bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and Organogenesis in Tissue Cultures of Allium cepa var. proliferum
Authors: FRIDBORG GUNNAR
Published: April 2006

Callus isolated from aerial bulbs of Allium cepa var. proliferum was grown in agar and liquid cultures on a synthetic medium containing 5 × 10−6M 2,4‐D. Root formation occurred in the absence of 2,4‐D and was highly stimulated by 5 × 10−6M NAA. Cytokinin was not necessary for growth and organ formation but slightly stimulated the formation of leafy buds. Combinations of NAA or IAA and cytokinin stimulated growth and root formation to a greater extent than anyone of these substances added alone. Pieces of callus in liquid culture developed roots in one week in root‐inducing medium, but bud or embryo formation was not observed in liquid cultures.
Iwanoff Effect in Leaves of Cotton (Gossypium hirsutum)
Authors: BRITTAIN E. G. , NAGARAJAH S.
Published: April 2006

When a leaf is excised from a plant by cutting the petiole in air, the stomata sometimes exhibit an “Iwanoff effect” or temporary increase of aperture before entering the phase of hydroactive closure. Simultaneous and separate measurements of transpiration from upper and lower leaf surfaces, derived from thermocouple psychrometers, photosynthesis measurements from either or both surfaces obtained with an Infrared Gas Analyser and measurements with a nitrous oxide diffusion porometer have been made on leaves of Gossypium hirsutum (cotton) before and after severing the petiole. The effect of previous illumination of the plant on the occurrence of the Iwanoff effect has been studied. The results obtained are consistent with the suggestion that an Iwanoff effect is observed when there is little or no water stress, but fails to appear if water stress has developed, even though it may not yet have reached the level at which hydroactive stomatal closure would occur. Furthermore the Iwanoff effect appears to be limited to the stomata of the upper surface in cotton leaves. This seems to be due to the greater accessibility of the upper than the lower epidermal cells, to the water demand of the internal tissues which follows excision. Evidence is also presented to show that the adaxial stomates do not necessarily close completely in the dark.
Cytokinin Function: Increase in [Methyl−14C] Metabolism to Phosphatidylcholine and a Decrease in Oxidation to Carbon Dioxide−14C
Authors: SCHAEFFER G. W. , SHARPE F. T.
Published: April 2006

Axillary buds of Nicotiana tabacum L. cv. Maryland Catterton normally suppressed by apical dominance are released from dormancy with 6‐benzylaminopurine. This work was done to determine the change in the [methyl−14C] metabolism from methionine during bud stimulation with cytokinin. Dormant buds metabolize [methyl−14C] ‐methionine to 14CO2 more effectively than buds released from dormancy. This oxidation of the methyl group is inhibited with benzylaminopurine. On the other hand, the methylation of polar membrane components, including phosphatidylcholine, is enhanced by the cytokinin during the period preceding the increase in bud weight. The interpretation is presented that the enhanced synthesis of membrane components, as well as the preservation of the methyl groups, are mechanisms for the cytokinin release of bud dormancy with 6‐benzylaminopurine.
14C‐Studies on Apple Trees. VII. The Early Seasonal Growth in Leaves, Flowers and Shoots as Dependent upon Current Photosynthates and Existing Reserves
Authors: HANSEN POUL
Published: April 2006

The young leaves' consumption proper of photosynthates and their contribution to the growth of flowers, fruits and shoots by exposing spurs and shoots to 14CO2 at the earliest stages of the growth period in apple trees (Malus X domestica) were studied. By a parallel determination of the growth intensity in various organs an attempt is made to evaluate their relative dependence on current photosynthates and on reserves from inside the tree.

The proper fixation of 14C by growth in the exposed leaves is high in the earliest phases of growth. The fixation of 14C is considerable in the flowers, including the petals, immediately prior to flowering, in intensely growing fruits, and in the woody parts of the current year's shoots, when the main part of the terminal growth has been completed. Under conditions of high intensity of growth in an organ, the total fixation by growth in the parts studied may amount to as much as 80–90% of the 14C absorbed.

Only in the very earliest phases of development does the growth of flowers and shoots appear to be based to a greater extent on materials supplied from reserves than from current photosynthesis. Quantitatively the greater part by far of the total new growth in fruits and shoots appears to be based on materials from current photosynthesis.
Studies on Auxin Protectors X. Protector Levels and Lignification in Sunflower Crown Gall Tissue
Authors: STONIER TOM , YANG HSIN‐MEI
Published: April 2006

The lignification and differentiation of phloem fibers in sunflower stems is inhibited by growing crown gall tumors. Crown gall tumor tissue has previously been shown to contain large quantities of auxin protectors. Since auxin protectors are antioxidants which inhibit peroxidase‐catalyzed reactions, and since the formation of lignin is known to involve a peroxidase‐catalyzed reaction, an investigation was undertaken to examine the relationship between auxin protectors and lignification in sunflower crown gall tissue.

Sunflower crown gall tissue placed into media low in mineral content, rapidly lignifies. In the low mineral media, protectors appear in the medium within an hour or two, implying that endogenously‐synthesized protectors rapidly leak out of the tissue. In control media, the tissue neither lignified appreciably, nor did it exhibit an excessive amount of protector release. The addition of Ca2+ to the low mineral medium markedly slowed, but did not entirely prevent lignification; similarly Ca2+ markedly slowed the release of protector into the low mineral medium. Auxin protectors added to the low mineral medium did not inhibit lignification apparently because, in the medium, the protectors are rapidly oxidized to quinones. The addition of catechol, a substance which mimics protector, also failed to inhibit lignification and also formed a colored compound in the medium suggesting o‐qui none formation. In contrast, dithiothreitol, a strong anti‐oxidant which upon oxidation does not form a strong oxidant (such as o‐quinone), when added to the low mineral medium does inhibit lignification.

