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  • Nicotiana
  • nitrogen
  • phosphorus
  • Springer  (123)
  • Blackwell Publishing Ltd
  • National Academy of Sciences
  • 1990-1994  (93)
  • 1980-1984  (30)
  • 1925-1929
  • 1994  (93)
  • 1980  (30)
Collection
Keywords
Publisher
  • Springer  (123)
  • Blackwell Publishing Ltd
  • National Academy of Sciences
Years
  • 1990-1994  (93)
  • 1980-1984  (30)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    Historical changes in sediments of Pyramid Lake, Nevada, USA: consequences of changes in the water balance of a terminal desert lake (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 87-101 
    Details
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678089
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  • 2
    Electronic Resource
    Electronic Resource
    Fertilizer regime and changes in the phosphate and potash status of a silty marine clay soil during 25 years (1980)
    Springer
    Nutrient cycling in agroecosystems 1 (1980), S. 95-101 
    Details
    ISSN: 1573-0867
    Keywords: soil fertility ; phosphorus ; potassium ; green manure ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the soil phosphorus and potassium status on three farming systems in the Northeast Polder during 25 years are related to the fertilizer regime over this period. The changes in the nutrient status of the soil are reflected in fertilizer policy. High rates of phosphate dressings markedly increased the phosphate status of the soil and built up a reserve of phosphate. In contrast, the potassium status decreased by about half, because only potatoes in the rotation were dressed with potassium. Methods of fertilization are discussed and suggestions are made with regard to possible improvements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073181
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  • 3
    Electronic Resource
    Electronic Resource
    Environmental impact of fertilizing soils by using sewage and animal wastes (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    Details
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750669
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  • 4
    Electronic Resource
    Electronic Resource
    Using hydrophilic polymers to control nutrient release (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 53-59 
    Details
    ISSN: 1573-0867
    Keywords: controlled-release fertilizer ; gel ; iron ; manganese ; nitrogen ; polyacrylamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using diverse technological approaches, many types of delivery devices have been used to supply plant nutrients at a controlled rate in the soil. One new approach is the use of hydrophilic polymers as carriers of plant nutrients. These polymers may be generally classified as 1) natural polymers derived from polysaccharides, 2) semi-synthetic polymers (primarily cellulose derivatives), and 3) synthetic polymers. By controlling the reaction conditions when forming the polymers, various degrees of cross-linking, anionic charge, and cationic charge can be added, thereby changing their effectiveness as fertilizer carriers. When fertilizer-containing solutions are mixed with hydrophilic polymers to form a “gel” prior to application in the soil, the release of soluble nutrients can be substantially delayed compared with soluble fertilizer alone. The effectiveness of a specific controlled-release polymeric system is determined in part by its specific chemical and physical properties, its biodegradation rate, and the fertilizer source used. Addition of some polymers with nutrients has been shown to reduce N and K leaching from well-drained soils and to increase the plant recovery of added N, P, Fe, and Mn in some circumstances
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750062
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  • 5
    Electronic Resource
    Electronic Resource
    Land application of poultry litter and water quality in Oklahoma, U.S.A. (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    Details
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750462
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  • 6
    Electronic Resource
    Electronic Resource
    Response of ensete (Ensete ventricosum W.) to mineral fertilizers in southwest Ethiopia (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    Details
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00748551
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of nitrogen catch crop species on the nitrogen nutrition of succeeding crops (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 227-234 
    Details
    ISSN: 1573-0867
    Keywords: catch crop ; mineralization ; nitrogen ; plant species ; residual effects ; soil depletion ; winter hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten widely different plant species were compared for their ability to reduce soil mineral nitrogen levels in the autumn and their ability to improve the nitrogen nutrition of the succeeding crop. The species included monocots and dicots, crops that survived the winter (persistent) or were winter killed (non-persistent) as well as legumes and non legumes. Their ability to reduce soil mineral nitrogen content was dependent on both root depth and persistency of the crops in the autumn. For non-persistent catch crops most of the mineralization of plant nitrogen occurred during the winter, and for some of these so early as to allow leaching of some mineralized nitrogen. For persistent crops most of the mineralization occurred shortly after incorporation in the spring. The effect of the catch crops on nitrogen uptake by the succeeding barley crop varied from 13 to 66 kg N ha−1 and the differences between the crops could not be related to any single character, but to a combination of root depth, persistency, plant nitrate accumulation, and depletion of the soil mineral nitrogen pool in spring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00748941
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  • 8
    Electronic Resource
    Electronic Resource
    Application of15N-labelled urea to sugar cane through a drip-irrigation system in Mauritius (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 223-228 
    Details
    ISSN: 1573-0867
    Keywords: drip-fertigation ; efficiency ; nitrogen ; sugar cane ; uptake ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen (N) fertilizer use efficiency by sugar cane in Mauritius rarely exceeds 40%. Since drip-irrigation delivers water uniformly and directly to the root zone with little run-off, application of N via the drip-irrigation system could therefore provide a means of enhancing fertilizer N use by sugar cane. A study was initiated in Mauritius to determine what benefits would accrue from applying urea (120 kg N per ha) to sugar cane through the drip-irrigation network. The data obtained showed that the efficiency of fertilizer N when measured at harvest was nearly doubled by supplying the N daily over 10 to 20 weeks by fertigation. Increased yields of sugar or cane did not, however, accompany the improved N use efficiency. Furthermore, when N was applied through the drip-irrigation network, recovery of N at harvest did not accurately reflect N use efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750250
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of phosphate on the sorption, desorption and plant-availability of selenium in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 189-197 
    Details
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750246
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  • 10
    Electronic Resource
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    Urea management for lowland transplanted rice as affected by application of farmyard manure (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 199-203 
    Details
    ISSN: 1573-0867
    Keywords: farmyard manure ; floodwater ; nitrogen ; Oryza sativa L. ; partial pressure of ammonia ; urea ; Vietnam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Farmyard manure (FYM) applied to rice-growing soils can substitute for industrial fertilizers, but little is known about the influence of FYM on the effectiveness and optimal management for industrial N fertilizers. A field experiment was conducted in northern Vietnam on a degraded soil in the spring season (February to June) and summer season (July to November) to determine the effect of FYM on optimal timing for the first application of urea. The experimental design was a randomized complete block with two rates of basal incorporated FYM (0 or 6 Mg ha−1) in factorial combination with two timings of the first application of 30 kg urea-N ha−1 (basal incorporated before transplanting or delayed until 14 to 16 d after transplanting). The FYM was formed by composting pig manure with rice straw for 3 months. Basal incorporation of FYM, containing 23 kg N ha−1, increased rice grain yield in both seasons. The yield increase cannot be attributed to reduced ammonia loss of applied urea-N, because FYM did not reduce partial pressure of ammonia (pNH3) following urea application in either season. Basal and delayed applications of urea were equally effective in the absence of FYM, but when FYM was applied rice yields in both seasons were higher for delayed (mean = 3.2 Mg ha−1) than basal (mean = 2.9 Mg ha−1) application of urea. Results suggest that recommendations for urea timing in irrigated lowland rice should consider whether farmers apply FYM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750247
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  • 11
    Electronic Resource
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    Phosphorus and nitrogen limitation of algal biomass across trophic gradients (1994)
    Springer
    Aquatic sciences 56 (1994), S. 16-28 
    Details
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877432
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  • 12
    Electronic Resource
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    Contribution of nitrogen and phosphorus by precipitation in the drainage basin of the Santillana Reservoir (Madrid) (1994)
    Springer
    Environmental geology 23 (1994), S. 99-104 
    Details
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766982
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  • 13
    Electronic Resource
    Electronic Resource
    Comparison of proteins synthesized in vivo and in vitro by mRNA from isolated protoplasts (1980)
    Springer
    Planta 148 (1980), S. 453-454 
    Details
    ISSN: 1432-2048
    Keywords: mRNA ; Protein synthesis ; Protoplasts ; Nicotiana ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies of proteins synthesized in vitro by messenger RNA (mRNA) extracted from tobacco protoplasts showed that the changes in protein synthesis and especially the lack of certain proteins observed previously in isolated protoplasts did not result from a failure of translation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395314
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  • 14
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    Influence of leaves and roots on meristem development inNicotiana tabacum L. cv. Wisconsin 38 (1980)
    Springer
    Planta 148 (1980), S. 462-467 
    Details
    ISSN: 1432-2048
    Keywords: Flower formation ; Leaves (in flower formation) ; Meristem (shoot) ; Nicotiana ; Roots (and flower formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The terminal, apical shoot meristem ofN. tabacum cv. Wisconsin 38 normally differentiates into a flower after producing 30 to 40 nodes. The influence of leaves and roots on the regulation of flowering was evaluated by counting the number of nodes produced after removal of leaves or the induction of adventitious roots. Leaf removal has no effect on the number of nodes produced before flower formation. Root induction significantly increases the number of nodes produced before flower formation. The plant behaves as if it were measuring the number of nodes between the meristem and the roots as a means of regulating meristem conversion from vegetative to floral differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395316
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  • 15
    Electronic Resource
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    Polysomes from expanded tobacco leaves (1980)
    Springer
    Planta 148 (1980), S. 491-497 
    Details
    ISSN: 1432-2048
    Keywords: Leaves (polysomes) ; Nicotiana ; Polysomes ; Poly(A)+ RNA ; Protein synthesis ; RNA (polysomal, polyA+)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of intact polysomes from leaves of tobacco (Nicotiana tabacum L.) is dependent on the age and state of development of leaves. Undegraded polysomes from young leaves in the early stages of expansion can be isolated easily by extracting the leaves in ice-cold extraction buffer (200 mM tris(hydroxymethyl)aminomethylmethane(Tris)-HCl, pH 9.0; 400 mM KCl; 200 mM sucrose; 35 mM MgCl2). Medium-size leaves give best yields of undegraded polysomes when extractions are carried out in the above buffer and in the presence of ethyleneglycol-bis-(β-amino-ethyl ether)-N,N′-tetracetic acid (EGTA) and mercaptoethanol. Isolation of polysomes from large, nearly fully expanded (mature) leaves requires all of the above plus diethyldithiocarbamate (DIECA) in the extraction medium. An extraction medium consisting of 25 mM EGTA, 0.01 M mercaptoethanol, 25 mM DIECA and 0.5% of the nonionic detergent, Nonidet-P40 (NP 40) was found to be very suitable for extraction of polysomes from all developmental stages of leaves. The polysomes extracted in the above medium showed active translation of protein in the wheat-germ in-vitro protein-synthesizing system. The translational products were similar when translations were carried out directly with polysomes or polysomal RNA, or polysomal poly(A)+ RNA from tobacco leaves. Poly(A)− polysomal RNA was a poor template in the in-vitro wheat-germ system.
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    URL: http://dx.doi.org/10.1007/BF02395320
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  • 16
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    Nutritional requirements of protoplast-derived, haploid tobacco cells grown at low cell densities in liquid medium (1980)
    Springer
    Planta 149 (1980), S. 7-18 
    Details
    ISSN: 1432-2048
    Keywords: Auxin metabolism ; Cell suspensions (low density) ; Medium conditioning ; Nicotiana ; Nitrogen metabolism ; Protoplasts ; Vitamin requirements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preliminary attempts to define a completely synthetic medium able to support divisions of haploid tobacco mesophyll protoplasts at low initial densities have failed. High protoplast concentrations together with large amounts of naphtaleneacetic acid in the medium (3 mg l-1 NAA) were required for maximal induction of protoplast division. However, cell suspensions derived from haploid protoplasts after four days of preculture at high initial cell densities could be diluted to densities as low as 1–4 cells ml-1, provided the concentration of NAA in the medium was lowered to below 0.3 mg l-1. The optimal NAA supply for low cell density growth was affected by the nature of the nitrogen source. A simple minimal medium which supports the growth of these haploid cells with a plating efficiency of 30–40%, independent of the cell density in the range of 1–4 to 3·104 cells ml-1, has been established. In this medium inositol was the only vitamin stringently required for growth. Growth of cells at low densities was also possible in a medium initially containing 3 mg l-1 NAA, provided it was conditioned by the growth of protoplasts at high densities. Preliminary experiments with [14C]NAA showed that the amount of free NAA remaining in the medium after preincubation at high densities was drastically reduced. Simultaneously, NAA conjugates accumulated in the medium. The implications of these results are discussed.
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    URL: http://dx.doi.org/10.1007/BF00386221
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  • 17
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    Characterization of a cytoplasmic auxin receptor from tobacco-pith callus (1980)
    Springer
    Planta 149 (1980), S. 44-47 
    Details
    ISSN: 1432-2048
    Keywords: Auxin receptor ; Callus ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultured tobacco-pith tissue contains a cytoplasmic receptor for indoleacetic acid (IAA). The concentration of binding sites is very low in comparison to that of several auxin receptors found by other investigators. A few obvious possible causes (degradation or inactivation) were investigated. From the results we conclude that the low number of binding sites is real. The receptor binds IAA optimally at pH 7.5–7.8 and at a temperature of 24–30°C, when incubated for 25–30 min. The binding is very specific, as is shown by competition experiments. The concentration of the receptor in the callus tissue changes dramatically during each culture period, which suggests a possible role in development. The receptor was partly purified by gel filtration on Sepharose 6B followed by ion-exchange chromatography on DEAE-cellulose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386225
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  • 18
    Electronic Resource
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    The effect of light on the production of ethylene from 1-aminocyclopropane-1-carboxylic acid by leaves (1980)
    Springer
    Planta 149 (1980), S. 196-199 
    Details
    ISSN: 1432-2048
    Keywords: 1-Aminocyclopropane-1-carboxylic acid ; Avena ; Ethylene ; Etiolation ; Light (ethylene production) ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract White light inhibits the conversion of 1-amino-cyclopropane-1-carboxylic acid (ACC) in discs of green leaves of tobacco (Nicotiana tabacum L.) and segments of oat (Avena sativa L.) leaves by from 60 to 90%. Etiolated oat leaves do not show this effect. The general nature of the effect is shown by its presence in both a mono- and a dicotyledon. Since the leaves have been grown and pre-incubated in light, yet can produce from 2 to 9 times as much ethylene in the dark as in the light, it follows that the light inhibition is fully reversible. The inhibition by light is about equal to that exerted in the dark by CoCl2; it can be partly reversed by dithiothreitol and completely by mercaptoethanol. Thus the light is probably acting, via the photosynthetic system, on the SH group(s) of the enzyme system converting ACC to ethylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380882
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  • 19
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    Correlation between the nicotine content of tobacco plants and callus cultures (1980)
    Springer
    Planta 149 (1980), S. 205-206 
    Details
    ISSN: 1432-2048
    Keywords: Callus cultures ; Nicotiana ; Nicotine ; Tissue cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Callus cultures of two low-alkaloid lines of Nicotiana tabacum L. had considerably lower nicotine contents than cultures from the respective highalkaloid cultivars which were isogenic except for the two loci for alkaloid accumulation. Thus, there was a strong correlation between the nicotine content of callus cultures and the plants from which they were derived.
