesis increases 3–5 times more than when the corresponding amount of CO2 is added to the water surroundings the leaves. As the CO2 content in lakes where Lobelia grows is very limited, Lobelia must absorb CO2 from the sediment, and the carbon dioxide will have to diffuse from the roots up into the leaves through the intercellular system of the plant. In conjunction with Lobelia's CO2 uptake from the sediment O2 is liberated. The plant, therefore, acts as an oxygen pump, which oxidizes the sediment down to a depth of 20 cm.
The Effect of Cyclopropane on Ion Uptake and Protoplasmic Streaming in Barley Roots
Authors: JACOBSON L. , YOUNG L. C. T.
Published: April 2006

Increasing concentrations of cyclopropane up to about 95 % C3H6—5 % O2 caused an increasing inhibition of uptake by excised barley roots from KC1 solution, much more so for Cl than K. No inhibition of K uptake from K2SO4 occurred under similar conditions. It is suggested that the small decrease in K uptake from KC1 is related to the large decrease in Cl uptake and that C3H6 primarily inhibits Cl uptake with little or no effect on K uptake. Time curves of uptake in 80 % C3H6 20 % O2 revealed no indication of cumulative injury in either KC1 or K2SO4 for periods up to 3 hours.

The amount of organic acid production associated with K uptake from K2SO4 was about the same in 80 % C3Hg— 20 % O2 as in air. Oxygen consumption in K2SO4 was unaffected by the gas mixture and only slightly affected in KC1.

Protoplasmic streaming in epidermal cells was rapidly stopped at C3H6 concentrations of 20 % or higher. In 80 % C3H6–20 % O2 the effect on streaming was confined mostly to the outer two or three layers of root cells. A connection between the cessation of streaming and the inhibition of Cl uptake appeared to exist but very little if any relationship between streaming and K uptake was observed.
Luminescence Induced in Intact Leaves and Isolated Chloroplasts by Alcohols and Other Substances
Authors: BJöRN L. O. , SIGFRIDSSON BJöRN
Published: April 2006

Elodea leaves and spinach chloroplasts emit red light when treated with alcohols or certain other solvents for chlorophyll. The intensity of the light, the lag phase and the threshold concentration vary considerably between different alcohols.

Light emission from a leaf starts a few seconds to a few minutes after the addition of alcohol to the medium, reaches a maximum after 2–45 minutes (sometimes more) and then continues for many hours. Despite the faintness of the glow, the total number of photons given off from a leaf after addition of alcohol may exceed the number of photons given off from the same sample as long‐lived afterglow after saturating irradiation with far‐red light. The maximum yield of photons per chlorophyll molecule is a little more than 10–5. The alcohol‐induced luminescence is not influenced by a decrease in the oxygen tension to one fifth of the normal.

Electron micrographs of treated leaves reveal that the thylakoid lipids contract to drops at the edges of the grana. Treatment of isolated chloroplasts with ethanol results in light emission when the concentration is high enough to dissolve the chlorophyll. It is estimated that the surface free energy in the thylakoid lipid‐aqueous interface, due to ordinary interfacial tension, is large enough to account for the light emission observed when the interfaces contract or disappear.
Effects of Some Chemical Compounds on the Slow, Far‐red Induced Afterglow from Leaves of Elodea and the Lack of Effect of N‐methyl Phena zonium Methosulfate on Far‐red induced Glucose Uptake in Chlorella
Authors: BJöRN L. O.
Published: April 2006

N‐methyl phenozonium methosulfate,3–(3,4‐dichlorophe‐nyl)–l, l‐dimethylurea and carbonylcyanide‐m‐chlorophenyl hydrazone have similar effects on the slow, far‐red induced afterglow component in intact Elodea leaves as has previously been shown for Chlorella. The first compound increases the rate constant for emission. Contrary to the case with Chlorella, it also markedly increases the total amount of light emitted from 10 sec. to infinity (maximally by 50 percent). The second compound decreases the rate constant and the amount of light, and the third compound increases the rate constant and decreases the amount of light. Electron micrographs are compared with the hypothetical units that can be deduced from the afterglow experiments, and it is found that the small thylakoids (“grana thylakoids”) have a size of the same order of magnitude as that expected for the afterglow units.

