bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Model of the Photosynthesizing Leaf
Authors: Brown K. W. 
Published: April 2006

AbstractA model is proposed for the relationship between net photosynthetic rate (N) and light Intensity at a given concentration of CO2 in the air ([CO2]a). The model provides a prediction of the sum of the diffusion resistances (Σr), the capacity (K) of the leaf to fix CO2, the concentration of CO2 at the point of photosynthesis ([CO2]g), and the respiration rate (R). The model fits the available data well and provides a frame work by which future research may be guided.The calculated values of [CO2]g decreased from [CO2]g at the compensation point to a nearly constant value at high tight intensities. [CO2]g high light infensitit‐s range from 32 to 144 μ/l (volume) depending on the species. When these values of [CO2]g, are used in the diffusion equation, the resulting levels of the mesophyll resistance (rm) are lower than those calculated by using the assumptions that [CO2]g equals zero. The plants which had (he higher photosynthetic rates at a given light intensity and [CO2]a had grealer values of [CO2]g than those with lower photo‐synthetic rates.The calculated rates of respiration of wheat leaves were twice as high as those measured in the dark. This suggests that the light respiration rate may be twice as great as the dark respiration rate at the same temperature.The calculated values of K demonstrate variability within and between species. The maximum N was independent of K. A relationship between K and the maximum quantum efficiency, at constant levels of [CO2]g, was demonstrated in several species.The Σr was inversely related to the maximum rate of photosynthesis for the species investigated. The values of rm calculated for cotton were inversely related to [CO2]a suggesting that the transfer of [CO2] in the cell may involve a concentration dependent chemical reaction in addition to or rather than a physical diffusion process.
Auxin Synergists in Rooting of Cuttings
Authors: Basu R. N. , Bose T. K. , Roy B. N. , Mukhopadhyay A. 
Published: April 2006

AbstractLeafy cuttings of Eranthemum tricolor were treated with tannic acid, gallic acid, p‐hydroxybenzoic acid and salicylic acid at the concentrations of 1000, 100, 10 and 1 nig/1 for 24 hours, whereafter they were dipped quickly in a 1000 mg/l solution of IAA, IBA and NAA for ten seconds.None of the phenolics showed any root promoting effect when used singly. In combination with NAA and IBA tannic acid promoted rooting, however, with IAA there was no effect to be seen. Gallic acid also markedly increased the number of roots of cuttings treated with NAA and IBA. Even in this case there was no effect with IAA.Synergism was also recorded between p‐hydroxybenzoic acid and IAA or NAA but not with IBA.Salicylic acid greatly promoted rooting in combination with both IAA, IBA and NAA.
Mechanism for the Uptake of Zinc by Fontinalis antipyretica
Authors: Pickering D. C. , Puia I. L. 
Published: April 2006

AbstractThe rate of uptake, the effects of carrier ions, temperature, light intensity and dinitrophenol (DNP) upon the uptake of zinc (using zinc‐65 as tracer) by Fontinalis antipyretica were investigated. The absorption medium contained 0.5 mW CaSO4 and the pH was kept constant using boric acid and sodium hydroxide as buffer.About 50 per cent of the zinc absorbed at equilibrium was taken up in the first half hour, Analysis by semi‐log plot procedures showed that, at least, three sections may be distinguished in the uptake curve, suggesting that three successive processes (stages) were involved. The first stage was very short, and not influenced by temperature, light intensity and DNP. The second stage, lasting no more than 90 minutes, mi very slightly affected by the same three factors. In this stage freshly killed plants absorb more zinc than living material. The third stage, lasting several days, was very slow and was light, temperature and DNP dependent.Based on these findings, a mechanism for zinc uptake is proposed.
Non‐Reversibility of Gibberellin‐Induced Inhibition of Regeneration in Begonia Leaves
Authors: Heide Ola M. 
Published: April 2006

