bluuebunny/crossref_metadata_2025_split huggingface dataset:
The After‐Effect of Water Stress on Transpiration Rate and Changes in Abscisic Acid Content of Young Wheat Plants
Authors: BENGTSON CURT , FALK STIG OLOF , LARSSON STIG 
Published: April 2006

AbstractYoung wheat plants (Triticum aestivum L. cv. Weibulls Starke II) were exposed to water stress for 1, 2 or 3 hours by cooling the roots. The plants were subjected to a constant water stress during the stress periods. By this treatment the leaf water potential was lowered from −6.5 to −11.5 bars. Leaf water potential, transpiration rate and abscisic acid content were determined during the stress periods and during the recovery.The water stressed plants showed an after‐effect on transpiration rate lasting for between 10 and 24 hours depending on the duration of the stress. The amount of water stress in the stressed plants compared with the controls is defined as the difference in leaf water potential between the controls and the stressed plants during the stress period integrated over time. The amount of after‐affect on transpiration is analogously defined as the difference in transpiration rate between the controls and the stressed plants during the recovery period integrated over time. There was a linear relationship between the amount of water stress and the amount of after‐effect on transpiration of the leaves.The abscisic acid content of the leaves increased between 3.0 and 4.5 times the original content depending on the duration of the stress. However, during the recovery the abscisic acid content reattained the pre‐stress level within 3 hours for all three stress periods. There was thus no direct relationship between the after‐effect and the abscisic acid content of the leaf.
Effect of Treatments with Growth Retardant Chemicals on Petiole Abscission in Coleus
Authors: SEVERI ALDO , LAUDI GIANNINO 
Published: April 2006

AbstractA bscission of debladed petioles of Coleus was observed following spray applications of growth retardant chemicals and particularly of Phosfon D to the foliage. Sprays were applied to some branches, which were left intact (inducing branches), or to adjacent branches the leaves of which were later debladed (induced branches). In all experiments two applications of growth retardant chemicals were made, after which the induced branches were debladed. Treatments on induced branches accelerated the petiole abscission relative to the controls. Treatments on inducing branches, instead, decreased abscission speed of debladed petioles. The evidence suggests that phosfon D affects abscission by interfering with the indoleacetic acid mechanism.
Nitrogenase Activity in the Lichen Stereocaulon paschale: Recovery after Dry Storage
Authors: HUSS‐DANELL KERSTIN 
Published: April 2006

AbstractThe effect of prolonged storage on nitrogenase activity in Stereocaulon paschale (L.) Fr. was studied. The thalli had a very low water content during the storage over silica gel at 4°C in the dark. For C2H2‐reduction measurements the lichen samples were remoistened and held at 15°C in the light for 1–36 h before the addition of C2H2. With the longest pre‐incubation time preceding the nitrogenase activity measurements there was no significant decrease in nitrogenase activity during 75 weeks of storage. The method of storage was simple and inexpensive and the nitrogenase activity characteristic of each lichen batch, due to seasonal variation, was well preserved during the storage.
A Comparison of the Endogenous Hormone Levels in Stolons and Sprouts of the Potato Solanum tuberosum
Authors: DIMALLA G. G. , VANSTADEN J. , SMITH A. R. 
Published: April 2006

AbstractWhereas the gibberellin and inhibitor levels of potato (Solanum tuberosum L. cv. BP‐1) sprouts and stolons differ, their auxin and cytokinin levels apparently remain more or less unchanged. The levels of gibberellin in the sprouts is higher than that of the stolons; however, with regard to inhibitor levels the reverse is true. It would appear as if an internal balance of different hormones controls whether or not tuberization will occur. High gibberellin and low inhibitor levels (sprouts) may favour cell elongation and at the same time limit cell division. Decreased gibberellin and increased inhibitor levels (stolons) seems to favour cell division. As cell division is not retarded despite high inhibitor levels, it would appear as if the effect of the inhibitor is mainly directed at countering the gibberellins.
Uptake of Amino Acids by Barley Leaf Slices: Kinetics, Specificity, and Energetics
Authors: LIEN RAGNVALD , ROGNES SVEN ERIK 
Published: April 2006

