bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Temperature on Floral Initiation in the Olive
Authors: Hackett Wesley P. , Hartmann Hudson T. 
Published: April 2006

AbstractFloral initiation is completely inhibited when the olive is grown in a glasshouse at a minimum temperature of 16°C and a maximum temperature of 27°–30°C but occurs when it is grown at natural winter conditions in California. This study was undertaken to determine more specifically the temperature requirements for flowering and to show the relation of temperature treatment to hud development and floral initiation. Results of experiments performed with trees in containers grown at constant temperatures in controlled environment growth rooms show that the optimum temperature for flowering is 10°–13°C. Either higher (18°C) or lower (4°C) temperatures inhibit flowering completely. Morphological studies show that axis elongation and floral initiation occur in buds during temperature treatment at 10°C and 13°C but fail to occur during 4°C or 18°C treatments, or following these treatments when the temperature is raised to 21°C. When plants were exposed to 13°C for varying durations, it was found that no inflorescences formed after a 7.5 week exposure but that many formed after an 11‐week exposure. A subsequent experiment showed that many more inflorescences formed after a 10‐week exposure at 13°C than after 9 weeks exposure. Morphological changes in the bud seem to be associated with this increase in flowering affected by duration of treatment.
Direct and Synergistic Influence of Tweens on Avena Coleoptile Section Elongation
Authors: Méndez J. , Vázquez A. , Mato M. C. , Vieitez E. 
Published: April 2006

AbstractThe Avena cylinder test was used with Tweens at 3 different concentrations with and without the addition of varying concentrations of IAA.Tween 20 was a toxic substance for oat coleoptile sections at such concentration as 0.1 %. Tween 40 gave erratic results and Tween 80 has practically no direct effect on cell elongation. An inhibitory effect continues to increase with increasing HLB values.The second object of this experiment was to ascertain whether cell elongation promoted by IAA would be enhanced by osmotic substances such as Tweens, as consequence of a specific modification in the permeability when the membranes are lipid in nature. The hypothesis was supported by the experimental work when 0.05 % Tweens were assayed although the inverse was also true, with concentrations of Tweens as low as 0.01 %. Accordingly, evidence must be verified by further investigation.
Arsenite‐BAL as an Inhibitor of Germination
Authors: McDonough Walter T. 
Published: April 2006

AbstractImbibition of light‐sensitive lettuce seeds in mixed solutions of sodium arsenite and 2,3‐dimercaptopropanol (BAL) inhibits light‐induced germination more potently than does arsenite alone, particularly at higher temperatures. There is limited reversal of the enhanced inhibition at high BAL/arsenite ratios. The complex is also more inhibitory than arsenite after shorter periods of imbibition. Monothiol compounds do not give the increased inhibition, nor do combinations of BAL with other thiol group reagents. Greater penetrability, possibly into some internal compartment of the cell, is suggested as the cause of the enhancement. Induction of germination by gibberellic acid or low temperature is equally sensitive to arsenite‐BAL. The extent of the inhibition of germination of 9 other species by arsenite‐BAL is not clearly related to their light‐sensitivity.
Nitrate Reductase in the Citrus Plant: Properties, Assay Conditions and Distribution within the Plant
Authors: Bar‐Akiva A. , Sagiv J. 
Published: April 2006

AbstractA nitrate reductase enzyme preparation has been obtained from citrus plant tissue extract and the optimal assay conditions have been established. The enzyme has been found to be similar or even identical to those of many other annual plants, i.e., cysteine is required for its extraction in the active state, it is DPNH‐specific, and in some cases FAD‐dependent.Comparisons were made between the activity measured in fragments with that of the extracted preparation of the same plant tissues.The occurrence of the enzymes was demonstrated in germinating seeds, cotyledons, rootlets, shoots, leaves and fruit of citrus plants.
The Effect of Blue and Red Light on NADP‐linked Glyceraldehydephosphate Dehydrogenases in Excised Roots
Authors: Björn L. O. 
Published: April 2006

Abstract d‐Glyceraldehyde 3‐phosphate: NADP oxidoreductasc (phosphorylating), EC 1.2. 1.13, is formed in excised roots of wheat and pea grown in blue light, but not in red light or darkness. The nonphosphorylating d‐glyceraldehyde 3‐phosphate: NADP oxidoreductase, EC 1.2.1.9, if present at all, constitutes only a minor fraction of the total activity. In wheat roots the time‐course for increase in enzyme activity agrees completely with the time course for increase in chlorophyll content, with a lag phase of 3 days for both. The results for pea roots are similar, but less clear‐cut due to interfering enzymes. The results are discussed with reference to a previously published scheme for chloroplast development.
The Use of Polarography in the Assay of Oxygen Diffusing from Roots in Anaerobic Media
Authors: Armstrong W. 
Published: April 2006