AbstractWith applied to the petioles of detached Begonia x cheimantha leaves before planting, Gibberellic acid (GA3) inhibited the formation of adventitious buds and roots ill an apparently irreversible manner. Bud formation was entirely suppressed by 10−6M and higher concentrations and a significant inhibition was still present at 10−9M the lowest concentration tested. Root formation was not affected by GA3 below 10−7M and was possible even at 10−4 M GA3. Petiole elongation was stimulated by GA3 with an optimum at 10−5M.GA3 also blocked the action of 6‐benzyiamino‐purine (BAP) and 1‐naphthaleneacetic acid (NAA), compounds which are potent stimulators of bud and root formation, respectively. When applied simultaneously with GA3 they were, at their optimal concentrations, devoid of any effect in counteracting or reversing the gibberellin‐induced inhibitions. Abscisic acid and the growth retardants CCC and Phosfon also were unable to restore bud and root formation.In leaves initially treated with water or 10−5M BAP, endogenous bud and root formation as well as BAP‐induced bud formation were entirety suppressed when 10−5M GA3 was applied 8 days after the initial treatments. Even when delayed for 14 days GA3 treatment inhibited BAP‐induced bud formation, while treatment after 21 days bad little effect on bud and root formation. Development of pre‐existing, visible bud primordia was not inhibited by GA3.BAP and NAA competitively inhibited the action of GA3 in petiole extension growth.The results are discussed in relation to results obtained in other plant systems. It is suggested that GA3 acts by blocking of the organized cell divisions initiating the formation of bud and root primordia.
The Demand for Iodine and Bromine of three Marine Brown Algae grown in Bacteria‐free Cultures
Authors: Pedersen Marianne 
Published: April 2006

AbstractThree marine brown algae have been cultivated with different additions of iodine and bromine in bacteria‐free cultures. Ectocarpus jasciculatus appeared to have an absolute demand for iodine and was inhibited by a concentration of 64 μmol of KJ per 1. Lithosiphon pusillus had the best growth in the highest concentration tested (64 μmol/1) but there was always some growth in the series without iodine. Additions could be made either as inorganic iodine or as organically bound iodine. Additions of KJ to a culture medium consisting of vitamin‐free Asp 6 F with B12 (1 μg/1) and kinetin (20 μmol/1) remarkably increased the growth of the zoospores of Pylaiella litoralis. Lithosiphon pusilius proved to be indifferent to bromide additions in media containing KJ. In media lacking KJ addition of 1 μmol of KBr per 1 is stimulating but higher concentrations of KBr are inhibiting. The inhibiting effect is overcome by iodide addition.
Effect of Sucrose and Gibberellic Acid on Floral Induction of Xanthium
Authors: Mukherjee Ilabanta 
Published: April 2006

AbstractApplication of gibberellic acid (GA3) before and sucrose after the inductive dark period promotes flowering in Xanthium. The promotive effects of these two compounds are independent but additive. Sucrose application either before or utter the dark period has promotive effect on the flowering response. These effects are additive. The roles of pre‐ and post‐induction high‐intensity light period and of GA3 in the promotion of flowering have been discussed. It has been suggested that sucrose application promotes flowering by increasing translocation of the flowering stimulus and by promoting the rate of development of the terminal male inflorescence. It has also been suggested that GA3‐induced promotion of flowering is due to the increased synthesis as well as translocation of the flowering hormone.
Effect of Gibberellic Acid on the Elongation Rate of Agrostis alba Root Hairs
Authors: Devlin Robert M. , Brown Daniel P. 
Published: April 2006

AbstractThe influence of gibberellic acid over a wide range of concentrations on the rate of elongation of root hairs of redtop grass was investigated. The rate of root hair elongation was increased by GA over the concentration range of 10−7 to 10−12 M inclusive, with peak stimulation occurring at 10−6 M. Although root hair growth was slightly accelerated by 10−6 M GA, this concentration damaged many root hairs and caused some to stop growing altogether. Rate of root hair elongation was reduced to less than 84% of the control by 10−5 M GA.
Ribonuclease in Leaves of Phaseolus vulgaris during Maturation and Senescence
Authors: Phillips D. R. , Fletcher R. A. 
Published: April 2006

AbstractThe levels of the enzyme ribonuclease (RNase) were determined in primary leaves of Phaseolus vulgaris in an attempt to correlate changes in RNA with maturation and senescence. RNase, RNA and chlorophyll levels increased in expanding and maturing tissue and subsequently declined in senescing tissue. Senescence of the primary leaves started with the onset of flowering. A simultaneous increase of RNA and RNase in maturing tissue and a decrease during senescence suggests that the enzyme activity is correlated with the rate of‘turnover’of RNA rather than the absolute levels of RNA present in the tissue.
Phytochrome Control of Nyetinasty in Samanea as Modified by Oxgen, Submergence, and Chemicals
Authors: Sweet Haven C. , Hillman William S. 
Published: April 2006