It is suggested that in the in vitro situation lignification and senescence occurs in low mineral media because the protectors leak out rapidly causing the cell's metabolism to favor peroxidase‐catalyzed oxidations including those leading to lignification, while in the in vivo situation the excess protectors produced by crown gall tumor tissue diffuse into surrounding tissue, maintaining a reduced state in such tissues and thereby inhibiting differentiation and lignification. The synthesis of large quantities of protectors by the tumor tissue therefore could account for the anaplasia of the bundle caps observed in sunflower internodes in the vicinity of growing crown gall tumors.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 3. Effect on Uptake of Potassium, Magnesium and Inorganic Phosphate
Authors: OLSEN ROLF A.
Published: April 2006

A venacin, the resistance factor in oat roots against Ophiobolus graminis var. graminis, and a related triterpeneglycoside, aescin, inhibited the uptake of K+ and Mg2+ in the fungal mycelium both in phosphate and succinate buffers. The uptake of the cations in Neurospora crassa was similarly inhibited when the inhibitors were dissolved in phosphate or acetatebuffer, while no decrease in the uptake of K+ and Mg2+ was observed when the inhibitors were dissolved in succinate buffer. The uptake of cations in Aspergillus niger and Pythium irregulare was more or less unaffected by aescin. The uptake of inorganic phosphate was in no case inhibited, but some decrease of the accumulation of inorganic phosphate in Ophiobolus graminis and Ncurospora crassa due to inhibitor treatment in phosphate buffer was observed.

No accumulation of Ca2+ was observed in any of the tested fungi.
Studies of the Biochemical Background to Differences in Glucosinolate Content in Brassica napus L. II. Administration of Some Sulphur‐35 and Carbon‐14 Compounds and Localization of Metabolic Blocks
Authors: JOSEFSSON EGON
Published: April 2006

The aim of the investigation was to study the differences in the metabolism of substances that are utilized in the synthesis of glucosinolates between the Brassica napus cv. Bronowski, which is very low in glucosinolate content, and a cultivar (cv. Regina II) that contains approximately average amounts of these compounds.

By experiments in which the plants were grown in nutrient solutions supplied with sulphate‐35S, it was shown that the rate of sulphate uptake was similar in the two cultivars. No accumulation of intermediate metabolites could be demonstrated by autoradiography in Bronowski.

Sulphate‐35S, methionine‐35S, methionine‐2‐14C, 2‐amino‐6‐(methylthio)caproic acid‐2‐14C, and S‐(β‐d‐glucopyranosyl)‐4‐pentenethiohydroximic acid (desulpho‐3‐butenylglucosinolate) (glucose‐U‐14C or 35S) were fed to shoots of the two cultivars. After incubation, the plant material was extracted with methanol. The extracts were separated into various fractions, and in some experiments glucosinolates or derivatives of their degradation products were isolated. When measuring the radioactivity of the various fractions or isolated products, the incorporation of radioactivity into glucosinolates was found to be poor in Bronowski from sulphate, methionine, and 2‐amino‐6‐(methylthio)caproic acid. Desulpho‐3‐butenyl‐glucosinolate was an efficient precursor of 3‐butenylglucosinolate in Bronowski, but a poor precursor of 2‐hydroxy‐3‐bute‐nylglucosinolate, which suggests a metabolic block at the hydroxylation step in this cultivar. In Regina II desulpho‐3‐butenylglucosinolate was a good precursor of both 3‐butenylglucosinolate and of 2‐hydroxy‐3‐butenylglucosinolate, which demonstrates that these glucosinolates may be synthesized without prior formation of the corresponding co‐methylthioalkyl glucosinolates and that the hydroxylation can take place after the formation of desulpho‐3‐butenylglucosinolate.

The results indicate that the low glucosinolate content of Bronowski is caused by block(s) in the separate pathway leading to the biosynthesis of glucosinolates.
Chloroplasts, Kinetin and Protein Synthesis
Authors: RICHMOND AMOS E. , SACHS BETSY , OSBORNE DAPHNE J.
Published: April 2006

The effect of kinetin on protein synthesis of isolated chloroplasts was investigated by following the incorporation of 14C‐leucine into isolated chloroplasts from Nicotiana tabacum. The incorporation activity varied greatly during the year, being largest in the winter and smallest in the summer. Conversely, the relative effect of kinetin on the incorporation of 14C‐leucine, whether applied as a pretreatment to the leaves or directly in the incubation medium, was largest in the summer and smallest or absent altogether in the winter. Kinetin did not prolong the net incorporation period, which lasted about 40 min, but only enhanced the initial rate of the reaction. Chloroplasts extracted from leaves that had been detached for 24 or 48 h displayed very little of their original, pre‐aged incorporation activity and treating the leaves with kinetin did not, essentially, prevent this loss. It was concluded that the major effect of kinetin upon chloroplasts may be related primarily to an effect upon hydration and permeability of the chloroplast and its membranes, and not to an effect directly upon its machinery for protein synthesis.
The Effect of Reaction Media on the Coupling and Uncoupling of Respiration in Corn Mitochondria
Authors: KOEPPE D. E. , MILLER RAYMOND J.
Published: April 2006