AbstractA “polarographic” technique by which the rate of outward diffusion of oxygen from plant roots may be measured, is described in detail.Oxygen has been found to diffuse from the roots of all of the ten species of bog‐plants so far tested, and the oxygen diffusion rates (ODR) of eight of these species show the existence of interspecific differences. Model roots made from silicone rubber tubing give “polarographs” identical with those obtained around the living roots.Suberization accompanying root maturation is thought to account for a. the association of oxygen diffusion with the apical regions of roots, and b. the lowered diffusion rates associated with winter dormancy. This localisation of root oxygen diffusion may be of survival value in reduced soils.Experiments suggest that aerenchyma can function as an oxygen reservoir in the plant if the stomata were closed for long periods.Calculations of expected ODR based on the internal gas concentrations of a model system give readings very similar to the ODR obtained experimentally using the silicone rubber tubing models.Further calculations, based on reported internal gas concentrations for Menyanthes, rice, Spartina, and Schoenus, also show a close similarity between real and expected values. It is concluded that in these species at least, there is negligible resistance in certain regions of the root to the passage of oxygen from the root intercellular spaces to the surrounding medium.Results have shown that root bases are relatively impermeable to oxygen, and it is suggested that oxygen intake into roots in the basal regions reported by other workers, probably occurs through basally‐borne laterals.One important function of diffusing oxygen from the root is probably the supply of an external source of oxygen to the root meristem.
The Influence of Dormancy‐Inducing Desiccation Treatments on the Respiration and Germination of Sorghum
Authors: Nutile G. E. , Woodstock L W. 
Published: April 2006

AbstractSeeds of sorghum (Sorghum vulgare Pers.) dried in a forced‐air dryer from an initial moisture content of 12 percent to either 10 percent or 7 percent exhibited physiological dormancy. Dormancy was more marked in seeds dried to 7 percent than to 10 percent moisture, and was more pronounced in germination at 15° or 20° than at 25°C. Expression of dormancy at the lower temperatures was influenced decidedly by the four germination media (paper towels, blotters, sand, and soil). Percent dormancy was lowest in towels and highest in soil. Osmotic tension is suggested to be a factor influencing dormancy in these media. Dormancy was relieved by cutting the integumentary membrane or by rehydration of dried seeds. Respiration rates were lower and respiratory quotients higher in dormant seeds than in the controls. Differences in respiration rates were detected within 2 hours after the start of imbibition.Dormancy and differences in respiration rates appear to be associated with changes induced in the seeds by drying.
Relationships between Photo‐induced and Gravity‐induced Electrical Potentials in Zea Mays
Authors: Johnsson Anders 
Published: April 2006

AbstractA comparison is made between gravity‐induced and light‐induced transversal electrical potentials in excised coleoptiles of Zea Mays. The potentials are measured with a vibrating condensor method, thus the plants are not touched at the measuring point. It is found that all experimental evidence supports the assumption that the reaction chains leading to the potentials are identical in the two cases, apart of course from the perception stages. This theory is based on the following points which have been experimentally verified:

The stimulus‐response functions are quite similar. In both cases the voltage is a logarithmic function of the stimulation time (at least for shorter stimulation times). When continuous stimulation is used, the stimulation time must exceed a threshold value to cause a transversal potential.
Some inhibitors (DNP and NaN3) diminish both types of potential.
A latency time is found in photo‐induced potentials as well as in gravity‐induced ones. The Q10 for the latency period of the photo‐induced potentials is found to be 2.8, which is the same as for the chemical part of the latency period of the gravity‐induced potentials.
In both cases the potential‐generating process is controlled by a Q10 of 1.6–1.8, thus indicating this process as separate from the one mentioned above.
The temperature dependence of the maximum voltage follows in both cases the same pattern with a maximum at about 25–30°C.

