bluuebunny/crossref_metadata_2025 huggingface dataset:
Abscisic Acid Effects on Growth and Metabolism in the Roots ofLemna minor
Authors: NEWTON RONALD J.
Published: April 2006

The effects of abscisic acid (ABA) on individual plants of Lemna minor L. were studied. The effects on growth and metabolism of the roots were the most noticeable and the most desirable to measure. Two mg/1 of ABA inhibited the root growth rate by 60% and this was accompanied by a 60% deceleration in the rate of uridine incorporation. The uptake of uridine and leucine and the incorporation of leucine were not affected by ABA. The latent period of root growth inhibition was 1 hour, whereas the inhibition of ribonucleic acid (RNA) synthesis occurred 2 to 4 hours after application. The growth inhibition caused an accumulation of starch in the peripheral, differentiated cell layer of the cortex. Apparently, the growth inhibition by ABA was not entirely due to an inhibition of RNA synthesis, and other plausible mechanisms of growth inhibition are discussed.
Bulblet Formation in Achimenes longiflora
Authors: DEUTCH BENTE
Published: April 2006

The bulblet formation in Achimenes longiflora D.C. cv. Major was investigated under controlled conditions in growth chambers. The bulblet formation in Achimenes longiflora cuttings was found to be inhibited by long‐day treatment such as continuous illumination. The degree of inhibition depended, however, on the quality of the light. High intensity far red and especially infrared emission was needed to effectively suppress the bulbing. As opposed to this, red light was found to be stimulatory. When red light (660 nm) was substituted for 20% of the white light, the bulbing was promoted over 400%.

Gibberellic acid was totally inhibitory in all cases. The cytokinins benzyladenine and 6‐γ,γ‐dimethylallylaminopurine were strongly promotive and even inductive under inhibitory light conditions. The growth inhibitor N‐dimethylamino succinamic acid also stimulated bulblet formation. α‐Naphthyl‐acetic acid was strongly inhibitory, an effect which could not be overcome by benzyladenine.
Organogenesis in Callus from Shoot Apices of Pisum sativum
Authors: GAMBORG O. L. , CONSTABEL F. , SHYLUK J. P.
Published: April 2006

Shoot formation was observed in callus from apical cells of pea (Pisum sativum L. cv. Century). Shoot apices from 4‐day‐old plants were macerated and the resulting cell masses grown on agar media. The callus formation and shoot production occurred within 4 to 6 weeks in defined media containing 0.2 to 5.0 μM benzyladenine and 1 μM naphthaleneacetic acid. While most callus produced one or more shoots at high frequency, root formation did not occur regularly. Plants obtained by these procedures were grown to maturity producing flowers and pods.
Induction of Biplanar Growth in Fern Gametophytes
Authors: RAGHAVAN V.
Published: April 2006

The inhibition of biplanar growth in the protonemata of different ages of Asplenium nidus by the pyrimidine analog, 5‐fluorouracil has been investigated. Under favorable light conditions, older protonemata become biplanar in concentrations of 5‐fluorouracil which inhibit biplanar growth in younger ones. Treatment of 4‐ or 5‐celled protonemata with a high concentration of 5‐fluorouracil or transfer of germinated spores to progressively higher concentrations of the inhibitor lead to their continued filamentous growth. It is suggested that the age of the protonemata and the counteracting effects of light should be taken into account in evaluating the effect of metabolic inhibitors on the inhibition of biplanar growth in fern gametophytes.
The Pool Size of Protochlorophyllide during Different Stages of Greening of Dark Grown Wheat Leaves
Authors: SUNDQVIST CHRISTER
Published: April 2006

The pool size of protochlorophyllide in wheat leaves irradiated for 5 minutes to 6 hours was studied. Protochlorophyllide then accumulated in the dark, but the pool size of regenerated protochlorophyllide was considerably smaller in leaves irradiated for six hours than in leaves irradiated for 5 minutes. The decrease in pool size of regenerated protochlorophyllide was found to take place at the time when the chlorophyll formation had accelerated and reached the linear phase. The protochlorophyllide accumulated is the form with absorption maximum at 650 nm, which is phototransformed to chlorophyllide with maximum absorption at 684 nm. This species goes through the Shibata shift when formed even after 6 hours of irradiation.

If leaves, irradiated for 1 or 6 hours, were fed with δ‐amino‐levulinic acid the protochlorophyllide synthesis was only 1.2 times faster in the leaves irradiated for 6 hours than in those irradiated for 1 hour. In the case of leaves fed with δ‐amino‐levulinic acid the absorption maximum of protochlorophyllide is at 636 nm and the absorption maximum of the chlorophyllide formed is at 672 nm.
Interaction between 2,4‐Dichlorophenoxyacetic Acid and Vitamin K in Datura stramonium
Authors: JANSSON OWE
Published: April 2006

Plants of the cross Datura stramonium L. var. stramonium×Datura stramonium L. var. inermis (Juss. ex Jacq.) Timm. were sprayed either with a water solution of the sodium salt of 2,4‐dichlorophenoxyacetic acid (2,4‐D) or with a combination of 2,4‐D (sodium salt) and the vitamin K compound menadione sodium bisulfite in water solution. The plants were found to differ in one of their responses to the treatments, namely the development of necrotic spots on the leaf blades. Many necroses appeared on the plants treated with 2,4‐D plus menadione sodium bisulfite while only a few necroses or none at all developed on the plants treated with 2,4‐D alone. Furthermore, 2,4‐D in combination with menadione sodium bisulfite induced much larger necrotic spots than did 2,4‐D by itself. Spraying with menadione sodium bisulfite in water solution did not produce any observable effects upon Datura plants. The great increase in necrotic lesion formation was probably due to an interaction between 2,4‐D and menadione sodium bisulfite (or a metabolite of this compound) within leaf cells.
Relative Activities of Some Cytokinin Fractions of Developing Cotton Fruit
Authors: SANDSTEDT ROBERT
Published: April 2006

Ion‐exchange fractionization, paper chromatography, and soybean callus bioassay have partly resolved an apparent discrepancy in the sequence of cytokinin appearance in developing cotton (Gossypium hirsutum L.) fruit compared to the sequence reported in corn (Zea mays L.).