Abstract Samanea saman has rapid phytochrome‐regulated nyctinasty: red light preceding darkness causes pinnules to close while far‐rod light allows opening‐ Not only the initial angle of the pinnules, but the degree of control by phytochrome depends on the “subjective time of day” at which the tissue is exposed. Excised pairs of pinnules close rapidly when submerged in water; such closure is prevented by bubbling oxygen through the water. However, if submergence closure were due solely to low oxygen levels, then nonsubmerged pinnules in a pure nitrogen atmosphere should also close. Instead, they neither close nor respond to light, but they do respond when air is readmitted, indicating that oxygen is necessary for movement rather than for photoreception. The closure of submerged pinnules remains unexplained. Attempts to detect effects of red or far‐red on oxygen uptake by pulvinus tissue were unsuccessful.The following method has been used to test the effects of various inhibitors and other substances: pinnules are excised at the first hour of the day, trimmed, submerged in a sealed chamber, given far‐red light, and left in darkness while oxygen is bubbled through the medium. Concentrated test solutions are injected either initially or when the red and far‐red exposures are given. Thus far, the substances tested have had little or no effect on the phytochrome response.
Malonate Metabolism, Stimulation of Conidiation and Succinate Dehydrogenase Activity in Neurospora crassa
Authors: Ojha M. N. , Velmelage R. , Turian G. 
Published: April 2006

AbstractMalonate was studied for its effect on succinate dehydrogenase activity and conidiation. It Was found to stimulate the succinate dehydrogenase activity and also conidiation of Neurospora crassa.The efficiency of sucrose metabolization for cellular synthesis was improved in malonate supplemented cultures. High Concentration (0.5 M) had a distinct toxic effect on conidiation and economic efficiency. Teratological structures were observed at 0.5 M malonate concentration.A stimulation of the glyoxylate cycle is considered to be one of the factors responsible for the conidiogenic effect.
Der Einfluss verschiedener Salze und verschiedener Inhibitoren auf den Wurzeldruck von Zea mays
Authors: Mengel K. , Pflüger R. 
Published: April 2006

Abstract The effect of different salts and inhibitors on the root pressure of Zea mays.— The influence of various salt solutions and inhibitors on the exudation rate has been investigated with young excised primary roots of Zea mays. The following results were obtained. — The effect of chlorides on the exudation rate was higher than the effect of sulphates K+ and Na+ effected higher flux rates than Ca2+ and Mg2+ The highest exudation rate was obtained with KCl. — In comparison to an isotonic Lutrol‐solution (a liquid condensed polyethylenoxid) a 0.5525 molar KCl‐solution, applicated on the root stump, increased the exudation rate considerably. — Metabolic inhibitors and anaerobic conditions decreased the exudation rate. — Experiments, concerning the influence of metabolic inhibitors on the exudation and on the Rb‐uptake showed a highly significant positive correlation (r =+0.72***) between the exudation rates and the Rb‐concentrations in the exudates. The Rb‐accumulation in the root tissue was not correlated to the exudation rate. — The experimental data agree with the concept of a transversal water transport in the root tissue, effected by osmotic forces. The root pressure is based on the osmotic gradient between the xylem sap and the outer solution. This gradient is built up by the metabolic secretion of ions into the xylem sap. It is supposed that the transversal water transport in the roots mainly goes through the free space of the cortex.
The Effect of Nonanal on Dipodascus aggregatus IV. Studies with Different Carbon Sources
Authors: Nyman Brita 
Published: April 2006

AbstractNonanal (80 μ) in ethanolic solution stimulated the growth of Dipodascus aggregatus with fructose (55.5 mM) as carbon source (inoculum grown with fructose or glucose). If the inoculum had been grown with galactose, neither growth with galactose nor growth with glucose was affected by nonanal. If the inoculum had been grown with glucose, growth with galactose was weakly. stimulated. —Growth with galactose (galactose‐grown inoculum) was strongly stimulated by nonanal if xylose at a low concentration (0.53 mM) was added. — The oxygen uptake of glucose grown cells with glucose as substrate was stimulated by 200 μM nonanal in the absence of ethanol. The respiratory activity of galactose‐grown cells was also stimulated with galactose as well as with glucose as substrate. In the absence of exogenous substrate the oxygen uptake of glucose‐grown cells was weakly stimulated by nonanal whereas that of galactose‐grown cells was strongly stimulated.
The Effects of Auxins, Amino Acids, and Catechols on the Formation of Red Pigment in Helianthus tuber slices
Authors: Suzuki Yonezo , Kanamori Tetsuo 
Published: April 2006

