bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperature of the Culture Medium on Growth and Nitrogen Fixation of Inoculated Legumes and Rhizobia
Authors: Roponen Ilma , Valle Eero , Ettala Terttu
Published: April 2006

Two pea (Pisum sativum L.) cultivars and a kidney bean (Phaseolus vulgaris L.) cultivars were grown in water cultures at different diurnal temperatures (15, 20, 24, 27, 30°C) or at 10°C night temperature combined with various day temperatures (20, 24, 27, 33 or 35°C) in the root medium. The inoculated plants were, more sensitive to the extreme temperatures than the plants supplied with combined nitrogen (KNO3). The middle‐European pea cv. Violetta was adapted to somewhat higher root temperatures than the northern one cv. Torsdag II, the latter showing better growth at lower temperatures, when the plants were inoculated with the same Finnish Rhizobinm strain (HA1). Especially at optimum day temperatures the nitrogen fixation and consequently the dry weights of the inoculated plants were greatly increased when the night temperature was lowered.

The optimum temperature for the growth of free‐living Rhizobium strains (HA1 and H43) for peus was found to be 25°C and that of a strain (P103) for beans somewhat higher.

Effective nitrogen fixation by nodulated legumes without a supply of combined nitrogen is achieved only when the optimum temperature range for root function is very close to the optimum for the rhizobia.
Investigations on Cytokinins. IV. The Metabolism of 6‐Benzylaminopurine in Lemna minor
Authors: BEZEMER‐SYBRANDY SYTSKE M. , VELDSTRA H.
Published: April 2006

The metabolism of 14C‐labeled 6‐benzylaminopurine in aseptic cultures of Lemna minor was investigated. This cytokinin is slowly taken up by the plants; part of it can be released and part of it is rapidly metabolized to several compounds, among which the corresponding nucleotides can be identified. In this connection the feasibility of locating the site of hormone receptors (sites of primary action) in plants is discussed. Incorporation of the labeled cytokinin into Lemna tRNA was not observed, although tRNA hydrolysates, isolated from plants grown on a cytokinin‐free medium, contain a fair amount of cytokinin activity and therefore presumably cy okinin molecules.
Spring Mobilization of Storage Nitrogen in Isolated Shoot Section of Apple
Authors: TROMP J. , OVAA J. C.
Published: April 2006

The process of mobilization of nitrogenous compounds in trees during spring development was studied in short isolated shoot sections (usually bearing one bud each) of Golden Delicious apple trees. During leafing‐out of the bud, changes in the amounts of total, protein and soluble nitrogen and of soluble amino acids and amides in bark and wood were followed. The nitrogen required by the growing parts came mainly from protein breakdown in the tissues below the bud; in the tissues above the bud, total nitrogen decreased little, whereas the drop in protein nitrogen was considerable. In de‐budded sections and in internode sections where total nitrogen remained almost unchanged, protein hydrolysis occurred as well. It is concluded that the protein breakdown is not strongly dependent on the demand of the bud for nitrogen.

Inversion of the sections did not result in any change in the pattern of nitrogen mobilization: a marked drop occurred in the nitrogen content of the physiologically basal part of the section and only a slight decrease in the apical part. The translocation of stored nitrogenous compounds to the growing parts seems to occur in the phloem, at least over short distances.

Asparagine and arginine were found to be the major components of the soluble amino‐nitrogen fraction throughout. The relative importance of asparagine was reduced in tissue where a substantial loss of nitrogen occurred during leafing‐out of the bud. This is explained in terms of a preferential export of asparagine to the bud.
Abscisic Acid Action on Basipetal Auxin Transport
Authors: PILET P. E.
Published: April 2006

Several experiments have been performed to analyse the ABA effects on the basipetal transport of IAA‐2‐14C, using sections of epicotyls prepared from etiolated Lens seedlings. The sections were incubated in an ABA solution or ABA was applied in the donor blocks containing IAA. For each type of assay, the uptake (analyses of the donor blocks) and the movement of IAA‐C14 (analyses of the receiver blocks) were inhibited by ABA. The distribution of continuous decrease of the radioactivity, along the sections' axis, showed a 14C level from the apical towards the basal segments. ABA caused a decrease in the 14C concentration for the total sections, but a relative increase for the basal segment. When ABA was applied simultaneously with IAA in the donor blocks, the transport velocity of IAA, through the sections, was not changed significantly, while an ABA pretreatment caused a significant decrease.
Investigations of the Geotropic Curvature of the Avena Coleoptile
Authors: JOHNSSON A. , RENGMAN K. , GRAHM L.
Published: April 2006

The geotropic presentation time was studied in Avena coleoptiles as a function of the distance from the tip. Curvatures of decapitated plants, allowed to curve in IAA‐solutions, were recorded. Extrapolated values of the presentation times are roughly the same (about 4 min) in coleoptiles from which 1, 3, or 5 mm, respectively, of the tip have been removed by decapitation. Presentation times reported in the literature are generally longer and are stated to increase considerably with the length of the portion of the tip removed by decapitation. No such relationship was found in the present study. The discrepancies can, at least to a large extent, be explained by differences in principles and methods of measurement.