Cotton fruit cytokinins were separated into three fractions: A combined n‐butanol and ethylacetate extractable fraction comprisedc. 10% of the cytokinin activity, a fraction not retained by a polymethacrylate weakly acidic cation‐exchange resin comprised c. 45%, and a fraction that was retained by the resin, c. 45%. The latter fraction differs from cytokinin fractions reported in corn. However, like cytokinin ribonucleotides, its cytokinin activity remains below Rf 0.3 on paper chromatograms developed with water‐saturated sec‐butanol, thus complicating studies of sequential cytokinin appearance in cotton. An anion‐exchange resin did not retain the cytokinin activity of this fraction.
Tryptophan Decarboxylase Activity in Developing Cucumber Seedlings
Authors: ELKINAWY MAHASEN , RAA JAN
Published: April 2006

The rate of decarboxylation of DL‐tryptophan‐carboxyl‐14C in homogenates of cotyledons, hypocotyls and roots of sterile and non‐sterile cucumber seedlings of 4, 8 and 11 days was measured. Tryptophan decarboxylating activity is highest in hypocotyls, lowest in cotyledons. In all organs the activity decreases with age. This enzyme activity does not parallel the IAA level in the organs during ageing.
Shock Pulse Effects on Wheat Growth
Authors: MURRAY SYLVIA A.
Published: April 2006

Wheat seedlings (Triticum aestivum cv. Pacific Blue Stem) grown under continuous low‐level illumination were used to study the effects of pressure variation and its duration. Growth was determined by dry weights, leaf length, and types of secondary roots produced. Two sublethal shock pulses (1.41 and 2.82 kg cm −2) and three pressure duration intervals (0.1, 1.0 and 10.0 seconds) were studied. The results indicated a general overall reduction in growth associated with the shock pulse and that the pressure duration interval influenced the shock‐ growth response. The long pressure duration interval was found to be the most influential on shock pulse response. Present knowledge indicates that a pulse rise‐time of 1 ms and a pressure duration interval of at least 1.0 second affect plant growth at sublethal shock pulses, such that the growth response is linear or bi‐directional, depending on the magnitude of the shock pulses, and either linear or complex with respect to pressure duration interval for any shock pulse level.
Evidence for the Presence of Cytokinins in Malt and Yeast Extracts
Authors: VAN STADEN J.
Published: April 2006

Compounds that bring about growth in soybean callus were extracted from yeast and malt extracts. In the former most of the activity is due to a compound that co‐chromatographed with zeatinriboside. This substance is also present in malt extract and coconut milk, together with a component which has the same elution volume as zeatin. Partition chromatography on Sephadex LH‐20 revealed the presence of an extremely active unidentified substance in both malt extract and coconut milk. Indications are that this compound is not diphenylurea.
The Role of Cellulase and Polygalacturonase in Abscission of Young and Mature Shamouti Orange Fruits
Authors: GREENBERG J. , GOREN R. , RIOV J.
Published: April 2006

During the first eight weeks after setting young citrus fruits gradually lose their ability to abscise at the abscission zone between the stem and the pedicel; in fruits older than eight weeks abscission occurs at the calyx area. The activity of cellulase and polygalacturonase in the two abscission zones was markedly increased before and during abscission, and was localized mainly in the abscission zone. Ethylene accelerated the increase in enzymic activity after an 8‐ to 10‐h lag period; 2,4‐D delayed abscission and enzymic activity when applied during the first 24 h after excision. During this period 2,4‐D also partly suppressed the enhancing effect of ethylene. Early application of cyclo‐heximide inhibited the formation of the enzymes and thus abscission was delayed to a certain extent.

Although there are some indications that the relationship between enzymic activity and abscission is a complex one, the data presented indicate that cellulase and polygalacturonase play a significant role in abscission of citrus fruits at various developmental stages. Both enzymes act almost simultaneously and are equally controlled by ethylene and 2,4‐D.
Glutamate Dehydrogenase Activity in Roots: Distribution in a Seedling and Storage Root, and the Effects of Red and Far‐red Illuminations
Authors: DUKE STANLEY H. , KOUKKARI WELLARD L. , SOULEN THOMAS K.
Published: April 2006

Pisum seedling and Pastinaca storage roots contained high glutanrate dehydrogenase (GDH) activity in areas of reported rapid growth and high phytoctrome content. A similar distribution was observed for malate dehydrogenase. Freeze‐thawings of mitochondrial preparations from Pisum roots always resulted in increases of GDH specific activity; however, the observed increases were much larger with basal than apical sections. Both intact and freeze‐thawed mitochondrial preparations from seedling roots exhibited increases in GDH activity with time after isolation. In intact mitochondrial preparations from roots of etiolated seedlings, an increase in malate dehydrogenase activity was observed similar to that of GDH activity; however, no increased malate dehydrogenase activity was noted in preparations from light‐grown seedlings.