AbstractUptake of 14C‐labelled L‐lysine. L‐arginine, L‐glutamic acid, L‐aspartic acid, and glycine was studied in 0.75 mm wide barley (Hordeum vulgare L. cv. Lise) leaf slices. After an initial period (10 min) of rapid accumulation amino acid uptake proceeded at a steady, lower rate for several hours. Uptake was stimulated by 10−4M Ca−2+ ions. Uptake was strongly pH dependent with the following optima: aspartic acid pH 3.5. glutamic acid pH 4.1. glycine pH 5.8, lysine pH 6–7, and arginine pH 5–8 (a broad plateau). The optimal temperature was about 30°C. and the temperature coefficient in the range 0–20gGC was 2.3–2.5. Concentration‐dependence data gave uptake isotherms which appeared to be multiphasic for all the amino acids used. The amino acids inhibited each other in a competitive fashion, indicating that they were all transported by a single carrier system. Uptake of lysinc was strongly inhibited by 10−4M 2.4‐dinitrophenol. Lysine uptake was not stimulated by light under aerobic conditions. However, it was much reduced in the dark under anaerobic conditions. This reduction was almost compensated for by light. The light‐stimulation of uptake under anaerobic conditions was abolished by 10−5M 3‐(3,4‐dichlorophenyl) 1.1‐dimethylurea.
Variations among Woody Angiosperms in Response to Flooding
Authors: PEREIRA J. S. , KOZLOWSKI T. T. 
Published: April 2006

AbstractEffects of flooding on young Populus deltoides, Salix nigra, Eucalyptus camaldulensis, E. globulus, Ulmus americana, Quercus rubra and Fraxinus pennsylvanica plants were studied. Flooding variously induced several sequential physiological disturbances, with stomatal closure among the earliest responses. Subsequent responses included inhibition of root growth, alterations in root and stem morphology, formation of adventitious roots, and leaf senescence. In amphistomatous species (Populus deltoides, Salix nigra, Eucalyptus camaldulensis) flooding rapidly induced stomatal closure on the adaxial leaf surface. It also significantly induced stomatal closure on the abaxial epidermis of Populus deltoides but not that of Salix nigra or Eucalyptus camaldulensis. In hypostomatous species (Eucalyptus globulus, Ulmus americana) flooding significantly induced stomatal closure on the abaxial surface within 3 days. Stomatal responses to flooding were not correlated with leaf water stress. In both long‐ and short‐term experiments, flooding did not significantly increase plant water stress. These results deemphasized the importance of plant water stress in inducing plant responses to flooding. The importance of various hormones in inducing flooding symptoms is discussed.
Atractyloside Inhibition of Adenine Nucleotide Translocation in Mitochondria from Hypocotyls of Vigna sinensis cv. Seridó
Authors: LIMA M. SILVA , DENSLOW N. D. , de MELO D. FERNANDES 
Published: April 2006

AbstractThe translocation of adenine nucleotides into mitochondria isolated from hypocotyls of Vigna sinensis (L.) Savi cv. Serido was examined as a function of oxidative phosphorylation. Mitochondria membrane integrity was assessed by respiratory control and ADP:O ratios.A kinetic analysis of the translocation of adenosine diphosphate into the mitochondria revealed that the mechanism of translocation obeys classical Michaclis‐Menten kinetics with a Km of 25 μM for adenosine diphosphate. At moderate ratios of atraetyloside to adenosine diphosphate (lower than 0.03), atractyloside appears to be a competitive inhibitor of the translocation process, with a Ki of 0.4 μM. However, non‐linear kinetic parameters are observed with ratios higher than 0.06. A concentration of 2.5 μM atractyloside is sufficient to reduce the translocation of 100 μm ADP by 50%. This represents a higher level of sensitivity to atractyloside than reported for other plants.
Changes in Photosynthetic Activity and Related Processes Following Decapitation in Mulberry Trees
Authors: SATOH M. , KRIEDEMANN P. E. , LOVEYS B. R. 
Published: April 2006