The present results are in accord with measurements on the geoelectric effect in coleoptiles.
Photosynthetic Action Spectra of Scots Pine Needles of Different Ages from Seedlings Grown under Different Nursery Conditions
Authors: LINDER SUNE
Published: April 2006

Photosynthetic action spectra of pine needles have been measured with an automatic recording method. A thin longitudinal cut from the flat surface of the needle was placed on top of an oxygen sensor and illuminated with monochromatic light in the range 400–700 nm. Good correspondence between absorption and action spectra was obtained in the range 550–700 nm. In the blue part of the spectrum photosynthetic efficiency was low compared with absorption. This low effect in blue light is probably due to screening absorption by photosynthetically inactive carotenoids.

One‐year‐old needles showed a higher effect in the blue part of the spectrum than did current year needles. Needles from seedlings grown in the open had a lower photosynthetic effect in the blue part than needles from seedlings grown in a greenhouse. Pigment analyses support the idea that these differences are due to differences in the ratio chlorophylls/total carotenoids and/or differences in the composition of the carotenoid pigments.
Causes of Centrifugal Root Promotion
Authors: KAWASE MAKOTO
Published: April 2006

Role of water in centrifugal root promotion, effect of centrifugation on ethylene concentration of cuttings, and effect of ethylene on root formation were investigated using Salix jragilis softwood cuttings.

When cuttings were centrifuged with water, more roots formed with increasing water depth. Soaking of cuttings upright in water for 24 h stimulated root formation and produced more roots as the depth of water was increased, with submerged cuttings producing the highest number of roots. Soaking of cuttings upright in hot water for 1 h also stimulated root formation with the best root formation occurring at 40°C. Submerging in, or centrifuging with water increased ethylene concentration in cuttings. Ethylene gas and Ethrel treatments stimulated root formation. It is suggested that submerging in water increases the ethylene concentration in Salix fragilis softwood cuttings which in turn stimulates root formation of the cuttings.

Centrifuging cuttings with water increased water content of the cuttings. It is suggested that this increase in water content plays a role similar to the submersion of cuttings as described above.
Changes in Phosphorus Fractions and Phytase Activity of Rice Seeds during Germination
Authors: MUKHERJI S. , DEY B. , PAUL A. K. , SIRCAR S. M.
Published: April 2006

The present experiment provides information on the phosphorus compounds in rice seeds and elucidates the changes they undergo during germination. In ungerminated seeds, the bulk of total‐P appears in phytin (about 76 per cent). It is then dephosphorylated in course of germination with a simultaneous accumulation of large amounts of inorganic‐P. Lipid‐P increases very rapidly from 0 to 24 hours. The increase up to 72 hours is gradual, after which it drops at 96 hours and again rises to a maximum after 120 hours. The ester‐P and RNA‐P, fractions increase in concentration with time of germination (except 120 hours). Protein‐P begins to fall after 48 hours, while DNA‐P remains more or less constant throughout the experiment.

The two pH optima recorded for phytase activity at 4.0 and 9.0, suggests that there exist two phytases, one acidic and the other alkaline. Both behave similarly during germination with a continuous increase throughout the course of the experiment. The enzyme with an optimal pH at 4 hydrolyses phytin more actively than the other with the pH optimum at 9.0. Phytase shows maximum activity at a stage when most of the phytin has disappeared; the metabolic significance is uncertain.
NAD‐ and NADP‐Linked Glyceraldehyde‐3‐Phosphate Dehydrogenases in Light‐ and Dark‐Germinated Seeds of Scots Pine (Pinus silvestris)
Authors: NYMAN BENGT
Published: April 2006

By means of arsenate in optical tests the occurrence of both NAD‐ and NADP‐linked glyceraldehyde‐3‐phosphate dehydrogenase activity has been found in embryo and endosperm tissues from Scots pine seeds. By exclusion of arsenate also evidences for the activity of a non‐phosphorylating NADP‐linked form have been demonstrated. The results are sustained by inhibition experiments. The enzyme activities have been followed principally during the first 24 hours of the germination process and in relation to the germination‐controlling light factor. Homogenates from complete seeds and partly also from separated embryo and endosperm tissues have been studied. The predominant activity in both of the tissues was linked to the NAD‐form, expressed either on seed (part) or protein basis. No indications for a light‐regulation of anyone of these enzymes have been found contrary to findings from other plant materials.
Aromatic Substances in Leaves of Populus tremula as Inhibitors of Mycorrhizal Fungi
Authors: OLSEN ROLF A. , ODHAM GÖRAN , LINDEBERG GÖSTA
Published: April 2006