Illuminating Pisum seedlings with far‐red light slowly increased GDH activity in roots over a period of two weeks. Since these observed increases were not due to direct exposure of roots to light, other factors were likely involved.
Inter‐organ Control of Chlorophyll Synthesis in Primary Leaves of Dark‐grown Phaseolus aureus
Authors: HOLE C. C. , DODGE A. D.
Published: April 2006

The changing roles of the cotyledons and hypocotyl in the development of dark‐grown Phaseolus aureus seedlings are described. The effect of the cotyledons on total chlorophyll synthesis declined with age, but on a chlorophyll per gram fresh weight basis this was less pronounced. In five‐day‐old plants the hypocotyl was more effective than the cotyledons in increasing the chlorophyll level, and together their effect was less than additive. The promoting factors in the cotyledons were at a saturating level at this stage. The relationship between the effects of the two organs is discussed with particular reference to the components which they supply to the leaves.
Effect on the Progeny of Applying Different Day Length and Hormone Treatments to Parent Plants of Lactuca scariola
Authors: GUTTERMAN Y. , THOMAS T. H. , HEYDECKER W.
Published: April 2006

Seedlings of the self‐fertilizing species Lactuca scariola L. grown continuously in 8 h days did not flower even one year from sowing. Seedlings grown in 16 h days uatil flower buds appeared 96 days after germination were either transferred to 8 h days or treated weekly with gibberellic acid (GA3), abscisic acid (ABA) or chlormequat (CCC) and retained, together with untreated control plants, in 16 h days. Each growth regulator caused characteristic morphological changes in the treated plants. All these plants flowered and produced seeds but the seeds showed distinct differences in weight, in their time to germination and in the seedlings which they produced. Germination and seedling characters depended on the light regime during germination as well as on the chemical applied to the parent plant and the rate of application. The parental treatment also affected the shape and size of the seedlings on a given day after germination, and certain treatments of the parent plant (transfer from long to short days and treatment with CCC in long days) advanced the flowering date of the seedlings. The gibberellin level in the seeds was raised, in increasing order, by treatment of the parent plant with 100 mg/1 GA3, transfer from long to short days, 10 mg/1 GA3, and 5000 mg/l CCC. It is suggested that the effect of day length on plant performance is mediated by the level of growth regelating substances within the plant and that the behaviour of seeds can be modified by the parental environment via the accumulation of different levels of certain growth factors in the seeds. A rise of one growth substance in the parent plant can result in the accumulation of a different one in the seeds.
Scopoletin: Kinetic Nature of Isoperoxidase A3 Catalyzed Oxidation and Its Possible Relation to the Physiological Action of This Naturally‐occurring Growth Effector
Authors: REIGH DARRYEL L. , WENDER SIMON H. , SMITH EDDIE C.
Published: April 2006

Isoperoxidase A3 from tobacco tissue culture, Nicotiana tabacam W‐38, apparently does not have a subunit structure. Its molecular weight is approximately 54,000.

The oxidation of scopoletin appears to occur in more than a single step since a blue intermediate is first formed. This is followed by the production of the final yellow product. A plausible explanation for this observation is the coupling of free radicals generated by the primary enzyme catalyzed reaction.
Action of Cordycepin on Gibberellic Acid Stimulated Cell Elongation in Coleoptiles from Gamma‐Plantlets of Wheat
Authors: KERN HARTMUT
Published: April 2006

The inhibitory effect of cordycepin (3′‐deoxyadenosine) on transcriptional processes has been used to follow the kinetics in the action of gibberellic acid on cell elongation in the coleoptiles from gamma‐planilets. It has been shown that, after a Sag period of 1 h, a high response to the phytohormone within a limited time is detectable.
Photosynthesis of Desiccating Leaves of Poplar
Authors: PIETERS G. A. , ZIMA M.
Published: April 2006

The relation between photosynthesis and water content was investigated using detached leaves of Populus euramericana (Dode) Guinier cv. Robusta.

The time course of photosynthesis was measured at different light intensities, at different CO2 contents of the air and at constant temperature during the desiccation of the leaves. The time course of decreasing water content was obtained from continuous measurement of water transpired from the leaves.

A large reduction of light saturated (400 W × m−2) photosynthetic rates was observed with decreasing water contents between 78 and 64% (water potential between −14 and −24 atm (bar)). This reduction was much greater in air with 0.3 % CO2 than in air with 5 % CO2, indicating a significant influence of CO2 diffusion resistance on rate of photosynthesis. The reduction of the rate of light and CO2 saturated photosynthesis (at 400 W × m–2 and 5% CO2 in the air) is a measure of the inactivation of the photosynthetic enzyme system by desiccation. A proportional reduction of the light saturated and light limited rate of photosynthesis (for different H2O contents) was found, when measured in air containing a saturating amount of CO2 (5 %). The reduction of the light limited rate of photosynthesis (at 20 W × m−2) was the same at both CO2 levels.
The Relation between Photosynthesis and Stomatal Resistance of Each Leaf Surface in Cotton Leaves
Authors: NAGARAJAH S.
Published: April 2006

The relation between photosynthesis and stomatal resistance of each leaf surface in cotton leaves (Gossypium hirsutum) was studied during ageing and with increase in light intensity.

During ageing of leaves the stomatal resistance of the upper surface increases before that of the lower surface. This observation would suggest that the stomata of the upper leaf surface commence to age before those of the lower leaf surface. The earlier commencement of the increase in upper stomatal resistance results in the decline in photosynthesis at an early stage of ageing being negatively correlated with the upper stomatal resistance and not related to the lower stomatal resistance. The results indicate that in this initial phase of ageing the decrease in photosynthesis and increase in stomatal resistance of the upper surface are not causally related but occur simultaneously. At a more advanced stage of ageing the lower stomatal resistance also increases and then the decline in photosynthesis becomes related to the increase in stomatal resistance of both leaf surfaces.