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    URL: http://dx.doi.org/10.1007/BF00380884
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    Auxin-binding by particulate fractions from tobacco leaf protoplasts (1980)
    Springer
    Planta 150 (1980), S. 9-12 
    Details
    ISSN: 1432-2048
    Keywords: Auxin binding ; Nicotiana ; Plasma membrane ; Protoplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro binding of 1-naphthaleneacetic acid (NAA) to particulate fractions from tobacco leaf protoplasts was studied. In freshly isolated protoplasts no specific binding could be detected, whereas it was present in particulate fractions from tobacco leaves. It is concluded that the NAA-binding-sites are probably located at the external face of the plasma membrane; they are destroyed during protoplast isolation by proteolytic enzymes in the cellulase and macerozyme preparations. After culturing the protoplasts for 3–4 d, the first cell divisions were observed and at the same time specific NAA-binding became detectable. The affinity constant for NAA was approx. 2·106 mol-1 and the number of binding sites increased during further culture.
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    URL: http://dx.doi.org/10.1007/BF00385607
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  • 21
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    Factors influencing the incidence of habituation for cytokinin of tobacco pith tissue in culture (1980)
    Springer
    Planta 150 (1980), S. 264-268 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinin habituation ; Habituation, cytokinin ; Nicotiana ; Position effects (habituation) ; Size effects (habituation) ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pith tissue of Nicotiana tabacum L. cv. “Havana 425” exhibits a gradient in its tendency to habituate for cytokinin on an auxin-containing medium at 35° C, about 10° C above the standard culture temperature. Explants of pith from below the 8th to 11th internode, counting from the bottom of the plant, rarely habituate for cytokinin; explants from above this threshold habituate rapidly. The explants must also be above a critical size, about 20–30 mg, to habituate. There was a pronounced interaction between size and position effects; the threshold position for cytokinin habituation shifted upward with decreasing explant size.
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    URL: http://dx.doi.org/10.1007/BF00390836
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    Stimulation by abscisic acid of RNA synthesis in discs from healthy and tobacco mosaic virus-infected tobacco leaves (1980)
    Springer
    Planta 150 (1980), S. 349-353 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Nicotiana ; Ribonucleic acid synthesis ; Tobacco mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uptake of abscisic acid from the culture medium by discs of healthy and tobacco mosaic virus-infected tobacco leaves was measured. Small (two to five-fold) increases in abscisic acid concentration in discs caused increases in rates of [3H]uridine and [3H]adenine incorporation into total nucleic acid, virus RNA and host ribosomal RNA. Net accumulation of virus RNA was also enhanced by abscisic acid. This evidence for stimulation of RNA synthesis is compared with previous reports showing inhibition of RNA synthesis in other tissues. It is suggested that the increase in endogenous abscisic acid caused by tobacco mosaic virus infection may be at least partly responsible for observed increases in rates of RNA synthesis after infection.
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    URL: http://dx.doi.org/10.1007/BF00390168
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  • 23
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    Factors affecting the re-formation of vacuoles in evacuolated protoplasts and the expression of the two vacuolar proton pumps (1994)
    Springer
    Planta 192 (1994), S. 395-403 
    Details
    ISSN: 1432-2048
    Keywords: Nicotiana ; Protoplast ; Pyrophosphatase ; Vacuolar ATPase ; Vacuole (regeneration)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The re-formation of vacuoles in miniprotoplasts (evacuolated mesophyll protoplasts) of tobacco was investigated under different conditions. When a constant osmolarity was maintained, increasing the concentration of NaCl in the medium enhanced the regeneration of vacuoles compared to the control (0.5 M mannitol used as osmoticum). An enhanced growth rate of miniprotoplasts could also be observed under low-osmolarity conditions, by substitution of NaCl for KCl or NaNO3, or with different effectors (glycinebetaine and methyljasmonate). Using the polymerase chain reaction, one cDNA fragment of the B-subunit of the vacuolar ATPase and two fragments of the tonoplast-bound pyrophosphatase (PPase) of tobacco were cloned. Southern blot analyses indicates that for both proteins more than one gene is present in tobacco. During the regeneration of vacuoles the transcript level of the PPase increased earlier than that of the B-subunit of the vacuolar ATPase under all conditions tested (0.5 M mannitol, 0.3 M mannitol, and 0.25 M NaCl, respectively). Under salt-stress conditions (0.25 M NaCl used as osmoticum), the expression level of both proton pumps is enhanced compared to the control. This increase is not specifically due to salt stress but generally to an increased growth rate of the vacuole, since under low-osmolarity conditions the expression of the vacuolar pumps is enhanced, too.
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    URL: http://dx.doi.org/10.1007/BF00198576
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    A Nicotiana tabacum mRNA encoding a 69-kDa glycoprotein occurring abundantly in pollen tubes is transcribed but not translated during pollen development in the anthers (1994)
    Springer
    Planta 192 (1994), S. 441-445 
    Details
    ISSN: 1432-2048
    Keywords: Glycosylation in vitro ; mRNA translation control ; Nicotiana ; Pollen development ; Pollen tube ; Translation in vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regulation of expression of a 69-kDa glycoprotein which occurs abundantly in tobacco (Nicotiana tabacum L.) pollen tubes but is absent in ungerminated pollen has been studied in vitro by means of a coupled translation/glycosylation system with RNA isolated from various stages of pollen development. Pollen mRNA could be translated in a rabbit reticulocyte lysate and the products glycosylated with canine pancreatic microsomal membranes. The electrophoretic pattern of translation products obtained with pollen-tube RNA showed a prominent polypeptide with an apparent molecular mass of 58 kDa. In the presence of the canine pancreatic microsomal membranes this polypeptide was glycosylated, producing the 69-kDa glycoprotein. The presence of mRNA encoding the 58-kDa precursor polypeptide was also demonstrated in ungerminated pollen and in young mid-binucleate pollen isolated from anthers. Initiation of synthesis of the 69-kDa glycoprotein at the onset of pollen germination thus occurs through unmasking of the mRNA transcribed during pollen differentiation and stored during pollen maturation and dormancy in an inactive state.
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    URL: http://dx.doi.org/10.1007/BF00198581
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    Fructose 2,6-bisphosphate levels in mature leaves of tobacco (Nicotiana tabacum) and potato (Solanum tuberosum) (1994)
    Springer
    Planta 193 (1994), S. 16-20 
    Details
    ISSN: 1432-2048
    Keywords: Fructose 2,6-bisphosphate ; Photosynthesis ; Nicotiana ; Solanum ; Starch ; Sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Here we show that fructose 2,6-bisphosphate cannot be reliably measured in mature leaves of tobacco (Nicotiana tabacum L.), potato (Solanum tuberosum L.), or stinging nettle (Urtica dioica L.) using conventional extraction techniques, since the recoveries of fructose 2,6-bisphosphate added during extraction are poor. However, fructose 2,6-bisphosphate could be extracted by boiling leaves in ethanol and aqueous buffer. Evidence for the reliability of this technique is provided by high recovery measurements of fructose 2,6-bisphosphate added to the leaves before extraction. This extraction method was used to measure changes in the level of fructose 2,6-bisphosphate throughout the photoperiod in tobacco and potato leaves. These changes are compared with the rate of accumulation of sucrose and starch in the leaf samples. Variations in the levels of fructose 2,6-bisphosphate, and the relationship between this metabolite and sucrose and starch accumulation in these leaves during the photoperiod are similar to the pattern observed in leaves of other plant species.
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    URL: http://dx.doi.org/10.1007/BF00191601
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    Cell-wall-bound oxidases from tobacco (Nicotiana tabacum) xylem participate in lignin formation (1994)
    Springer
    Planta 194 (1994), S. 9-14 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall ; Lignification ; Nicotiana ; Oxidase ; Peroxidase ; Xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A band of cells closest to the cambium in the xylem of tobacco (Nicotiana tabacum L. cv. Samsun) stems oxidized 2,2-azinobis-(3-ethylbenzo-thiazoline-6-sulphonate) (ABTS), o-dianisidine and syringaldazine in the absence of exogenously added hydrogen peroxide. The oxidation was not prevented by catalase which suggests that the oxidation is not dependent on the production and utilisation of endogenous hydrogen peroxide by cell-wall peroxidases. Cell walls, isolated from tobacco xylem, also oxidized these substrates in the absence of added hydrogen peroxide. The cell walls consumed molecular oxygen whilst oxidizing a range of compounds including coniferyl alcohol. The substrate preference and sensitivity to inhibitors suggest the presence of laccasetype polyphenol oxidases (p-diphenol:O2 oxidoreductase EC 1.14.18.1) which are covalently bound to the wall. The oxidation of coniferyl alcohol by the xylem cell walls was confirmed by assays based on the disappearance of coniferyl alcohol and was not affected by the presence of 500 units·mi-1 catalase or Superoxide dismutase. Prolonged incubation of cell walls with coniferyl alcohol led to the production of a yellow-orange water-insoluble material that precipitated with the cell walls. Although a proportion of this material was soluble in methanol, the majority was tightly associated with the cell walls. These coloured cell walls had elevated lignin contents when assayed by the acetyl-bromide method. Fourier transforminfrared spectroscopic analysis of the coloured cell walls indicated that the increased lignin content is due to the deposition of guaiacyl-type lignin. Digestion of the xylem cell walls with Driselase, a mixture of fungal glycases, produced a wall residue that had a dramatically reduced ability to oxidize ABTS in the absence of added H2O2. However, oxidase activity could not be detected in the Driselase-solubilized extract, although small amounts of oxidase activity could be recovered from the Driselaseresistant wall residue by extraction in 3 M CaCl2.
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    Deletion analysis of a nitrite-reductase promoter from spinach in transgenic tobacco (1994)
    Springer
    Planta 194 (1994), S. 186-192 
    Details
    ISSN: 1432-2048
    Keywords: Gene expression ; Nitrate ; Nitrite-reductase ; Phytochrome ; Transgenic tobacco ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deletion analysis of the nitrite-reductase (NiR) promoter from spinach (Spinacia oleracea L.) fused to theβ-glucuronidase (GUS) reporter gene and introduced into tobacco (Nicotiana tabacum L., cv. Coker 176) indicates that basic elements required for light- and nitrate-dependent expression of the reporter are located within the promoter sequence -200/+131 relative to the transcription-initiation site. Detailed analysis indicates that positive regulatory elements exist between -200 and-330 as well as between -1450 and -1730, stimulating the level of GUS gene expression under all experimental conditions. Induction/reversion light-pulse experiments show that the promoter sequence -200/+131 suffices for phytochrome-mediated expression of the reporter gene. The observation that the NiR promoter from spinach exhibits full reversibility in transgenic tobacco confirms the previous conclusion that the NiR promoter from spinach fused to a GUS reporter gene and introduced into tobacco responds to nitrate and phytochrome as would be expected for tobacco (host) and not as would be expected for spinach (donor). When the plastids were damaged by photooxidation in the presence of Norflurazon, GUS activity levels were reduced to the same extent for all NiR-promoter/GUS fusions tested, indicating that the promoter region involved in the action of the ‘plastidic factor’ is between -200 and +131. The GUS gene expression under the control of the CaMV-35S promoter is not affected by light, nitrate or the ‘plastidic factor’.
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    URL: http://dx.doi.org/10.1007/BF01101677
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    Sterol overproduction is the biochemical basis of resistance to a triazole in calli from a tobacco mutant (1994)
    Springer
    Planta 194 (1994), S. 295-305 
    Details
    ISSN: 1432-2048
    Keywords: Mutant (tobacco calli) ; Nicotiana ; Sterolbiosynthesis inhibitors ; Triazole resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sterol overproduction is shown to be the biochemical basis of resistance to the triazole LAB 170250F (2-(4-chlorophenyl)-3-phenyl-1-(1H-1,2,4-triazol-1-yl)-2,3-oxidopropane), an inhibitor of cytochrome P450-dependent-obtusifoliol-14α-demethylase, in the tobacco (Nicotiana tabacum L. cv. Xanthi) mutant LAB 1-4. Genetic analysis at the callus level indicates that the resistance and the biochemical phenotypes co-segregate during meiotic recombination and therefore result most probably from the same mutation. Analysis of the intracellular distribution of sterols shows that in LAB 1-4 calli containing tenfold the sterol amount of the wild type, the overproduced metabolites, mainly obtusifoliol, are esterified by fatty acids and stored in hyaloplasmic lipid droplets. Thus, the mutant calli maintain a concentration of free sterols in cell membranes, mainly end-products of the sterol-biosynthesis pathway, which corresponds to physiological requirements, whereas the level of free sterols in the wild-type calli treated with the triazole is too low to ensure viability. We also show that sterol overproduction confers resistance to other phytotoxic sterolbiosynthesis inhibitors.
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    URL: http://dx.doi.org/10.1007/BF00197528
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  • 29
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    Deletion analysis of a nitrite-reductase promoter from spinach in transgenic tobacco (1994)
    Springer
    Planta 194 (1994), S. 186-192 
    Details
    ISSN: 1432-2048
    Keywords: Gene expression ; Nitrate ; Nitrite-reductase ; Phytochrome ; Transgenic tobacco ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deletion analysis of the nitrite-reductase (NiR) promoter from spinach (Spinacia oleracea L.) fused to the β-glucuronidase (GUS) reporter gene and introduced into tobacco (Nicotiana tabacum L., cv. Coker 176) indicates that basic elements required for light- and nitrate-dependent expression of the reporter are located within the promoter sequence -200/+131 relative to the transcription-initiation site. Detailed analysis indicates that positive regulatory elements exist between -200 and-330 as well as between -1450 and -1730, stimulating the level of GUS gene expression under all experimental conditions. Induction/reversion light-pulse experiments show that the promoter sequence -200/+131 suffices for phytochrome-mediated expression of the reporter gene. The observation that the NiR promoter from spinach exhibits full reversibility in transgenic tobacco confirms the previous conclusion that the NiR promoter from spinach fused to a GUS reporter gene and introduced into tobacco responds to nitrate and phytochrome as would be expected for tobacco (host) and not as would be expected for spinach (donor). When the plastids were damaged by photooxidation in the presence of Norflurazon, GUS activity levels were reduced to the same extent for all NiR-promoter/GUS fusions tested, indicating that the promoter region involved in the action of the ‘plastidic factor’ is between -200 and +131. The GUS gene expression under the control of the CaMV-35S promoter is not affected by light, nitrate or the ‘plastidic factor’.
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    URL: http://dx.doi.org/10.1007/BF00196387
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    Fertilization in Nicotiana tabacum: Cytoskeletal modifications in the embryo sac during synergid degeneration (1994)
    Springer
    Planta 194 (1994), S. 200-214 
    Details
    ISSN: 1432-2048
    Keywords: Actin ; Cytoskeleton ; Embryo sac ; Fertilization ; Microtubule ; Nicotiana ; Synergid degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytoskeletal organization of the embryo sac of tobacco (Nicotiana tabacum L.) was examined at maturity and during synergid degeneration, pollen-tube delivery and gamete transfer using rapid-frozen, freeze-substituted and chemically fixed material in combination with immunofluorescence and immunogold electron microscopy. Before fertilization, the synergid is a highly polarized cell with dense longitudinally aligned arrays of microtubules adjacent to the filiform apparatus at the micropylar end of the cell associated with major organelles. The cytoskeleton of the central cell is less polarized, with dense cortical microtubules in the micropylar and chalazal regions and looser, longitudinally oriented cortical microtubules in the lateral region. In the synergid and central cell, F-actin is frequently found at the surface of the organelles and co-localizes with either single microtubules or microtubule bundles. Egg cell microtubules are frequently cortical, randomly oriented and more abundant at the chalazal end of the cell; actin filaments are associated with microtubules and the cortex of the egg cell. At 48 h after pollination and before the pollen tube arrives, the onset of degeneration is evident in one of the two synergids: the electron density of cytoplasmic organelles and the ground cytoplasm increases and the nucleus becomes distorted. Although synergids otherwise remain intact, the vacuole collapses and organelles degenerate rapidly after pollen-tube entry. Abundant electron-dense material extends from the degenerated synergid into intercellular spaces at the chalazal end of the synergid and between the synergids, egg and central cell. Rhodamine-phalloidin and anti-actin immunogold labeling reveal that electron-dense aggregates in this region contain abundant actin forming two distinct bands termed “coronas”. This actin is part of a mechanism in the egg apparatus which appears to precisely position and facilitate the access of male gametes to the egg and central cell for fusion.