The inhibitory principles of aqueous extracts of aspen leaves, acting upon mycorrhizal fungi of forest trees, were isolated by extraction with ethyl acetate and chromatography on silicic acid. Two inhibitors were identified as benzoic acid and catechol by gas chromatography and mass spectrometry. When added to a synthetic medium, these substances had a strong inhibitory effect on the growth of different Boletus‐species and a weaker inhibitory effect on litter‐decomposing Marasmius‐species. When the fraction of the extract which was not soluble in ethyl acetate was included in the medium, the aromatic compounds still inhibited the mycorrhizal fungi while the growth of the litter‐decomposers was stimulated.
Crystalline Ferredoxin from a Blue‐Green Alga, Nostoc sp.
Authors: MITSUI AKIRA , ARNON DANIEL I.
Published: April 2006

Ferredoxin isolated from a blue‐green alga, Nostoc sp., was purified and crystallized. The absorption spectrum of Nostoc ferredoxin had, in the oxidized state, peaks at 276, 331, 423, and 470 nm, a pattern characteristic of chloroplast‐type ferredoxin. The 423:276 absorption ratio was 0.57. The midpoint oxidation‐reduction potential of Nostoc ferredoxin was found to be –406 mV, at pH 7.5. Nostoc ferredoxin mediated the photoreduction of NADP by isolated Nostoc chromato‐phores and spinach chloroplasts from which the native ferredoxin was removed. The molar ratio of Nostoc ferredoxin to chlorophyll a was about 1:50, a ratio higher than usually found in photosynthetic cells.

The possible evolutionary significance of the properties of Nostoc ferredoxin compared with those of ferredoxins from other photosynthetic organisms is discussed.
The Influence of n‐Propanol on the Growth and Conidiation of Pestalotia rhododendri
Authors: NORRMAN JONAS
Published: April 2006

Pestalotia rhododendri was exposed to vapours from 1 ml propanol solution in water and linear growth, formation of aerial hyphae and production of conidia were determined. A special Petri dish technique was used and maximum stimulation of conidial formation was induced by the vapours from a propanol concentration of 3–4 % (v/v) at 25°C. When propanol was added directly to the medium, a concentration of 1.2 × 10−2M was optimal for growth and sporulation at 30°C.

Sporulation stimulated by propanol was observed at temperatures from 20–32°C, with an optimum at 30°C. Certain observations indicated that an exposure to propanol for 24 hours was enough to induce a stimulated spore production. The stimulation was noticed on different media at 25°C, and was more pronounced at 30°C. One exception was observed. Propanol did not promote sporulation when the fungus was grown on maltagar at 30°C.

Propanol 3 ° (v/v) in combination with the standard medium containing (NH4)2‐tartrate as sole nitrogen source, inhibited the linear growth at 15–20°C, was inactive at 22.5° and 25°C, and stimulated growth at 27.5–31°C. The stimulatory effect was maximal at 30°C. Other media were tested at 25° and 30°C. At both temperatures stimulations of linear growth caused by propanol were observed with a medium containing KNO3 as sole nitrogen source, and inhibitions with maltagar and another medium containing l‐asparaginc as sole nitrogen source. The linear growth could be either inhibited or stimulated while the sporulation was stimulated.
Nodulation in Sesbania aculeata as Affected by Some Pyrimidine Bases and Their Analogues
Authors: MATHUR S. N. , SINGH H. S.
Published: April 2006

Effects of uracil, thymine and their analogues, 5‐nitrouracil, 2‐thiouracil, 6‐azauracil, and 6‐azathymine on nodulation in Sesbania aculeata have been studied. The seeds were dipped partially in a 15 ml solution of each of different concentrations. The experiments included treatments for 6 or 12 h with distilled water as control. The treated seeds were inoculated with a pure culture of Rhizobium leguminosarum and sown in sand cultures, weekly supplied with modified White's basic N‐free solution.

Nodulation in Sesbania aculeata was promoted by uracil, nitrouracil and thymine, but inhibited by analogues. Higher concentrations caused greater inhibition than lower ones. Nodulation was affected by changes in the nucleic acid and protein metabolisms.
Effects of Hydroxyurea and Deoxyadenosine on the Synthesis of Deoxycytidine Phosphate and on the Uptake of Nucleosides in Excised Root Tips of Vicia faba
Authors: ODMARK GÖRAN
Published: April 2006

The effects of hydroxyurea and deoxyadenosine on the synthesis of deoxycytidine phosphate was studied by measuring the incorporation of [14C]‐cytidine into acid soluble deoxycytidine phosphate in root tips of Vicia faba. Hydroxyurea and deoxyadenosine both markedly depressed the incorporation of [14C]‐cytidine.