When illumination of leaves is increased stepwise, the resultant increase in photosynthesis is related to the reduction in stomatal resistance of each leaf surface. At low light intensities the stomatal resistance of the lower surface is low while that of the upper surface is relatively high. The difference between them decreases with increase in light intensity. This would indicate that the upper stomata require a higher light intensity to open than the lower stomata.

The stormatal resistance of the two leaf surfaces is not related to the stomatal frequencey.
The Effect of Benzimidazole and Red Light on the Senescence of Detached Leaves of Oryza sativa cv. Ratna
Authors: SINGH N. , MISHRA D.
Published: April 2006

Excised rice leaves (Oryza sativa L. cv. Ratna) werefloated on a 10–3M solution of benzirnidazole under dark or continuous red light. Compared to the water control a degradation of chlorophyll, protein, RNA, DNA and a decrease in the activity of alkaline inorganic pyrophosphatase was delayed at the same time as an increase of α‐amino nitrogen and the activity of acid inorganic pyrophosphatase occurred, Benzimidazole was more effective under red light than in the dark in retarding senescence. The possible role of inorganic pyrophosphatases is discussed with respect to biosynthesis during leaf senescence.
Endogenous Cytokinins in Solanum tuberosum as Influenced by Photoperiod and Temperature
Authors: FORSLINE P. L. , LANGILLE A. R.
Published: April 2006

Using the cucumber cotyledon bioassay, in combination with paper and column chromatographic techniques, 4 compounds exhibiting cytokinin activity were detected in extracts of Katahdin potato plant tissues. Two of these compounds were significantly higher in plants grown under inducing conditions (26°C day and 12°C night with an 8‐h photoperiod) than those grown under non‐inducing conditions (28°C day and 25°C night with a 16‐h photoperiod). One compound increased 10‐fold in above‐ground tissue after only 2 Inductive cycles. Both compounds reached their maximum values in below‐ground tissue after 6 days under inducing conditions, with tuber initiation observed after 8 to 10 days.
Nutritional and Hormonal Requirements for the Growth of Vigna sinensis Callus in vitro
Authors: MATSUBARA SATOSHI
Published: April 2006

Nutritional and hormonal requirements for in vitro growth of callus tissue of Vigna sinensis Endl. were studied. Callus was formed on hypocotyl and root sections, when they were cultured on Linsmaier and Skoog's basal medium solidified with 10 g/1 agar and supplemented with only 0.5 mg/12,4‐D or 2 mg/1 IAA. Further addition of 0.2 mg/1 kinetin and 1 g/l yeast extract resulted in more active callus formation. For unlimited vigorous growth of subcultured callus which was originally isolated from root sections, yeast extract was indispensable besides 2,4‐D and kinetin. Such growth‐promoting activity was observed also in malt extract and Ebios (dried cell powder of brewery yeast). Of known compounds tested, nicotinic acid, nicotinamide., methyl nicotinate and NAD were promotive to the growth of the callus, although much less effective than yeast extract. Other pyridine derivatives, vitamins and amino acids tested were ineffective or slightly effective. Sucrose was the most suitable carbon source. Fructose, glucose and maltose also supported the growth. Kinetin stimulated cell proliferation of the callus and cell differentiation to tracheary element.
Photosynthesis in Wood
Authors: WIEBE HERMAN H.
Published: April 2006

The capacity for photosynthesis, measured as light enhanced 14CO2 uptake, was demonstrated in the wood of first and fourth year twigs of Betula pendula Roth, Populus tremuloides Michx., Syringa vulgaris L., and Tilia Americana L, but not in Gleditschia triacanthos L. In Betula and Syringa, but not in the others, photosynthesis occurred in the secondary xylem as well as in the primary xylem.
Effects of the Commercial Polychlorinated Biphenyl Mixture Aroclor 1242 on Growth, Viability, Phosphate Uptake, Respiration and Oxygen Evolution in Scenedesmus
Authors: LARSSON CARL‐MAGNUS , TILLBERG JAN‐ERIC
Published: April 2006

The commercial polychlorinated biphenyl (PCB) mixture Aroclor 1242 was tested regarding its effects on the uni‐cellular green alga Scenedesmus obtusiasculus Chod. The algae were grown in liquid medium at PCB concentrations between 10 and 1000 ppb. Growth was inhibited at 300 ppb and above, viability was only affected at the highest concentration, 1000 ppb. Reduction of phosphate uptake was seen at 300 ppb and above. The inhibition of phosphate uptake had almost exactly the same appearance in light as in darkness. It is suggested that this inhibition is mainly caused by PCB action on the plasmalemma. At 800 ppb some experiments indicated an uncoupling of the oxidative phosphorylation. 1000 ppb inhibited both respiration and O2 evolution.
Hormonal Regulation of Pedicel Abscission in Begonia Flower Buds
Authors: CATE CH. H. HÄNISCH TEN , BERGHOEF J. , VAN DER HOORN A. M. H. , BRUINSMA J.
Published: April 2006

In order to analyse the hormonal regulation of flower bud shedding in Begonia, levels of indoleacetic acid (IAA), abscisic acid (ABA) and ethylene were determined in buds and pedicels. The translocation and metabolism of 14C‐labeled IAA in pedicel segments were also studied.

In a monoecious Begonia fuchsioides hybrid, abscising male flower buds contain about 1% of the IAA present in non‐abscising female flowers. In a male Begonia davisii hybrid, the seasonal variation in bud drop coincides with changes in the IAA content of the buds, while also the release of IAA from the bud to the pedicel is hampered.

