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Articles 1 - 30 of 77
Full-Text Articles in Life Sciences
Source Leaf Carbon Allocation And Plant Morphology In Beta Vulgaris, L. During Development Under 14-H And 8-H Daylengths, Leanne Jablonski, Donald Geiger
Source Leaf Carbon Allocation And Plant Morphology In Beta Vulgaris, L. During Development Under 14-H And 8-H Daylengths, Leanne Jablonski, Donald Geiger
Donald R. Geiger
No abstract provided.
Structural And Physiological Changes In Sugar Beet Leaves During Sink To Source Conversion, Robert Fellows, Donald Geiger
Structural And Physiological Changes In Sugar Beet Leaves During Sink To Source Conversion, Robert Fellows, Donald Geiger
Donald R. Geiger
The onset of export during leaf development was correlated with changes in metabolism and ultrastructure and with patterns of solute distribution in the developing seventh leaf of sugar beet (Beta vulgaris L.) in order to study the cause of initiation of translocation. Infrared gas analysis of carbon dioxide uptake showed a broad peak for net photosynthesis dm−2 at 35 to 40% final laminar length. Pulse labeling with 14CO2 demonstrated that maximum import of translocate occurred at 25% final laminar length; export was first observed at 35% final laminar length. Between 40 and 50% final laminar length a rapid increase in …
Balance Among Parts Of The Source-Sink System: A Factor In Crop Productivity, Donald Geiger, Jerome Servaites, Wen-Jang Shieh
Balance Among Parts Of The Source-Sink System: A Factor In Crop Productivity, Donald Geiger, Jerome Servaites, Wen-Jang Shieh
Donald R. Geiger
Over the last decade plant biologists have become increasingly aware of the importance and complexities of interactions between the environment and plant physiological processes. This book considers the integrated effects of a large amount of variables on the photosynthetic processes of plants growing in a range of contrasting environments, each presenting a different set of ecophysiological problems to plants. The papers describe the characteristic physico-chemical features of the environment and provide an up-to-date account of the knowledge of plant photosynthetic performance in that environment in terms of the constraints imposed by climatic and edaphic parameters and adaptations.
Effect Of Sink Region Anoxia On Translocation Rate, Donald Geiger, A. Christy
Effect Of Sink Region Anoxia On Translocation Rate, Donald Geiger, A. Christy
Donald R. Geiger
Translocation rate, ATP level, and CO2 production of a developing leaf (sink leaf) were studied in sugar beet (Beta vulgaris) plants prior to and during anaerobic treatment of the sink leaf. Within 3 to 5 minutes after onset of treatment with a N2 atmosphere, translocation into the sink leaf Dec.reased to near zero and then recovered to a level of about 50% of the control over the next 2 hours. A Dec.line in CO2 output and ATP levels coincided with the attainment of the new translocation rate. All three quantities returned to near control levels within 60 to 120 minutes …
Effect Of N-(Phosphonomethyl)Glycine On Carbon Assimilation And Metabolism During A Simulated Natural Day, Wen-Jang Shieh, Donald Geiger, Jerome Servaites
Effect Of N-(Phosphonomethyl)Glycine On Carbon Assimilation And Metabolism During A Simulated Natural Day, Wen-Jang Shieh, Donald Geiger, Jerome Servaites
Donald R. Geiger
The effects of N-(phosphonomethyl)glycine (glyphosate) on the regulation of carbon assimilation, metabolism, and translocation were studied in leaves of sugar beet (Beta vulgaris L., Klein E-type multigerm) under a light regimen that began with gradually increasing irradiance as generally occurs on a natural day. Soon after application, glyphosate caused a marked increase in ribulose bisphosphate and a Dec.rease in phosphoglyceric acid. The response is most simply explained by direct inhibition of ribulose bisphosphate carboxylase activity. The extent of inhibition was small, and the carbon assimilation rate did not Dec.rease. As predicted, photosynthesis Dec.lined within an hour after glyphosate was applied …
Regulation Of Ribulose 1, 5-Bisphosphate Carboxylase/Oxygenase By Metabolites, Jerome Servaites, Donald Geiger