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    URL: http://dx.doi.org/10.1007/BF00196389
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    Trypsin inhibitor activity in mature tobacco and tomato plants is mainly induced locally in response to insect attack, wounding and virus infection (1994)
    Springer
    Planta 195 (1994), S. 29-35 
    Details
    ISSN: 1432-2048
    Keywords: Lycopersicon ; Manduca ; Nicotiana ; Proteinase inhibitor ; Tobacco Mosaic Virus ; Wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wounding of plants by insects is often mimicked in the laboratory by mechanical means such as cutting or crushing, and has not been compared directly with other forms of biotic stress such as virus infection. To compare the response of plants to these types of biotic and abiotic stress, trypsin inhibitor (TI) activity induced locally and systemically in mature tobacco (Nicotiana tabacum L.) and tomato (Lycopersicon esculentum L.) plants was followed for 12 days. In tobacco, cutting, crushing and insect feeding all induced comparable levels of TI activity of approx. 5 nmol·(mg leaf protein)−1 in wounded leaves, while tobacco mosaic virus (TMV) infection of tobacco induced 10-fold lower amounts in the infected leaves. In tomato, feeding by insects also led to the induction of a level of TI activity of 5 nmol·(mg leaf protein)−1. In contrast, both cutting and crushing of tomato leaves induced 10-fold higher amounts. These data show that biotic stress, in the form of insect feeding and TMV infection, and abiotic stress, in the form of wounding, have different effects on local levels of induced TI activity in mature tobacco and tomato plants. Irrespective of the type of wounding, in neither tobacco nor tomato could systemic induction of TI activity be observed in nearby unwounded leaves, which suggests that systemic induction of TI activity in mature tobacco and tomato plants is different from systemic TI induction in seedlings. Wounding of tobacco leaves, however, did increase the responsiveness to wounding elsewhere in the plant, as measured by an increased induction of TI activity.
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    The kinetics of ribulose-1,5-bisphosphate carboxylase/oxygenase in vivo inferred from measurements of photosynthesis in leaves of transgenic tobacco (1994)
    Springer
    Planta 195 (1994), S. 88-97 
    Details
    ISSN: 1432-2048
    Keywords: Gas exchange ; Nicotiana ; Photosynthesis (C3) ; Ribulose-1,5-bisphosphate carboxylase/oxygenase kinetics ; Transgenic tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic tobacco (Nicotiana tabacum L. cv. W38) with an antisense gene directed against the mRNA of the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit was used to determine the kinetic properties of Rubisco in vivo. The leaves of these plants contained only 34% as much Rubisco as those of the wild type, but other photosynthetic components were not significantly affected. Consequently, the rate of CO2 assimilation by the antisense plants was limited by Rubisco activity over a wide range of CO2 partial pressures. Unlike in the wild-type leaves, where the rate of regeneration of ribulose bisphosphate limited CO2 assimilation at intercellular partial pressures above 400 ubar, photosynthesis in the leaves of the antisense plants responded hyperbolically to CO2, allowing the kinetic parameters of Rubisco in vivo to be inferred. We calculated a maximal catalytic turnover rate, kcat, of 3.5+0.2 mol CO2·(mol sites)−1·s−1 at 25° C in vivo. By comparison, we measured a value of 2.9 mol CO2·(mol sites)−1·−1 in vitro with leaf extracts. To estimate the Michaelis-Menten constants for CO2 and O2, the rate of CO2 assimilation was measured at 25° C at different intercellular partial pressures of CO2 and O2. These measurements were combined with carbon-isotope analysis (13C/12C) of CO2 in the air passing over the leaf to estimate the conductance for transfer of CO2 from the substomatal cavities to the sites of carboxylation (0.3 mol·m−2·s−1·bar−1) and thus the partial pressure of CO2 at the sites of carboxylation. The calculated Michaelis-Menten constants for CO2 and O2 were 259 ±57 μbar (8.6±1.9μM) and 179 mbar (226 μM), respectively, and the effective Michaelis-Menten constant for CO2 in 200 mbar O2 was 549 μbar (18.3 μM). From measurements of the photocompensation point (Γ* = 38.6 ubar) we estimated Rubisco's relative specificity for CO2, as opposed to O2 to be 97.5 in vivo. These values were dependent on the size of the estimated CO2-transfer conductance.
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    The role of peroxidase isoenzyme groups of Nicotiana tabacum in hydrogen peroxide formation (1980)
    Springer
    Planta 147 (1980), S. 467-470 
    Details
    ISSN: 1432-2048
    Keywords: Hydrogenperoxide ; Lignification ; Nicotiana ; Peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three peroxidase isoenzyme-groups found in cell walls of tobacco were tested for their capacity to form H2O2. Isoenzyme-group GI, located only in cell walls (GII and GIII are also found in protoplasts) showed the highest Kapp-value for H2O2-formation. The lowest Kapp-value, i.e., maximal H2O2-formation was received for group GIII which is ionically bound to the cell wall. As shown before, GI yields maximal polymerization rates for coniferyl- and p-coumarylalcohol. These facts indicate that each of the peroxidase isoenzyme groups of the cell wall is involved with different catalytic functions within the same pathways of H2O2-formation and succeeding lignification. H2O2-formation catalyzed by all 3 groups was increased by very low concentrations of Mn2+-ions. The required amount of Mn2+ leading to maximal stimulation was in each case dependent on the basic rate of H2O2-formation. Maximal stimulation of H2O2-formation by phenolic compounds was achieved by coniferylalcohol at a concentration of 10-4M for all groups. Stimulation by p-coumaryl-and by sinapylalcohol was not as significant.
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    The induction of cytokinin habituation in primary pith explants of tobacco (1980)
    Springer
    Planta 149 (1980), S. 402-407 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinin ; Habituation rates ; Nicotiana ; Temperature and habituation ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pith parenchyma tissue ofNicotiana tabacum L. cv. “Havana 425” becomes cytokinin habituated when incubated at 35°C on an auxin-containing medium. Under these conditions, habituated, hyperplastic nodules appear on the tissues. We used these nodules to estimate the incidence of habituation by a statistical method. The rate of habituation varied with the season. Tissue isolated from plants in the spring habituated approx. 7 times faster than did tissue isolated from plants in winter. The fact that the average rate, 〉4×10−3 per cell generation, was 100–1,000 times faster than the rate of somatic mutation inNicotiana species and depended on the physiological state of the tissue provides further evidence that habituation involves epigenetic changes rather than rare, random genetic mutations. We also found that kinetin (6-furfurylaminopurine) induced habituation and that the concentration required depended on the duration of cytokinin treatment. For long incubation times, approx. 6×10−10 M kinetin, which is about 1,000-fold lower than the concentration optimal for growth of cytokinin-requiring pith tissue, was sufficient to induce habituation. These results support the hypothesis that the habituated state is maintained by a positive feedback loop in which cytokinins either induce their own synthesis or inhibit their own degradation.
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    Fatty-acid composition and biosynthesis in cell suspension cultures of Glycine max (L.) Merr., Catharanthus roseus G. Don and Nicotiana tabacum L. (1980)
    Springer
    Planta 147 (1980), S. 384-388 
    Details
    ISSN: 1432-2048
    Keywords: Acetate incorporation ; Catharanthus ; Cell suspension cultures ; Fatty acids ; Glycihe ; Nicotiana ; Temperature and fatty-acid synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fatty-acid composition of C. roseus and N. tabacum cell suspension cultures was unaffected by subculture on Wood and Braun, Murashige and Skoog, or Gamborg B5C media. However, placing the cultures — which were normally grown at 25° C — at 15° C reduced growth but resulted in enhanced formation of oleic and linolenic acids in C. roseus cultures and increased levels of linoleic and linolenic acids in cultures of G. max and N. tabacum, respectively. The incorporation of [14C]acetate into [14C]linoleic acid was more rapid in N. tabacum cells than in G. max cells, but was very poor in C. roseus where the [14C] label was distributed mainly between palmitic and oleic acids.
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    Expression of nuclear and chloroplastic genes coding for fraction-1 protein in somatic hybrids of Nicotiana tabacum + rustica (1980)
    Springer
    Planta 147 (1980), S. 414-417 
    Details
    ISSN: 1432-2048
    Keywords: Fraction-1 protein ; Hybrid, somatic ; Nicotiana ; Protein (Fraction 1) ; Ribulose-1,5-bisphosphate carboxylase ; Somatic hybrid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the sexual interspecific cross, Nicotiana rustica L.xN. tabacum L., N. rustica can serve as the female but not as the male parent. By fusion of protoplasts, the barrier to fertilization was overcome and somatic hybrids containing N. tabacum cytoplasm were produced as shown by isoelectric focusing of the Fraction-1 protein (F-1-protein). All somatic hybrids displayed polypeptides of the large subunit of F-1 protein (which is coded by the chloroplast genome) characteristic of only one or the other parental species. Two hybrids had large subunits of the N. tabacum type and two hybrids had those of the N. rustica type. Three hybrids contained three smallsubunit polypeptides (coded by the nuclear genome), one being characteristic of N. rustica, one characteristic of N. tabacum, and one with an isoelectric point common to both species. A fourth hybrid contained only two small-subunit polypeptides of the N. tabacum type but in a F-1 protein macromolecule whose large subunits were of the N. rustica type. One somatic hybrid was self-fertile and its F2 progeny contained large- and small-subunit polypeptides indistinguishable in their isoelectric points from those in the parent F1 hybrid. All somatic hybrids showed an aneuploid chromosome number and morphological characteristics intermediate between those of N. rustica and N. tabacum.
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    The effect of different temperatures on fatty-acid synthesis and polyunsaturation in cell suspension cultures (1980)
    Springer
    Planta 147 (1980), S. 389-395 
    Details
    ISSN: 1432-2048
    Keywords: Catharanthus ; Cell suspension cultures ; Glycine ; Fatty acids (synthesis, desaturation) ; Nicotiana ; Linoleic, linolenic, oleic, acids ; Temperature and fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension cultures of Catharanthus roseus G. Don, Glycine max (L.) Merr. and Nicotiana tabacum L. were incubated with [14C]acetate, [14C]oleic acid and [14C]linoleic acid at five different temperatures ranging from 15 to 35° C. When the incubation temperature was increased, [14C]acetate was incorporated preferentially into [14C]palmitate, with a concomitant drop in [14C]oleate formation. Between 15 and 20° C, [14C]oleic acid accumulated in C. roseus cells. In all cultures, optimum desaturation of [14C]oleic acid to [14C]linoleic acid occurred between 20 and 25° C, and in G. max this was also the optimal range for desaturation of [14C]linoleic acid to [14C]linolenic acid. Elongation of [14C]palmitic acid was inhibited when cultures grown at 15° C for 25 h were subsequently incubated with [14C]acetate at 25° C. [14C]oleic acid accumulated in G. max and C. roseus cultures grown at 35° C for 25 h and subsequently incubated at 25° C. Desaturation of [14C]oleic acid increased up to 25° C, but then decreased or leveled off depending on the cell line and on the temperature prior to incubation.
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    Polysomes from expanded tobacco leaves (1980)
    Springer
    Planta 148 (1980), S. 491-497 
    Details
    ISSN: 1432-2048
    Keywords: Leaves (polysomes) ; Nicotiana ; Polysomes ; Poly(A)+ RNA ; Protein synthesis ; RNA (polysomal, polyA+)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of intact polysomes from leaves of tobacco (Nicotiana tabacum L.) is dependent on the age and state of development of leaves. Undegraded polysomes from young leaves in the early stages of expansion can be isolated easily by extracting the leaves in ice-cold extraction buffer (200 mM tris(hydroxymethyl)aminomethylmethane(Tris)-HCl, pH 9.0; 400 mM KCl; 200 mM sucrose; 35 mM MgCl2). Medium-size leaves give best yields of undegraded polysomes when extractions are carried out in the above buffer and in the presence of ethyleneglycol-bis-(β-amino-ethyl ether)-N,N′-tetracetic acid (EGTA) and mercaptoethanol. Isolation of polysomes from large, nearly fully expanded (mature) leaves requires all of the above plus diethyldithiocarbamate (DIECA) in the extraction medium. An extraction medium consisting of 25 mM EGTA, 0.01 M mercaptoethanol, 25 mM DIECA and 0.5% of the nonionic detergent, Nonidet-P40 (NP 40) was found to be very suitable for extraction of polysomes from all developmental stages of leaves. The polysomes extracted in the above medium showed active translation of protein in the wheat-germ in-vitro protein-synthesizing system. The translational products were similar when translations were carried out directly with polysomes or polysomal RNA, or polysomal poly(A)+ RNA from tobacco leaves. Poly(A)− polysomal RNA was a poor template in the in-vitro wheat-germ system.
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    Suitable conditions for characterization, identification, and isolation of the mRNA of the small subunit of ribulose-1,5-bisphosphate carboxylase from Nicotiana sylvestris (1980)
    Springer
    Planta 148 (1980), S. 211-216 
    Details
    ISSN: 1432-2048
    Keywords: mRNA ; Nicotiana ; Protein synthesis ; Ribulose-1,5-bisphosphate carboxylase ; RNA (messenger) ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The products synthesized in vitro by messenger RNA (mRNA) extracted from Nicotiana sylvestris were analyzed by electrophoresis on polyacrylamide slab gels. Only three of the major polypeptides synthesized are considered here: P55, P32, and P20. P55 and P32 were translated from chloroplast mRNA. P55 corresponds to the large subunit of ribulose-1,5-bisphosphate (RuP2) carboxylase; P32 is probably a chloroplast membrane protein. P20, the polypeptide synthesized from cytoplasmic poly(A)+ RNA, is the precursor of the small subunit of RuP2 carboxylase. The balance between P20 and P32, in which their relative proportions varied inversely, was regulated by the age of the leaves and the time of illumination; we took advantage of this phenomenon to isolate the mRNA from the small subunit in relatively large amounts. This mRNA has a molecular weight of 350,000.
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    Properties and regulation of adenosine 5′-phosphosulfate sulfotransferase from suspension cultures ofNicotiana sylvestris (1980)
    Springer
    Planta 150 (1980), S. 140-143 
    Details
    ISSN: 1432-2048
    Keywords: Adenosine 5′-phosphosulfate sulfotransferase ; Cell suspension culture ; Cysteine ; Enzyme regulation ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The properties and the regulation of adenosine 5′-phosphosulfate sulfotransferase extracted from cell suspension cultures ofNicotiana sylvestris was investigated. Optimal adenosine 5′-phosphosulfate sulfotransferase activity was obtained from the cells by extraction with 0.1 M tris-HCl, pH8.0, containing 2 M MgSO4 and 10 mM dithioerythritol. The K m for adenosine 5′-phosphosulfate in the sulfotransferase reaction was about 11 μM. Adenosine 5′-phosphosulfate in concentrations above 50 μM were inhibitory. The extratable adenosine 5′-phosphosulfate sulfotransferase activity decreased during cultivation with sulfate as the sole sulfur source, but after about 3 days it reached a constant level (50 to 100 nmol activated sulfate transferred h-1 mg-1 protein) which was maintained for at least 24 h. Addition of 0.5 mM cysteine to the culture medium decreased the extractable adenosine 5′-phosphosulfate sulfotransferase activity and blocked growth completely. With 0.1 mM cysteine an enzyme level of about 10% of the initial value was reached within 6 to 12 h without significant inhibition of growth. The added cysteine was absorbed rapidly and after 24 h cysteine could no longer be detected in the medium. Before the cysteine was completely depleted, the activity of adenosine 5′-phosphosulfate sulfotransferase started to increase, reaching ultimately a level which was comparable to the initial value.