The afterglow from Elodea, in contrast to that from Chlorella, is not affected by desaspidin except at extremely high concentrations.

Far‐red induced glucose uptake in Chlorella is not affected by 10–7M N‐methyl phenazonium methosulfate, which was previously shown to have a large effect on afterglow kinetics in the same organism.
Stress‐relaxation Properties of the Avena Coleoptile Cell Wall
Authors: YAMAMOTO RYOICHI , MASUDA YOSHIO
Published: April 2006

Changes in the cell wall properties of Avena coleoptile segments were studied under various conditions by stress‐relaxation analysis. Rheological models consisting of four or an infinite number of Maxwell viscoelastic components were used. The stress‐relaxation parameters of these models, t1, to, T, Gi and stress/strain ratio, were determined. The following results were obtained.

1. The 1/T1 increased and stress/strain ratio decreased with the age of the coleoptiles. Decapitation caused a decrease in l/t1.

2. Auxin increased I/T1 but decreased to and stress/strain ratio within 5 minutes after application.

3. Treatment with a fungal β‐l,3‐glucanase increased 1/T1 both in living and methanol‐killed, pronase‐treated coleoptiles. Cellulase did not cause the changes observed in the parameters of the isolated cell wall of the coleoptile segments. This held true for all treatments (with and without auxin, killed and pronase‐treated).

The results obtained suggest that auxin primarily causes a partial degradation of the non‐cellulosic physaccharide components of the cell wall.
Studies on Ectomycorrhizae of Pine II. Growth Inhibition of Mycorrhizal Fungi by Volatile Organic Constituents of Pinus silvestris (Scots Pine) Roots
Authors: MELIN ELIAS , KRUPA SAGAR
Published: April 2006

The effects of several monoterpenes and the sesquiterpene longifolene on the vegetative growth of two mycorrhizal fungi, Boletus variegatus and Rhizopogon roseolus, were studied in petri plate experiments on an agar medium. The test substances are natural constituents of Pinus silvestris (Scots pine) roots. Vapors from 20 μl of all the test substances, upon a 5 day exposure inhibited the growth of both the mycorrhizal fungi 55% to 86%. The two fungi, however, differed in their tolerance to individual compounds. It is suggested that the terpenes and the sesquiterpenes play an important role in the development of the symbiotic condition in ectomycorrhizae by restricting the growth of the mycorrhizal fungi within the host root.
Apparent Free Space of Germinating Pea Seeds
Authors: MOROHASHI Y. , SHIMOKORIYAMA M.
Published: April 2006

The apparent free space (AFS) of pea seeds was determined by measurement of the exodiffusion of solutes from the seeds previously equilibrated with radioactive solutions. AFS (per cent of volume of water taken up by dry seeds) varied with the kinds of solutes used, that is, values of 27–30% were obtained for mannitol or leucine and 12% for malonate, at pH 6. When the seeds were incubated in a radioactive solution at lower pH (3.5), higher AFS values were obtained, especially for malonate. The AFS of imbibing seeds showed a tendency to increase during the course of imbibition.
The Relationship between Stimulus Intensity and Oriented Phototactic Response (Topotaxis) in Chlamydomonas
Authors: FEINLEIB MARY ELLA HARMAN , CURRY GEORGE M.
Published: April 2006

Two techniques have been used to study the quantitative relationship between stimulus intensity and oriented phototactic response (topotaxis) in Chlamydomonas. The net response of a cell population was monitored photometrically and was recorded continuously against time. The responses of individual cells were observed through a microscope and their swimming tracks were recorded on film.

The net response of the population is positive at low stimulus intensity and negative at high intensity. The direction of response can be reversed within two seconds by raising or lowering the intensity. The intensity‐response curve for phototaxis is similar to the dose‐response curve for phototropism. The net response has no distinct threshold; it increases linearly with log intensity; then it decreases and finally becomes negative.