The coupling and uncoupling properties of isolated corn mitochondria were analyzed using three substrates in Tris buffered sucrose and KC1 reaction medias containing inorganic phosphate (Pi), bovine serum albumin (BSA), or Pi and BSA. In these media, without other cofactors, respiratory control (RCR) and ADP/O ratios, and the respiratory burst affected by dinitrophenol (DNP), gramicidin D, calcium chloride and ADP were measured. Bovine serum albumin enhanced the respiratory burst caused by DNP and gramicidin D in the absence of Pi, and in most instances enhanced the stimulation of oxygen uptake by ADP and calcium chloride in the presence of Pi. Mitochondria oxidizing succinate, malate‐pyruvate or NADH exhibited better RCR and ADP/O ratios in buffered 200 mM KCl than they did in buffered 300 mM sucrose. In all instances RCR and ADP/O ratios were enhanced in reaction medias containing BSA.
A Modified Method for Extraction and Identification of Abscisic Acid and Gibberellin‐like Substances from the Olive (Olea europaea)
Authors: BADR SAYED A. , MARTIN GEORGE C. , HARTMANN HUDSON T.
Published: April 2006

A procedure for extracting and identifying plant hormones, particularly abscisic acid (ABA) and the gibberellins (GA) was developed through modification of methods described in the literature. The procedure is particularly useful for studying more than one hormone simultaneously in a given sample, and when the supply of plant material is limited.

The procedure was used to isolate ABA and GA‐like substances from olive tissue (i.e., leaves, buds and inflorescences). Gibberellin‐like substances were identified by their action on α‐amylase release from embryoless barley half‐seeds.

Characterization of an acidic inhibitor extracted from olive inflorescences by thin‐layer chromatography, fluorescence under ultraviolet light, gas chromatography, and physiological effects on wheat coleoptile sections indicate that this inhibitor, or at least a component of it, is very similar if not identical with at least one isomeric form of synthetic abscisic acid.
Carbohydrate Uptake and Metabolism of Ophiobolus graminis
Authors: RAADE P. E.
Published: April 2006

The carbohydrate nutrition of Ophiobolus graminis, the cause of the take‐all disease of wheat, was investigated in growth and respiration experiments. In a synthetic medium, d‐mannitol was the only carbohydrate of thirteen studied which the fungus could not use for growth. However, the fungus was found to take up mannitol by an active mechanism, which was stopped by 2,4‐dinitrophenol.

Di‐ and trisaccharides were hydrolyzed extracellularly, and the monosaccharides were assimilated at different rates.
Photosynthesis and Transpiration as a Function of Gaseous Diffusive Resistances in Orange Leaves
Authors: KRIEDEMANN P. E.
Published: April 2006

The CO2 and H2O vapour exchange of single attached orange, Citrus sinensis (L.), leaves was measured under laboratory conditions using infrared gas analysis. Gaseous diffusive resistances were derived from measurements at a saturating irradiance and at a leaf temperature optimum for photosynthesis. Variation in leaf resistance (within the range 1.6 to 60 s cm‐1) induced by moisture status, or by cyclic oscillations in stomatal aperture, was associated with changes in both photosynthesis and transpiration.

At low leaf resistance (ri less than 10 s cm‐1) the ratio of transpiration to photosynthesis declined with reduced stomatal aperture, indicating a tighter stomatal control over H2O vapour loss than over CO2 assimilation. At higher leaf resistance (ri greater than 10 s cm‐1) changes in transpiration and photosynthesis were linearly related, but leaf resistance and mesophyll resistance were also positively correlated, so that strictly stomatal control of photosynthesis became more apparent than real.

This evidence, combined with direct measurements of CO2 diffusive resistances (in a ‐O2 gas stream) emphasised the presence of a significant mesophyll resistance; i.e., an additional and rate limiting resistance to CO2 assimilation over and above that encountered by H2O vapour escaping from the leaf.
Investigations on Cytokinins. I. Effect of 6‐Benzylaminopurine on Growth and Starch Content of Lemna minor
Authors: JONG JUDITH G. TASSERON‐DE , VELDSTRA H.
Published: April 2006

An excessive starch accumulation in the fronds of Lemna minor L. was observed microscopically and confirmed by direct starch determinations after application of growth inhibiting 6‐benzylaminopurine concentrations. As a high growth rate was coupled with a low starch content and vice versa, the influence of the cytokinin on growth and starch content was compared. It appeared that apart from the expected influence of the growth rate on the starch content, 6‐benzylaminopurine favoured starch accumulation also by itself.
Investigations on Cytokinins. II. Interaction of Light and Cytokinins as Studied in Lemna minor
Authors: JONG JUDITH G. TASSERON‐DE , VELDSTRA H.
Published: April 2006

In Lemna minor under non optimal growth conditions, due to light shortage, a cytokinin is able to supplement this shortage partly. The cytokinin seems to substitute the effect of non‐photosynthetic light.
Oxygen Diffusion from the Roots of Rice Grown under Non‐waterlogged Conditions
Authors: ARMSTRONG W.
Published: April 2006

Three rice varieties, cv. Norin 36, cv. Norin 37 and cv. Yubae, were grown in a loam with a 20 cm water‐table which gave aerobic conditions to a depth of not less than 15 to 17 cm. Under these conditions Norin 36 grew more vigorously and tillered more frequently than the other two varieties.