AbstractPhysiological responses to decapitation, in combination with bud removal or bud retention, were followed for 45 days in mature leaves of potted mulberry trees (single shoot with 24 to 28 leaves) held in a greenhouse. Mature leaves, whose photosynthetic activity had already attained a maximum, initially increased and subsequently maintained their rates of gas exchange after decapitation. Equivalent leaves on intact trees showed a gradual decline in photosynthesis together with other changes generally associated with early senescence viz. loss of chlorophyll, increased starch, and accumulation of one category of cytokinin‐like material presumed to be a glucose ester. Maintenance of physiological activity following decapitation, especially when combined with bud removal, was associated with greater chlorophyll content, mesophyll cell enlargement (palisade cells appeared more elongate), lower starch, and alteration in foliar levels of cytokinin‐like substances. Internal constraints on CO2 assimilation, i.e. residual resistance (rr), rather than stomatal factors, appeared to be the major influence on gas exchange. The higher photosynthetic activity of leaves on decapitated trees relative to control trees of the same age was attributed to lower r, but was also associated with higher chlorophyll content (leaf area basis) so that CO2 assimilated per unit chlorophyll was not substantially altered by treatment.
The Water Relations of Pinus sylvestris
Authors: HELLKVIST JERK , PARSBY JAN 
Published: April 2006

AbstractThe water potential (β) in ten‐year‐old Scots pine trees (Pinus sylvestris L.) from four different latitudinal provenances ranging from 57° N to 67° N, growing in close proximity to each other, was measured in a pressure chamber during five selected periods between May 1972 and March 1973. Diurnal and seasonal patterns of φ are presented in relation to irradiance, air temperature and vapour pressure deficit (D) for one cloudy and one clear day in each experimental period.The largest daily amplitude in φ was found at the beginning and end of summer, indicating a larger resistance to water flow from soil to needles. As the soil water potentials (measured as pre‐dawn values) were, at the same time, the highest for the year, it is suggested that these changes in resistance from period to period mainly take place in the trees.Plots of φ against D during clear days, showed marked hysteresis as the result of the simultaneous influence on φ of several environmental factors. Close linear relations resulted when φ was plotted against potential evaporation rate (calculated from the Pennman‐Monteith formula). The slopes of these regression lines, essentially the flow resistance, showed marked seasonal variations, with the largest resistance found at the beginning and end of summer.In most periods the water relations of the trees from different provenances were strikingly similar. A continuous change in the water relations of the remote provenances towards the situation for the “home‐provenance” is indicated by the experimental results. It is concluded that trees from different latitudes after ten years of growth have about the same chance as the home provenance to survive periods during which their water balance might become critical.
The Fate of L‐Tyrosine‐UL−14C in Shoot‐Forming Tobacco Callus
Authors: HASEGAWA PAUL M. , MURASHIGE TOSHIO , MUDD J. BRIAN 
Published: April 2006

AbstractTobacco callus fed L‐tyrosine‐UL−14C was sampled at 3‐day intervals for 15 days, homogenized and studied with respect to distribution of incorporated radioactivity. The supernatant obtained by centrifuging of the homogenates at 270 g contained the bulk of the radioactivity although significant activity was also detected in the pellet. Sucrose density gradient centrifugation of the supernatant showed over 90% of the recovered label to be associated with a fraction designated as “less dense than mitochondria”, with the remainder being found in the fraction identified as “mitochondria”. During tissue culture, virtually all of the radioactivity in the fraction “less dense than mitochondria” was recovered in the supernatant obtained by centrifugation at 100,000 g. From 4 to 18% of the labeling in the 100,000 g supernatant fraction was attributable to tyrosine‐containing protein, and the rest to free tyrosine and unidentified anionic constituents. The highest proportions of radio‐activity in the 270 g pellet were associated with substances extractable with NaCl, pronase, 4.6 N NaOH, and acetolyzing reagent. Low but substantial labeling characterized the extracts obtained with Triton X‐100 and 1 N NaOH. The final unextractable residue contained 20% of the 270 g pellet radioactivity.
Effects of Pargyline on Mitochondrial Amine Oxidase Activity, Indoleacetic Acid Synthesis and Growth of Crown‐Gall Tumor Callus
Authors: DAVIES FREDERICK S. , McDANIEL ROBERT G. 
Published: April 2006