Deoxyadenosine had the additional effect of inhibiting the uptake of [14C]‐cytidine. Furthermore, millimolar concentrations of deoxyadenosine inhibited the uptake of micromolar concentrations of adenosine, thymidine, and deoxycytidine.

The incorporation of [14C]‐cytidine into RNA was only slightly affected by hydroxyurea. Deoxyadenosine inhibited the incorporation into RNA to about the same extent as the uptake of [14C]‐cytidine.

It is suggested that hydroxyurea reduced the incorporation of radioactive cytidine into deoxycytidine phosphate mainly by interfering with ribonucleotide reduction. The depression of [14C]‐cytidine incorporation into deoxycytidine phosphate in the presence of deoxyadenosine is believed to be the result of an inhibition of both ribonucleotide reduction and [14C]‐cytidine uptake.
The Effect of Boron and Gibberellic Acid on the Senescence of Leaf Discs from Lycopersicon esculentum cv. Rutgers
Authors: PARMAR AMAR S. , HAMMOND H. DAVID
Published: April 2006

When leaf discs of Lycopersicon esculentum Mill. cv. Rutgers were floated on solutions containing 4.33 × 10–6 M gibberellic acid (GA3), 1.0 ×x 10–6M boron (B), separately and together, senescence was retarded with respect to controls. Degradation of chlorophyll, total protein, RNA, and DNA was delayed, and decreases in fresh weight and leaf disc diameter checked. The loss of chlorophyll, protein, RNA, DNA, fresh weight, and diameter were 10, 20, 30, 8, 28, and 0 per cent with GA3 alone; 15, 25, 35, 8, 31, and 0 per cent with B alone; 8, 14, 25, 7, 25, and 0 per cent with GA3 plus B; contrasted with 50, 40, 50, 9, 42, and 3 per cent for the controls. An analysis of variance was performed on all data except for disc diameter. All sources of variance were significantly or highly significant at the 1 per cent level except for the effect of boron on DNA level, which was significant only at the 2.5 per cent level. Retardation of senescence by GA3 may be associated with the known ability of GA3 to stimulate m‐RNA and protein synthesis. The effect of boron may be due to an effect on sugar and starch balance, translocation of sugar, or on water balance, but more likely boron plays a role in nucleotide and protein metabolism in plants. Boron may be involved in the synthesis of DNA, a role perhaps mediated by GA3.
Crown Gall Development Stimulated by Wound Washing
Authors: THERMAN EEVA , KUPILA‐AHVENNIEMI SIRKKA
Published: April 2006

A number of experiments on the effect of wound washing on the development of crown gall were made varying the following factors: Host species; bacterial strain; non‐washing versus washing for different periods; sterile versus inoculated wound; time of inoculation. Washing did not have a recognizable effect on the healing of sterile wounds. Neither did it seem to overcome incompatibility between host and bacterial strain. Washing promoted tumor growth significantly under the following conditions: Vicia faba inoculated with T37 20 hours after washing for 1 hour; Helianthus annuus inoculated with B6 immediately after washing for 2 hours.
Strontium‐substitution for Calcium and Algal Cell Size
Authors: MOSS SAMUEL W. , THOMAS JERRY P. , O'KELLEY JOSEPH C.
Published: April 2006

Mature cells of several algal species (Protosiphon bo‐tryoides, Chlorococcum echinozygotum, Asterococcus superbus, Chlamydomonas reinhardtii, Chlorella pyrenoidota) that will grow in a strontium‐substitution for calcium are larger and more highly vacuolated than control cells in calcium. In logarithmic phase cultures average cell size of cells in strontium‐replacement medium is greater than for control cells in calcium. The water content of strontium‐replacement cells is indicated to be greater than of control cells. Mechanisms whereby water content and cell size differences may become established are discussed.
Changes in Pigment Composition and Photosynthesis Induced by Iron‐Deficiency in the Blue‐Green Alga Anacystis nidulans
Authors: ÖQUIST GUNNAR
Published: April 2006

Absorption spectra and photosynthetic action spectra have been determined for living Anacystis grown in complete and iron‐deficient inorganic media. The absorption studies have shown a spectral shift from 679 nm to 673 nm in the chlorophyll a absorption peak when the algae had to grow without iron. The shift is believed to reflect a changed ratio between at least two chlorophyll a forms denoted Ca670 and Ca680 in this work. Action spectra determinations have revealed a similar shift from 677 nm to 672 nm in the photosynthetic activity peak of chlorophyll a when Anacystis was transferred to a medium without iron. It is proposed that both Ca670 and Ca680 participate in light absorption for photo‐system I.
Radial Oxygen Losses from Intact Rice Roots as Affected by Distance from the Apex, Respiration and Waterlogging
Authors: ARMSTRONG W.
Published: April 2006

Radial oxygen losses (ROL) from the roots of intact rice plants were assayed by the cylindrical Pt electrode technique.