The rates of oxygen diffusion at 23°C from roots up to 11 cm in length were however appreciably lower for Norin 36 (4.3 × 10−8g · cm−2 of root surface · min−1) than for Norin 37 or Yubae (c. 7.8 × 10−8g).

A considerable increase (up to 200 %) in the oxygen diffusion rate (ODR) from the roots occurred if they were cooled to 3°C, and at this temperature differences in ODR between the varieties were not significant. For a purely physical system, because of the decrease in the diffusion coefficient of oxygen in water, and, the increase in oxygen solubility, a drop of c. 20 % in ODR should accompany the above 20°C drop in temperature. A 16 % drop was recorded for artificial ‘roots’ under these conditions. It was concluded that respiratory activity at the higher temperature must have been responsible for the low readings and intervarietal differences observed at 23°C.

By increasing the 3°C values by 25 % a mean value of 14.2 × 10−8g · cm−2 of root surface · min−1 was recorded for the three varieties, being the probable ODR at 23°C in the absence of a respiratory factor. Calculations show that respiratory activity removed enough oxygen to reduce the ODR for Norin 36 by more than 9 × 10−8g, and for Norin 37 and Yubae by c. 6.7 × 10−8g · cm−2 of root surface · min−1.

Anatomical investigations showed that cortical breakdown was always extensive at 4 to 4.5 cm from the apex of the roots. In some cases however breakdown had not occurred in the basal segment of the root. No opinion could be formed as to whether differences in the amount of cortical breakdown between the varieties might have occasioned the respiratory differences observed.

An interesting feature of the root anatomy was the failure of breakdown in those regions of the roots through which lateral roots emerged.
The Response of Transpiration Resistance to Leaf Temperature as a Desiccation Resistance Mechanism in Tree Seedlings
Authors: WUENSCHER JAMES E. , KOZLOWSKI THEODORE T.
Published: April 2006

Transpiration rate and leaf transfer resistance to water vapor loss were determined under a range of leaf temperatures for Quercus macrocarpa, Q. velutina, Q. alba, Q. rubra, and Acer saccharum. Transfer resistance increased with rising leaf temperatures between 20 and 40°C in all species, but the rate of increase in resistance was greatest in species which normally occupy xeric sites. Increased transfer resistance with rising leaf temperature may be significant in preventing rapid desiccation of leaves under the large evaporative stress imposed by high leaf temperature.
A Requirement for DNA Synthesis during Auxin Induction of Cell Enlargement in Tobacco Pith Tissue
Authors: MAHESHWARI M. G. , NOODÉN L. D.
Published: April 2006

IAA (indoleacetic acid) is known to induce cell enlargement without cell division in tobacco pith explants grown on an agar medium without added cytokinin. The very long lag period before IAA (2 × 10−5M) stimulates growth, about 3 days, can be useful to study the metabolic changes which lead to the promotion of growth. When the disks are transferred to a medium without IAA after 2 days or less of treatment with IAA, the IAA does not stimulate growth. Disks transferred after 3 days, subsequently show an auxin response, almost as great as those given IAA continuously. At 5 × 10−4M, 5‐fluorodeoxyuridine (FUDR), which inhibits DNA synthesis by blocking formation of thymidylate, completely suppresses the lAA‐induced growth if it is added together with the IAA or 1 day later. When the FUDR is given 2 days after the IAA, there is a small increment of auxin‐induced growth, and an even greater amount if added after 3 days. The period when exogenous auxin must be present to stimulate growth corresponds to the period of FUDR sensitivity. The FUDR inhibition is prevented by thymidine but not by uridine. Other inhibitors of DNA synthesis, hydroxyurea and fluorouracil, also inhibit auxin‐induced growth. Thus DNA synthesis seems to be required for auxin induction of cell enlargement in tobacco pith explants. In contrast, FUDR does not inhibit auxin‐induced growth in corn coleoptile and artichoke tuber sections.
Nitrate Uptake by Roots as Regulated by Nitrate Reduction Products of the Shoot
Authors: ZIONI A. BEN , VAADIA Y. , LIPS S. HERMAN
Published: April 2006

A mechanism is proposed by which secondary products of nitrate reduction in the shoot control the uptake of nitrate by the roots. KNO3 enters the roots and is translocated to the shoot where nitrate is reduced and, at the same time, malate is produced. The reduction of nitrate is stoichiometric to the synthesis of malate (1). Part of the K‐malate moves down to the root system in which malate is oxidized, yielding KHCO3 which exchanges for KNO3.

Nitrate reduction in the shoot promotes the synthesis of malate which, after its translocation to the root, allows the preferential uptake of nitrate. Thus, plants reducing large amounts of nitrate may take up the anion without a superfluous accumulation of the cation. Furthermore, the utilization of nitrate by the shoot regulates its uptake by the root.
Factors Affecting Flower Abortion and Malformation in Roses
Authors: MOE ROAR
Published: April 2006

The formation of blind shoots and malformed flowers in rose plants grown under various temperatures and light intensities, and subjected to different cut back procedures has been studied.

Low temperature, low light intensity and low cut back promoted blind shoot formation. Hybrid tea cultivars are more sensitive for unfavourable temperature, light and cut back treatments than Floribunda cultivars. The process of floral abortion is initiated during the early stages of shoot growth before the differentiation of floral parts has been completed. Low temperatures (12–15°C) in this critical stage of development strongly promote blind shoot formation, but have no effect when stamen and pistil primordia had been formed in the apical flower bud.