The individual‐cell studies reveal that the intensity‐dependent increase in net topotactic response is due primarily to an increase in the number of cells responding and in the directness of their swimming path. As stimulus intensity is raised, the swimming path becomes increasingly well‐aligned with the stimulus beam, whether net response is positive throughout the intensity range tested, negative throughout that range, or changing from positive to negative.

Changes in swimming rate do not contribute significantly to the intensity‐dependent changes in net response. Swimming rate shows virtually no change throughout the intensity range of positive topotaxis and shows only a small increase in the negative range. However, a transient decrease in swimming rate (stop response) is often observed at the onset of stimulation. The implications of these results for the orientation mechanism are discussed.
Phytol Changes in Dark Grown Leaves of Barley after Varying Light Treatments
Authors: LILJENBERG CONNY
Published: April 2006

Gas chromatographic determinations revealed a certain amount of free phytol in dark‐grown barley leaves. When a short light impulse or continuous light is given to the leaves, the phytol pool is partly emptied due to esterification of chlorophyllide a. The regeneration is slow during the first 2–3 hours. A pretreatment with light flashes followed by a dark period accelerates the regeneration, which stops however after approximately 30 min. Some evidence points to the existence of an acceptor for excess phytol entering at this stage.

Connections between phytol changes during irradiation and the lag phase of chlorophyll formation are discussed.
Regulators of Cell Division in Plant Tissues XII. A Cytokinin Bioassay Using Excised Radish Cotyledons
Authors: LETHAM D. S.
Published: April 2006

A rapid bioassay for cytokinins is described. This is based on the ability of these compounds to promote markedly the expansion of radish cotyledons excised soon after seed germination. The response, which is due largely to a promotion of cell enlargement, is inhibited by abscisic acid. Gibberellins, certain amino acids and calcium salts, naturally occurring substances without cytokinin activity, induce small growth increments in the assay. Cytokinin structure‐activity relationships observed for the assay are very similar to those which apply in the tobacco‐pith tissue culture assay.
Imbibition and Germination: Influence of Hard Seed Coats on RNA Metabolism
Authors: BARTON KENNETH A. , ROE CATHY H. , KHAN ANWAR A.
Published: April 2006

RNA metabolism of Indian rice grass seeds was studied in relation to imbibition and germination. These seeds germinate only after scarification of the seed coats. The hard seed coats restrict germination but not water intake or changes in the quantity and quality of RNA formed during early hours of soaking. These changes differ markedly from those in scarified (H2SO4 treated) seeds which are able to germinate. Gibberellic acid hastens germination of scarified seeds and causes changes in the population of RNA transcribed.
Studies on the Physiology of Host‐parasite Relationship in Orobanche. II. Growth and Mineral Nutrition of Host and Parasite
Authors: SINGH JAI N. , SINGH JAGDISH N. , RAI T. B.
Published: April 2006

The effects of Orobanche infection on the growth and mineral compostition of the host were studied. Parallel observations were made in host and parasite.

Orobanche infection reduces the height of main shoot, the length of root, the number of branches, and the number and total area leaves per plant. Consequently the fresh and dry weight of the host is also decreased. Infection affects NAR and LAR only slightly but reduces RGR and RLGR at a later period of infection. The retardation in the growth of host seems to be due mainly to a continuous extraction of metabolites and inorganic nutrients. Infection increases the nitrogen, calcium and magnesium content in the host, especially in the leaves. This fact is connected with the retarded growth in the host. The process of absorption is probably not changed. The phosphorus and potassium contents diminish in the infected host, a fact related to the higher translocation to the parasite.

The Orobanche plants grow faster during early stages and accumulate 88 % of total dry matter before flowering, The growth stages of Orobanche do not coincide with those of the host suggesting that the parasite is capable of synthesizing its own growth substances. Studies with 32P show that the flow of minerals is mainly in the direction from host to parasite. The major part of the requirement of the parasite is met by the host. Orobanche maintains a higher phosphorus and potassium content in its tissues than the host, while the nitrogen, calcium and magnesium content is lower.