Some measurements on potential oscillations are described and discussed. The origin of the potentials is discussed.
Effect of 2‐deoxy‐D‐glucose on the Respiration of Tropical Anthracnose Fungi
Authors: Greene G. L. 
Published: April 2006

AbstractThis study begins an investigation of the chemical activities of one of the most destructive groups of spoilage organisms of tropical foods, the anthracnose fungi. The present paper treats of an introductory investigation on carbohydrate metabolism.Two fungi isolated from rotted banana tissue, Gloeosporium musarum and Colletotrichum gloeosporioides, were grown in the presence of 2‐deoxy‐D‐glucose, a metabolic blocking agent, in shake culture. The mycelia produced were studied in the Warburg respirometer in the presence of glucose, 2‐deoxyglucose, and 2,4‐dinitrophenol. Gloeosporium musarum was found to be incapable of growth in the presence of 2‐deoxyglucose as the sole carbon source, but did grow when glucose was added. Colletotrichum gloeosporioides grew normally, but at a slower rate on 2‐deoxyglucose than on glucose. Glucose grown G. musarum and C. gloeosporioides both exhibited respiratory inhibition in the presence of 2‐deoxyglucose, whereas 2‐deoxyglucose adapted C. gloeosporioides did not. The uncoupling agent 2, 4‐dinitrophenol induced respiratory stimulation except in the presence of 2‐deoxyglucose in glucose grown C. gloeosporioides where it caused a drop in oxygen uptake.
The Metabolism of Carbon‐14 Specifically Labelled Glucose in Leaves Showing Tobacco Mosaic Virus Induced Local Necrotic Lesions
Authors: Merrett M. J. , Sunderland D. W. 
Published: April 2006

AbstractGlucose metabolism of healthy and tobacco mosaic virus‐infected leaf‐discs of Nicotiana tabocum L. var. Xanthi showing local‐necrotic lesions was investigated using glucose‐14C. Local lesion formation following inoculation with tobacco mosaic virus resulted in enhanced glucose metabolism reflected by an increased rate of release of 14CO2 from glucose‐U‐14C and greater incorporation of 14C into all cell fractions. When specifically labelled glucose was fed to healthy and tobacco mosaic virus infected leaves, the C6/C1 ratio (rate of release of 14CO2 from glucose‐6‐14C/rate of release of 14CO2 from glucose‐l‐14C) was similar for healthy and virus‐infected leaves. The C6/C1 ratios recorded from 0.30 to 0.50 indicate that both the glycolytic and pentose phosphate pathways participate in glucose catobolism in healthy and virus‐infected leaves. Although the C6/C1 ratio was the same as that of the healthy leaf the rate of release of 14CO2 from glucose‐6‐14C and glucose‐1‐14C was greatly increased in the virus‐infected leaf. The increased glucose catabolism occurs by both glycolytic and pentose phosphate pathways in the virus‐infected leaf.
The Cultivation of Tissues of Cupressus lusitanica in vitro
Authors: Borchert Rolf 
Published: April 2006

AbstractConditions for In vitro culture of initial explants of Cupressus lusitanica were determined as the first step of an investigation of physiological differences between tissues obtained from plants, or plant parts, of different ages. Explants proliferated well on a basal agar medium containing only Heller's mineral salts and sucrose. Addition of several vitamins, phytohormones, and coconut water to this basal medium stimulated callus growth only slightly or not at all, and transplanted callus soon died. Proliferation of initial explants was considerably stimulated by increasing the concentration of mineral salts in the medium, and the growth habit changed from compact to friable. Callus could be transplanted to, and maintained on, a high‐salt medium enriched by vitamins. Whereas added auxins still stimulated proliferation of initial explants and transplanted callus only slightly, added coconut water was considerably more effective than on basal medium. Thus results confirm observations by others with tobacco tissues: Additions of phytohormones and other organic substances may not exert their potential effects if growth is limited by sub‐optimal mineral nutrition.
The Effect of ATP (Disodium Salt) upon Rotational Streaming
Authors: Pop Emil , Soran Viorel , Lazǎr Georgeta 
Published: April 2006

AbstractThrough the continuous treatment with various solutions of ATP disodium salt the rotational streaming of the cytoplasma in barley root hairs has been stimulated about 1.2–1.7 times. With the concentrations employed the stimulation of the streaming did not depend on the external ATP supply, but on the initial rate of streaming. It is assumed that the main source of energy supporting the protoplasmic streaming is ATP. Therefore, the results obtained may be interpreted on the basis of variations in ATP content and its degradation products. The differences between initial rates of streaming are supposed to be due to variations of the endogenous ATP level. The ATP taken up probably stimulates the rotational streaming both through the supply of delivered energy and by lowering the cytoplasm viscosity. On the contrary, products of ATP hydrolysis increase the cytoplasm viscosity and induce a lowering or even cessation of the streaming.
Subcellular Location of Phosphoglucomutase and UDP Glucose Pyrophosphorylase in Avena Coleoptiles
Authors: Hall M. A. , Ordin L. 
Published: April 2006