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    Ribosylzeatin and zeatin in tobacco crown gall tissue (1980)
    Springer
    Planta 147 (1980), S. 269-273 
    Details
    ISSN: 1432-2048
    Keywords: Crown gall ; Cytokinins ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytokinins were extracted from two cultures of tobacco crown gall tumor tissue: an unorganized tissue and a teratoma which produced leafy shoots. On Sephadex LH-20 column chromatography, extracts of both types of tissue yielded two peaks of cytokinin activity with elution volumes similar to ribosylzeatin and zeatin. Ribosylzeatin and zeatin were detected and quantified by coupled gas chromatography — mass spectrometry selected ion monitoring (GC/MS SIM), comparable quantities being found in the two extracts. Full mass spectral evidence for the presence of ribosylzeatin in both tissues was obtained. No evidence was found for the presence of N6-(Δ2-isopentenyl)adenosine (i6Ade) or N6-(Δ2-isopentenyl)adenine (i6Ade) although these compounds have been reported to occur in cytokinin-habituated tobacco callus tissues.
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    Multistage disruption of protoplasts by dikegulac (1980)
    Springer
    Planta 147 (1980), S. 274-276 
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    ISSN: 1432-2048
    Keywords: Cell division ; Dikegulac ; Lysis ; Nicotiana ; Plasmalemma ; Protoplasts ; Tonoplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dikegulac (2,3:4,6 di-o-isopropylidine-2-keto-I-gulonate) is a growth regulator used to differentially kill terminal apices, and it analogously inhibits basic metabolic functions in dividing cells, but not stationary cells, in suspension culture. This report demonstrates an analogous situation in isolated tobacco protoplasts. At the lowest concentrations, dikegulac partially suppresses division of the protoplasts. Higher concentrations are required to produce visual cytoplasmic damage to the protoplasts, which probably first occurs at the level of the plasmalemma, as the vacuoles can be released intact. Later, tonoplast disruption occurs.
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    Isolation of abscisic acid-resistant variants from tobacco cell cultures (1980)
    Springer
    Planta 148 (1980), S. 97-102 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Cell cultures ; Nicotiana ; Variants, resistant ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The goal of this work was to begin a genetic study of the molecular mode of action of abscisic acid (ABA), by isolating variant cultured cells resistant to the hormone, or to a factor which induces ABA synthesis, namely water stress. Cell cultures of Nicotiana tabacum L. cv. Wisconsin 38 and N. silvestris Speg. and Comes were chosen as the experimental materials. Studies of the effects of the two stresses on the growth of the cultures demonstrated that ABA or water stress imposed by mannitol could completely inhibit growth. These effects arose in both cases from a constant reduction of the growth rate of the cells throughout the culture period. Mannitol also induced an increase in ABA content of the cells and media of suspension cultures, although not to the concentrations required to achieve the same degree of growth inhibition when the hormone was applied exogenously.
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    Isolation of abscisic acid-resistant variants from tobacco cell cultures (1980)
    Springer
    Planta 148 (1980), S. 103-107 
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    ISSN: 1432-2048
    Keywords: Abscisic acid ; Cell cultures ; Nicotiana ; Variants, resistant ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variant clones were isolated from Nicotiana silvestris Speg. et Comes cell cultures at low frequencies following severe abscisic-acid (ABA) or mannitol-induced water-stress treatments of plated cells. N. tabacum L. variants were not recovered. Variants from the ABA selection experiments exhibited a 10-fold increase in resistance to the hormone. This trait was stable in non-selective conditions for as long as was tested (200 days), but did not alter the response of the cells to water stress. Cell lines from the waterstress selection were not more resistant to mannitol than the parent line, and had a wide range of response to ABA.
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    Comparison of proteins synthesized in vivo and in vitro by mRNA from isolated protoplasts (1980)
    Springer
    Planta 148 (1980), S. 453-454 
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    ISSN: 1432-2048
    Keywords: mRNA ; Protein synthesis ; Protoplasts ; Nicotiana ; Translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies of proteins synthesized in vitro by messenger RNA (mRNA) extracted from tobacco protoplasts showed that the changes in protein synthesis and especially the lack of certain proteins observed previously in isolated protoplasts did not result from a failure of translation.
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    Influence of leaves and roots on meristem development inNicotiana tabacum L. cv. Wisconsin 38 (1980)
    Springer
    Planta 148 (1980), S. 462-467 
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    ISSN: 1432-2048
    Keywords: Flower formation ; Leaves (in flower formation) ; Meristem (shoot) ; Nicotiana ; Roots (and flower formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The terminal, apical shoot meristem ofN. tabacum cv. Wisconsin 38 normally differentiates into a flower after producing 30 to 40 nodes. The influence of leaves and roots on the regulation of flowering was evaluated by counting the number of nodes produced after removal of leaves or the induction of adventitious roots. Leaf removal has no effect on the number of nodes produced before flower formation. Root induction significantly increases the number of nodes produced before flower formation. The plant behaves as if it were measuring the number of nodes between the meristem and the roots as a means of regulating meristem conversion from vegetative to floral differentiation.
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    The diversity of interspecific pollen-pistil incongruity in Nicotiana (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 250-258 
    Details
    ISSN: 1432-2145
    Keywords: Reproductive barrier ; Interspecific hybridization ; Nicotiana ; Unilateral incongruity Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nicotiana tabacum was used as a pistillate parent and crossed with three self-compatible species, N. rustica, N. repanda and N. trigonophylla, which were previously reported to have pollen tubes unilaterally inhibited by N. tabacum pistil. Temporal and morphological observations revealed distinct differences of pollen tube behavior among these incongruous crosses. Pollen tubes of N. repanda were arrested in stigma and those of N. rustica in the middle of the style. On the other hand, pollen tubes of N. trigonophylla continued growing at a slow rate. Tubes of N. repanda and N. rustica showed morphological abnormalities such as swelling, thick wall, and irregular callose deposition. In addition, tubes of N. rustica often elongated in reverse direction and wound about in the middle of the style. Although the tubes of N. trigonophylla were apparently normal in morphology, they were distributed throughout the transmitting tissue, differing from the self-pollination of N. tabacum in which they were confined to the peripheral region of it. The diversity of pollen tube behavior indicates that physiological causes of incongruity are different among the three crosses. Bud pollination enabled pollen tubes to reach the ovary in all crosses, indicating that the N. tabacum pistil acquired its ability to inhibit foreign pollen tube elongation with its development. When interspecific hybrids between N. tabacum and the other three species were pollinated by parental species, tubes reached the ovary in all crosses, but the elongation rate of tubes slowed down and morphology was abnormal.
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    Transport coefficients of argon, nitrogen, oxygen, argon-nitrogen, and argon-oxygen plasmas (1994)
    Springer
    Plasma chemistry and plasma processing 14 (1994), S. 451-490 
    Details
    ISSN: 1572-8986
    Keywords: Transport coefficients ; transport properties ; viscosity ; thermal conductivity ; electrical conductivity ; diffusion coefficient ; Chapman Enskog method ; argon ; nitrogen ; oxygen ; plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Calculated values of the viscosity, thermal conductivity, and electrical conductivity of argon, nitrogen, and oxygen plasmas, and mixtures of argon anti nitrogen and of argon anti oxygen, are presented. In addition, combined ordinary, pressure, and thermal diffusion coefficients are given for the gas mixtures. These three combined diffusion coefficients fully describe di fusion of the two gases, irrespective of their degree of dissociation or ionizati on. The calculations, which assume local thermodynamic equilibrium, are performed! for atmospheric-pressure plasmas in the temperature range /torn 300 to 30,000 K. A number of the collision integrals used in calculating the transport coefficients are significantly more accurate than values used in previous theoretical studies, resulting in more reliable values of the transport coefficients. The results are compared with those of published theoretical and experimental studies.
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    The tRNASer-isoacceptors and their genes in Nicotiana rustica: genome organization, expression in vitro and sequence analyses (1994)
    Springer
    Plant molecular biology 24 (1994), S. 889-901 
    Details
    ISSN: 1573-5028
    Keywords: genome organization ; in vitro transcription ; in vitro processing ; Nicotiana ; pseudogenes ; serine tRNA genes ; serine tRNAs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The existence of six serine codons results in a complex pattern of tRNASer isoacceptors in organisms and organelles. According to the original wobble hypothesis, a minimum of three isoacceptors should be sufficient to read the six serine codons. We have isolated five cytoplasmic tRNAsSer from leaves of Nicotiana rustica. Their nucleotide sequences identify them as four different isoacceptors with the anticodons cm5UGA, CGA, IGA and GCU. For tRNASer with IGA anticodon, two species have been detected which vary only by one nucleotide in the long extra arm. The first three isoacceptors recognize codons of the type UCN whereas the fourth isoacceptor reads the two serine codons AGC and AGU. The tRNASer sequences were used to design appropriate primers for the amplification of Nicotiana nuclear tRNASer genes by the polymerase chain reaction (PCR). A total number of eight tRNASer genes differing in the coding region were thus identified. Selected PCR DNA fragments were then employed as probes for the isolation of the corresponding genes from a nuclear DNA library of N. rustica. Sequence analyses revealed that five of the isolated seven clones contained tRNASer genes which are identical in sequence with the five cytoplasmic tRNAsSer mentioned above. None of them contains an intervening sequence. This is the first time that all putative cellular tRNASer isoacceptors and their corresponding genes have been characterized in an eukaryotic organism. Most of the tRNASer genes are functional as deduced from in vitro transcription and processing studies. Two of the genes yield pre-tRNAsSer which are not or poorly converted to mature tRNA in a plant extract. The approximate tRNASer gene number was estimated by hybridization of specific DNA probes to Eco RI-cleaved Nicotiana nuclear DNA. The overall hybridization pattern indicates that members of each particular tRNASer gene family do not appear to be clustered but distributed randomly throughout the Nicotiana genome.
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    Characterization of the tobacco eIF-4A gene family (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1747-1757 
    Details
    ISSN: 1573-5028
    Keywords: cDNA gene family ; NeIF-4A ; RNA helicase ; translation initiation factor ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Characterization of cDNAs encoding eukaryotic translation initiation factor 4A (eIF-4A) indicates the expression of a minimum of ten related genes in tobacco leaf cells. The ten groups fall into two gene families, NeIF-4A2 and NeIF-4A3. The majority of the cDNAs exhibit significant sequence similarity to the NeIF-4A2 family at both the DNA and deduced amino acid levels. Northern analysis using specific probes indicates variable expression of four family members in various tobacco organs. Western analysis, using an anti-tobacco eIF-4A polyclonal antibody, reveals a complex pattern of immunologically related polypeptides of approximately 46 kDa. Subcellular fractionation suggests that at least one eIF-4A-related polypeptide is located in the chloroplast where it is ribosome-associated.
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    Simultaneous induction of postabscission and germination mRNAs in cultured dicotyledonous embryos (1994)
    Springer
    Planta 192 (1994), S. 384-394 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Brassica ; Glycine ; Gossypium ; Lea mRNAs ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cloned mRNAs identify three programs of gene expression in cotton (Gossypium hirsutum L.) embryos that are associated with the maturation (reserve accumulation) stage, the postabscission stage, which is marked by expression of Late-embryogenesis-abundant (Lea) mRNAs, and germination (broadly defined as including all events through early postgerminative growth). In order to test if the regulation of these programs is the same in other dicotyledonous species, their expression was studied in normal and cultured maturation-stage, postabscission-stage, and mature embryo-stage embryos or seed of oilseed rape (Brassica napus L.), soybean (Glycine max [L.] Merr.), and tobacco (Nicotiana tabacum L.) using cotton and other cDNA probes. During postabscission, Lea mRNAs accumulated in all test species and were induced in earlier maturation-stage embryos by excision and culture on basal medium. Abscisic acid often enhanced this induction in the test species. Germinationspecific mRNAs were induced in cultured maturationstage and postabscission-stage embryos of all test species. These results indicate that the regulation of embryonic and germination programs is similar in all dicotyledons tested. Because excised embryos simultaneously induced postabscission and germination programs, the effects of exogenous growth regulators and other factors on such embryos probably reflect stress responses of germinating mature embryos rather than the identity of endogenous regulators of embryogenesis.
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    Accumulation of hexoses in leaf vacuoles: Studies with transgenic tobacco plants expressing yeast-derived invertase in the cytosol, vacuole or apoplasm (1994)
    Springer
    Planta 194 (1994), S. 29-33 
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    ISSN: 1432-2048
    Keywords: Amino acid ; Hexose uptake ; Nicotiana ; Photosynthesis ; Sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The subcellular distribution of hexoses, sucrose and amino acids among the stromal, cytosolic and vacuolar compartments was analysed by a nonaqueous fractionation technique in leaves of tobacco (Nicotiana tabaccum L.) wild-type and transgenic plants expressing a yeast-derived invertase in the cytosolic, vacuolar or apoplasmic compartment. In the wild-type plants the amino acids were found to be located in the stroma and in the cytosol, sucrose mainly in the cytosol and up to 98% of the hexoses in the vacuole. In the leaves of the various transformants, where the contents of hexoses were greater than in wild-type plants, again 97–98% of these hexoses were found in the vacuoles. It is concluded that leaf vacuoles contain transporters for the active uptake of glucose and fructose against a high concentration gradient. A comparison of estimated metabolite concentrations in the subcellular compartments of wild-type and transformant plants indicated that the decreased photosynthetic capacity of the transformants is not due to an osmotic effect on photosynthesis, as was shown earlier to be the case in transformed potato leaves, but is the result of a long-term dedifferentiation of tobacco leaf cells to heterotrophic cells.
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    Fertilization inNicotiana tabacum: Cytoskeletal modifications in the embryo sac during synergid degeneration (1994)
    Springer
    Planta 194 (1994), S. 200-214 
    Details
    ISSN: 1432-2048
    Keywords: Actin ; Cytoskeleton ; Embryo sac ; Fertilization ; Microtubule ; Nicotiana ; Synergid degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytoskeletal organization of the embryo sac of tobacco (Nicotiana tabacum L.) was examined at maturity and during synergid degeneration, pollen-tube delivery and gamete transfer using rapid-frozen, freeze-substituted and chemically fixed material in combination with immunofluorescence and immunogold electron microscopy. Before fertilization, the synergid is a highly polarized cell with dense longitudinally aligned arrays of microtubules adjacent to the filiform apparatus at the micropylar end of the cell associated with major organelles. The cytoskeleton of the central cell is less polarized, with dense cortical microtubules in the micropylar and chalazal regions and looser, longitudinally oriented cortical microtubules in the lateral region. In the synergid and central cell, F-actin is frequently found at the surface of the organelles and co-localizes with either single microtubules or microtubule bundles. Egg cell microtubules are frequently cortical, randomly oriented and more abundant at the chalazal end of the cell; actin filaments are associated with microtubules and the cortex of the egg cell. At 48 h after pollination and before the pollen tube arrives, the onset of degeneration is evident in one of the two synergids: the electron density of cytoplasmic organelles and the ground cytoplasm increases and the nucleus becomes distorted. Although synergids otherwise remain intact, the vacuole collapses and organelles degenerate rapidly after pollen-tube entry. Abundant electron-dense material extends from the degenerated synergid into intercellular spaces at the chalazal end of the synergid and between the synergids, egg and central cell. Rhodamine-phalloidin and anti-actin immunogold labeling reveal that electron-dense aggregates in this region contain abundant actin forming two distinct bands termed “coronas”. This actin is part of a mechanism in the egg apparatus which appears to precisely position and facilitate the access of male gametes to the egg and central cell for fusion.
