bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Exogenous Fatty Acids on Cottonseed Germination
Authors: BARTKOWSKI EDMUND J. , KATTERMAN FRANK R. H. , BUXTON DWAYNE R. 
Published: April 2006

AbstractEffects of exogenous free fatty acid application on percentage germination and radicle length were investigated with more chill sensitive (Pima S‐4) and less chill sensitive (Pima S‐5) cottonseed (Gossypium barbadense L.) at chilling (14°C) and optimal (34°C) temperatures. Of the organic solvents able to solubilize free fatty acids, aqueous solutions as high as 5% dimethyl sulfoxide did not adversely affect germination at 34°C. Palmitic, oleic and linoleic acids (120 μM) were solubilized in 5% DMSO.At 14°C, percent germination of fatty acid treated Pima S‐5 significantly increased, while no difference was observed for Pima S‐4. Conversely, radicle length of fatty acid treated Pima S‐4 significantly increased especially with oleate and linoleate, while no difference was detected for Pima S‐5. Fatty acid supplementation influenced neither germination nor radicle length for Pima S‐4 and Pima S‐5 at 34°C.
Formation of Cytokinin Nucleotides in a Detached Inflorescence Stalk and the Occurrence of Nucleotides in Phloem Exudates from Attached Yucca Plants
Authors: VONK C. R. 
Published: April 2006

AbstractThe metabolism of isopentenyl adenine, Δ‐isopentenyl pyrophosphate, DL‐mevalonic acid and adenine in detached inflorescence stalks of Yucca has been studied using radioactive tracer techniques.Xylem feeding of detached stalks with Δ‐isopentenyl pyrophosphate, DL‐mevalonic acid or adenine did not result in the formation of zeatin‐ or isopentenyl adenine cytokinins.In contrast isopentenyl adenine fed to a detached inflorescence stalk lead to the formation of isopentenyl‐ and zeatin nucleotides in the exudate. After alkaline phosphatase treatment of this exudate an unknown compound, presumably isopentenyl adenine‐7‐glucoside was also detected. The same compound was found after incubation of phloem exudate with isopentenyl adenine.The occurrence of both zeatin‐ and isopentenyl adenine nucleotides in phloem exudate from an attached inflorescence stalk of Yucca is described.
Effect of Salinity on the Activities of RNase, DNase and Protease during Germination and Early Seedling Growth of Mung Bean
Authors: SHEORAN I. S. , GARG O. P. 
Published: April 2006

AbstractSeeds and seedlings of mung bean (Phaseolus aureus Roxb.) were treated separately with NaCl, KCl, Na2SO4 and K2SO4 solutions of 5 and 10 S/cm conducitivity. The activity of RNase, DNase and protease were estimated in cotyledons, embryo axis, leaves, and roots. Salinity caused inhibition of RNase activity in the cotyledons and roots, but increase in embryo axis and leaves. Activity of DNase was also increased; sodium salt was more effective than potassium irrespective of associated anion. Salinity in general either reduced or had no effect on protease activity in all organs, with the exception of NaCl which doubled it in leaves.
Polarity of Xylem Formation in Isolated Stem Segments of Pinus silvestris
Authors: ZAJĄCZKOWSKI STEFAN , ROMBERGER J. A. 
Published: April 2006

AbstractThe culture of isolated stem sogments was used as a technique to study polarity of xylem formation in Pinus silvestris L. Cambial activity was greatest at the apical or the basal end, whichever received the complete fresh medium, but decreased more abruptly with increasing distance when the basal end was so supplied. Whether gradients of activity increased basipetally or acropetally also depended upon the end to which the auxin and the sugar components were supplied. Ring‐barking of segments, then cultur‐ing them with apical supply of medium to the xylem, resulted in inhibition of xylem production below, and above, the ring. Cambial activity at the apical ends of such segments was expressible as a logarithmic function of the uninterrupted length of contiguous extraxylary tissues. The involvement of polarity phenomena in control of cambial activity in isolated stem segments is confirmed.
Seasonal Effects on Chlorophyll‐Protein Complexes Isolated from P‐inus silvestris
Authors: ÖQUIST GUNNAR , MÅRTENSSON OLLE , MARTIN BJÖRN , MALMBERG GUNILLA 
Published: April 2006