Abstract Vinca rosea L. crown‐gall tumor callus tissue cultures treated with N‐benzyl‐N methyl propargylamine (pargyline) exhibited a decrease in the level of endogenous indoleacetic acid from 0.42 μg/mg of protein to less than 0.30 μg/mg of protein. A simultaneous decrease in the specific activity of mitochondrial amine oxidase from 3000 units to less than 250 units at 1.0 μM, 0.01 mM, 0.1 mM and 1.0 mM pargyline, suggested a relationship between amine oxidase function and indoleacetic acid synthesis. Tryptamine incorporation into indoleacetic acid was also decreased at these concentrations. Pargyline inhibited tumor callus growth significantly (based on fresh weight measurements) at the highest concentration, 1.0mM.These data support the hypothesis of a coordinate metabolic system linking mitochondrial amine oxidase activity and indole acetic acid synthesis. Inhibitory action of pargyline on the enzyme is reflected in reduced indoleacetic acid levels and, ultimately, in reduced callus growth rates.
Utilization of Photosynthates for Growth, Respiration, and Storage in Tops and Roots of Lolium multiflorum
Authors: HANSEN G. K. 
Published: April 2006

Abstract Lolium multiflorum L. was grown in pots in controlled environments. CO2‐exchange rates were continuously measured on two pots during 46 and 52 days, respectively, separating between tops and roots. After 20 days, the plants were entirely defoliated and the plants were then followed during the regrowth period. During the experiment, alternating 2–3 day periods of high and low irradiance were applied. Analogously treated plants were frequently harvested to obtain the distribution of assimilates between tops and roots. From integration of CO2‐exchange rates, diurnal photosynthesis and respiration were obtained, and utilization of assimilates was analysed.The respiration associated with the synthesis of new structural material (growth respiration) was dependent on assimilates originating from both the current and the preceding 24 h diurnal cycles. The amount of new structural material synthesized during the current 24 h diurnal cycle was estimated from the relative contribution of assimilates accumulated from the preceding and the current 24 h and diurnal cycles to growth respiration of the current 24 h. From this approximation, the respiratory components connected to synthesis of new structural material and to maintenance of already established material were found.Growth and maintenance respirations of the tops were alike during the predefoliation and the regrowth periods. For the roots, however, growth respiration was higher and maintenance respiration lower in the regrowth period. The difference between daily integrated CO2‐exchange and the amount converted into new structural material was assumed to be the daily change in assimilates stored. On the first day of a period of high irradiance, the assimilation per unit leaf weight was higher than on the following day of high irradiance, and an accumulation of storage material took place. On the first day of a period of low irradiance, the assimilation per unit leaf weight was lower than on the following day of low irradiance, and there was a depletion of assimilates stored. These effects were most pronounced during the regrowth period, indicating a change in the metabolic sink demand. This indicates a strong feedback mechanism between sources and sinks, in the sense that accumulation of products will inhibit assimilation.
Localization of Adenyl Cyclase in Meristems of Young Pea Hypocotyls
Authors: HILTON GARY M. , NESIUS KNEELAND K. 
Published: April 2006

AbstractElectron micrographs of Pisum sativum L. hypocotyl tips treated to localize adenyl cyclase revealed discrete deposits on the internal membranes of cytoplasmic vacuoles which correspond to previously localized enzymes described as acid phosphatases. It remains to be determined whether the specificity of the substrate, adenylyl‐imidodiphosphate, used in the present study is such as to exclude all phosphatase activity other than adenyl cyclase. The acid phosphatase localized in earlier studies by other investigators may be an adenyl cyclase. In the differentiated cells of the root cap, lead precipitate was localized in distinct areas bound to the smooth endoplasmic reticulum.
Ionic Balance of Root‐Shoot Nitrate Transfer in Dwarf Bean
Authors: BRETELER HANS , CATE CHARLOTTE H. HÄNISCH TEN 
Published: April 2006

AbstractThe Dijkshoorn‐Ben Zioni model about potassium recycling in higher plants proposes a stoichiometric coupling between the upward transport of nitrate and potassium, and therefore a 1:1 ratio of these ions in the xylem sap. Phaseolus vulgaris grown in media with different NO3: K+ ratios, however, only rarely showed equimolar concentrations of the two ions in the bleeding sap. Ratios between 0.2 and 11 were observed and the ratios between concentrations of the ions in the exudate and in the external solution were positively correlated. An analysis of the major inorganic constituents of the exudate revealed an ionic balance that requires negligible amounts of charges from organic molecules.
Connection between the Synthesis of Differentiation Specific Proteins and the Capacity of Cells to Respond to Cytokinin in the Moss Funaria
Authors: BOPP MARTIN , ERICHSEN UTA , NESSEL MANFRED , KNOOP BERND 
Published: April 2006