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    Histochemistry and composition of the cell walls of styles of Nicotiana alata Link et Otto (1994)
    Springer
    Planta 195 (1994), S. 217-225 
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    ISSN: 1432-2048
    Keywords: Arabinogalactan protein ; Cell wall ; Lignin ; Nicotiana ; Polysaccharide ; Style
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell walls of styles of Nicotiana alata Link et Otto (ornamental tobacco; Solanaceae) were analysed chemically and examined histochemically. Cell-wall preparations were obtained from whole styles and from isolated transmitting-tissue cells. The style epidermal cells were shown histochemically to have thick, lignified secondary walls. These walls probably constituted a large proportion of the cell-wall preparation from whole styles as analysis of whole-style walls indicated that the major polysaccharides were xylans and cellulose, which are typical of lignified secondary walls of Magnoliopsida (dicotyledons). Lignification of the style epidermal walls was also demonstrated histochemically in 10 other species (5 genera including Nicotiana) of the sub-family Cestroideae of the Solanaceae, but not in 15 species (9 genera) of the sub-family Solanoideae of the Solanaceae, nor in 3 other species of dicotyledons and 2 species of Liliopsida (monocotyledons). Analysis of the cell-wall preparation from isolated transmitting-tissue cells of N. alata indicated that these contained cellulose, xyloglucans, and pectic polysaccharides, which is typical of primary cell walls of dicotyledons. However, the analysis indicated that the walls also contained an unusually high proportion of Type II arabinogalactans. Staining of the transmitting-tissue cell-wall preparation with β-glucosyl Yariv reagent, a histochemical reagent specific for arabinogalactan proteins, confirmed their presence, which may be related to the role of these cells in secreting the stylar extracellular matrix.
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    Uptake, accumulation and metabolism of auxins in tobacco leaf protoplasts (1994)
    Springer
    Planta 195 (1994), S. 159-167 
    Details
    ISSN: 1432-2048
    Keywords: Auxin (accumulation, metabolism) ; Nicotiana ; Protoplast (leaf)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uptake and metabolism of exogenous naphthalene-1-acetic acid (NAA) and indole-3-acetic acid (IAA) have been studied in tobacco (Nicotiana tabacum L. cv. Xanthi) mesophyll protoplasts. Both auxins entered protoplasts by diffusion under the action of the transmembrane pH gradient without any detectable participation of an influx carrier. Molecules were accumulated by an anion-trapping mechanism and most of them were metabolized within hours, essentially as glucose-ester and amino-acid conjugates. Protoplasts were equipped with a functional auxin-efflux carrier as evidenced by the inhibitory effect of naphthylphtalamic acid on IAA efflux. Basically, similar mechanisms of NAA and IAA uptake occurred in protoplasts. However, the two auxins differed in their levels of accumulation, due to different membrane-transport characteristics, and the nature of the metabolites produced. This shows the need to estimate the accumulation and the metabolism of auxins when analyzing their effects in a given cell system. The internal auxin concentration could be modulated by changing the transmembrane pH gradient, giving an interesting perspective for discriminating between the effects of intra- and extracellular auxin on physiological processes.
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    URL: http://dx.doi.org/10.1007/BF00199674
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    Light-stimulated proton transport into the vacuoles of leaf mesophyll cells does not require energization by the tonoplast pyrophosphatase (1994)
    Springer
    Planta 193 (1994), S. 203-207 
    Details
    ISSN: 1432-2048
    Keywords: Nicotiana ; Photosynthesis ; Proton pumping ; Pyrophosphatase ; Transgenic tobacco ; Vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics of transgenic tobacco (Nicotiana tabacum L.) plants with a soluble pyrophosphatase in the cytosol of their leaf cells were compared to those of wild-type plants. Although the development of the transgenic plants was somewhat retarded compared to the wild type, as shown by stunted growth and delayed flowering, photosynthetic responses were comparable in transgenic and wild-type leaves of similar physiological age. In particular, light-dependent proton transport into the vacuoles of leaf mesophyll cells was not decreased in leaves of the transgenic plants, which did not contain pyrophosphate in the cytosol owing to the presence of a soluble pyrophosphase. This shows that light-stimulated proton pumping did not require the pumping activity of the tonoplast pyrophosphatase. Apparently, light-stimulated proton pumping can be based solely on the activity of the tonoplast ATPase.
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    URL: http://dx.doi.org/10.1007/BF00192531
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    Changes in polypeptide patterns in tobacco roots colonized by two Glomus species (1994)
    Springer
    Mycorrhiza 4 (1994), S. 215-221 
    Details
    ISSN: 1432-1890
    Keywords: Nicotiana ; Glomus species ; arbuscular mycorrhiza ; gene expression ; specific polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in gene expression were studied during the establishment of arbuscular mycorrhizal symbiosis in tobacco roots from an amphidiploid hybrid Nicotiana glutinosa x N. debneyi. Polypeptide patterns from control roots and from roots infected by Glomus mosseae or G. intraradices were resolved by two-dimensional polyacrylamide gel electrophoresis and followed in a time-course analysis. Arbuscular mycorrhizal infection led to significant modifications in polypeptide patterns with: (a) decreased amounts of some polypeptides, (b) increased accumulation of others, and (c) appearance of newly-induced polypeptides. Comparisons made during infection development by the two Glomus species demonstrated that protein modifications changed in relation to the mycorrhizal state of the tobacco roots.
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    URL: http://dx.doi.org/10.1007/BF00206783
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    Restoration of fertility in cytoplasmic male sterile (CMS) Nicotiana Sylvestris by fusion with X-irradiated N. tabacum protoplasts (1980)
    Springer
    Theoretical and applied genetics 58 (1980), S. 121-127 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana ; Cytoplasmic-male-sterility ; Somatic hybridization ; Plastid segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restoration of male fertility was achieved by fusing protoplasts from male sterile (CMS) Nicotiana sylvestris plants with X-irradiated protoplasts derived from fertile N. tabacum plants. The CMS N. sylvestris plants were derived from a previous somatic hybridization experiment and contained alien (Line 92) cytoplasm. About one quarter of the regenerated plants were found to be cybrids. i.e. they consisted of N. sylvestris nuclei combined with all or some components of N. tabacum cytoplasm. In one half of these cybrids male fertility was restored to different levels. The chloroplasts of the two parental donors differ in respect to tentoxin sensitivity: chloroplasts of CMS N. sylvestris are sensitive while those of N. tabacum are insensitive. It could therefore be demonstrated that there was an independent segregation of chloroplast type and male fertility/sterility: several somatic cybrids were male fertile but tentoxin sensitive and others were tentoxin insensitive yet they were male sterile. Only in about one half of the somatic cybrids was male fertility restored together with restoration to tentoxin insensitivity.
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    URL: http://dx.doi.org/10.1007/BF00263102
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    Dry matter content and mineral composition of potatoes grown in Cyprus (1980)
    Springer
    Potato research 23 (1980), S. 371-375 
    Details
    ISSN: 1871-4528
    Keywords: nitrogen ; phosphorus ; potassium ; calcium ; sodium ; nitrate ; sulphate ; micronutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The specific gravity and dry matter content of 193 tuber samples (cultivars: Arran Banner, Spunta, Up-to-Date, Cara) from crops grown at Kokkinochoria, the major potato growing area of Cyprus, were related to each other as follows: Dry matter (%)=−269.59+268.24×specific gravity. This regression accounted for 82.4% of the variation; the fiducial limits (P〈0.05) for single determinations of specific gravity were±1.54 percentage units. The mineral contents of the tubers were similar to those reported in other countries.
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    URL: http://dx.doi.org/10.1007/BF02360677
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    Selection of embryogenic pollen from cold-treated buds ofNicotiana tabacum var. badischer burley and their development into embryos in cultures (1980)
    Springer
    Protoplasma 105 (1980), S. 161-167 
    Details
    ISSN: 1615-6102
    Keywords: Embryogenic pollen ; Nicotiana ; Pollen culture ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By using density gradient centrifugation, employing 55% percoll and 4% sucrose as suspension medium, it is possible to select embryogenic pollen from buds after cold treatment at 10 °C for 8 or more days. These buds at the uninucleate stage of pollen were collected from plants grown in 8 hours photocycles at 18 °C and supplied with mineral salts. The embryogenic pollen are small, starch-free with a clear cytoplasm whereas large starch-filled ones are nonembryogenic. The embryogenic pollen regularly form embryos at a frequency of 2% on a mineral medium supplemented with glutamine, asparagine and sucrose at pH 6.5. These results demonstrate, for the first time, that it is possible to have embryos in appreciable frequencies in “ab initio” pollen cultures raised from cold treated anthers.
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    URL: http://dx.doi.org/10.1007/BF01279858
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    The role of suspended matter in the distribution of dissolved inorganic phosphate, iron and aluminium in the Ems estuary (1994)
    Springer
    Aquatic ecology 28 (1994), S. 383-395 
    Details
    ISSN: 1573-5125
    Keywords: Ems estuary ; phosphorus ; iron ; fluorescence ; aluminium ; adsorption ; suspended matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In winter 1992/1993, a persistent local maximum in fluorescence, dissolved iron, dissolved aluminium and dissolved inorganic phosphate was found, upstream of the turbidity maximum in the freshwater zone of the Ems estuary (The Netherlands — Federal Republic Germany; western Europe). Upstream of this local maximum values ranged from 6 to 9 rel. units fluorescence, 0.9 to 2.4 μmol dm−3 iron, 0.5 to 0.7 μmol dm−3 aluminium and 0.6 to 2.3 μmol dm−3 dissolved inorganic phosphate. Within the maximum peak values of 24 rel. units fluorescence, 5.8 μmol dm−3 iron, 1.4 μmol dm−3 aluminium and 8.3 μmol dm−3 dissolved inorganic phosphate were observed. Downstream, fluorescence (indicator of dissolved organic carbon) showed conservative mixing with sea water, whereas dissolved iron, aluminium and dissolved inorganic phosphate did not. Dissolved aluminium and iron were quickly removed from solution to reach values of ∼100 nmol dm−3 aluminium and ∼0.3 μmol·dm−3 Fe at salinities of approximately 7 PSU. Further seaward iron concentrations gradually decreased to levels below 0.04 μmol dm−3. Dissolved aluminium first decreased to ∼20 nmol dm−3 at 29 PSU and increased again to concentrations of 30–44 nmol dm−3 at higher salinities. Dissolved inorganic phosphate, however, first decreased to upstream concentrations before reaching a secondary peak in the mid-estuarine reaches. At salinities 〉25 PSU dissolved inorganic phosphate mixed conservatively with sea water. It is hypothesized that adsorption-desorption equilibria are responsible for the local maximum values of fluorescence (DOC), iron, aluminium and dissolved inorganic phosphate. The similarity between the observed curves suggests a common underlying process, possibly related to the adjustment of new equilibria between suspended matter of marine and riverine origin.
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    URL: http://dx.doi.org/10.1007/BF02334208
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    A coded checklist and ecological indicator values of freshwater diatoms from The Netherlands (1994)
    Springer
    Aquatic ecology 28 (1994), S. 117-133 
    Details
    ISSN: 1573-5125
    Keywords: checklist ; diatoms ; The Netherlands ; pH ; salinity ; nitrogen ; oxygen ; saprobity ; trophic state ; moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This first comprehensive checklist of the diatoms from fresh and weakly brackish water in The Netherlands comprises 948 taxa, belonging to 776 species in 56 genera. The generaNavicula, which has a very wide ecological amplitude, andNitzschia, which has many pollution tolerant species, are most numerous. Each taxon is identified with a unique eight-letter code, to facilitate computer processing of data. Ecological indicator values for pH, salinity, nitrogen uptake metabolism, oxygen, saprobity, trophic state and moisture are presented.
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    URL: http://dx.doi.org/10.1007/BF02334251
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    Determination of orthophosphate in highly saline waters (1994)
    Springer
    International journal of salt lake research 3 (1994), S. 159-173 
    Details
    ISSN: 1573-8590
    Keywords: phosphorus ; orthophosphate ; phosphomolybdenum blue ; salt effect ; hypersaline ; saline ; lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Standard methods for the determination of phosphorus as phosphate ion are now well established for fresh and marine waters. In highly saline waters, however, salt effects due to ionic strength, or to particular ions present, may result in method interferences. Three methods of analysis of phosphate based on the formation of phosphomolybdenum blue complexes have been evaluated here for hypersaline waters. Stannous chloride reduction in aqueous media exhibits a substantial salt effect and its use is not recommended. Stannous chloride reduction following extraction into non aqueous solvents shows a significant salt effect (up to 30 per cent) in solutions of salinity 〉100 g L−1. Dilution of hypersaline waters to below this salinity may overcome the salt effect but the method suffers from other disadvantages involving resource constraints and health and safety considerations. Ascorbic acid reduction, catalysed by antimony (III) ions, appears to offer the most promise for hypersaline waters. Turbidity in samples having high salinity (〉 100 g L−1) and high phosphorus concentrations (〉 500 μg P L−1) changes the spectral characteristics of solutions but linear calibration curves still result for concentrations in the range 400 to 1,000 μg P L−1. The occurrence of turbidity is also affected by the ionic composition of hypersaline waters since solutions made from sea salt give different results to those made from sodium chloride. Dilution of samples, to give salinities less than 100 g L−1 prior to reduction is recommended to avoid turbidity. The salt effect in these lower salinity waters is less than 3 per cent up to 100 g L−1.
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    URL: http://dx.doi.org/10.1007/BF01990492
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    Growth and elemental content of several sagebrush-steppe species in unburned and post-wildfire soil and plant effects on soil attributes (1994)
    Springer
    Plant and soil 164 (1994), S. 35-41 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
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    Subterranean clover decline in permanent pastures in north-eastern Victoria (1994)
    Springer
    Plant and soil 164 (1994), S. 231-241 
    Details
    ISSN: 1573-5036
    Keywords: phosphorus ; root disease ; soil acidity ; subterranean clover ; yield decline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35–140%) were obtained with subterranean clover at both sites, with corresponding decreases in Al in the 0–10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4 μg g−1) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg−1 at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p=0.05) at both sites. An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.
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    Comparison between a chemical and a biological method to determine the N mineralization potential of temperate-humid region soils (1994)
    Springer
    Plant and soil 162 (1994), S. 147-150 
    Details
    ISSN: 1573-5036
    Keywords: biological method ; chemical method ; mineralization potential ; nitrogen ; soil incubation ; temperate humid-zone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potentially mineralizable organic N of 33 different soils was estimated by a chemical test (hot extraction with 2N KCl) and the values compared with those previously obtained by a biological method (aerobic incubation in the laboratory). On average, the organic N solubilized by the chemical procedure was significantly lower than that mineralized by a two weeks aerobic incubation for all the soils as a whole. The same was true for soils developed over acid rocks and over sediments. However, the values obtained for the soils developed over limestone and basic rocks were similar by both methods. The values obtained by both methods were not significantly correlated neither when considering all soils together nor when considering different groups according to soil management or parent material. Significant correlations between both methods were only found when the soils were separated into two groups according to their organic N content: soils with less than 400 mg N 100 g−1 soil and soils with more than 400 mg N 100 g−1 soil. The organic N solubilized by the chemical procedure was significantly correlated with the hexosamine-N content; however, it was not correlated with the factors that control the biological mineralization of the organic N, except with the soluble Al content. Therefore, the chemical extraction did not seem to address the biologically active N pool in a selective way.