Regulation Of Ribulose 1, 5-Bisphosphate Carboxylase/Oxygenase By Metabolites, Jerome Servaites, Donald Geiger
Donald R. Geiger
Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and other enzymes and their common metabolites form a system regulated by feedforward and feedback mechanisms that is directly involved in assimilation of carbon. The interaction of these components in the chloroplast gives rise to properties, which can not be predicted from the study of isolated components alone. Experiments were conducted to explain how the observed pattern of system level regulation is consistent with the individual characteristics of Rubisco measured in vitro. In vitroRubisco is responsive to a wide range of ribulose 1,5-bisphosphate and phosphoglycerate concentrations, similar to those found in leaves under field conditions. Metabolite …
Flowering Phenology Change And Climate Warming In Southwestern Ohio, Ryan Mcewan, Robert J. Brecha, Donald R. Geiger, Grace P. John
Flowering Phenology Change And Climate Warming In Southwestern Ohio, Ryan Mcewan, Robert J. Brecha, Donald R. Geiger, Grace P. John
Donald R. Geiger
Global surface temperature has increased markedly over the last 100 years. This increase has a variety of implications for human societies, and for ecological systems. One of the most obvious ways ecosystems are affected by global climate change is through alteration of organisms’ developmental timing (phenology). We used annual botanical surveys that documented the first flowering for an array of species from 1976 to 2003 to examine the potential implications of climate change for plant development. The overall trend for these species was a progressively earlier flowering time. The two earliest flowering taxa (Galanthus and Crocus) also exhibited the strongest …
Programmed Responses Partitioning To Internal And Environmental Factors, Donald Geiger, Brigette Fondy
Programmed Responses Partitioning To Internal And Environmental Factors, Donald Geiger, Brigette Fondy
Donald R. Geiger
No abstract provided.
Leaf Structure And Translocation In Sugar Beet, Donald Geiger, Dominic Cataldo
Leaf Structure And Translocation In Sugar Beet, Donald Geiger, Dominic Cataldo
Donald R. Geiger
Anatomical and ultrastructural details of a translocating 10-cm leaf of sugar beet (Beta vulgaris L. var. Klein Wanzleben) were correlated with translocation rate data. The minor veins were found to be 13 times as extensive as the major veins and measure 70 cm/cm2 leaf lamina. Measurements disclosed that a 33-μ length of minor vein services 29 mesophyll cells with the result that translocate moves an average of 73 μ or 2.2 cell diameters during transport from mesophyll cells to a minor vein. High-resolution, freeze-dry autoradiography revealed that assimilates accumulate in organelle-rich cells of the minor vein phloem. Correlation of phloem …
Carbon Assimilation And Leaf Water Status In Sugar Beet Leaves During A Simulated Natural Light Regimen, Donald Geiger, Wen-Jang Shieh, Lynn Lu, Jerome Servaites
Carbon Assimilation And Leaf Water Status In Sugar Beet Leaves During A Simulated Natural Light Regimen, Donald Geiger, Wen-Jang Shieh, Lynn Lu, Jerome Servaites
Donald R. Geiger
Carbon assimilation and leaf water status were studied in sugar beet (Beta vulgaris L., Klein E-type multigerm) leaves during a light period in which illumination either increased rapidly to full irradiance or changed gradually in a sinusoidal manner as generally occurs during a natural day. A light regimen that simulated the light of a natural day was produced by adjusting irradiance with a neutral-density filter under the control of a computer. Under this light regimen, photosynthesis, transpiration, and stomatal conductance followed the irradiance pattern very closely and ribulose bisphosphate carboxylase was nearly fully activated. When illumination was increased rapidly at …
Glyphosate Inhibits Photosynthesis And Allocation Of Carbon To Starch In Sugar Beet Leaves, Donald Geiger, Shelly Kapitan, Michelle Tucci
Glyphosate Inhibits Photosynthesis And Allocation Of Carbon To Starch In Sugar Beet Leaves, Donald Geiger, Shelly Kapitan, Michelle Tucci