AbstractExtraction of phosphoglucomutuse and UDP glucose pyrophosphorylase from oat coleoptiles using both aqueous and non‐aqueous systems showed that both enzymes are largely soluble. Phosphoglucomutase was completely absent from the cell wall fraction. The inhibition of phosphoglucomutase by peroxyacetyl nitrate was confirmed and the enzyme in the subcellular participate fractions was shown to be more inhibited than that in the soluble fraction. UDP glucose pyrophosphorylase was not inhibited by peroxyacetyl nitrate or ozone in vivo but was inhibited by peroxyacetyl nitrate in vitro. The SH reagents, iodoacetamide and p‐chloromercuribenzoate, inhibited phosphoglucomutase severely but UDP glucose pyrophosphorylase moderately or not at all.
The Components of the CO2‐Indluced Stomatal Movements
Authors: Stålfelt M. G. 
Published: April 2006

AbstractLeaf discs of Vicia Faba were allowed to float on water in glass dishes placed in vessels containing KOH. The vessels were kept in darkness at constant temperature. The stomatal width and osmotic values of the guard cells and epidermal cells were measured, generally at one‐hour intervals.When the CO2 content of the air surrounding the leaf specimen falls, it causes a disturbance in the osmotic equilibrium between guard cells and epidermal cells. Sometimes the changes start in the form of falling osmotic values in both kinds of cell. In other cases the values rise, and in still others the changes may be confined chiefly to one of these kinds of cell. Since the changes are not the same in guard cells and epidermal cells, the osmotic difference between them rises or falls. The difference rises during the time immediately after removal of CO2 from the surrounding air. This causes an osmotic surplus to arise or increase in the guard cells. Later, this change may take place in the opposite direction. The stomatal movements occurring simultaneously follow, on broad lines, the osmotic surplus of the guard cells.Consequently, the CO2‐induced stomatal movement is the result of an interaction between an active component—i.e., the intrinsic osmotic changes in the guard cells—and an osmopassive component, by which is meant here the osmotic changes in the epidermal cells.
Effect of Gibberellic Acid and Cycocel on Tryptophan Metabolism and Auxin Destruction in the Sunflower Seedling
Authors: Valdovinos Jack G. , Ernest Leland C. 
Published: April 2006

AbstractA comparative study of tryptophan conversion in different regions of the sunflower seedling indicates that the regions most active in converting tryptophan on a pathway to auxin are the root apical segments and young leaves; next highest in activity is the cotyledonary tissue. The stem apex proper with leaf primordia is less active than the above regions in converting the auxin precursor. Hypocotyl tissue was observed to be least active. Pre‐treatment of the apical bud region of the stem with gibberellic acid (GA) gives rise to tryptophan conversion rates which are 2.1 times those in untreated seedlings. The enhanced tryptophan conversion in the apical bud is followed by an increased elongation rate of the 1st internode which is 2.2 times that in the 1st internode of untreated seedlings. Treatment of the seedlings with Cycocel [(2‐chloroethyl)trimethylamnionium chloride] does not reduce tryptophan conversion in the apical bud region of the seedling although elongation of the stem is greatly retarded.Indoleacetic acid (IAA) destruction in cell free preparations as well as in whole sections of the elongating region of the seedling stem was studied. IAA‐1‐14C destruction rates with the release of 14CO2 in whole sections of 1st internode tissue were approximately 3 times those in cell free preparations of the same region. No significant changes in IAA destruction rates in seedlings pre‐treated with GA or Cycocel were observed.
Effect of Some Dithiocarbamates on Respiration Activity of a Myxomycete
Authors: de Meester C. , Lambert R. , Wiaux A. 
Published: April 2006