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    URL: http://dx.doi.org/10.1007/BF01416100
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    A simple model for estimating the contribution of nitrogen mineralization to the nitrogen supply of crops from a stabilized pool of soil organic matter and recent organic input (1994)
    Springer
    Plant and soil 162 (1994), S. 259-271 
    Details
    ISSN: 1573-5036
    Keywords: mineralization rate ; nitrogen ; stabilized organic matter ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple model was developed to estimate the contribution of nitrogen (N) mineralization to the N supply of crops. In this model the soil organic matter is divided into active and passive pools. Annual soil mineralization of N is derived from the active pool. The active pool comprises stabilized and labile soil organic N. The stabilized N is built up from accumulated inputs of fresh organic N during a crop rotation but the labile N is a fraction of total N added, which mineralizes faster than the stabilized N. The passive pool is considered to have no participation in the mineralization process. Mineralization rates of labile and stabilized soil organic N from different crop residues decomposing in soil were derived from the literature and were described by the first-order rate equation dN/dt =-K*N, where N is the mineralizable organic N from crop residues andK is a constant. The data were groupedK 1 by short-term (0–1 year) andK 2 by long-term (0–10 years) incubation. Because the range of variation inK 2 was smaller than inK 1 we felt justified in using an average value to derive N mineralization from the stabilized pool. The use of a constant rate ofK 1 was avoided so net N mineralization during the first year after addition is derived directly from the labile N in the crop residues. The model was applied to four Chilean agro-ecosystems, using daily averages of soil temperature and moisture. The N losses by leaching were also calculated. The N mineralization varied between 30 and 130 kg N ha−1 yr−1 depending on organic N inputs. Nitrogen losses by leaching in a poorly structured soil were estimated to be about 10% of total N mineralized. The model could explain the large differences in N- mineralization as measured by the potential N mineralization at the four sites studied. However, when grassland was present in the crop rotation, the model underestimated the results obtained from potential mineralization.
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    Root architectural responses of Betula lenta to spatially heterogeneous ammonium and nitrate (1994)
    Springer
    Plant and soil 158 (1994), S. 129-134 
    Details
    ISSN: 1573-5036
    Keywords: Betula lenta L. ; black birch ; nitrogen ; root architecture ; soil heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inorganic soil nitrogen is often heterogeneously distributed, both spatially and in form (ammonium versus nitrate). Here we present information on the architecture of black birch (Betula lenta L.) root systems exposed to homogeneous and heterogeneous nitrogen environments. The major effects on root architecture were at the whole root system level in response to heterogeneity of nitrogen form rather than the effect of local of local nitrate or ammonium supply on local root growth. In the heterogeneous treatment, plant root systems had greater link lengths and more simple branching patterns. Root architectural responses to heterogeneous nitrogen, independent of localized responses to patches, suggest that in a seedling of B. lenta whole plant integration of its environment may override local control of root growth.
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    Phosphorus depletion in the rhizosphere as influenced by soil moisture (1994)
    Springer
    Plant and soil 159 (1994), S. 213-218 
    Details
    ISSN: 1573-5036
    Keywords: concentration gradient ; diffusion ; phosphorus ; rhizosphere ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the influence of soil moisture on phosphorus (P) depletion in the rhizosphere, maize (Zea mays cv. Trak) was pre-grown in vermiculite filled-PVC tubes for 9 days and then the plants with the tubes were transplanted into soil columns maintained at two soil moisture levels (θ) of 0.14 and 0.20 cm3 cm−3 for 10 days. The soil columns were separated at 1 cm depth by a nylon screen of 53 μm inner mesh size, into 1 cm soil layer above and 3 cm soil column below screen. A root mat developed over the screen, but root hairs only could penetrate it. Regardless of the soil moisture level in the columns, and adequate and equal water and nutrients supply was maintained via wicks from an external nutrient solution to the plant roots in vermiculite. After 10 days, the soil columns were separated from the root mats, quickly frozen in liquid nitrogen and sliced into thin layers (0.2mm) using a refrigerated microtome to give soil samples at defined distances from the root mats for analyses. Lower soil moisture (θ=0.14) resulted in narrower and steeper depletion profile of 0.5 M NaHCO3 extractable P (NaHCO3-Pi) as compared to higher soil moisture (θ=0.20). Depletion of P in soil solution in the immediate vicinity of root mats did not differ much but the extension of the depletion zones was 0.10 cm at θ=0.14 and 0.20 cm at θ=0.20. The depletion up to 0.05cm with θ=0.14 and up to 0.07 cm with θ=0.20 was uniform, and may be attributed to the depletion in the root hair zone. Beyond the root hair zones, the theory of diffusion and mass flow was able to explain the observed differences in shape and extent of the P depletion profiles at the two soil moisture levels.
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    URL: http://dx.doi.org/10.1007/BF00009283
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    Root response to CO2 enrichment and nitrogen supply in loblolly pine (1994)
    Springer
    Plant and soil 165 (1994), S. 21-32 
    Details
    ISSN: 1573-5036
    Keywords: allocation ; CO2 ; image analysis ; loblolly pine ; nitrogen ; root morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper examines how elevated CO2 and nitrogen (N) supply affect plant characteristics of loblolly pine (Pinus taeda L.) with an emphasis on root morphology. Seedlings were grown in greenhouses from seeds during one growing season at two atmospheric CO2 concentrations (375 and 710 μL L-1) and two N levels (High and Low). Root morphological characteristics were determined using a scanner and an image analysis program on a Macintosh computer. In the high N treatment, elevated CO2 increased total plant dry weight by 80% and did not modify root to shoot (R/S) dry weight ratio, and leaf and plant N concentration at the end of the growing season. In the low N treatment, elevated CO2 increased total dry weight by 60%. Plant and leaf N concentration declined and R/S ratio tended to increase. Nitrogen uptake rate on both a root length and a root dry weight basis was greater at elevated CO2 in the high N treatment and lower in the low N treatment. We argue that N stress resulting from short exposures to nutrients might help explain the lower N concentrations observed at high CO2 in other experiments; Nitrogen and CO2 levels modified root morphology. High N increased the number of secondary lateral roots per length of first order lateral root and high CO2 increased the length of secondary lateral roots per length of first order lateral root. Number and length of first order lateral roots were not modified by either treatment. Specific root length of main axis, and to a lower degree, of first order laterals, declined at high CO2, especially at high N. Basal stem diameter and first order root diameters increased at high CO2, especially at high N. Elevated CO2 increased the proportion of upper lateral roots within the root system.
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    Effect of elevated CO2 on mycorrhizal colonization of loblolly pine (Pinus taeda L.) seedlings (1994)
    Springer
    Plant and soil 165 (1994), S. 81-88 
    Details
    ISSN: 1573-5036
    Keywords: carbohydrates ; ectomycorrhizae ; elevated CO2 ; phosphorus ; Pinus taeda L. ; Pisolithus tinctorius (Pers.) Coker & Couch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactive effects of elevated atmospheric CO2 and phosphorus supply on mycorrhizal colonization rates were investigated using loblolly pine (Pinus taeda L.) seedlings from Florida and coastal North Carolina. Seedlings from both populations were grown in greenhouses maintained at either 35.5 Pa or 71.0 Pa CO2. In both CO2 treatments, seedlings were grown in a full factorial experiment with or without mycorrhizal inoculum and with an adequate or a limiting supply of phosphorus. Seedlings were harvested 60, 90 and 120 days after emergence and at each harvest root subsamples were examined to determine the percent of fine roots that were mycorrhizal. Additionally, root carbohydrate and nutrient levels were measured at each harvest. Root starch, sugar and total non-structural carbohydrate (TNC) concentrations were increased by growth in elevated CO2 and decreased by mycorrhizal colonization. Phosphorus stress decreased root starch concentrations, increased root sugar concentrations and did not significantly affect TNC concentrations. However, despite significant effects on root carbohydrate levels, there were generally no significant treatment effects on mycorrhizal colonization. Additionally, at all harvests, root starch and sugar concentrations were not correlated with percent of fine roots that were mycorrhizal. These results suggest that although elevated CO2 may significantly increase root carbohydrate levels, the increases may not affect the percent of fine roots that are mycorrhizal.
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    URL: http://dx.doi.org/10.1007/BF00009965
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    Enhanced root system C-sink activity, water relations and aspects of nutrient acquisition in mycotrophic Bouteloua gracilis subjected to CO2 enrichment (1994)
    Springer
    Plant and soil 165 (1994), S. 139-146 
    Details
    ISSN: 1573-5036
    Keywords: blue grama ; Bouteloua gracilis ; C4 grass ; CO2 enrichment ; mycorrhizae ; nitrogen ; phosphorus ; VAM ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to better elucidate fixed-C partitioning, nutrient acquisition and water relations of prairie grasses under elevated [CO2], we grew the C4 grass Bouteloua gracilis (H.B.K.) lag ex Steud. from seed in soil-packed, column-lysimeters in two growth chambers maintained at current ambient [CO2] (350 μL L−1) and twice enriched [CO2] (700 μL L−1). Once established, plants were deficit irrigated; growth chamber conditions were maintained at day/night temperatures of 25/16°C, relative humidities of 35%/90% and a 14-hour photoperiod to simulate summer conditions on the shortgrass steppe in eastern Colorado. After 11 weeks of growth, plants grown under CO2 enrichment had produced 35% and 65% greater total and root biomass, respectively, and had twice the level of vesicular-arbuscular mycorrhizal (VAM) infection (19.8% versus 10.8%) as plants grown under current ambient [CO2]. The CO2-enriched plants also exhibited greater leaf water potentials and higher plant water use efficiencies. Plant N uptake was reduced by CO2 enrichment, while P uptake appeared little influenced by CO2 regime. Under the conditions of the experiment, CO2 enrichment increased root biomass and VAM infection via stimulated growth and adjustments in C partitioning below-ground.
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    URL: http://dx.doi.org/10.1007/BF00009970
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    Growth response and phosphorus uptake of rye with long and short root hairs: Interactions with mycorrhizal infection (1994)
    Springer
    Plant and soil 167 (1994), S. 247-254 
    Details
    ISSN: 1573-5036
    Keywords: efficiency ; Glomus intraradices ; phosphorus ; root hair ; rye ; Secale cereale L. ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth and phosphorus (P) uptake of two selections of rye (Secale cereale L.) differing in length of root hairs, in response to mycorrhizal infection were investigated. Rye plants with short root hairs (SRH) had a greater length of root infected by Glomus intraradices (up to 32 m pot−1) than those with long root hairs (LRH) (up to 10 m pot−1). Application of P decreased the percentage of root length infected in both selections. In low-P soil, mycorrhizal infection increased shoot and root P concentration, especially in LRH plants. Generally, LRH had higher shoot dry weight than SRH plants. P uptake was increased both by LRH and by mycorrhizal infection. Differences in specific P uptake and P utilization efficiency between SRH and LRH plants were observed in non-mycorrhizal plants. With low P supply, P utilization efficiency (dry matter yield per unit of P taken up) of LRH plants increased with time. However, mycorrhizal infection reduced P utilization efficiency, particularly of SRH plants. SRH plants, which were agronomically less efficient (i.e. low dry matter yield at low P supply) were more responsive to either mycorrhizal infection or P addition than the LRH plants. No interaction was observed between mycorrhizal infection and root hair length.
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    Photoautotrophic growth of soybean cells in suspension culture III. Characterization of carbon fixation products under high and low CO2 levels (1994)
    Springer
    Plant cell, tissue and organ culture 39 (1994), S. 239-244 
    Details
    ISSN: 1573-5044
    Keywords: carbon ; elevated CO2 ; nitrogen ; suspension culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A photoautotrophic soybean suspension culture (SB-P) was used to study CO2 assimilation while exposed to elevated or ambient CO2 levels. These studies showed that under elevated CO2 (5% v/v) malate is the dominant fixation product, strongly suggesting that phosphoenolpyruvate carboxylase (PEPCase) is the primary enzyme involved in carbon fixation in these cells under their normal growth conditions. Citrate and [aspartate + glutamate] were also significant fixation products during fifteen minutes of exposure to 14CO2. During the ten minute unlabeled CO2 chase however, 14C-malate continued to increase while citrate and [aspartate + glutamate] declined. Fixation of 14CO2 under ambient CO2 levels (0.037%) showed a very different product pattern as 3-phosphoglycerate was very high in the first one to two minutes followed by increases in [serine + glycine] and [aspartate + glutamate]. Hexose phosphates were also quite high initially but then declined relatively rapidly. Thus, the carbon fixation pattern at ambient CO2 levels resembles somewhat that seen in C3 leaf cells while that seen at elevated CO2 levels more closely resembles that of a C4 plant. The initial fixation product of C3 plants, 3-PGA, was never detectable under high CO2 conditions. These data suggest that an in vitro photoautotrophic system would be suitable for studying carbon fixation physiology during photosynthetic and non-photosynthetic growth.
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    URL: http://dx.doi.org/10.1007/BF00035976
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    Somatic hybridization as a tool for tomato breeding (1994)
    Springer
    Euphytica 79 (1994), S. 265-277 
    Details
    ISSN: 1573-5060
    Keywords: Somatic hybridization ; Lycopersicon ; Solanum ; Nicotiana ; somatic incongruity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Protoplast fusion can be used to produce somatic hybrids of species that cannot be obtained by sexual hybridization. The possibility to introgress genes from Solanum species into the cultivated tomato species Lycopersicon esculentum, and to obtain novel cytoplasm-nucleus combinations (cybrids) was considered as an important strategy to extend the genetic variation available for tomato breeding. Somatic hybrids between L. esculentum and other Lycopersicon species, as well as between L. esculentum and Solanum or Nicotiana species, have been produced. Specific mutants, genotypes with antibiotic resistances, and metabolic inhibition by iodoacetate or iodoacetamide and irradiation were used for the selection of hybrids. In addition, the improvement of protoplast culture techniques and the use of the favourable tissue culture traits derived from species such as L. peruvianum, which have been introduced into tomato by classical breeding, allowed the efficient recovery of somatic hybrids. However, the occurrence of somatic incongruity in fusion combinations of L. esculentum and Solanum and even more in L. esculentum and Nicotiana, did not allow the production of true cybrids and/or fertile hybrids, indicating the importance of both cytoplasm-nucleus and nucleus-nucleus interactions in somatic incongruity. Another problem with fusions between distantly related species is the strongly reduced fertility of the hybrids and the very limited homoeologous recombination between chromosomes of the parental species. Partial genome transfer from donor to recipient through microprotoplast (+) protoplast fusion, and the production of monosomic or disomic chromosome addition lines, light overcome some of these problems. In symmetric somatic hybrids between L. esculentum and S. tuberosum the occurrence of limited somatic and meiotic recombination was demonstrated. Fertile progeny plants could be obtained, though at a low frequency, when embryo rescue was performed on a large scale after backcrossing hexaploid somatic tomato (+) potato hybrids with a tetraploid potato genotype. The potential value of genomic in situ hybridization (GISH) and RFLPs for the analysis of the genome/chromosome composition of the hybrids has been demonstrated for intergeneric somatic hybrids between Lycopersicon and Solanum.