AbstractThe seasonal changes in the relative distribution of P700 chlorophyll‐protein complex a1 and light harvesting chlorophyll‐protein complex a/b were studied in a natural stand of Pinus silvestris. Similar measurements were made after artificial photobleaching of chlorophyll in pine seedlings or in isolated pine chloroplasts. The chlorophyll‐protein complexes were solubilized by sodium dodecyl sulphate and separated by polyacrylamide gel electrophoresis. When autumn and winter destruction of chlorophyll occurs, the chlorophyll a antenna associated with P700 in photosystem 1 (P700‐CPa1) is relatively more affected than the light harvesting complex, which lacks a reaction centre. These results are further supported by low‐temperature fluorescence emission properties of isolated chloroplasts presented in this work and elsewhere. The destruction of chlorophyll in stressing autumn and winter climates is most probably caused by photosensitized oxidation of chlorophyll.
Daily Patterns under the Life Cycle of a Maize Crop
Authors: ANDRÉ M. , MASSIMINO D. , DAGUENET A. , RICHAUD C. , VIVOLI J. 
Published: April 2006

AbstractTogether with photosynthesis, transpiration and respiration, the daily uptake of NO3−, NH4+, H2PO4−, K+, Ca2+, Mg2+, SO42−, the root respiration, root volume increase and root excretions have been studied by daily measurements during the growth period of whole maize plants (Zea mays L. cv. INRA F7 × F2) raised until complete maturity on nutrient solution. The uptake patterns show a maximum absorption of NO3−, K+ and Ca2+ during the vegetative growth phase. The absorption of these ions declines during maturation while that of H2PO4− reaches a maximum. Root respiration and particularly the uptake of NO3− and K+ are well correlated with the rate of root growth. Root excretion is more notable in young plants than in the old. It represents less than 0.2% of the net assimilation of adult plants.
Morphology and Physiology of Lyngbya nigra with Reference to Copper Toxicity
Authors: GUPTA A. B. , ARORA ASHA 
Published: April 2006

AbstractThe effect of copper sulphate on morphology and physiology of Lyngbya nigra has been studied. The growth was inhibited in all treatments (0.4 to 80.0 μM) of copper sulphate. There were no apparent morphological changes up to 0.8 μM and during the first two days of treatment even in the higher concentrations of copper sulphate.In concentrations above 0.8 μM the first symptom of toxicity was the formation of separation discs in large numbers. The trichomes contracted longitudinally and the cells became swollen and constricted at the cross walls. The cells also became yellowish due to loss of photosynthetic pigments. Finally, in 4 μM and above, vacuoles appeared in large number indicating the moribund state of the cells.Copper sulphate increased respiration at 2 μM, and optimum effect was observed in 8 μM after 96 h. Inhibition of photosynthesis was detectable in 0.8 μM, and 100% inhibition took place in 8 μM after 96 h. In higher concentrations the effect was immediate, and a conspicuous inhibition of photosynthesis could be observed within 10 min.The copper content of the alga increased with increased concentration of copper sulphate while potassium content decreased. With rise in outside concentrations of copper, there was a comparatively great increase of absorption in 2 and 4 μM, while further increases were gradually less. The observations indicate that changes in the physiological activity of the alga under treatment are closely interlinked with marked changes in morphology.
Lipid Properties of Carex aquatilis from Hot Spring and Permafrost‐Dominated Sites in Alaska: Implications for Nutrient Requirements
Authors: KEDROWSKI RICHARD A. , CHAPIN F. STUART 
Published: April 2006

AbstractSelected lipid properties were compared between populations of Carex aquatilis occupying adjacent hot spring and permafrost‐dominated sites in interior Alaska. Analyses were carried out on a variety of plant parts and results correlated with prevailing ambient temperature. Phospholipid concentrations were higher in plants from permafrost than from hot spring areas, even though there was no consistent interpopulation difference in total lipid content. The population differences in phospholipid content were greatest in those plant parts that experienced the greatest interpopulation temperature difference. Despite lower soil phosphorus availability, permafrost plants had higher total phosphorus concentrations, and a larger proportion of their phosphorus was contained in phospholipid than in hot spring plants. There was no consistent relationship between the proportion of various classes of phospholipids present and prevailing ambient temperature. Fatty acid chain length and degree of unsaturation of the phospholipid fraction were inversely correlated with temperature both between populations and among plant parts. No such relationship was found in the fraction containing neutral lipids. We suggest that the high tissue phosphorus content that characterizes northern plants may be necessary in part to maintain large quantities of phospholipid‐containing membrane. Increased amounts of membrane in turn may be a prerequisite for the high rates of membrane‐associated processes characteristic of plants in the cold subarctic environment.
Gibberellin like Substances in Parts of Developing Barley Grain
Authors: MOUNLA M. A. KH. 
Published: April 2006