Donald R. Geiger
Application of glyphosate (N-[phosphonomethyl] glycine) to exporting leaves of sugar beet (Beta vulgaris, L.) during the day lowered stomatal conductance and carbon fixation. Allocation of newly fixed carbon to foliar starch accumulation was nearly completely inhibited, being Dec.reased by the same amount as net carbon fixation. In contrast, Dec.reasing net carbon fixation in untreated leaves by lowering CO2 concentration caused starch accumulation to Dec.rease, but only in the same proportion as net carbon fixation. Shikimate level increased 50-fold in treated leaves but the elevated rate of carbon accumulation in shikimate was only 4% of the Dec.rease in the rate of …
Mechanism Of Inhibition Of Translocation By Localized Chilling, Robert Giaquinta, Donald Geiger
Mechanism Of Inhibition Of Translocation By Localized Chilling, Robert Giaquinta, Donald Geiger
Donald R. Geiger
Arrhenius plots of translocation velocity as a function of petiole temperature show a marked increase in temperature dependence below 10 C in bean (a chilling-sensitive species) but not in sugar beet (chilling-resistant). The increased temperature dependence below 10 C was not observed for cytoplasmic streaming or oxygen uptake in bean. Bean petioles were served to release pressure in order to determine whether sieve tubes are obstructed in cold-treated petioles. The resulting pressure release caused serious displacement of the crystalline protein bodies in the sieve tubes of petioles at 25 C, but in those locally cooled to 0 C for 30 …
Translocation And Accumulation Of Translocate In The Sugar Beet Petiole, Donald Geiger, M. Saunders, Dominic Cataldo
Translocation And Accumulation Of Translocate In The Sugar Beet Petiole, Donald Geiger, M. Saunders, Dominic Cataldo
Donald R. Geiger
Accumulation of translocate during steady-state labeling of photosynthate was measured in the source leaf petioles of sugar beet (Beta vulgaris L. monogerm hybrid). During an 8-hr period, 2.7% of the translocate or 0.38 μg carbon/min was accumulated per cm petiole. Material was stored mainly as sucrose and as compounds insoluble in 80% ethanol. The minimum peak velocity of translocation approached an average of 54 cm/hr as the specific activity of the 14CO2 pulse was progressively increased. The ratio of cross sectional area required for translocation to actual sieve tube area in the petiole was 1.2. A regression analysis of translocation …
Sugar Selectivity And Other Characteristics Of Phloem Loading In Beta Vulgaris L., Bernadette Fondy, Donald Geiger
Sugar Selectivity And Other Characteristics Of Phloem Loading In Beta Vulgaris L., Bernadette Fondy, Donald Geiger
Donald R. Geiger
The rate of phloem loading, its selectivity, and the disposition of labeled carbon were studied following application of 14C-labeled sugars to the free space of source leaves of sugar beet (Beta vulgaris L.). Buffered 10 mM solutions of 14C-labeled sucrose, fructose, stachyose, mannitol, 3-0-methyl glucose or L-glucose were applied to the abraded epidermis of source leaves held in the dark. Distribution of the labeled carbon from sugar taken up from the free space was studied by micro-densitometry of autoradiographs. Uptake of labeled sugar from the free space, partition between mesophyll and minor veins, metabolic conversions, export and respiration were followed …
Inhibitors Of Aromatic Amino Acid Biosynthesis (Glyphosate), Donald Geiger, Mark Fuchs
Inhibitors Of Aromatic Amino Acid Biosynthesis (Glyphosate), Donald Geiger, Mark Fuchs
Donald R. Geiger
This book presents the progress made in the study of the mode of action of phytotoxic compounds that have been developed as herbicides in the recent past. The 13 chapters are written by experts in herbicide research and development, chemists, biochemists, and plant physiologists. The biochemistry of the target enzymes is described together with model assays, molecular genetics and special reference to transgenic herbicide-resistant crops. Additional chapters deal with new synthetic chemical pathways, chirality effects found in certain herbicide classes, and transcuticular pesticide penetration.