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    URL: http://dx.doi.org/10.1007/BF00022527
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    Mineralization of carbon and nitrogen in acid forest soil treated with fast and slow-release nutrients (1994)
    Springer
    Plant and soil 164 (1994), S. 187-193 
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    ISSN: 1573-5036
    Keywords: apatite ; biotite ; forest soil ; mineralization ; nitrogen ; nutrient additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of slow (apatite, biotite) and fast-release nutrients (P, K, Mg) on C and N mineralization in acid forest soil were studied. These nutrients were applied alone or together with urea or urea and limestone. The production of CO2 in the soil samples taken one and three growing seasons after the application was lower in the soils treated with the fast-release nutrients than in the untreated soils. Similar reduction of microbial activity was not seen after the apatite and apatite+biotite treatments. In the first growing season, urea and urea+limestone enhanced CO2 production, but after three growing seasons, the opposite was true. Apatite and apatite+biotite added together with urea did not compensate for the decreasing effect of urea on the CO2 production. The addition of fast-release salts increased somewhat the concentration of NH inf4 sup+ in the soil and more NH4 + accumulated during laboratory incubation in the soil samples taken one growing season after the application. The urea addition immediately increased the concentrations of NH4 + and of NO3 − in the soil, but, three growing seasons after application, urea had only a slight increasing effect on mineral N content of the soil. Slow-release nutrients seem to have a more favourable effect than fast-release salts on nutrient turnover in acid forest soil.
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    URL: http://dx.doi.org/10.1007/BF00010070
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    Nitrogen effects on rhizosphere processes of range grasses from different successional seres (1994)
    Springer
    Plant and soil 161 (1994), S. 241-250 
    Details
    ISSN: 1573-5036
    Keywords: carbon ; microorganisms ; nitrogen ; plant succession ; range grasses ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen and rhizosphere microorganism effects on nitrogen and carbon dynamics of Sitanion hystrix (early successional species), Stipa comata and Poa secundu which are (mid-successional species), and Agropyron spicatum (late successional species) were evaluated in a growth chamber study. Rhizosphere inocula resulted in increased nitrogen in both root and shoot tissue, and also of water-extractable carbon in the rhizosphere. Plant species, rhizosphere inocula and nitrogen level showed a three-way significant interaction for total and plant-available nitrogen. Rhizosphere microbe presence resulted in higher plant-available nitrogen in the rhizosphere of S. hystrix and less with A. spicatum, suggesting nitrogen immobilization with the later successional grass. Higher nitrogen resulted in decreased active bacteria in the rhizosphere of all plants tested, and decreased fungal hyphal lengths in the rhizosphere of the later successional P. secunda and A. spicutum. Exudate carbon in the rhizosphere of the late successional species A. spicatum, was more recalcitrant, which also may contribute to nitrogen immobilization. These differential responses of early- and late-successional grasses may be important factors contributing to plant succession.
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    URL: http://dx.doi.org/10.1007/BF00046395
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    Effects of ammonium sulphate application on the rhizosphere, fine-root and needle chemistry in aPicea abies (L.) Karst. stand (1994)
    Springer
    Plant and soil 162 (1994), S. 71-80 
    Details
    ISSN: 1573-5036
    Keywords: ammonium sulphate ; fine roots ; needles ; nitrogen ; Norway spruce ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rhizosphere, fine-root and needle chemistry were investigated in a 28 year old Norway spruce stand in SW Sweden. The uptake and allocation pattern of plant nutrients and aluminium in control plots (C) and plots repeatedly treated with ammonium sulphate (NS) were compared. Treatments started in 1988. Current year needles, one-year-old needles and cylindrical core samples of the LFH-layer and the mineral soil layers were sampled in 1988, 1989 and 1990. Compared to the control plots, pH decreased significantly in the rhizosphere soil in the NS plots in 1989 and 1990 while the SO4-S concentration increased significantly. Aluminium concentration in the rhizosphere soil was generally higher in the NS plots in all soil layers, except at 0–10 cm depths, both in 1989 and 1990. Calcium, Mg and K concentrations also increased after treatment with ammonium sulphate. Ammonium ions may have replaced these elements in the soil organic matter. The NS treatment significantly reduced Mg concentrations in fine roots in all layers in 1990. A similar trend was found in the needles. Ca concentrations in fine roots were significantly lower in the NS plots in the LFH layer in 1990 and the same pattern was found in the current needles. The N and S concentrations of both fine roots and needles were significantly higher in the NS plots. It was suggested that NS treatment resulted in displacement of Mg, Ca and K from exchange sites in the LFH layer leading to leaching of these cations to the mineral soil. Further application of ammonium sulphate may damage the fine roots and consequently adversely affect the water and nutrient uptake of root systems.
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    URL: http://dx.doi.org/10.1007/BF01416091
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    Decomposition of tree leaf litters grown under elevated CO2: Effect of litter quality (1994)
    Springer
    Plant and soil 163 (1994), S. 121-130 
    Details
    ISSN: 1573-5036
    Keywords: decomposition rates ; enriched CO2 ; lignin ; litter respiration ; microcosms ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ash (Fraxinus excelsior L.), birch (Betula pubescens Ehrh.), sycamore (Acer pseudoplatanus L.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) leaf litters were monitored for decomposition rates and nutrient release in a laboratory microcosm experiment. Litters were derived from solar domes where plants had been exposed to two different CO2 regimes: ambient (350 μL L-1 CO2) and enriched (600 μL L-1 CO2). Elevated CO2 significantly affected some of the major litter quality parameters, with lower N, higher lignin concentrations and higher ratios of C/N and lignin/N for litters derived from enriched CO2. Respiration rates of the deciduous species were significantly decreased for litters grown under elevated CO2, and reductions in mass loss at the end of the experiment were generally observed in litters derived from the 600 ppm CO2 treatment. Nutrient mineralization, dissolved organic carbon, and pH in microcosm leachates did not differ significantly between the two CO2 treatments for any of the species studied. Litter quality parameters were examined for correlations with cumulative respiration and decomposition rates: N concentration, C/N and lignin/N ratios showed the highest correlations, with differences between litter types. The results indicate that higher C storage will occur in soil as a consequence of litter quality changes resulting from higher atmospheric concentrations of CO2.
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    URL: http://dx.doi.org/10.1007/BF00033948
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    Nutrient uptake in eastern deciduous tree seedlings (1994)
    Springer
    Plant and soil 160 (1994), S. 193-199 
    Details
    ISSN: 1573-5036
    Keywords: gaps ; ion uptake ; nitrogen ; nutrient acquisition ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.
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    Above- and belowground response of Populus grandidentata to elevated atmospheric CO2 and soil N availability (1994)
    Springer
    Plant and soil 165 (1994), S. 45-51 
    Details
    ISSN: 1573-5036
    Keywords: CO2 ; gas exchange ; nitrogen ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with 15N to trace the flux of N within the plant-soil system. Above-and belowground growth, CO2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems, and leaves were analyzed for total N and 15N. There was no CO2 treatment effect on leaf area, root length, or net assimilation prior to the completion of N addition. Following the N addition, leaf N content increased in both CO2 treatments, but net assimilation showed a sustained increase only in elevated CO2 grown plants. Root relative extension rate was greater at elevated CO2, both before and after the N addition. Although final root biomass was greater at elevated CO2, there was no CO2 effect on plant N uptake or allocation. While low soil N availability severely inhibited CO2 responses, high CO2 grown plants were more responsive to N. This differential behavior must be considered in light of the temporal and spatial heterogeneity of soil resources, particularly N which often limits plant growth in temperate forests.
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    Soil pCO2, soil respiration, and root activity in CO2-fumigated and nitrogen-fertilized ponderosa pine (1994)
    Springer
    Plant and soil 165 (1994), S. 129-138 
    Details
    ISSN: 1573-5036
    Keywords: carbon dioxide ; nitrogen ; ponderosa pine ; soil respiration ; soil carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this paper is to describe the effects of CO2 and N treatments on soil pCO2, calculated CO2 efflux, root biomass and soil carbon in open-top chambers planted with Pinus ponderosa seedlings. Based upon the literature, it was hypothesized that both elevated CO2 and N would cause increased root biomass which would in turn cause increases in both total soil CO2 efflux and microbial respiration. This hypothesis was only supported in part: both CO2 and N treatments caused significant increases in root biomass, soil pCO2, and calculated CO2 efflux, but there were no differences in soil microbial respiration measured in the laboratory. Both correlative and quantitative comparisons of CO2 efflux rates indicated that microbial respiration contributes little to total soil CO2 efflux in the field. Measurements of soil pCO2 and calculated CO2 efflux provided inexpensive, non-invasive, and relatively sensitive indices of belowground response to CO2 and N treatments.
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    Carbon cost of root systems: an architectural approach (1994)
    Springer
    Plant and soil 165 (1994), S. 161-169 
    Details
    ISSN: 1573-5036
    Keywords: carbon cost ; phosphorus ; Phaseolus vulgaris ; root architecture ; root growth ; root simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root architecture is an important component of nutrient uptake and may be sensitive to carbon allocational changes brought about by rising CO2. We describe a deformable geometric model of root growth, SimRoot, for the dynamic morphological and physiological simulation of root architectures. Using SimRoot, and measurements of root biomass deposition, respiration and exudation, carbon/phosphorus budgets were developed for three contrasting root architectures. Carbon allocation patterns and phosphorus acquisition efficiencies were estimated for Phaseolus vulgaris seedlings with either a dichotomous, herringbone, or empirically determined bean root architecture. Carbon allocation to biomass, respiration, and exudation varied significantly among architectures. Root systems also varied in the relationship between C expenditure and P acquisition, providing evidence for the importance of architecture in nutrient acquisition efficiency.
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    Effects of growth period, plant age and changes in solution aluminium concentrations on aluminium toxicity in wheat (1994)
    Springer
    Plant and soil 166 (1994), S. 21-30 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
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    Root growth and nitrogen uptake in sycamore (Acer pseudoplantanus L.) seedlings in relation to nitrogen supply (1994)
    Springer
    Plant and soil 158 (1994), S. 233-238 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; precoditioning ; roots ; sycamore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acer pseudoplatanus L. trees were grown in sand culture for 2 years and, in 1988, supplied with either 1.0 mol N m-3 (low N) or 6.0 mol N m-3 (high N) to precondition their growth. In 1989, the same trees received either high or low nitrogen, producing four treatments; High N in 1988/High N in 1989; High N in 1988/Low N in 1989; Low N in 1988/Low N in 1989; and Low N in 1988/High N in 1989. Plant growth was affected by N supply in both years. In 1989 the Low N/High N treated trees had the same overall mass, leaf mass and stem girth as the High N/High N treatment. Early spring growth of foliage and roots was conditional on nitrogen supplied in the previous season. Later, the rapid increases in leaf, stem and root growth under high N was through root uptake. Internal partitioning of growth was affected, with the Low N/High N treatment producing more new leaves on axillary shoots, and more new white roots on existing structures, than the Low N/Low N treatment. Despite effects of the N preconditioning on the structure of both canopy and root system, nitrogen uptake was solely dependent on the current nitrogen supply.
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    Triphenyltetrazolium chloride as an indicator of fine-root vitality and environmental stress in coniferous forest stands: Applications and limitations (1994)
    Springer
    Plant and soil 159 (1994), S. 297-300 
    Details
    ISSN: 1573-5036
    Keywords: enzymes ; fine root vitality ; nitrogen ; Picea abies ; Pinus sylvestris ; triphenyltetrazolium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present study is an attempt to investigate whether triphenyltetrazolium chloride (TTC), a chemical compound which measures dehydrogenase activity, could be used to study fine-root vitality from two different points of view: (i) in relation to ageing; (ii) as an indicator of environmental stress, in this case of excess nitrogen. The study was performed with excavated fine-roots from middle-aged Norway spruce and Scots pine stands. The ageing aspect was investigated by applying TTC to fine roots separated into different vitality classes, based on certain morphological characteristics. A significant difference in activity was demonstrated only in the case of roots that could be referred to as living and dead, respectively. The use of TTC on fine roots grown at different nitrogen supply levels indicates a possible increase in dehydrogenase activity with increasing nitrogen supply.
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    Colonisation of wheat by VA-mycorrhizal fungi was found to be higher on a farm managed in an organic manner than on a conventional neighbour (1994)
    Springer
    Plant and soil 160 (1994), S. 33-40 
    Details
    ISSN: 1573-5036
    Keywords: organic agriculture ; phosphorus ; rock phosphate ; VA-mycorrhizas ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Levels of colonisation by vesicular-arbuscular (VA)-mycorrhizal fungi were compared between adjacent farms, one operated in a conventional manner and the other run according to organic farming principles. Wheat grown on the organic farm was found to have VA-mycorrhizal colonisation levels consistently 2 to 3 times higher than wheat on the conventional farm. Glasshouse and field trials indicated that the lower colonisation levels on the conventional farm were due to continual use of fertiliser containing soluble phosphorus (P). The fertiliser appeared to have an immediate negative effect on the rate of colonisation, and also appeared to have a long term negative effect through maintaining higher levels of soluble P in the soil, and by decreasing inoculum levels. Use of the relatively insoluble reactive rock phosphate fertiliser on the organic farm did not decrease levels of VA-mycorrhizas. Colonisation levels did not vary between wheat varieties, and herbicides and seed dressings were also not found to be having any significant effect on levels of colonisation.
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  • 88
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    Effect of nitrogen and sucrose on the primary and secondary metabolism of transformed root cultures of Hyoscyamus muticus (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 263-272 
    Details
    ISSN: 1573-5044
    Keywords: Fatty acids ; hyoscyamine ; Hyoscyamus muticus ; nitrogen ; sucrose ; transformed root cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abatract The effect of carbon and nitrogen sources on two well-established hairy root clones, LBA1S and C58A, of Hyoscyamus muticus strain Cairo, were investigated. Both clones exhibited completely different patterns with regards to their growth rate, hyoscyamine accumulation, and fatty acid contents. Clone C58A grew faster and yielded more biomass (17.4 g l-1, in 21 days), but produced less hyoscyamine. The maximum hyoscyamine content (120 mg l-1) in clone LBA1S was reached in 28 days. Neither of the clones could use lactose or fructose as the sole carbon source, nor ammonium as the sole nitrogen source. The growth in the medium containing glucose was significantly reduced compared to that containing sucrose. Clone LBA1S was sensitive to the changes in sucrose concentration and an increase in ammonium in the culture medium, whereas C58A tolerated these changes better but was more sensitive to the increase in total nitrogen. Lipid synthesis was active in the exponential growth phase, and the total fatty acid content varied from 5 to 34 mg g-1 of dry root material. The major fatty acids were linoleic, palmitic and linolenic. There were considerable differences in the total amount of lipids and in their relative ratios when different nutrients were applied.