AbstractIn husks, the activity of gibberellin‐like substances extracted with aqueous methanol (M‐“free” GAs) showed a maximum on the 9th day after pollination. In developing embryos, M‐“free” GAs showed no biological activity, whereas biological active component(s) were obtained when the embryos were extracted with Tris buffer. The “free” GAs found in the buffer homogenates (B‐“free” GAs) of developing embryos showed a maximum of activity on the 33rd day after pollination. Bound GAs recovered from the precipitated protein of the buffer homogenate (“Protein‐bound” GAs) were found in embryo and endosperm.Developing endosperm generally contains the major amount of the extractable gibberellin‐like substances. In this tissue, the amount of all examined fractions (M‐“free” GAs, B‐“free” GAs and “protein‐bound” GAs) increased after pollination to reach a maximum on the 21st day, before decreasing to a minimum at grain maturity. Moreover, the curves for dry weight increase and gibberellin like substances follow a remarkably similar course, with the latter reaching its maximim slightly earlier than the former one. This result indicates that gibberellines may participate in the regulation of the accumulation process in the endosperm of barley grain.
Action de quelques phytohormones sur la respiration et ľabsorption du phosphate par des disques de tubercules de pomme de terre en survie
Authors: HOURMANT Par ANNICK , PENOT Et MICHEL 
Published: April 2006

Abstract Action of some phytohormones on the respiration and on the absorption of phosphate by aging potato tuber discs.Discs of potato tuber incubated in aerated medium show an increase of the rates of respiration and phosphate absorption with aging time; the rates increase by two and nine respectively during the time period between 5 and 24 h of aging. Adenine or some N‐6 substituted adenines [benzylaminopurine (BAP), furfurylaminopurine (FAP), methylaminopurine (MAP)], which present variable degrees of cytokinin activity, partially inhibit the increase of the rate of phosphate absorption and, to a lesser extent, the increase of the rate of respiration. Also abscisic acid (ABA), indole 3‐acetic acid (IAA), and gibberellic acid (GA3) produce inhibition of the increase of the rate of phosphate absorption with varied effects on the respiration. With regard to phosphate uptake, the effects of ABA, 1AA and GA3 were additive to those of BAP. The effects on respiration were different from the effects on phosphate uptake, so that there is no direct relationship between inhibition of respiration and inhibition of phosphate uptake.
The Influence of Photoperiod and Temperature on the Development of Frost Hardiness in Seedlings of Pinus silvestris and Picea abies
Authors: CHRISTERSSON LARS 
Published: April 2006

AbstractThe influence of short days and low temperature on the development of frost hardiness in seedlings of Scots pine (Pinus silvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown for 6 months in glasshouses and climate chambers, was investigated. The degree of hardiness was estimated by freezing the shoots of the seedlings to predetermined temperatures. After 8 weeks in a glasshouse the viability of the seedlings was determined by establishing bud flushing.The most effective climate for the development of frost hardiness was short days (SD) and low temperature (2°C); the next most effective was SD and room temperature (20°C). However, long days (LD) and low temperature also had a marked effect on the development of hardiness. A combination of 3 weeks’treatment with SD and 20°C, and 3 weeks with SD and 2°C gave the same results as 6 weeks with SD and 2°C. The results clearly demonstrate the importance of the photoperiod prior to low temperature for the development of frost hardiness.In conclusion both short days and low temperature induce frost hardiness development. Probably this occurs by initiation of different processes in the two cases. The degree of frost hardiness development appears to depend on the sum of these different processes and on the timing between them.
Ca2+‐ and Mg2+‐stimulated ATPases from Roots of Plantago major and Plantago maritima: Response to Alterations of the Level of Mineral Nutrition and Ecological Significance
Authors: KUIPER DAAN , KUIPER PIETER J. C. 
Published: April 2006