At 23°C losses from roots grown in waterlogged soil proved to be about double those from non‐waterlogged plants.

Cooling which lowers respiratory activity led to increased ROL and it was estimated that at 23°C respiratory activity had been reducing oxygen loss by 8 to 10 10–8g O2 cm–2 root surface min–1 (c. 50 %) in the non waterlogged, and by 4.5 to 5.5 10–8g O2 cm–2 min–1 (2C–30 %) in the waterlogged roots.

Lacunae formation occurred nearer to the apex and was eventually more extensive in the waterlogged roots while the presence of more intact and presumably functional tissue in the non‐waterlogged roots coincides with the greater respiratory effect noted.

Estimated flux rates at 23°C (respiration inactive) were respectively 15–17 × 10–8g O2 cm–2 min–1 (non‐waterlogged) and 20–23 × 10–8g O2 cm–2 min–1 (waterlogged). A major part of this difference can probably be accounted for directly by the differences in root porosity, and Meakiness' superimposed upon lower porosity in the non‐waterlogged plants may account for the remainder.

ROL was also examined in relation to distance from the apex. With respiratory activity lowered by cooling, two patterns of oxygen loss were detected. Pattern I was a property of younger roots of length between 5–9 cm, while pattern 2 was found in longer roots 11–16 cm bearing numerous emergent laterals. In both, ROL fell rapidly towards the base and at 4–5 cm approached zero in pattern 1 and near zero to about 16% of the maximum in pattern 2.

The rapid drop in oxygen loss in both patterns which indicates a concomitant decrease in root wall permeability was associated with the appearance of cortical lacunae at 2–3 cm from the apex.

In pattern 2 a rise in ROL began at 5–6 cm from the apex. The presence of lateral root initials in both the pericycle and unbroken segments of cortex was associated with maintained permeability in this pattern as well as with the basal increase in ROL.

With a 3‐electrode system placed around the apical 3 cm regions of waterlogged roots, it was found that ROL was substantially affected by respiratory activity at 0.5 cm, a little less so at 1.7 cm, but much less or not at all at 3 cm from the apex. The drop in respiratory effect parallelled the formation of cortical lacunae.
Calcium and Salt Toleration by Bean Plants
Authors: LAHAYE PHILIP A. , EPSTEIN EMANUEL
Published: April 2006

The role of calcium in the salt relations of the bean plant, Phaseolus vulgaris, was examined. Brittle wax bush bean plants were cultured in nutrient solutions containing 50 mM NaCl. In the absence of added calcium the plants showed a general breakdown of the roots. A low concentration of calcium in the nutrient solution (0.1 mM) prevented this. Without added calcium the plants absorbed and translocated sodium at such a rate that high concentrations of it built up in the leaves within two days. With increasing concentrations of calcium in the nutrient solution the leaves contained progressively less sodium, and at 3 mM CaSO4 the concentrations of sodium in the leaves was equal to that of the control plants grown without addition of salt. Even after both roots and stems had reached a high concentration of sodium, the leaves of plants grown in the presence of adequate concentrations of calcium contained little sodium.
Evidence for Hormonal Regulation of the Selectivity of Ion Uptake by Plant Cells
Authors: ILAN I.
Published: April 2006

Kinetin exerted opposing effects on the uptake of K+ and of Na+ by leaf discs of Helianthus annuus: The absorption of K+ was stimulated and that of Na+ was inhibited. The K+/Na+ ratio in kinetin‐treated discs was 80–100 % higher than in control tissue.

Kinetin also promoted K+ uptake by detached cotyledons which had been removed from light‐grown seedlings. On the other hand, no clear effect on the absorption of Na+ by these cotyledons could be established.

Benzyladenine brought about a significant elevation in the K+/Na+ ratio in attached cotyledons.