Abscission zones of these pedicels always contain abscission promoting ethylene concentrations. The tissue is prevented from responding with abscission by IAA from the flower buds. The buds also contain ABA but without influencing abscission considerably.

Pretreatment with ethylene or ABA does not affect IAA transport in pedicel segments. The rate of this transport is 4–6 mm × h–1:; the capacity increases with the transverse area. In young segments, IAA is decarboxylated and also otherwise metabolized.
Evidence for Three Different Systems of Movement of Indoleacetic Acid in Intact Roots of Phaseolus coccineus
Authors: MITCHELL E. K. , DAVIES P. J.
Published: April 2006

Indoleacetic acid (IAA)‐5‐3H (2 × 10−9M) was applied to intact roots of Phaseolus coccineus seedlings, at the apex or 2 cm above the apex, at various pHs and in the presence of Cu2+ and NaCl. The transport of label in the roots was then examined after 6 h by cutting the roots into 1 mm sections above and below the zone of treatment. Basipetal movement from 2 cm above the apex was unafected by pH, Cu2+ or NaCl. Acropetal movement from the same area decreased with increasing pH from 5.4 to 8.0, probably due to an effect of pH on the entry of IAA into the cells. pH had no effect on sucrose transport. Cu2+ also inhibited acropetal movement but NaCl had no effect. Basipetal movement of label from the apex was reduced by Cu2+ and increasing pH, but not as much as with acropetal movement, and increased by the presence of NaCl. These facts are interpreted as showing 3 different systems of IAA movement in intact roots: basipetal from 2 cm up the root in some extracellular physical system; acropetal from 2 cm up the root, and basipetal from the apex, in a metabolically dependent intracellular system, but in different tissues of the root. It is proposed that endogenous IAA not only moves into the root from the stem but is also synthesized in the root apex, and moves basipetally for a short distance to the root growing zone in a separate system from the IAA descending from the stem.
Some Effects of Triazines on Growth, Photosynthesis and Translocation of Photosjuthate in Pinus Species
Authors: SHAUKAT S. SHAHID , MOORE K. G. , LOVELL P. H.
Published: April 2006

The effects of triazines on growth, 14CO2‐fixation and translocation of 14C‐assimilates by young Pinus seedlings were investigated. Post‐emergenceroot application of moderate and high concentrations of simazine and atrazine resulted in severe toxicity to the seedlings of Pinus nigra and P. coniorta as depicted by reduction in dry weight, chlorosis, wilting and mortality. Atrazine was more toxic than simazine and P. nigra was more susceptible than P. contorta to both the triazines. Simazine treatment to the roots of P. nigra seedlings, not only caused inhibition of 14CO2‐fixation but also reduced the short‐term downward transloca‐tion of l4 C‐assimilates. Various possible mechanisms whereby simazine reduced the downward movement of I4C‐assimilates in Pinus seedlings are discussed.
Comparisons between Photosynthesis and Transpiration in Birch
Authors: HARI PERTTI , LUUKKANEN OLAVI , PELKONEN PAAVO , SMOLANDER HEIKKI
Published: April 2006

Changes in photosynthesis and transpiration of a potted birch seedling were simultaneously followed in the field using two infrared gas analyzers. Wet and dry temperature measurements alone explained 81% of the variation in the transpiration rate when the plant was not suffering from water deficit. During drought and the period after the water balance had been restored, net photosynthesis decreased more distinctly than transpiration. This result was in accordance with our previous results on the after‐effects of water deficit on photosynthesis, and it was also interpreted as evidence for at least partly separate control mechanisms for photosynthesis and transpiration.
Effect of Debudding on Photosynthesis in Leaves of Cotton
Authors: NAGARAJAH S.
Published: April 2006

An experiment was carried out to study the effect of reduced growth on the photosynthetic rate of leaves in cotton (Gossypium hirsutum). It was planned to reduce growth by the continuous removal of axillary buds.

The results show that debudding did not reduce the growth of plants but only altered the distribution pattern of assimilates. The shoot weight of the control and debudded plants was not significantly different. However, debudding prevented reproductive development in the debudded plants. Comparison of the photosynthetic rates of the control and debudded plants indicate that reproductive development did not affect the photosynthesis of young fully expanded leaves but slightly increased the rate of decline in photosynthesis during their ageing.
The Effect of IAA on Sugar Accumulation and Basipetal Transport of 14C‐labelled Assimilates in Relation to Root Formation in Phaseolus vulgaris Cuttings
Authors: ALTMAN A. , WAREING P. F.
Published: April 2006

The effect of indol‐3yl‐acetic acid on root formation, accumulation of 80% ethanol‐soluble sugars and basipetal transport of 14C‐labelled assimilates has been investigated in Phaseolus vulgaris (cv. Canadian Wonder) hypocotyl cuttings. The removal of leaves reduced root formation in the hypocotyl, while excision of the apical bud was less detrimental. The expression of the IAA effect in inducing more roots was dependent on the area of leaves, and was found to be better when all leaves were present. Sugars accumulated slowly at the base of cuttings during a four‐day period after excision, and IAA greatly enhanced this accumulation. By comparing sugar content at the base of green and starved cuttings it was established that IAA greatly increased it concurrently with root formation.