AbstractGrowth of Plantago major L., ssp. major L. and ssp. pleiosperma Pilger and P. maritime L. was followed at two levels of mineral nutrition (low‐salt and high‐salt). In addition the response of transfer of plants from low‐salt conditions to high‐salt conditions and vice versa was studied. Growth of the studied Plantago species was strongly stimulated by high‐salt conditions.The Ca2+‐ and Mg2+‐stimulated ATPase activity of microsomal preparations of the roots was also studied. In P. major ssp. major and P. maritime a major pH optimum was observed at pH 6.5, and in addition a second pH optimum was found at pH 8.0. High‐salt plants of these two species were characterized by biphasic stimulation curves for Ca2+ and Mg2+, whereas P. major ssp. pleiosperma showed a monophasic pattern. The ATPase activity per g dry weight of P. major and P. maritima was highest in high‐salt plants. The species investigated here are adapted to relatively nutrient‐rich conditions, and the properties of ATPases (Km, Kmax, protein content) and the growth responses are discussed in relation to this ecological property.
Enzymes Related to Serine Synthesis in Spinach Chloroplasts
Authors: LARSSON CHRISTER , ALBERTSSON ELISABETH 
Published: April 2006

AbstractThe three enzymes D‐3‐phosphogIycerate dehydrogenase (E.C. 1.1.l.s), eqglutamate dependent O‐phospho‐L‐serine aminotransferase (E.C. 2.6.1.52), and O‐phospho‐L‐serine phosphatase (E.C. 3.1.3.3.), which together catalyse the turnover of D‐3‐phos‐phoglycerate (3‐PGA) to serine were assayed in chloroplast and leaf extracts from spinach (Spinacia oleracea). Relatively high activities of the dehydrogenase and the phosphatase were found in both chloroplast and leaf extracts, whereas the specific activity of the aminotransferase was 10 times higher in leaf extracts than in chloroplast extracts. The results suggest that spinach chloroplasts are able to produce minor amounts of serine directly from 3‐PGA, but that the main part of the phosphohydroxypyruvate formed is exported, and probably used in a parallel pathway to serine outside the chloroplasts. Some kinetic properties of the enzymes were also determined.
Uptake and Distribution of Nitrogen in Young Apple Trees after Application of Nitrate or Ammonium, with Special Reference to Asparagine and Arginine
Authors: TROMP J. , OVAA J. C. 
Published: April 2006

AbstractApple rootstocks M.7 were given either nitrate or ammonium at the end of September. Until the following June, total and protein nitrogen and the composition of the soluble nitrogen fraction were followed in the roots, stem‐bark, and new growth. Nitrogen from both sources was readily absorbed in roughly the same amounts. Absorption occurred in the autumn and especially in the following spring. Incorporation of the absorbed nitrogen took place exclusively in the young roots. Arginine and, to a lower degree, asparagine were by far the most abundant of the soluble amino compounds and reached levels far above those in the unfertilized trees. The asparagine/arginine ratio was rather high during the first few weeks after fertilization but then dropped steadily to a low winter level. During May and June there was a gradual decrease to very low levels, especially in the new growth. The data suggest that the absorbed nitrogen is incorporated into asparagine and that arginine is formed from asparagine if the supply of nitrogen exceeds the immediate needs.Throughout the experimental period, ammonium fertilization led to higher values of the asparagine/arginine ratio than did nitrate nutrition. This is explained in terms of an enhanced production of asparagine and a retarded conversion into arginine. It is argued that asparagine is the main translocation compound for nitrogen. The possibility is discussed that, in addition, arginine moves upwards by a process of exchange along the negatively charged walls of the xylem vessels.
The Effect of Coumarin on Young's Modulus in Sunflower Stems and Maize Roots and on Water Permeability in Potato Parenchyma
Authors: UHRSTRÖM INGER , SVENSSON SVEN‐BÖRJE 
Published: April 2006

AbstractBy means of the resonance frequency method Young's, modulus has been determined after coumarin treatment of growing segments of etiolated sunflower hypocotyl segments and in maize roots. Coumarin caused a decrease in Young's modulus in both shoot and root tissue. The response was very rapid; in sunflower hypocotyls the decrease in elastic modulus appeared 3 min after application of coumarin. The effects produced by coumarin were similar to those found by auxin. Coumarin increased the rate of water efflux out of potato parenchyma by about 20%. The increase in water permeability was evident within 3 min.
Effects of Ultraviolet‐B Radiation Stress on the Abscisic Acid Status of Rumex patientia Leaves
Authors: LINDOO SUSAN J. , SEELEY SCHUYLER D. , CALDWELL MARTYN M. 
Published: April 2006