AbstractThe differentiation stage of the caulonema in Funaria hygrometrica protonema is distinguished from the chloronema stage by three additional protein bands (CSP) in the soluble protein fraction. During the change of caulonema to chloronema, which is induced by isolation of single filaments (regeneration), the CSP disappear. This is not the consequence of an accelerated degradation or turnover but of a gradual termination in the de novo synthesis of CSP during regeneration as demonstrated by pulse‐chase experiments with l‐[4,5–3H] leucine. Cytokinin inhibits the termination of the synthesis of CSP. The decrease in synthesis parallels the decrease in ability of the isolated caulonema cells to respond to cytokinin via bud formation. It is therefore concluded that the CSP are involved in the competence of caulonema cells to respond to cytokinins.
A Comparative Anatomical Study of Organogenesis in Cultured Tissues of Maize, Wheat and Oats
Authors: CURE W. W. , MOTT R. L. 
Published: April 2006

AbstractFive cereals and two related grasses were tested for adventitious shoot production from tissue cultures using methods concordant with those reported to be successful for cereals. The five cereals I wheat (Triticum aestivum L.), oats (Avena sativa L.), and maize (Zea mays L.) Pioneer hybrid 3369A, the Bolivian race Pororo and the Equadorian race Chococenõl were all found to proliferate in culture through an aberrant root‐like mechanism of growth which had the external appearance of callus. Two related species, teosinte (Zea mexicana Reeves and Mangelsdorf) and tripsacum (Tripsacum dactyloides L.), were less successful in culture, but grew in the same way. Oats, and probably Pororo and Chococeño, initiated presumptive shoot meristems directly from root vascular tissues within this root‐like growth. Hybrid maize and wheat initiated no shoot meristems and produced only roots. The occasional shoot production observed in wheat was discounted as simple carryover of existing shoot apices from the primary embryo cultures. This study suggests that the incidence of shoot regeneration in cultures of these cereals may be related more directly to adventitious bud formation on roots than to any controlled de novo organogenesis from undifferentiated callus.
The Effect of Phosphorus and Potassium Deficiencies on Transpiration in Tea (Camellia sinensis)
Authors: NAGARAJAH S. , RATNASURIYA G. B. 
Published: April 2006

AbstractThe effect of phosphorus and potassium deficiencies on transpiration in tea (Camellia sinensis L. Clone DT 1) was studied. The plants were grown in sand culture, and measurements were made after the plants showed phosphorus or potassium deficiency symptoms. The overall growth of plants was reduced by potassium deficiency but not by phosphorus deficiency. Both deficiencies reduced stomatal aperture and increased leaf water potential. Stomatal density decreased in phosphorus deficient leaves and it increased in potassium deficient leaves. The transpiration of whole plants was reduced by both deficiencies. The relative sensitivity of transpiration to water stress was increased by potassium deficiency but not by phosphorus deficiency.
Levels of Growth Regulating Substances during Vernalization of Winter Wheat
Authors: REDA FATMA , LARSEN† POUL , RASMUSSEN OLE S. 
Published: April 2006

AbstractSeeds of winter wheat (Triticum vulgare L.) cultivars Fema and Ferto, were vernalized at 3°C in the dark. Samples were taken 9, 18, 27, 36 and 45 days after the start of vernalization, and extracts were analysed for auxins, gibberellins and growth inhibiting substances. As vernalization progressed the levels of auxins and gibberellins increased whereas the levels of growth inhibitors decreased. The pattern of growth regulator changes was almost similar in both the cultivars. Vernalization seemingly controls the balance between growth promoting and growth inhibiting substances in winter wheat.
Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays
Authors: MATSUBARA SATOSHI , SUGIYAMA TAMIJI , HASHIZUME TAKESHI 
Published: April 2006

AbstractCytokinin activities of 6‐benzoylamino‐1, 6‐benzoylamino‐3‐, 6‐pentanoylamino‐1‐ and 6‐pentanoylamino‐3‐deazapurines and their corresponding purine analogs, 6‐benzoylaminopurine and 6‐pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6‐Benzoylamino‐ and 6‐pentanoylamino‐1‐deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6‐benzoylamino‐1‐deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6‐benzoylamino‐ and 6‐pentanoylamino‐3‐deazapurines were as active as or less active than corresponding purine analogs.