The formation of malformed flowers, so‐called “bullheads”, which have significantly more petals than normal flowers, is also promoted by low temperature and low cut back. Light intensity seems to have no effect. Shoots subjected to low temperature (12°C) during the early stages of development, before the differentiation of the floral organs are fully completed, produce malformed flowers to a greater extent than shoots subjected to high temperature (18–24°C) during this period.

It is suggested that blind shoot formation in roses is subject to hormonal control.
Activity and Compartmentation of Photosynthetic Carboxylases in Normal and Chloroplast‐mutant Maize Leaves
Authors: H.‐NAGY ANNA , PACSÉRY MARIA , FALUDI‐DÁNIEL ÁGNES
Published: April 2006

The activity of ribulose‐l,5‐diphosphate carboxylase (RudiP‐carboxylase) and phosphoenolpyruvate carboxylase (PEP‐carboxylase) measured in vitro was independent from the chlorophyll content of the leaves. The relatively high activity of PEP‐carboxylase as compared to the RudiP‐carboxylase activity was particularly pronounced in the mutants. Realization of the potential (in vitro measured) carboxylating activities in fixation of CO2in vivo was practically complete in normal leaves. In the mutants, however, CO2 fixation was lower than the level permitted by the carboxylase activity. This could be explained only in part by the impaired rate of photophosphorylation. Compartmentation of PEP‐carboxylase was different in normal and mutant leaves: in contrast to the normal ones, parenchyma‐sheath cells of the mutants exhibited high PEP‐carboxylase activity. Competition of PEP‐carboxylase with RudiP‐carboxylase for CO2 in the mutants led to accumulation of organic acids, and can account for their low photosynthetic activity.
Uptake of Sulfate by Roots and Leaf Slices of Barley: Mediated by Single, Multiphasic Mechanisms
Authors: NISSEN PER
Published: April 2006

The uptake of 10−1M–2.5 × 10−1M sulfate by roots and leaf slices of barley can be described by a single isotherm having, respectively, 8 and 5 phases with regularly increasing kinetic constants. Each phase covers a limited concentration range and obeys Michaelis‐Menten kinetics. The uptake of sulfate is proposed to be rate‐limited by a single mechanism or structure which is located in the plasmalemma (or cytoplasm) and which changes characteristics at certain discrete external concentrations (inflection points). Examination of published data indicates that the uptake of other inorganic ions by higher plant cells is also mediated by single, multi‐phasic mechanisms.
Decarboxylation and Transport of Auxin in Segments of Sunflower and Cabbage Roots. II. A Chromatographic Study Using IAA‐1‐14C and IAA‐5‐3H
Authors: AASHEIM TORBJÖRN , IVERSEN TOR‐HENNING
Published: April 2006

The polar movement of IAA has been examined in 5‐mm root segments of Brassica oleracea and Helianthus annum. The movement was studied partly with IAA‐1‐14C and partly with IAA‐5‐3H. In both plants a slight acropetal flux of 14C and IAA‐3H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time.

A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with in‐dole reagent (DMCA).

Chromatograms run in isopropanol: ammonia: water, 8:1:1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with Rf 0.4–0.6, probably representing IAA.
Metabolic Changes in Developing Rice Seeds
Authors: PAUL A. K. , MUKHERJI S. , SIRCAR S. M.
Published: April 2006

Metabolic changes in developing rice seeds were studied with respect to respiration, carbohydrate and nitrogen fractions, nucleic acids and hydrolytic enzymes, viz. α‐amylase, adenosine triphosphatase (ATPase) and phytase. — Respiration rate was maximum after 12 days from the date of pollination and became feeble afterwards with the fall in the moisture content of the maturing seeds. In the early stage, there was a preponderance of reducing sugars which were replaced later by nonreducing forms. Dry matter accumulation was mainly due to the steady rise in starch content. There was a gradual accumulation of protein nitrogen throughout the experiment, the rate being highest between 12–16 days. RNA content increased steadily till the seeds became mature, while DNA formed rapidly during the first 20 days and was maintained at the same level thereafter. —α‐Amylase activity increased up to 20 days and declined sharply afterwards. The peak activities of ATPase and phytase were recorded at 32 and 24 days after pollination, respectively.
Thermal Inactivation of Plant Growth: Effects on Cotyledon Metabolism
Authors: RAMESHWAR AKULA , STEPONKUS PETER L.
Published: April 2006

Temperature exposures which normally decrease growth of Pisum sativum seedlings by 50 % were found to be lethal in plants whose cotyledons were removed. Utilization of the two major reserves, starch and protein, decreased at high temperatures. However, the two enzymes responsible for their hydrolysis were thermostable. It appears that the influence of high temperatures on seedling growth is not due to direct effects of temperature on cotyledon metabolism, but rather indirectly through the axis.
The Relationship between Flower Abortion and Endogenous Auxin Content of Rose Shoots
Authors: MOE ROAR
Published: April 2006

The amount of endogenous growth substances in stem, flowers and leaves of rose plants grown under different temperature and light conditions has been determined.

It appeared to be two main growth promoting factors in the acidic fraction of the ether extract. One of them is assumed to be an auxin, probably indol‐3yl‐acetic acid (IAA); the other is not identified. The level of auxin was much higher in extracts from shoots grown at high temperature than in shoots grown at low temperature. Increasing light intensity also seemed to increase the auxin content of the shoots. Shoots which developed after a high cut back of the rose stem had a higher auxin content than shoots which developed after a low cut back.