Carbon Partitioning And Herbicide Transport In Glyphosate-Treated Sugar Beet (Beta Vulgaris)., Judy Gougler, Donald Geiger
Carbon Partitioning And Herbicide Transport In Glyphosate-Treated Sugar Beet (Beta Vulgaris)., Judy Gougler, Donald Geiger
Donald R. Geiger
Glyphosate [N-(phosphonomethyl)glycine] had several effects on carbon translocation in sugarbeet (Beta vulgaris L. 'Klein E multigerm'): a) import of carbon by sink leaves was inhibited, b) net starch accumulation in source leaves was stopped, and c) carbon export from source leaves in the dark was stopped following 10 h of treatment in the light. During periods when no carbon was exported, glyphosate also was not transported from treated leaves. The limitation of glyphosate transport, resulting from disruption of carbon metabolism, appears important in the study and use of the herbicide.
Relation Of Increased Potassium Nutrition To Photosynthesis And Translocation Of Carbon, Donald Geiger, Terrance Conti
Relation Of Increased Potassium Nutrition To Photosynthesis And Translocation Of Carbon, Donald Geiger, Terrance Conti
Donald R. Geiger
Effects of supplying K+ at 2 or 10 millimolarity concentration on net carbon exchange and translocation of products of photosynthesis were studied in plants of Beta vulgaris L. (var. Klein E). Transport of K+ into and out of leaves was studied with 42K over a 3-day period. Increasing the K+ supplied to the roots from 2 millimolarity, a level just sufficient to overcome obvious deficiency symptoms, to 10 millimolarity resulted in a gradual accumulation of K+ per unit area and an increased export of K+ to sink regions. No significant increase in net carbon exchange was observed in leaves that …
Causes Of Self-Limited Translocation Of Glyphosate In Beta Vulgaris Plants, Donald Geiger, Wen-Jang Shieh, Wen-Jang Shieh, Mark Fuchs
Causes Of Self-Limited Translocation Of Glyphosate In Beta Vulgaris Plants, Donald Geiger, Wen-Jang Shieh, Wen-Jang Shieh, Mark Fuchs
Donald R. Geiger
Causes of self-induced limitation of glyphosate translocation were studied in sugar beet plants that were susceptible to or tolerant of (Roundup Ready) glyphosate. Glyphosate was taken up in both types of plants at the same rate and essentially stopped at the same time, around 4 h after [14C]glyphosate was applied in 1% Roundup formulation. Tolerant plants continued to export glyphosate at a significant rate during the entire 30-h observation period while susceptible plants stopped after only 10 h and exported only half the amount. Herbicide was applied under three different experimental protocols to help identify causes for the inhibition of …
Effect Of Sink Region Cooling On Translocation Of Photosynthate, Donald Geiger
Effect Of Sink Region Cooling On Translocation Of Photosynthate, Donald Geiger
Donald R. Geiger
The effect of metabolic inhibition of the sink tissues on translocation of 14C-labeled photosynthate was studied by cooling part or all of the sink region in a translocating sugar beet plant (Beta vulgaris L. var Klein Wanzleben).When the sink region was cooled, 4 phases were observed: a temporary Dec.line, a period of translocation at the pre-treatment rate, a period of Dec.line, and a new steady rate at 35 to 45% of the original rate. The new rate persisted throughout 26 hours of cooling. Cooling half the blade of a developing leaf caused a Dec.line in translocation to the uncooled half. …
Carbon Partitioning Among Leaves, Fruits, And Seeds During Development Of Phaseolus Vulgaris L., Donald Geiger, Wen-Jang Shieh, Rose Saluke
Carbon Partitioning Among Leaves, Fruits, And Seeds During Development Of Phaseolus Vulgaris L., Donald Geiger, Wen-Jang Shieh, Rose Saluke
Donald R. Geiger
Development of vegetative and floral buds was found to be a key factor in establishing the way carbon is distributed among growing leaves and fruits inPhaseolus vulgaris L. plants. Leaves emerged principally during a period 14 to 32 days after planting while flowers were produced during a 10- to 12-day period near the end of leaf emergence. Timing of anthesis established the sigmoidal time course for dry weight accumulated by the composite of all fruits on the plant. During the first 12 days following anthesis, fruit growth mainly consisted of elongation and dry weight accumulation by the pod wall. Thereafter, …