It is concluded that cytokinins bring about a change in the selectivity of the cells of sunflower leaves and cotyledons towards K+ and Na+, such that the ‘affinity’ of the cells for pottasium is increased, as compared to the ‘affinity’ for sodium. The possible significance of such a change in selectivity is discussed.
α‐Glucosidase Activity Located at the Cell Surface in Callus of Convolvulus arvensis
Authors: KLIS F. M.
Published: April 2006

Cell wall preparations of Convolvulus callus were found to contain α‐glucosidase activity, the bulk of which could be solubilized by solutions of high ionic strength. Callus tissue incubated in 0.5 M KC1 released α‐glucosidase activity into the washing medium as distinct from tissue incubated in 1.0 M sorbitol. The wall‐bound activity of KCl‐treated tissue was found to be less than that of sorbitol‐treated tissue, while the difference between both activities proved to be equal to the enzyme activity found in the washing medium of KCl‐treated tissue. Since no trace of cell leakage was observed, it is concluded that α‐glucosidase activity is located at the cell surface. The level of this surface‐located enzyme was not affected by the presence of maltose in the nutrient medium.
Growth Regulators in Populus tremula IV. Apical Dominance and Suckering in Young Plants
Authors: ELIASSON LENNART
Published: April 2006

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

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

The influence of ice crystal formation in tissues of unhardened and hardened seedlings of Pinus silvestris L. and Picea abies (L.) Karst. was determined. An apparatus for this purpose was constructed.

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

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

The rate of phytylation and the rate of the in vivo Chl682→ Chl672 nm shift of the newly formed chlorophyllide were examined after a brief illumination of dark‐grown Phaseolus vulgaris leaves at different stages of development. Both processes were found to be age dependent but independent of one another. The Chl682→ Chl672 nm shift process precedes that of phytylation. In addition, there is a linear relationship between tissue age and the delay time between the two processes, indicating that they are not identical, although they are almost parallel. There was no evidence obtained of a far‐red light effect on any of the two processes. Experiments done with freeze‐dried etiolated plant tissue showed the presence of PChl650 and PChl637 forms, which by illumination form Chl678. If a trace of water is added to the etiolated freeze‐dried tissue before illumination the PChl650 and PChl637 are transformed to the non‐phototransformable PCh650 form. Moreover, no shift of the Chl678 form is observed, unless a trace of water is added to the freeze‐dried tissue. These results are explained by a mechanism of structural rearrangement in the chloroplast after protochlorophyllide phototransformation leading into monomeric chlorophyllide units, which can then be phytylized.

This explanation is substantiated by the results of experiments done with isolated protochlorophyllide‐holochrome: addition of 4M urea before or after illumination to the protochlorophyllide‐holochrome solution showed a PChl636→ PChl629 and Chl676→ Chl668 shift respectively.
The Effect of Growth Regulators and Cu2+ on the Activation of Amylopectin‐l,6‐glucosidase Activity in Pea Seedlings
Authors: VLODAWSKY LEA , HAREL E. , MAYER A. M.
Published: April 2006

No evidence could be obtained for hormonal control of amylopectin‐l,6‐glucosidase activity in germinating peas for the first 72 hours of germination. The embryonic axis did not stimulate the appearance of enzyme activity. The autolytic system which releases amylopectin‐l,6‐glucosidase activity from the particulate fraction, in which it originates, was studied in greater detail. Using Cu2+ ions to inhibit a proteolytic enzyme in vivo, it was shown that enzyme activation can occur in the zymogen‐like granules without liberation of the enzyme into the soluble cell fraction. Activity so formed is labile. Some of the data on proteolytic enzymes in peas is discussed and an attempt made to interpret the liberation of amylopectin‐l,6‐glucosidase in peas on the basis of the involvement of at least two distinct proteolytic enzymes.
Growth of Avocado Fruit Callus and Its Relation to Exogenous and Endogenous Cytokinins
Authors: BLUMENFELD A. , GAZIT S.
Published: April 2006

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

Studies of the marine green flagellate Dunaliella tertiolecta have confirmed and extended previous observations of Steemann Nielsen and his colleagues. Algae, grown at 12°C, assimilated carbon dioxide under light‐saturated conditions more rapidly than did those grown at 20°C; for both, the assimilation rate being higher at 20°C than at 12°C. Cells grown at the lower temperature contained higher concentrations of soluble protein, higher activities of ribulose diphosphate carboxylase and showed an enhanced relative rate of protein synthesis during the photosynthetic assimilation of carbon dioxide. This appears to represent true adaptation since it allowed the growth rate at 12°C to be almost the same as that at 20°C.