IAA applied in solution to the hypocotyl greatly enhanced the basipetal transport of 14C‐labelled assimilates and their accumulation at the hypocotyl during a 24‐h period. The IAA‐induced accumulation was found to be connected with a greater mobilization of labelled assimilates from upper parts of the cutting. Experiments involving pretreatment with IAA and transport in cuttings already possessing root primordia, suggest a dual effect of IAA: (I) a direct effect on transport, and (2) an increase in the root‐“sink”. It is concluded that both may be operating in inducing basipetal accumulation of labelled assimilates. It is suggested that one of the roles of IAA in promoting rooting of cuttings is to increase sugar availability at the site of root formation.
Cytological Studies on Tissue Culture of Pinus cembra
Authors: SALMIA M. AULIKKI
Published: April 2006

Callus tissue of Swiss stone pine, Pinus cembra L. var. sibirica Loud., has been grown successfully for 9 months through 7 transfers. Excellent initial growth was obtained from hypocotyl segments of 7‐day‐old seedlings. A complex agar medium was used supplemented with 2 mg/l 2,4‐D, 0.05 mg/l kinetin, 1 g/l Edamin and 10% v/v coconut milk. No deterioration of growth was observed on this medium after numerous transfers. The callus tissue did not produce shoots or roots, but showed an ability for cytodifferentiation. Tracheids or tracheid‐like structures were formed in every passage, but the tracheids of the primary callus culture differed markedly from those of the subcultures. The tracheids of the primary culture probably already existed in the hypocotyl, whereas those of the subcultures were formed in vitro. The callus tissue was mainly diploid during the period studied, and more than 86% of the mitoses were diploid. A few mitoses with tetraploidy or a higher ploidy also occurred, but the tissue did not show any tendency to polyploidization.
Regulation of Water Loss by Citrus Leaves
Authors: HALL ANTHONY E. , CAMACHO‐B SAUL E. , KAUFMANN MERRILL R.
Published: April 2006

The factors responsible for the low transpiration rates of citrus were investigated. Leaf resistance to water vapor exchange by orange seedlings (Citrus sinensis L. cv. Koethen) including a substantial boundary layer resistance, was as low as 1 s cm−1 in humid air. Leaf resistance of well watered plants increased to values as large as 5 s cm−1 when the difference in absolute humidity between leaf and air was increased. Leaf resistance was only slightly influenced by temperature between 20 and 30°C providing the humidity difference between leaf and air was kept constant. Leaf resistance increased when leaf temperature was increased between 20 and 30°C when the absolute humidity external to the leaf was kept constant. Increased humidity differences resulted in greater increases in leaf resistance during initial experiments than when the experiments were repeated with the same leaves indicating acclimation by the plant. It was concluded that the effects of humidity differences on leaf resistance are partially responsible for the low transpiration rates of citrus.
Inhibition and Requirement of Natural Stimulator for Cambial Xylem Production in Isolated Stem Segments of Pinus silvestris
Authors: ZAJACZKOWSKI STEFAN , WODZICKI TOMASZ J.
Published: April 2006

Formation of xylem in sterile culture of isolated pine stem segments supplied with synthetic media continues only for 4–6 weeks. The stem segments originally do not contain an eluable inhibitor affecting elongation in the test of pine hypocotyl sections. After 4 weeks inhibition is detected. Supplying the medium with a methanolic extract from the cambial region of pine stem prolongs xylem production up to 15 weeks. IAA interacts synergistically with a natural stimulator of cambial activity.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 8. Induced Leakage of Nucleotide Materials
Authors: OLSEN ROLF A.
Published: April 2006

Addition of aescin to mycelia of Ophiobolus graminis and Neurospora crassa induced leakage of ribonucleotide material together with pentose phosphate or pentose.

In O. graminis a rapid release of mono‐ and dinucleotides together with nucleosides and pentose occurred. In addition some oligonucleotides were released during the first 30 min of the treatment. A slow leakage of polynucleotides was also observed.

In N. crassa aescin induced only slight leakage during the first hour, and the mono‐ and dinucleotide leakage was actually decreasing. From that time on, however, a rapid release of mono‐ and dinucleotides together with nucleosides and pentose phosphate or pentose was observed. Only small amounts of poly‐ and oligonucleotides leaked and the cell content of oligonucleotides seemed to be released only during the last hour of the treatment period.

In Aspergillus niger, which was insensitive to the inhibitor, aescin only induced leakage of pentose or pentose phosphate and small amounts of mono‐ and dinucleotides.

Loss of viability in mycelia of O. graminis and N. crassa seemed to be correlated with the loss of oligonucleotides from the cells.
Studies on Moss Spores. IV. Mass Spectrometric Identification of Saturated and Monoenoic Long Chain Fatty Acids in the Triglyceride Fraction of Polytrichum commune Spores
Authors: KARUNEN PIRJO
Published: April 2006

The saturated long chain fatty acid methyl esters of the triglyceride fraction of Polytrichum commune spores were separated by silver nitrate TLC and identified by a combination of gas chromatographic‐mass spectrometric technique. The saturated fatty acid methyl esters were straight‐chained, and even‐numbered with carbon numbers ranging from 12 to 26 or odd‐numbered with carbon numbers ranging from 13 to 25. The major components of the fraction containing saturated fatty acid methyl esters were methyl palmitate and methyl stearate.