Sucrose Translocation In The Sugar Beet, Donald Geiger, C. Swanson
Sucrose Translocation In The Sugar Beet, Donald Geiger, C. Swanson
Donald R. Geiger
In a recent study, Jones et al. (7) reported on the translocation of C14 in tobacco following assimilation of C14O2 by a single leaf (the presentation leaf or source leaf).The labeled CO2 was supplied for varying periods of time (10 mins to 3 hr) after which photosynthesis was continued in normal air for the duration of the experiment (up to 96 hr continuous light). There was a complete turnover of the sucrose in the source leaf in about 24 hours without change in amount. Distribution of labeled translocate, at least to leaves above the source leaf, was completed in about …
Effects Of Decreased Net Carbon Exchange On Carbohydrate Metabolism In Sugar Beet Source Leaves, Theodore Fox, Donald Geiger
Effects Of Decreased Net Carbon Exchange On Carbohydrate Metabolism In Sugar Beet Source Leaves, Theodore Fox, Donald Geiger
Donald R. Geiger
The relationship between CO2 concentration and starch synthesis and degradation was studied by measuring leaf starch content and disappearance of14C-starch. At a concentration of 340 microliters CO2 per liter, starch accumulated without degradation of previously synthesized starch. Degradation of starch began when CO2 concentration was lowered, but its synthesis continued. At 120 microliters CO2 per liter rates of synthesis and degradation were equal. Even at the CO2 compensation point, synthesis of starch continued. Concomitant starch synthesis and mobilization supported export from the leaf. Changes in starch metabolism that occur when photosynthesis is CO2-limited provide a means to study regulation of …
Carbon 14 Labeling Of Photosynthate As A Means For Studying Translocation, Donald Geiger
Carbon 14 Labeling Of Photosynthate As A Means For Studying Translocation, Donald Geiger
Donald R. Geiger
No abstract provided.
Photosynthesis, Carbohydrate Metabolism, And Export In Beta Vulgaris L. And Phaseolus Vulgaris L. During Square And Sinusoidal Light Regimes, Bernadette Fondy, Donald Geiger, Jerome Servaites
Photosynthesis, Carbohydrate Metabolism, And Export In Beta Vulgaris L. And Phaseolus Vulgaris L. During Square And Sinusoidal Light Regimes, Bernadette Fondy, Donald Geiger, Jerome Servaites
Donald R. Geiger
Rates of photosynthesis, sucrose synthesis, starch accumulation and degradation were measured in sugar beet (Beta vulgaris L.) and bean (Phaseolus vulgaris L.) plants under a square-wave light regime and under a sinusoidal regime that simulated the natural daylight period. Photosynthesis rate increased in a measured manner in direct proportion to the increasing light level. In contrast to this close correspondence between photosynthesis and light, a lag in photosynthesis rate was seen during the initial hour under square-wave illumination. The leaf appeared to be responding to limits set by carbon metabolism rather than by gas exchange or light reactions. Under the …
Self-Limitation Of Herbicide Mobility By Phytotoxic Action, Donald Geiger, Hank Bestman
Self-Limitation Of Herbicide Mobility By Phytotoxic Action, Donald Geiger, Hank Bestman
Donald R. Geiger
Translocation of phloem-mobile herbicides was inhibited by their phytotoxic action on processes that maintain assimilate translocation. Glyphosate lowered import into developing sink leaves soon after it was applied to exporting sugarbeet leaves. Later, photosynthesis slowed down and starch accumulation stopped, but export of both assimilate and glyphosate continued until it was limited by starch availability at night. Experiments with field pennycress and Tartary buckwheat indicated that self-limitation of chlorsulfuron translocation probably occurred and that it resulted from lowered assimilate entry into phloem rather than from inhibition of photosynthesis or carbon allocation. Leakage of chlorsulfuron from the phloem when export was …
Temporary Inhibition Of Translocation Velocity And Mass Transfer Rate By Petiole Cooling, Donald Geiger, Susan Sovonick
Temporary Inhibition Of Translocation Velocity And Mass Transfer Rate By Petiole Cooling, Donald Geiger, Susan Sovonick
Donald R. Geiger
No abstract provided.