Studies of the marine diatom Phaeodactylum tricornutum have not revealed the same picture of temperature adaptation. Cultures grown at 5°C had significantly higher rates of photosynthesis than did those grown at 10°C, but the same was not true when algae grown at 10°C were compared with those grown at 20°C. In this organism, growth at the lower temperatures reduced its ability to photosynthesize at 20°C. Cells grown at the lower temperatures contained more protein than did those grown at 20°C; this was particularly marked in cells growing at 5°C, a temperature which reduced the growth rate. The relative rate of protein synthesis was higher in Phaeodactylum grown at lower temperatures; but this difference was most marked when the measurements were made at 20°C.
Translocation of Photosynthates in Tall and Dwarf Varieties of Pea, Pisum sativum
Authors: LOVELL PETER H.
Published: April 2006

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

The content of adenosine triphosphate (ATP) in roots of ‐wheat (Triticum aestivum L.) was determined with the fire‐fly‐luciferase method. The content is decreased by D‐mannose, which inhibits root growth, respiration and chloride uptake. In intact seedlings the inhibition of root growth is relieved by other sugars and also by the flavanone naringenin and by 2,4‐dinitrophenol. This reversal is combined with an increased content of ATP.

The inhibition of chloride uptake by mannose in excised roots is reversed by some other sugars (including D‐galactose which is in itself inhibitory to root growth), and also in this case the ATP content is increased. Naringenin and dinitrophenol do not relieve the inhibition of chloride uptake caused by mannose. Nor do they increase the content of ATP in this case.

The primary effect of mannose seems to be inhibition of glycolysis whereas the effect upon root growth is secondary. Galactose, which also inhibits root growth, does not inhibit respiration or reduce the ATP content and the primary effect of galactose (and also of 2‐deoxy‐D‐glucose and 2‐deoxy‐D‐galactose) seems to be on the synthesis of cell wall substances.
Transport and Degradation of Auxin in Relation to Geotropism in Roots of Phaseolus vulgaris
Authors: IVERSEN TOR‐HENNING , AASHEIM TORBJØRN , PEDERSEN KNUT
Published: April 2006

The movement of auxin in Phaseolus vulgaris roots has been examined after injection of IAA−3H into the basal root/hypocotyl region of intact, dark‐grown seedlings. Only a portion of the applied IAA−3H was transported unchanged to the root tip. The major part of the chromatographed, labelled compounds translocated to the roots was indole‐3‐acetylaspartic acid (IAAsp) and an unidentified compound running near the front in isopropanol, ammonia, water.

The velocity of the auxin transport (7.2 mm per hour) was calculated from scintillation countings of methanol extracts from serial sections of the root. An accumulation of radioactive compounds in the extreme root tip, was observed 5 h after the injection of IAA.

The influence of exogenous IAA on the geotropical behaviour of the bean seedling roots was examined. Pretreated roots were stimulated for 5 min in the horizontal position and then rotated parallel to the horizontal axis of the klinostat for 60 or 90 min. The resulting geotropic curvature of IAA‐injected and control roots showed significantly different patterns of development. When the stimulation was started 5 h after application of the auxin, the geotropic curvature became larger in roots of the injected plants than in the controls. If, however, the translocation period was extended to 20 h the geotropic curvature was significantly smaller in the roots of the injected plants. The auxin injection did not significally affect the rate of root elongation.

The change in geotropical behaviour of the roots is interpreted as a result of the influence of the conversion products of the applied IAA on the geotropical responsiveness.
The Interaction of pH and Aeration in CI Uptake by Barley Roots
Authors: JACOBSON L. , COOPER B. R. , VOLZ M. G.
Published: April 2006

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

As an initial step in the study of the molecular events surrounding the establishment of a mature root apex, analyses of the early germinative growth of the Allium radicle were undertaken. Changes in the level and pattern of the soluble proteins were investigated by polyacrylamide gel disc electrophoresis and Joyce‐Loebl densitometry. Histochemical studies revealed the presence of protein bodies in the terminal mm of the Allium radicle. These bodies underwent depletion and breakdown during germination.

The results of the electrophoretic fractionation of the soluble proteins during germination showed that there was not a proliferation of protein components but, rather, a considerable change in the concentration of existing protein fractions. Several fractions, assumed to be components of the reserve or storage proteins, showed a quantitative depletion correlated in time with the loss of the protein bodies.

Quantification of the soluble proteins during germination showed a 32% decrease per radicle tip over a 67‐hour period, but when expressed on a per cell basis a 32% increase was noted. A dramatic increase in protein synthesis, as measured by 3H‐leucine incorporation, was initiated after 36 hours' exposure to germinative conditions, that is, at the beginning of radicle protrusion.

A time‐ordered sequence of events was noted for the depletion of the protein bodies and their assumed reserve components, suggesting their ultimate utilization in new protein synthesis.
The Role of Light in the Interrelated Processes of Morphogenesis and Photosynthesis in the Fern Gametophyte
Authors: DONAHER D. J. , PARTANEN C. R.
Published: April 2006

The interrelationship of photosynthesis and photomorphogenesis in the gametophyte of the fern Pteridium aquilinum was examined in detail. High energy red light produces filamentous gametophytes composed of greatly elongated cells. Blue light of equal energy produces normal cordate gametophytes composed of isodiametric cells. The assimilative rates of the two forms are identical during the initial stages of development. However, the filamentous gametophytes eventually exhibit a decline in assimilation not matched by their normal counterparts.