The fatty acid methyl esters of the monoenoic fraction isolated by silver nitrate TLC were converted to TMSO derivates which were analysed by gas chromatography‐mass spectrometry. The analysis gave evidence of positional isomers. The fraction contained the following straight chain monoenoic fatty acid methyl ester isomers: methyl 7‐cis‐hexadecenoate, methyl 9‐cis‐hexadecenoate, methyl 9‐cis‐heptadecenoate, methyl 9‐cis‐octadecenoate, methyl 11‐cis‐octadecenoate, and methyl 11‐cis‐eicosenoate. The major components were methyl 9‐cis‐octadecenoate and methyl 7‐cis‐hexadecenoate.
The Role of Abscisic Acid in Senescence of Detached Tobacco Leaves
Authors: EVEN‐CHEN ZEEV , ITAI CHANAN
Published: April 2006

The role of abscisic acid in the regulation of senescence was investigated in detached tobacco leaves (Nicotiana rustica L.). Leaves senesced in darkness showed a sharp rise in abscisic acid level in the early stage of aging, followed by a rapid decline later. The same trend was found when leaves were aged in light, but the rise in abscisic acid occurred four days later than in darkness. Senescence was slower in light than in darkness, while salt stress accelerated the processes. Leaves treated with kinetin which senesced in light and darkness, did not show an increase in abscisic acid. Application of kinetin led to a transformation from free to bound ABA. These results may indicate that ABA and cytokinin are involved in a trigger mechanism which regulates senescence; the stage at which this trigger is activated determines the rate of senescence.
Divalent Cations and K/Na Selectivity in Excised Barley Roots
Authors: BANGE G. G. J.
Published: April 2006

The effect of Ca2+ and Mg2+ on the rate of K+ (Na+) uptake from different external concentrations ranging from 0 to 1 mM and in the absence and presence of a fixed concentration of Na+ (K+) in the same range, was determined. The object was to examine to what degree the qualitatively well‐established action of the polyvalent cations on these processes could be understood quantitatively from a twofold starting‐point: in the first place the theory of carrier competition (Bange 1962, Acta Bot. Neerl. 11: 139–146) and secondly the hypothesis that polyvalent cations influence carrier site accessibility at the cell surface.

It appears that along these lines a semi‐quantitative description of the phenomena observed is feasible. Possible causes of deviations are discussed.
Nitrogen Uptake by Apple Seedlings as Affected by Light, and Nutrient Stress in Part of the Root System
Authors: FRITH G. J. T. , NICHOLS D. G.
Published: April 2006

The adaptation of apple seedlings, Pyrus malus L., to localized nutrient stress was studied by measuring nitrogen uptake. Seedlings with split root systems were grown in nutrient solution. Various proportions of the roots were subjected to nutrient stress by placing some of the roots in water. The nitrogen uptake by stressed plants was measured under constant and varied lighting. Under optimum lighting it was found that if part of the root system was deprived of nitrogen, then the remainder partially compensated for this deficiency by increasing its uptake. This adaptation, however, was substantially reduced under low levels of lighting.
Influence of N‐Deficiency on the Abscisic Acid Content of Sunflower Plants
Authors: GOLDBACH EVA , GOLDBACH H. , WAGNER H. , MICHAEL G.
Published: April 2006

Sunflower plants (7 weeks old) were transferred from a modified Hoagland solution to a N‐free nutrient medium and kept there for 7 days. Abscisic acid (ABA) was determined in several parts of the plants and in exudates collected from the roots of some of these plants.

N‐deficiency considerably increased the ABA content of the leaves, especially the older ones, and also considerably increased the ABA content of the upper parts of the stem when compared to the control plants. In the roots and the exudates of these plants no ABA could be detected.

After dissecting the stems the ABA content in the roots of the control plants with normal N supply dropped quickly, probably due to rapid metabolization. Judging by results obtained, it seems unlikely that the roots are responsible for the remarkable increase of the ABA content in the shoots caused by N‐deficiency.
Bicarbonate Utilization in Anabaena
Authors: KEENAN JOHN D.
Published: April 2006

Blue‐green algal growth frequently occurs in water with relatively high pH and high levels of organic carbon which are related by the pH‐dependent ionization of inorganic carbon. This relationship, which may regulate natural populations, was examined using a factorial experimental design in which the metabolic response of Anabaena flos‐aquae was measured as a function of pH and total inorganic carbon. The concentration of the products of ionization were calculated. Algal responses were determined manometrically as rates of photosynthesis and respiration. The overriding factor regulating the growth of Anabaena was pH, and no obvious relationship was found to exist between oxygen evolution or uptake and the concentration of any form of inorganic carbon.
Light‐induced Activation of Cytoplasmic Protein Synthesis in Verticillium agaricinum
Authors: VALADON L. R. G. , TRAVIS R. L. , KEY JOE L.
Published: April 2006

The level of protein synthetic activity in dark‐grown cultures of Verticillium agaricinum was significantly enhanced by light. As expected the enhancement of protein synthetic activity was accompanied by a transformation of cytoplasmic monoribosomes to polyribosomes. Amino acid incorporation studies utilizing the synthetic mRNA, poly (U), suggest that the transformation was preceded by an activation of pre‐existing ribosomes. The change in ribosome activity related, at least in part, to an increase in the level of peptidyl‐tRNA associated with the ribosomes. In this regard the response of V. agaricinum ribosomes was similar to ribosome activation in several higher plant systems. The initial response at the level of the ribosome remains to be elucidated.
The Effects of Germination on the Subcellular Distribution of Cholinesterase in Cotyledons of Phaseolus vulgaris
Authors: LEES G. L. , THOMPSON J. E.
Published: April 2006

Homogenates of Phaseolus vulgaris cotyledons have been found capable of hydrolyzing acetylthiocholine. The hydrolysis occurs optimally at pH 8.0, and is inhibited by neostigmine but not eserine. Total activity of the enzyme increases about three‐fold between the second and third days of germination, and remains high until day 6 before dropping coincident with the appearance of visible morphological symptoms of senescence in the tissue.