Regulation Of Carbon Allocation And Partitioning: Status And Research Agenda, Donald Geiger, Brigette Fondy
Regulation Of Carbon Allocation And Partitioning: Status And Research Agenda, Donald Geiger, Brigette Fondy
Donald R. Geiger
No abstract provided.
Kinetic Characteristics Of Chloroplast Glucose Transport, Jerome Servaites, Donald Geiger
Kinetic Characteristics Of Chloroplast Glucose Transport, Jerome Servaites, Donald Geiger
Donald R. Geiger
Influx of labelled D‐glucose into isolated spinach (Spinacia oleracea L. cv. Melody hybrid) chloroplasts was initially rapid followed by a period ofslower influx. The stroma glucose concentration attained equilibrium rapidly with low external glucose concentrations and the two were linearly proportional. The period of slower influx resulted from conversion of glucose to acidic products that remained trapped in thechloroplast. As the external glucose concentration increased, the stroma glucose concentration increased less and less, attaining a maximal concentration of 72 mol m–3. The maintenance of an equilibrium stroma glucose concentration lower than that in the external medium is evidence that plastid …
Effect Of Rapid Changes In Sink-Source Ratio On Export And Distribution Of Products Of Photosynthesis In Leaves Of Beta Vulgaris L. And Phaseolus Vulgaris L., Bernadette Fondy, Donald Geiger
Effect Of Rapid Changes In Sink-Source Ratio On Export And Distribution Of Products Of Photosynthesis In Leaves Of Beta Vulgaris L. And Phaseolus Vulgaris L., Bernadette Fondy, Donald Geiger
Donald R. Geiger
Effects of increasing sink-source ratio on rate of translocation and net carbon exchange were studied by darkening all but one source leaf of Beta vulgaris L. or one primary leaf of Phaseolus vulgaris L. Rates of export of labeled material and patterns of its distribution among sinks were studied by means of GM detectors. Changes in export and import rates were compared with adjustments in starch, sucrose, and glucose levels in sugar beet source leaves before and during treatment. Sugar beet source leaf treatments which increased sink-source ratio had no sustained effect on rates of net carbon exchange, export, accumulation …
Control Of Partitioning And Export Of Carbon In Leaves Of Higher-Plants, Donald R. Geiger
Control Of Partitioning And Export Of Carbon In Leaves Of Higher-Plants, Donald R. Geiger
Donald R. Geiger
Within source leaves, partition of assimilated carbon and export are regulated to both leaf and plant ontogeny and to environmental conditions. System goals, adaptive responses, control mechanisms, and information flow are developed from the viewpoint that a well-adapted plant is an integrated system. Regulation of partitioning and export involves both feedforward control and feedback homeostasis. Export is controlled by regulation of metabolism which supplies assimilated material to be translocated, by control of efflux into the free space of material destined for export, and by regulation of phloem loading. Control of export by the latter two processes depends on responsive metabolic …