These findings are discussed in relation to the effect of temperature, light intensity and cut back practise on blind shoot formation in roses. The result of these investigations strongly indicate that abortion in roses is promoted by a low auxin level in the shoots.
Studies on the Physiology of Host‐parasite Relationship in Orobanche. I. Respiratory Metabolism of Host and Parasite
Authors: SINGH JAI NARAIN , SINGH JAGDISH NARAIN
Published: April 2006

The respiratory rate of the roots of mustard (Brassica cam‐pestris L.) and tomato (Lycopersicum esculentum Mill.) serving as hosts for the total root parasites Orobanche aegyptiaca Pers. and O.cernua Loefll. was measured using Warburg manometric technique. At the same time determinations were made of the respiration of the apical, basal and root regions of the parasites. The effects of sodium fluoride, malonic acid, sodium azide and DNP (2,4‐dinitrophenol) on the rate of respiration of the host roots as well as of the parasites were studied. The Orobanche infection results in a marked increase in the respiratory rate near the host‐parasite contact region. The damaging effect of infection seems to be due mainly to a continuous flow of water, minerals and metabolites from host to parasite. The haustorial invasion creates an obstruction in the translocation of metabolites. The respiration rate is lower in Orobanche than in the host, which might be related to its slower growth rate, inefficient oxidative processes and an escaping of certain energy‐requiring interconversion processes. Roots of O. aegyptiaca are more well‐developed and have higher rate of respiration. They can absorb more water and minerals from the soil. This fact might be connected with the specificity of the two species. NaF and malonic acid inhibit the respiration to a similar extent in healthy and infected roots. This indicates that the pathway of respiration does not change materially after infection. The EMP and Krebs cycle seem to operate at a lower intensity in Orobanche, which is proved by the lower inhibition of the respiration as compared to in the host. Azide causes a stronger reduction of the respiration in infected than in healthy roots. It would imply that the infection stimulates the activity of metal containing oxidases. The weaker inhibition of the respiration in Orobanche tissues indicates a mediation of other enzymes in the oxidation processes than in the host. The respiration is less stimulated by DNP in infected than in healthy roots. Contrary to the general effect of DNP, this substance decreases the O2 uptake in the parasite tissues. This fact may be explained by the occurrence of exceptionally high amounts of endogenous phenolic compounds and an insufficient production of ATP in the parasite.
Effect of Glucose and Auxins in Rooting Etiolated Stem Segments of Populus nigra
Authors: NANDA K. K. , JAIN M. K. , MALHOTRA SHIVA
Published: April 2006

2.5 cm long stem segments of Populus nigra L. did not root when cultured in water or in auxins alone but rooted in glucose. The number of rooted segments and roots produced on them increased with rising glucose concentrations up to 0.5%, but decreased with higher concentrations. An addition of 1.0 mg/1 IAA inhibited rooting at 0.01 % glucose, was ineffective at 0.1 % and stimulative at higher concentrations of glucose which were inhibitory when used alone. The results show that the auxin effects on rooting are influenced by the nutritional status of the stem cutting of a species, and that a proper balance of the two is necessary for root development.
Cytokinin Activity During Development of Cotton Fruit
Authors: SANDSTEDT ROBERT
Published: April 2006

Cytokinins in cotton fruits were detected by the soybean callus bioassay on the 1st day after anthesis. Peak cytokinin activity occurred from the 4th to the 9th day and then declined to little or none by the 18th day after anthesis. The principal cytokinin remained below Rf 0.2, when chromatographed on paper with water‐saturated sec‐butanol, and predominated throughout the period of cytokinin activity. Another cytokinin, migrating to Rf 0.8, remained less active.
Plant Growth Inhibition and Membrane Penetration by a Homologous Series of Dichlorobenzoate Esters
Authors: BUTA J. G. , STEFFENS G. L.
Published: April 2006

The homologous series of n‐alkyl esters (C1–C10) of 3,4‐dichlorobenzoic acid was synthesized and their effects in inhibiting the growth of Nicotiana meristems were studied. The inhibition of growth was considered in terms of penetration of chemicals into the plant tissue and subsequent cell membrane disruption. Penetration was investigated by applying the emulsified ester to the meristem and then measuring the compound recovered with the isolated surface lipids. Decreasing amounts of 3,4‐dichlorobenzoate esters penetrated into the plant as the alkyl chain length of the ester moeity was increased. Essentially no penetration occurred with the n‐C7 through C10 esters tested. The effect of the ester homologues on cell membranes was studied by measuring the efflux of betacyanin from beet root cells. Decreasing amounts of pigments were released as the alkyl chain length of the ester was increased. Minimal cell membrane disruption was found for the C7–C10 esters. Inhibition of the plant meristem may result from the more rapid penetration of the short chain ester homologues into the plant.
The Physiology of Groundnut
Authors: KHAN AZIZ A. , AKOSU FIDELIS I.
Published: April 2006

The distribution of labelled assimilates following the assimilation of 14CO2 in groundnut (Arachis hypogaea L.) by single leaves at different nodes was investigated using autoradiographic technique. In the vegetative stage growing leaves assimilated most of the 14carbon, while the fully expanded leaves exported most of its radiocarbon to the apices, young expanding leaves and to the roots. Soon after the formation of the pegs and the growth and development of the pods, the developing pods become the major sinks. At this stage translocation from the foliage of each branch was restricted mostly to the pods produced by this branch.
The Effect of Epidermal Cell Water Potential on Stomatal Response to Illumination of Leaf Discs of Vicia faba
Authors: GLINKA Z.
Published: April 2006