AbstractThe mechanism of red pigment formation in tuber slices of Helianthus tuberosus during incubation with auxins has been studied and the following results were obtained. 1. The degree of expansion of the tissue slices in the presence of indole‐acetic acid (IAA), 2,4‐dichloropbenoxyacetic acid (2,4‐D), or α‐naphthaleneacetic acid (NAA) was not parallel to the colour intensity which developed during incubation. 2. The pigment solutions which were extracted by pyridine. ethanol, or dioxane commonly showed a peak at around 515 nm in the absorption spectrum. 3. The o‐diphenol oxidase activity in the tissue slices was increased by incubation with 2.4‐D. 4. I.‐Proline or hydroxy‐L‐proline as reactants in the formation of red pigment by the o‐diphenol oxidase system could not be replaced by L‐arginine, L‐histidine and L‐tryptophan. 5. The red pigment may resemble 4‐(4′‐hydroxy‐2′‐carbethoxy ‐1′‐pyrrolidyl)‐5‐methyl‐o‐benzoquinone, formed by the o‐diphenol oxidase system in the presence of homocatechol and hydroxy‐L‐proline.
Studies in Physiological Analysis of Yield. IX, Effect of Light Intensity on the Development of the Wheat Grain
Authors: Asana R. D. , Parvatikar S. R. , Saxena N. P. 
Published: April 2006

AbstractUnder average tight intensities, 57,800 (sunlight, L), 12,900 (l1), 3900 (12) and 3300 (13) lux, during the fortnight after anthesis, the increase in the average shoot weight (excluding roots) of wheat cultivars, NP 823 and NP 824, varied as 100, 43, 24 and 10, and of cultivars, Ph C 281 and NP720, as 100, 35, 15 and 9; the corresponding increase in weight of ear varied as 100, 59, 45 and 40, in the first group and as 100, 58, 53 and 33, in the second. The increase in ear weight was relatively less affected by low light intensity than increase in shoot weight, probably because the stem‐sugars were utilized in grain‐filling. The stem‐sugars increased only in L and decreased in 11, 12 and 13. The grain number and its weight were also reduced under l1, 12 and l3. Assuming that increase in shoot weight is a measure of photo‐synthetic activity, it is inferred that during the fortnight after anthesis, current photosynthesis determines largely, but not entirely, the rate of growth of grain. After transfer to full sunlight, the grain weights of l1, 12 and 13 plants amounted, at maturity, to 93, 78 and 77 % of the value of L. The actual increase in grain weight was the same in L and l1 and slightly lower in l2, and 13. It is inferred that the same amount of photosynthate was produced in all the four treatments hut was not fully utilized in 12 and 13 because of considerable reduction in grain number. Since the sugar content of the stem in l1, I2 and l3 plants, on the 15th day after anthesis, was half as much as, or even lower than, in L, whereas the increase in grain weight was much less affected, it follows that the level of stem‐sugars does not determine the rate of growth of grain. During the fortnight before maturity, light intensity as low as 2500 lux had little effect on grain development. It is concluded that light intensity equal to that of full sunlight may not be required during the entire course of grain development. Considering that sugars accumulate in the stem during the fortnight after anthesis, and their concentration does not control the subsequent rate of growth of the grain, it is suggested that a more efficient sink (ear) may be the means by which photosynthates can be more effectively utilized and the yield potential raised further.
Regulators of Cell Division in Plant Tissues VUI. The Cytokinins of the Apple Fruit
Authors: Letham D. S. , Williams M. W. 
Published: April 2006

AbstractThe cytokinin activities of extracts of organs developed from the apple fruit bud were compared using the carrot phloem bioassay, and the identity of the cytokinins in the apple fruitlet was investigated. The activity of apple fruitlet extracts was slightly greater than the activity of pedicel extracts, and considerably greater than the activities of extracts of other organs. Extracts of the developing seeds of fruitlets were much more active than extracts of fruitlet flesh. Apple fruitlet extracts contained three principal cytokinins. One was identified as a 6‐(substituted amino)purine and was either zeatin or some very closely related compound. The two other cytokinins exhibited the chromatographic behaviour of zeatin riboside and zeatin ribotide. A cytokinin extracted from vegetative apple shoots was chromatographically indistinguishable from zeatin.
Isoenzyme Polymorphism in Flowering Plants. IV. The Peroxidase Isoenzymes of Maize (Zea mays)
Authors: Hamill D. E. , Brewbaker J. L. 
Published: April 2006