AbstractTo determine if increased abscisic acid (ABA) levels are associated with ultraviolet‐B (UV‐B) radiation (288–320 nm) stress, Rumex patientia L. plants were exposed to visible light with high or low (control) UV‐B irradiance and then assayed for ABA by gas chromatography. Though leaf growth was inhibited by the UV‐B irradiation, no differences in levels of free ABA were found between leaves from the two treatments after 1, 3 or 5 days of exposure. Unlike the situation in most environmental stresses, increased ABA levels are not associated with UV‐B radiation stress. Further, photolysis or isomerization are not likely explanations for the absence of ABA increase. Calculations indicate that if ABA in the leaf were fully exposed to solar UV‐B radiation only about 6.7% would be photolyzed by existing daily radiation at 40°N latitude, and 11.3% by radiation resulting from a 40% decrease in atmospheric ozone. The quantum yield for isomerization of cistrans‐ABA by radiation in the 288–312 nm waveband was determined. Existing daily solar UV‐B irradiation is capable of isomerizing ABA in solution to an equilibrium mixture of 50% cisjrans and 50%irans, trans‐ABA., However, because of radiation attenuation in the leaf, it is estimated that only a small fraction of the cistrans‐A.BA. would be isomerized.
Influence of Cytokinins and Temperature on Development of Asparagus plumosus Shoot Tips in vitro
Authors: FONNESBECH ANNE , FONNESBECH MOGENS , BREDMOSE NIELS 
Published: April 2006

AbstractLateral shoot tips from young shoots of Asparagus setaceus (Kunth) Jessop (syn. A. plumosus Baker) were grown on a modified Murashige and Skoog medium. PBA was the most effective cytokinin for growth and development of Asparagus plumosus shoot tips. The optimal range of PBA was between 0.02 and 2 mg/1. Zeatin was less effective, and kinetin, BA and 2iP were poor as cytokinins for A. plumosus. The optimal temperature for growth and development was 21°C. There was interaction between the temperature and the PBA concentration. With increasing temperature from 17 to 24°C the need for PBA increased from 0.2 to 2 mg/1.
Germination and Dormancy of Reed Canary‐Grass Seeds (Phalaris arundinacea)
Authors: LANDGRAFF ASBJÖRN , JUNTTILA OLAVI 
Published: April 2006

AbstractEffects of various chemical and physical factors on the germination of several seed lots of reed canary‐grass (Phalaris arundinacea L.) have been studied. Germination at the optimum constant temperatures of 24 to 27°C was significantly stimulated by the following treatments: moist chilling in light, red light given during the first 3 days of imbibition, three 2‐h periods at 12°C given during the second day of imbibition, ethylene, increased oxygen tension and soaking in aerated water for 4 days. Dry storage at 20–30°C had no effect on the germination ability of the seeds. No significant quantities of germination inhibitors were found either in water or methanol extracts of seed dispersal units.By comparing three cultivars with various degrees of seed dormancy, respiration measurements showed that there was a significant positive correlation between oxygen uptake prior to visible germination and germination capacity. Similarly, germination‐stimulating treatment significantly enhanced oxygen uptake prior to visible germination.
Promotion of Flowering on Mature Picea sitchensis by Gibberellin and Environmental Treatments. The Influence of Timing and Hormonal Concentration
Authors: TOMPSETT P. B. , FLETCHER A. M. 
Published: April 2006

AbstractMale and female flowering were significantly promoted by gibberellin A4/7+ A3 mixtures applied beneath bark flaps on branches of 11‐year‐grafted mature scions of Picea sitchensis (Bong.) Carr. growing in the open in Scotland; 4 mg/ml gave more flowering than higher or lower concentrations of gibberellins and application in June was more effective than in July.Gibberellins also increased male flowering on mature scions when applied directly to the buds in a polythene house. A gibberellin A4/7+ A3 mixture produced greater numbers of strobili when applied to 2‐year‐grafted plants in May and June than when applied in July and August. Flowering of 5‐year‐grafted plants increased with increasing concentrations of a gibberellin A4/7+ A9 mixture up to 19.7 mg/ml above which flowering decreased.Modifying the environment by keeping in a polythene house enhanced the combined male and female flowering of 5‐year‐grafted mature scions above the amount on control plants outside, the effect being more marked in June and July than in August and September. Larger numbers of gibberellin applications or longer total lengths of time in the polythene house gave significantly greater amounts of combined male and female strobili.