Illuminated leaf discs of Vicia faba were brought into equilibrium with a series of mannitol solutions. The width of stomatal aperture and the osmotic potential of guard cells and epidermal cells were determined. It was found that the maximal aperture was obtained when epidermal cells were at about incipient plasmolysis and that any increase in their turgor pressure brought about a decrease in stomatal aperture. These findings emphasize the importance of epidermal cells in determining the width of the stomatal pore.
The Influence of Cu on Photosynthesis and Growth in Diatoms
Authors: NIELSEN E. STEEMANN , WIUM‐ANDERSEN S.
Published: April 2006

Cu in ionic form in a balanced medium affects the rate of photosynthesis and growth in the diatom Nitzschia palea in about the same way as in the green alga Chlorella pyrenoidosa. Remarkable differences are found, however. Small concentrations of Cu influence the rate of photosynthesis considerably more in the diatom than in the green alga whereas the opposite is the case concerning growth. The latter is most likely a consequence of excretion of organic matter by the diatom in presence of Cu whereas this does not take place in Chlorella. Some of the excreted organic matter may bind Cu and thus make the medium suitable for growth. Although pre‐treatment with Cu in the dark has no influence on the subsequent rate of photosynthesis in the light, organic matter is excreted in the dark immediately after the addition of Cu. The influence of Cu on the rate of photosynthesis varies by a factor of about 30 according to the stage of growth in a synchronized culture.
A Labile‐Bound Component of Phosphate in the Free Space of Sunflower Plant Roots
Authors: PETTERSSON SUNE
Published: April 2006

An experimental method is described by which it is possible to follow continuously the uptake and release of certain radioactive isotopes and the uptake of water by the roots of young plants.

The method has been used in a study of the ion fractions related to the initial uptake of phosphate in the roots of sunflower plants. Two non‐bound fractions were identified: one which was leachable in distilled water and another which was released from the roots only by a bathing medium containing inactive phosphate. Experiments using conventional analysis technique corroborated the results obtained by the recording technique.
Regulation of Growth in Avena Stem Segments by Gibberellic Acid and Kinetin
Authors: JONES R. A. , KAUFMAN P. B.
Published: April 2006

Kinetin at physiological concentrations causes significant reduction of GA3‐promoted growth in excised Avena stem segments. Kinetin is therefore considered to be a gibberellin‐antagonist in this system. A Lineweaver‐Burke plot reveals that kinetin acts non‐competitively with GA3. The kinetin inhibition of GA3‐promoted growth can be seen within 6 hours. It was found that soluble protein is markedly increased by kinetin in the tissue during the first 3 hours, thus preceding the inhibition of GA3‐promoted growth by several hours. At the cellular level, kinetin negated the blocking effect of GA3 on cell division in the intercalary meristem portions of these segments. In fact, kinetin promotes both lateral and longitudinal cell divisions in intercalary meristem cells.
Effect of Inorganic Phosphate on the Extracellular Acid Phosphatase Activity of Tobacco Cells Cultured in vitro
Authors: UEKI KATSUJI , SATO SITIRO
Published: April 2006

Acid phosphatase activity in culture medium of tobacco cells growing in suspension increased with the age of the culture from which the medium was obtained. The increase in the activity was accelerated by omitting inorganic phosphate from nutrient medium, and it was depressed by addition of inorganic phosphate or cycloheximide. Amylase and β‐galactosidase activities were not induced by the omission of inorganic phosphate. It was concluded that derepression of acid phosphatase synthesis was involved in the increase in the extracellular acid phosphatase activity upon inorganic phosphate depletion.
Physiological Studies with Heavy Water. II. Germination and Growth Inhibition of Barley by D2O
Authors: BHANDARKAR M. K. , BHATTACHARYA S. , GAUR B. K.
Published: April 2006

Seed germination and barley seedling growth in various D2O concentrations have been studied. It was observed that the emergence of root and shoot was delayed, there being greater delay in shoot than in root emergence. A complete block was observed in germination in pure D2O and the germination rate was slowed down significantly in lower concentrations.

An initial germination delay by different D2O concentrations seemed to cause a subsequent retardation in the growth measured as shoot and root length. A comparison of root and shoot length with their respective dry weights suggested that the growth by cell division/elongation might have been affected more than the transport of food materials from the endosperm to the embryo.

Analysis of the total sugars of the endosperm and the embryo at 8 hour intervals showed that while the hydrolysis of starch to sugars was progressively decreased by increasing D2O concentrations, the transport rate from endosperm to embryo showed a sharp inhibition in 50% D2O and above. This indicated that the inhibition in the transport of materials, besides less hydrolysis of reserve food materials, may also be a causal factor of germination and growth inhibition in D2O.
Effect of Gibberellic Acid, 2,3,5‐Triiodobenzoic Acid and Indole Acetic Acid on Growth and Development of Impatiens balsamina during Different Photoperiods
Authors: SAWHNEY S. , TOKY K. L. , NANDA K. K.
Published: April 2006

This paper deals with the effect of 100 mg/1 each of GA3 TIBA and IAA singly and in combination with each other on stem elongation, development of lateral branches and floral bud initiation in Impatiens balsamina plants exposed to 8‐, 16‐ and 24‐h photoperiods. GA3 enhances stem elongation, the enhancing effect decreasing with IAA as well as with TIBA during 8‐h but increasing during 16‐ and 24‐h photoperiods. It decreases the number of lateral branches, the decrease being greatest during 16‐, less during 8‐ and the least during 24‐h photoperiods. The time taken for floral buds to initiate with and length of branches during 16‐h photoperiods.