AbstractTwenty‐four peroxidase isoenzymes were identified by starch gel electrophoresis of 250 varieties of maize. Twelve of these bands corresponded in electrophoretic mobility to bands observed in commercial horseradish peroxidase. Maize tissues varied greatly in isoenzyme pattern, many tissues having a characteristic and distinguishing complement. Ontogenetic variations were observed for the leaf blade, leaf sheath, and internodes during maturation, and were related to the rates of tissue enlargement. Genetic studies of two isoenzymes, C10 and C20, indicated that they were conditioned by alleles of a single locus, here designated Px1.
Labile‐Bound Sulfate in Wheat‐Roots: Localization, Nature and Possible Connection to the Active Absorption Mechanism
Authors: Persson Lennart 
Published: April 2006

AbstractThe aim of the investigation was to identify a readily exchangeable fraction of sulfate in wheat roots and to study the nature of the fraction and its possible connection to the active mechanism for sulfate uptake. The amount of sulfate absorbed during the initial phase of uptake was higher in plants with a low sulfate status (low sulfate plants) than in plants with a high sulfate status (high sulfate plants). By adding selenate to the test solution, the same amount of sulfate belonging to this phase was obtained both in high sulfate plants and in low sulfate plants. The variations between plants of different sulfate status were believed to be due lo different capacities for labile binding of sulfate to positive sites in the roots. Selenate replaced sulfate at these sites. By leaching experiments, the positive sites were shown to be located on or outside of a very delicate barrier in the cells. The maintenance of the positive sites was demonstrated to be dependent on concurrent metabolism by adding 2.4‐dinitrophenol to the test solution and by varying the root temperature. The amount of sulfate bound to positive sites in labile binding was shown to be dependent on the pH of the test solution. At low sulfate concentrations in the test solutions, there was a quantitative connection between the magnitude of the labile‐bound fraction and the rate of active uptake into the symplasm. At higher sulfate concentrations than 0.1 mM, sulfate positive sites of lower affinity to sulfate were believed lo disturb the quantitative connection mentioned above.
Pigments et salinité chez Porphyridium
Authors: Lelclerc J. C. 
Published: April 2006

Abstract Pigments and salinity in Porphyridium.—An opal glass light transmission method is used for estimating the proportions of pigments in Porphyridium sp. Lewin, grown in artificial media. The cells show an Increase in chlorophyll/B–phycoerythrin ratio in media twice or thrice as saline as sea water, Chlrophyll/carotenoïds ratio is low in media the salinity of which is either low or high. In the case of phycoerythrins, light–absorption ratio at 500 nm and 545 nm vary also with the salinity.Une méthode de mesure par transmission de lumière á travers des lames opalines est utilisée pour évaluer les proportions de pigments chez Porphyridium sp. Lewin cultivé milieux artificiels. Les cellules montrent une augmentation du rapport chlorophylle/B.‐phycoérythrine dans les milieux deux outrois fois plus salés que l'eau de mer. Le rapport chlorophylle/carotenoïdesest faible dans les milieux dont la salinityé est soit faible soit élevée. Dans le cas des phycoérythrines, le rapport des absorptions de lumière à 500 nm et 545 nm varie aussi avec la salinityé.
Effects of Leaf Shape and Boundary Layer Thickness on Photosynthesis in Cotton (Gossypium hirsutum)
Authors: Baker D. N. , Myhre D. L. 
Published: April 2006

AbstractIn upland cotton (Gossypium hirsutum L.) certain varieties are available with the mutant character “okra” leaves. These deeply lobed leaves were found to have thinner boundary layers than their normal analogues. Apparent photosynthesis and transpiration measurements were made in field‐grown stands under a variety of light intensities and carbon dioxide levels to assess the effect of leaf boundary layer diffusion resistance on photosynthetic efficiency. The thinner boundary layers associated with deeply lobed “okra” cotton failed to euhance carbon fixation rates per unit land area. It was concluded that the leaf boundary layer resistance under field conditions is small compared with the total CO2 diffusion resistance.
Production of Lytic Exoenzymes in Casamino Acids Media by Myxococcus virescens
Authors: Haskå Guno 
Published: April 2006

AbstractThe production of proteolytic enzymes and enzymes active on autoclaved aerobacter cells by Myxococcus virescens, strain B2, was studied In Casamino acids media. By modification of the N III–B media of Norén to a higher concentration of casamino acids and to a lower content of sodium chloride, the maximal production of lytic exoenzymes could be increased at least four times.Too high a concentration of casamino acids (more than 17 g/1) and sodium chloride (30 mM), as well as too low a concentration of sodium chloride, inhibited the enzyme production.