AbstractThe presenl article aims at giving some information concerning the mode of action of three dithiocarbamates: ferric dimethyldithiocarbamate (Ferbam), zinc dimethyl‐dithiocarbomate (Ziram) and tetramethylthiuram disulfide (Thiram). These inhibitors were tested on the respiratory activity of the Myxomycete: Physarum polycephalum. Its development is strongly inhibited at 285 mg/l. With such concentration, respiration measurements confirmed total inhibition of O2 uptake. After isolation of the mitochondria, the tests showed that there may be an inhibition of the succinic oxidase activity of this particulate fraction, at 28.5 mg/l of Thiram.Heavy concentration of reduced glutathione (1.4 %) reversed partially this Inhibition. This seems to prove that succinic dehydrogenase is a typical SH‐type enzyme.
Oxidative Enzymes of Ceratocystis fimbriata Isolates Differing in Host Specificity
Authors: Meagher R. B. , DeVay J. E. , Kosuge T. 
Published: April 2006

AbstractEight isolates of Ceratocystis fimbriata differing in pathogenicity on sweet potato roots were compared in vitro for peroxidase, catalase and polyphenol oxidase activities.Pathogenic isolates were generally lower in specific activities of peroxidase and catalase than the nonpathogenic isolates.Cultures of pathogenic isolates were distinguished by black culture liquid compared to the yellow color of nonpathogenic isolates.No consistent differences among the isolates were apparent when the specific activity of polyphenol oxidase preparations were compared on various phenolic substrates.The peroxidase of C. fimbriata had an approximate molecular weight of 81,000 when compared with known protein standards on a column of Sephadex G‐100 dextran gel. Its substrate specificity differed from horseradish peroxidase in that it was nonreactive with guaiacol.
The Effects of Sucrose and Light on the Level of Soluble and Particle‐bound Ribonuclease Activities in Excised Avena Leaves
Authors: Udvardy J. , Farkas G. L. , Marré E. , Forth G. 
Published: April 2006

AbstractIncubation of excised Avena leaves in a wet chamber in darkness resulted in an increase in both soluble and particle‐bound Rnase activities. Illumination promoted the increase in the total RNase which occurred upon leaf excision. The light‐induced increase in total RNase was due to an increase in soluble RNase. The increase in RNase activity in the particulate fraction was inhibited by illumination. Feeding 2 per cent sucrose to the tissues in the dark increased the level of soluble RNase and decreased the activity found in the particulate fraction. Treatment of the illuminated tissues with 10−4M dichlorophenyldimethylurea (DCMU) inhibited the effects of light on the RNase level. It is concluded that the light‐effect is explained at least in part by the photosynthetic production of sugars.In excised leaves kept in darkness the RNA content rapidly decreased. Feeding sugars to or illumination of the tissues lowered the rate of RNA breakdown due to leaf excision. DCMU counteracted the light effect. In general, the decrease of RNA was repressed by all treatments leading to an inhibition of the increase of particulate RNase. On the other hand, the observed changes of the soluble RNase were not related with the variations of RNA.Treatment with 3 M urea increased the RNase activity both in the particulate and the soluble fractions. The RNase activity of soluble preparations, partially purified on a Sephadex G‐50 column or by (NH4)2SO4 fractionation, was also stimulated by 3 M urea.Treatment with 10−5M kinetin repressed the increase in RNase activity due to leaf excision both in the soluble and the particulate fractions.
Effect of Reciprocal Bud‐Graft Transfers Between Old Home and Bartlett Pears and Centrifugatiou on Trans‐location of Endogenous Growth Substances in Hardwood Cuttings
Authors: Fadl Mostafa S. , Hartmann Hudson T. 
Published: April 2006

AbstractAn investigation was made of the effect of bud‐graft exchanges between two pear varieties—the easily‐rooted Old Home and the hard‐to‐root Bartlett—on the root‐promoting activity of extracts obtained from basal segments of hardwood cuttings of each variety. The effect of a centrifugal force obtained from 2000 rpm for 30 minutes on the root‐promoting activity of diffusates and extracts from bases of centrifuged cuttings of these two varieties was also studied.Bud exchange treatments showed no appreciable influence on the root‐promoting or inhibiting activity of basal extracts unless the transbudded shoots (used for making cuttings) were girdled one month prior to the sampling date; in such cases an influence did appear.The centrifugation treatment increased the number of buds sprouting on cuttings. It also increased the root‐promoting activity of extracts from the basal parts of cuttings and of their growth‐active components (separated by paper chromalography) when bioassayed by the mung bean rooting test. Apparently some inhibitory materials from the buds were removed through the bases of the cuttings by centrifuging.