During 8‐h photoperiods, IAA delays the initiation of floral buds, while GA3 hastens it when used together with TIBA or IAA or both. GA3 increases the number of floral buds on the main axis but decreases it on lateral branches, while TIBA decreases the number on the main axis but increases it on lateral branches. IAA reduces the number of floral buds on the main axis only when used alone, but on both the main axis as well as on lateral branches when used together with GA3 and TIBA. Floral buds were not produced on lateral branches when plants were treated with GA3, TIBA and IAA all together.

GA3 and TIBA induced floral buds even under non‐inductive photoperiods, the number of buds and reproductive nodes being less in TIBA‐ than in GA3‐treated plants during 24‐h photoperiods. The time taken for floral buds to initiate with GA3 and TIBA during noninductive photoperiods is much longer than that during 8‐h inductive photoperiods with or without GA3 or TIBA application. IAA completely inhibits the GA3‐ and TIBA‐caused induction during 24‐h, but only delays it and reduces the number of reproductive nodes and floral buds during 16‐h photoperiods.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A.
Published: April 2006

Avenacin, the resistance factor ioat roots against Ophiobolus graminisi ν graminis, and a related triterpeneglycoside, aescin, inhibited growth of various fungi, while the growth of a few fungi was unaffected.

The triterpenoidal saponins tested seemed to be fungicidal, as the mycelia did not grow after exposure to the inhibitors. The fungicidal effect, however, depended on the medium used. The inhibitors did not seem to act primarily on the endogenous respiration, since the oxygen uptake, although much reduced, continued after the time required to destroy the growth capacity. The leakage of UV‐absorbing substances from fungi, sensitive to the inhibitors, and the decrease of UV‐absorbing substances in the transient pool of the cells indicate a change in the cell membrane.
Characterisation of the High Temperature Inhibition of Germination of Lettuce (Lactuca sativa)
Authors: REYNOLDS T. , THOMPSON P. A.
Published: April 2006

Lactuca sativa L., lettuce (Arctic King) fruit germination is inhibited in the light at temperatures above 27°C(±1.5°). This value, which is precise and repeatable is referred to as the upper temperature cut‐off point, and is characteristic for a particular species. It was found, that this cut‐off point is shifted upwards by applying kinetin solutions (0.1–1 mg/1) or downwards by applying (±)‐abscisic acid solutions (over 1 mg/1), the amount of shift being proportional to the level of active compound. In the presence of both compounds a balance was achieved. Effects of stimulators and inhibitors can most explicitly be described by reference to the direction and magnitude of the shift in the upper temperature cut‐off point, which results from their application.
Some Effects of Amo‐1618 on Growth, Peroxidase and α‐Amylase Which Cannot Be Easily Explained by Inhibition of Gibberellin Biosynthesis
Authors: CASPAR THOMAS , VERBEEK RITA , KHAN ANWAR A.
Published: April 2006

Growth and peroxidase activity of roots and stems of lentil seedlings were compared after treatment with Amo‐1618, alone or in combination with gibberellic acid (GA) at varying concentrations. The peroxidase enhancement in Amo‐1618 treated stems could not be attributed to a decrease in the gibberellin content since GA alone had no effect on this enzyme.

In other experiments, AMO, at low concentrations, was able to induce α‐amylase production in barley aleurone layers; the lag period needed for this induction, was longer than for GA.

These facts seem to indicate that some growth retardants might act at least in some cases by mechanisms other than inhibition of gibberellin biosynthesis and reversal of GA action.
The Effect of Deleterious Concentrations of Mercury on the Photosynthesis and Growth of Chlorella pyrenoidosa
Authors: KAMP‐NIELSEN LARS
Published: April 2006

The effect of mercury ions on the photosynthesis and growth of Chlorella pyrenoidosa in a balanced medium has been studied and compared with the effect of copper. In many ways Hg treated algae behave like algae treated with Cu in concentrations of the same molarity, but important deviations occur. Hg acts at a lower and in a more narrow range of concentrations than does Cu due to a more specific binding. The depressing effect of Hg is not counteracted by other cations such as potassium and sodium, and iron has only a slight effect. Cell division is stopped after Hg addition and there is no accumulation of assimilation products. On the contrary the cells become pale yellow. Preliminary studies indicate a light‐independent leakage in the cytoplasmatic membrane leading to an outflow of potassium ions. This is the primary action of both Hg and Cu poisoning, but the leakage does not seem to be correlated with the decrease of photosynthesis. After a lapse of time — dependent on the mercury/cell concentration ratio — a detoxication takes place probably due to the binding of Hg to “insensitive sites” in the cells. Probable mechanisms for the action of Hg on photosynthesis and growth are discussed.
Changes in Nucleic Acids Associated with Maturation and Senescence in Hedera helix
Authors: MILLIKAN D. F. , GHOSH B. N.
Published: April 2006

Significant changes in nucleic acids are associated with both maturation and senescence of Hedera helix leaf tissues. DNA content was unaffected by senescence, and there were no quantitative differences between juvenile and transitional forms. The adult tissue, however, contained less DNA than the other forms. The total RNA content was reduced by senescence in juvenile and transitional tissue but not in adult. Maturation, on the other hand, progressively decreased the total RNA content. Similar changes in sRNA and rRNA indicate that maturation involves quantitative changes in these fractions. Quantitative differences in the nucleotide analyses suggest that different sRNA and rRNA species are responsible for the biological processes associated with maturation.