Although this decrease in assimilation of gametophytes exposed to red light may be traced to a decrease in the photo‐synthetic rate due to a decrease in chlorophyll synthesis, these events occur subsequent to the establishment of the filamentous mode of growth and are therefore a result, not a cause, of filamentous development.

Gametophyte assimilation is also impeded under low energy blue light, due to a reduction in the photosynthetic rate at this low energy; and the initial filamentous stage, in which the cells remain normally isodiametric, is not exceeded. The addition of extra exogenous sucrose restores the capacity for growth and normal cordate prothalli result.

It may therefore be concluded that the ultimate form of the gametophyte is under the control of a photoreceptor that is sensitive to blue light, and activated at a relatively low energy level. Red light at any level is ineffective in promoting normal cordate development, but is effective in supporting growth through vigorous photosynthesis, yielding a filament composed of greatly elongated cells. The eventual photosynthetic decline of the filamentous form is due directly to this particular growth mode.

Low energy blue light is sufficient to effect form (the cells remain isodiametric), but insufficient to provide the necessary energy for growth through vigorous photosynthesis. Therefore, in order for the gametophyte to reach maturity it must be supplied with light energy that not only satisfies the requirement for form but the requirement for growth as well. The implications of these requirements are discussed in the text.
A Cotyledonary Inhibitor of Root Nodulation in Pisum sativum
Authors: PHILLIPS DONALD A.
Published: April 2006

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

In a steady environment, leaf stomates of sour orange (Citrus aurantium L.) remained closed in the dark, whereas those of rough lemon (Citrus jambhiri Lush) underwent several 20‐minute periods of pronounced opening at intervals of 60–85 minutes. Peak nocturnal opening occurred about 10 minutes after the cycle began, as shown by a change in leaf diffusion resistance from 60 s cm−1 (closed) to 2 s cmminus;1 (open). This minimal leaf resistance equals that obtainable in rough lemon in strong illumination (26 kilolux).

The transitory stomatal opening detected by leaf resistance measurements was corroborated by measurements of leaf temperature and leaf thickness. During nocturnal opening, leaf temperature was 2°C below the value representing non‐cycling periods. Also, minimal leaf thickness coincided with maximal stomatal opening.

The triggering mechanism for nocturnal stomatal opening appears to originate within the plant, since the environmental factors of air temperature, humidity, carbon dioxide concentration, and substrate (aerated water culture) were held steady.
Lipids in Cruciferae IX. The Effect of Growth Temperature and Stage of Development on the Fatty Acid Composition of Leaves, Siliques and Seeds of “Zero‐erucic‐acid” Breeding Lines of Brassica napus
Authors: APPELQVIST LARS‐ÁRKE
Published: April 2006

Two breeding lines of “zero‐erucic‐acid” rapeseed (Brassica napus) were grown in climate chambers at a constant night temperature (12°C) and constant photoperiod (16 hours) but with different day temperatures (15, 20 and 25°C). Samples of leaves, siliques and immature seeds were analysed for total fatty acid pattern. The content of different acyl lipids and the fatty acid pattern of these lipids were also determined in some of the samples by use of preparative TLC followed by GLC of the fatty acids. The mature seeds produced by ten plants of each selection in each climate were analysed separately for total fatty acid composition.

Mono‐ and digalactosyl diglycerides (MGDG, DGDG) were the predominant acyl lipids in leaves and siliques. In developing seeds they also were more abundant than the phospholipids, but in this case the neutral lipids, mainly triacylglycerols, contained about 95% of the total fatty acids. Large variations were found in the fatty acid composition of monogalactosyl diglyceride and digalactosyl diglyceride, isolated from leaves, siliques and immature seeds. The palmitic acid content of leaf MGDG was about 15 %, atypically high for MGDG from photosynthetic tissue. The linolenic acid content of the MGDG was about 45 %, 30 % and 10 % in the leaf, silique and seed tissues respectively. A hexadecatrienoic acid (16: 3) was found almost exclusively in the MGDG samples of leaves, siliques and immature seeds (about 25 %, 10 % and 3 % 16:3 respectively). The lipids of siliques — mainly photosynthetising tissue — were different from those of leaves and had especially high contents of stearic acid (6–12 % in the different lipids).

For all lipid classes studied, leaves grown at the lowest day temperature had a slightly lower oleic and higher linolenic acid content than those grown at the highest temperature.

On the other hand, increasing the day temperature caused a decreased level of oleic, an increased level of linoleic and an essentially unchanged level of linolenic acids in the mature seeds from both selections.