Fractionation studies have revealed that the enzyme is enriched in preparations of purified cell wall and plasma membrane and is also present in a soluble fraction. The soluble enzyme accounts for more than 70% of the total cholinesterase activity two days after planting but by the fourth day of germination only about 30% of the total activity in the tissue is soluble. During the same period there is a large increase in the specific activities of both the cell wall and plasma membrane enzymes. By the seventh day of germination the particulate and soluble forms of the enzyme both show much reduced activities, but the specific activities of the cell wall and plasma membrane enzymes subsequently increase again. This is thought to reflect breakdown of protein other than cholinesterase in these structures as they in turn become subject to the increasing pressures of senescence.

Cholinesterase in plant tissue presumably serves to regulate the endogenous titre of acetylcholine. The behaviour of this enzyme in bean cotyledons has been interpreted in terms of patterns of physiological and ultrastructural change known to characterize this tissue during germination.
Photophysiology of Kalanchoë Seed Germination
Authors: FREDERICQ H. , ELDABH R. , GREEF J. DE , MATON J.
Published: April 2006

The effects of irradiations with different proportions of red/farred light and of gibberellic acid on the phytochrome‐mediated seed germination of Kalanchoë blossfeldiana cv. Feuerblüte, were studied.

The seed coat transmits much more red than far‐red light, and therefore the energy ratio between 660 nm and 730 nm is given only for the transmitted light. Decreasing this ratio from 65 to 1.0 caused only a very slight inhibition. If this ratio is further lowered to 0.64, a 10 min terminal irradiation after a 3‐h white light photoperiod is inhibitory, but a 12‐h photoperiod or continuous irradiation is not. If the ratio is decreased to 0.44 or 0.31, a 12‐h photoperiod is now also inhibitory, although continuous irradiation and 10 min terminal irradiation are still more inhibitory. These results are discussed in terms of phytochrome phototransformations.

Although gibberellic acid is unable to cause any germination in complete darkness, it can result in a very high germination percentage, if combined with treatments which by themselves do not induce any germination such as continuous far‐red, terminal far‐red after short photoperiods, or very short photoperiods at 25°C. These results point to a strong synergism between gibberellic acid and the so‐called stabilized form of phytochrome, P*FR.
Characterization of Plant Alcohol Dehydrogenase
Authors: LEBLOVÁ SYLVA , MANČAL PETR
Published: April 2006

The final activity of the alcohol dehydrogenase (E.C.1.1.1.1, abbreviated ADH) from germinating pea, isolated by fractionating with ammonium sulphate, chromatography on DEAE cellulose and gel filtration, was 80,000, from bean 25,000 and from lentil 13,500 units per mg protein. Molecular weights of the ADHs are close to each other: pea and bean ADH 60,000, lentil ADH 70,000. The Km values are mutually similar with three enzymes, i.e. of the order of 10−4M for NAD and 10−2M for ethanol. The pH optima lie in the alkaline region. These enzymes catalyse oxidation of a number of monovalent alcohols. At temperatures above 60°C the enzymes are thermally unstable. Stability is enhanced slowly by ethanol but not by NAD. Pyrazol, imidazol and pyridine inhibit plant ADH similarly to the enzyme from horse liver. There is a similarity between plant alcohol dehydrogenases and animal and yeast enzymes.
The Initiation and Maintenance of Vicia faba Tissue Cultures
Authors: MITCHELL J. P. , GILDOW F. E.
Published: April 2006

Explants obtained by removing the radicle tip and the plumule from embryos of Vicia faba have been induced to form callus in culture. Of a range of agar‐solidified culture media tested, only that of Schenk and Hildebrandt (1972) was consistently successful. Improved growth, measured as increasing fresh weight was obtained by increasing the nitrogen content of the medium, either as potassium nitrate or as ammonium nitrate. A kinetin concentration of 0.01 mg/1 (5 × 10−8M) and a 2,4‐dichlorophenoxyacetic acid (2,4‐D) concentration of 0.5 mg/1 (2.3 × 10−6M) allowed optimum initial callus growth. A 2,4‐D concentration of 2.3 × 10−8M, while insufficient to induce callus formation was able to inhibit lateral root development which occurred from embryo explants cultured without added 2,4‐D. Subcultured tissue grew well on media supplemented with casein hydrolysate or a mixture of the eight most common amino acids in casein hydrolysate. Growth in subcultures was inhibited by two other amino acid mixtures used by other workers for different species.
Translocation and Complex Formation of Root‐applied 2,4‐D and Picloram in Susceptible and Tolerant Species
Authors: HALLMÉN ULF
Published: April 2006

Translocation and complex formation of 14C‐labelled 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) in seedlings of sunflower (Helianthus annuus L. var. uniflorus), rape (Brassica napus L. cv. Nilla), wheat (Triticum aestivum L. cv. Starke), and Norway spruce (Picea abies (L.) H. Karst.) were studied. The herbicides were absorbed through the roots from the nutrient solution, Picloram was well translocated to the shoots of the four species; while the acropetal translocation of 2,4‐D was small except in rape.

In 2,4‐D‐susceptible sunflower and rape and in picloramsusceptible sunflower and spruce the herbicides were recovered mainly in the uncomplexed form. In 2,4‐D tolerant wheat and spruce most of the absorbed 2,4‐D was converted into water‐soluble or TCA‐insoluble complexes. In picloram‐tolerant wheat and in relatively picloram‐tolerant rape, the absorbed picloram was also converted into complexes recovered predominantly in the water‐soluble fraction. Most of the complexes released free herbicides by hydrolyzing in NaOH or HCI. The results further support the hypothesis that complex formation counteracts herbicide toxicity.