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  • 89
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    Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 359-369 
    Details
    ISSN: 1573-5117
    Keywords: agriculture ; blue-green algae ; eutrophication ; internal loading ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of agriculture was estimated on two shallow, eutrophic lakes, Lake Kotojärvi and Lake Villikkalanjärvi in southern Finland. The main emphasis was on phosphorus and nitrogen budgets and on the phytoplankton dynamics. Special attention was paid to internal P loading and blue-green algal blooms. The mean Tot-P load from agricultural land was 1.2 kg ha-1 a-1 in both basins and Tot-N loads were 19 kg ha-1 a-1 in L. Villikkalanjärvi and 12 kg ha-1 a-1 in L. Kotojärvi. The Tot-P input to L. Kotojärvi was on an average 0.62 g m-2 a-1 (per lake surface area), and the Tot-N input 9.1 g m-2 a-1. The corresponding inputs to L. Villikkalanjärvi were 3.1 and 57 g m-2 a-1, respectively. The annual variation followed the runoff volumes. About half of the Tot-P and one third of the Tot-N load was retained in L. Kotojärvi. In L. Villikkalanjärvi the retention was only 24% for Tot-P and 19% for Tot-N. The difference was very probably due to a longer theoretical retention time in L. Kotojärvi. In L. Villikkalanjärvi the mean concentration of Tot-P was 120 µg 1-1 and that of Tot-N 1700 µg 1-1 and the corresponding figures in L. Kotojärvi 67 and 990 µg 1-1, respectively. The mean chlorophyll a concentration was, however, higher in L. Kotojärvi (26 µg 1-1) than in L. Villikkalanjärvi (20 µg 1-1). This was probably due to an internal P load in L. Kotojärvi: in 1988 the internal load of dissolved P was estimated to be as much as twofold the external load. In L. Villikkalanjärvi the internal dissolved P load was only up to 50% of the external input. In L. Kotojärvi the high internal P load coupled with a low DIN:DIP ratio resulted in a strong blue-green algal bloom in the summer of 1988. In L. Villikkalanjärvi blue-green algae were observed only in small amounts. Even in August 1990, when the DIN:DIP ratio was low enough to favor the occurrence of blue-green algae, they contributed only up to 10–15% of the total phytoplankton biomass.
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  • 90
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    A diatom-phosphorus transfer function for shallow, eutrophic ponds in southeast England (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 391-410 
    Details
    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; palaeolimnology ; transfer function ; United Kingdom ; shallow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shallow ponds in southeast England are often eutrophic with high phosphorus concentrations. The aim of this study was to develop a diatom-phosphorus ‘transfer function’ to enable past phosphorus levels in such waters to be inferred from the sediment record. A water chemistry survey of 123 randomly chosen, shallow, artificial ponds in southeast England was carried out. Principal components analysis (PCA) revealed that phosphorus was an important environmental variable. A subset of 31 sites was selected along a total phosphorus (TP) gradient (winter TP range 7–1123 µg 1-1), in order to explore the relationship between the surface-sediment diatom assemblages and the contemporary water chemistry using canonical correspondence analysis (CCA). Annual mean TP was the most significant variable in explaining the variance in the diatom species data. Weighted averaging (WA) regression and calibration techniques were used to generate a transfer function, enabling annual mean TP (range 25–646 µg 1-1) to be inferred from the diatom species TP optima of 102 common taxa in the dataset (r 2 = 0.79; RMSE = 0.161; RMSE(boot) = 0.279; n = 30). The model was applied to fossil diatom assemblages in a sediment core from Marsworth Reservoir, Hertfordshire, a Site of Special Scientific Interest (SSSI), with currently high TP levels of 476 µg 1-1, to reconstruct past epilimnetic annual mean TP concentrations. The study shows that artificial, shallow waters can be suitable for palaeolimnological research and that it is possible to reliably infer lake water TP using the WA technique, across a large range of phosphorus concentrations. This method has the potential to provide limnologists, conservationists and water quality managers with an estimate of pre-enrichment phosphorus concentrations and an indication of the onset and development of eutrophication at a site. This information is essential for lake management strategies and restoration programmes.
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    URL: http://dx.doi.org/10.1007/BF00026729
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  • 91
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    Nutrient metabolism (C, N, P, and Si) in the trophogenic zone of a meromictic lake (1994)
    Springer
    Hydrobiologia 277 (1994), S. 17-39 
    Details
    ISSN: 1573-5117
    Keywords: carbon ; phosphorus ; nitrogen ; silica ; sedimentation ; mineralization ; meromixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75% of carbon, 80% of nitrogen and 25% of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.
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    URL: http://dx.doi.org/10.1007/BF00023983
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  • 92
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    The importance of avian-contributed nitrogen (N) and phosphorus (P) to Lake Grand-Lieu, France (1994)
    Springer
    Hydrobiologia 279-280 (1994), S. 133-147 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; birds ; lake ; nitrogen ; phosphorus ; eutrophisation ; oiseaux ; lac ; azote ; phosphore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le plus grand lac de plaine français, Grand-Lieu, est actuellement largement eutrophisé. Le but de cette étude est d'estimer l'importation annuelle de N et P par les fientes des oiseaux qui s'alimentent à l'extérieur du lac, et de la comparer avec les apports des rivières alimentant le lac. Deux années sont comparées: 1981–82 et 1990–91. Les populations nicheuses (jusqu'à 956 couples de hérons cendrés et 136 couples de grands cormorans et 30 000 canards) et hivernantes (jusqu'à 17 000 canards, 1100 grands cormorans, 15 000 goélands et 2,4 millions d'étourneaux) ont respectivement importé 5800 kg de N total en 1981–82 et 7640 en 1990–91, soit 0,7% et 0,4% des entrées totales du système, et 2000 à 2530 kg de P total soit 2,4 et 6,6% des entrées. Les étourneaux sont responsables des trois quarts des apports d'azote par les oiseaux, et les canards de l'essentiel du reste, tandis que la part des étourneaux baisse pour le phosphore (36% en 1981–82 et 41% en 1990–91), au profit des Canards et des Hérons (respectivement 35% et 27% en 1981–82, 22% et 24% en 1990–91). Mais pendant la phase de croissance végétale (avril–septembre), la part des oiseaux monte jusqu'à 37% des entrées totales de phosphore. L'action localisée des colonies d'oiseaux piscivores est significative, avec une teneur de phosphore 42 fois plus grande dans l'eau sous la colonie qu'à l'extérieur des colonies. A l'échelle du l'ac, l'action actuelle globalement mineure des oiseaux sur les apports totaux d'azote et de phosphore est largement due à l'augmentation catastrophique des apports d'origine humaine (agriculture intensive et stations d'épuration). La teneur moyenne des rivières atteint désormais 10 mg l−1 de N (jusqu'à 23 mg en crue) et 394 mg m−3 de P (jusqu'à 468 mg en crue). Avant cette pollution généralisée, l'eau des rivières bretonnes ne contenait dans les années 1960 que 0,1 à 1,1 mg l−1 de N et 1 à 5 mg m−3 de P lors des périodes de débits maximum. A cette époque, les oiseaux représentaient probablement jusqu'à 36% des apports de N et 95% des apports de P dans les entrées du système lacustre.
    Notes: Abstract The largest natural lake in France, Grand-Lieu, has suffered eutrophication. The objective of the study was to estimate the annual input of nutrients (N, P) resulting from avian excrement, deposited by birds feeding out of the lake and returning to its waters for breeding or roosting, as compared to the input by the rivers that enter in the lake. Two years are compared: 1981–82 and 1990–91. About 1600–2000 breeding herons and cormorants, 20 000–33 000 wintering ducks, gulls and cormorants and 1–2.4 million starlings deposited about 5800 kg total N in 1981–82 and 7640 kg in 1990–91. Respectively, 2000 and 2530 kg total P were deposited over the same time periods. These represent 0.7% and 0.4% of the total N input of the lake and 2.4 and 6.6% of the total P input in 1981–82 and 1990–91. Starlings account for 74% of the N and mallards most of the rest. P input by starlings (36% in 1981–82, 41% in 1990–91), and by mallards and herons (35% and 27% in 1981–82 and 22% and 24% in 1990–91 respectively) plays an appreciable role among birds. During the plant growing period (April–September), the contribution by birds can increase to 37% of total P input of the lake. Piscivorous bird colonies concentrate Phosphorus 42 times more within the colony than outside the colony. Overall, the role birds play in total N and P input is relatively small due to very high inputs from human sewage and agriculture run off. The monthly mean concentration of the water of the two rivers reaches currently 10 mg l−1 of N (to 23 mg during peak floods) and 394 mg m−3 of P (to 468 mg during peak floods). Earlier, for example in the 1960's, water in Brittany only contained 0.1 to 1.1 mg 1−1 of N and 1 to 5 mg m−3 of P during the maximum flow period. At this time, birds could probably have represented annually up to 37% of the N input and up to 95% of the P input to the lake.
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  • 93
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    Different responses to changes in phosphorus, P, among lakes. A study of slopes in chl-a = f(P) graphs (1994)
    Springer
    Hydrobiologia 286 (1994), S. 27-36 
    Details
    ISSN: 1573-5117
    Keywords: Lake ; eutrophication ; phytoplankton ; phosphorus ; non-linear interpolation ; chlorophyll-a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The least squares estimator of a linear regression coefficient βL will give an overall expression for the change in Δ with Δx. In fresh water ecology, however, subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\], of a parent population may have slopes which differ from the overall slope, βκ ≠ βL. By constructing frequency histograms for the set of angles: Arctang % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\],% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\]= para sa y and x% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadM% faliaadMgakiabgkHiTiaadMfaliaadQgakiaacMcacaGGVaGaaiik% aiaadIhaliaadMgakiabgkHiTiaadIhaliaadQgakiaacMcaaaa!42F0!\[(Yi - Yj)/(xi - xj)\], i 〈 j, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaSGaam% yAaOGaeyiyIKRaamiEaSGaamOAaaaa!3BAB!\[xi \ne xj\], peaks in the distribution may be identified and related to ecological phenomenon. To identify peaks we fit Gaussian distributions to the frequency histograms. For a set consisting of 142 observations of chlorophyll-a and total phosphorus (nutrient) concentrations (TP) from 16 lakes we found four Gaussian peaks corresponding to four subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\]k = 1,4. One group identified a response of chl-a to changes in TP which correspond approximately to the average slope found by least square regression (the slope was 0.49). The second group consisted of steeper response than the average (1.28). A third group showed that there is an enhanced proportion of cases where chl-a does not respond to TP (zero slope, all the three deep lakes 〉 10 m, included in the date set contributed to this group). The size of the last group, spanning a wide range of slopes, suggested that about 30% of the inter annual changes in chl-a is unrelated to TP. The results are compared to result obtained by simple least squares regression and to the Theil non-parametric slope estimator.
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  • 94
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    Chlorophyll-phosphorus relationship in acidified lakes of the High Tatra Mountains (Slovakia) (1994)
    Springer
    Hydrobiologia 274 (1994), S. 171-177 
    Details
    ISSN: 1573-5117
    Keywords: chlorophyll ; phosphorus ; mountain lakes ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of total phosphorus (TP) and chlorophyll a (CHLA) were measured in 28 lakes in the High Tatra Mountains (Slovakia) from 1983 to 1990. The relationship between log CHLA and log TP in the Tatra lakes is similar to relationships developed for lakes in other regions, but variation is higher. A part of this variation is caused by acidification of the lakes. In the lakes with pH between 4.9 and 6.3 the CHLA concentrations are often extremely low while TP concentrations decreased, but not as drastically.
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    Nutrient cycling in shallow, oligotrophic Lake Kvie, Denmark (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 267-276 
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    ISSN: 1573-5117
    Keywords: phosphorus ; redox potential ; sediment ; rhizosphere ; macrophyte ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of isoetids for the exchange of phosphorus between sediment and water was studied in the shallow Lake Kvie, Denmark. Vegetated sediments from the littoral zone (55% of lake area) were compared to unvegetated sediments from the littoral and profundal zone. Porewater concentration of soluble reactive phosphate (SRP) was in general low, however, different distributions were found in the three sediments. The vegetated littoral sediment showed highest conc. of SRP just below the surface and decreasing conc. with sediment depth. The SRP release was low on all stations ( 〈 40 µmol m-2 d-1). The observed release of SRP on the vegetated station was much lower than the calculated diffusional flux probably due to assimilation of P by isoetids and binding of SRP to oxidized Fe. The high redox potential in the rhizosphere was probably caused by oxygen excretion from roots. The annual P release from vegetated sediments were only 5% of the P requirements of the macrophytes. The efficient plant assimilation of SRP from the porewater resulted in a small SRP pool with a very fast turnover of P of 500–900 times per year. Both the effects of isoetids on the P cycle in littoral sediments and on the P budget of the entire lake indicate that this plant group is important for keeping lakes in an oligotrophic state.
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    Can Chara control phosphorus cycling in Lake Łuknajno (Poland)? (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 277-283 
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    ISSN: 1573-5117
    Keywords: phosphorus ; eutrophication ; Chara aspera ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Waters of Lake Łuknajno (623 ha, 3 m max. depth postglacial basin in Masurian Lakeland) are of meso-eutrophic type in spite of an intensive land impact and substantial phosphorus loading. The reason of this peculiarity is an abundance of 4 species of charophytes (Chara aculeolata, C. aspera, C. contraria and C. tomentosa) which dominate the submerged vegetation of the lake and yielded 417 g m-2 dry biomass in summer 1991. The plants have high potential for phosphorus uptake and accumulation as was checked in laboratory experiments. Due to this potential Chara can outcompete planktonic algae in mixed cultures at different mineral P supplies.
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    Phosphorus fluctuation in water and deposition into sediment within an emergent macrophyte stand (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 285-292 
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    ISSN: 1573-5117
    Keywords: phosphorus ; sediment ; lake littoral ; Equisetum fluviatile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal fluctuation of phosphorus in water, and total phosphorus and different inorganic P fractions (extracted by NH4Cl, NH4F, NaOH and H2SO4) and organic P fraction (residual P) in surface sediment, were measured in the littoral of oligotrophic Lake Pääjärvi (southern Finland). After the emergence of Equisetum fluviatile L. shoots in mid June, water exchange between the littoral and pelagial area diminished and phosphorus concentrations in water and in surface sediment increased in the inner and mid littoral zones. Phosphorus pool in flocculent, ‘easily resuspensible’ sediment composed on average 62% of inorganic phosphorus and 38% of organic phosphorus. 63% of the inorganic phosphorus, on the average, was extracted from ‘apatite-P fraction’ 29% from ‘iron-P fraction’ 7% from ‘aluminum-P fraction’ and less than 1% from ‘loosely-bound P fraction’. During the growing season, net accumulation of sediment and phosphorus was measured only in the inner littoral zone whereas the outer littoral zones acted rather as a source of phosphorus for the pelagic area. The results of this study indicated that nutrient dynamics in littoral environment was through changes in flow environment greatly governed by the macrophytes.
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    Recent palaeolimnology of three shallow Danish lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 411-422 
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    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; weighted averaging ; lake sediments ; carbonates ; radionuclides ; mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent eutrophication histories of three shallow lakes (mean depths 〈3 m) were studied using palaeolimnological methods. Freeze-cores were dated using 210Pb, 137Cs, 134Cs and 241Am. Resultant chronologies were problematical at two sites (Væng Sø and Vesterborg Sø) due to sediment-water interface mixing, indicated by uniform 137Cs profiles over the surface 20–30 cm. Sediments at Langesø and Vesterborg Sø have a high carbonate content, which together with the high mixing rate have resulted in diatom dissolution below 30 cm at Vesterborg Sø. Diatom stratigraphy indicates relatively small biological changes at both Væng Sø and Langesø both lakes have been eutrophic for at least the last 150–200 years. Væng Sø is dominated by planktonic diatoms together with high percentages of benthic Fragilaria spp., and Langesø by planktonic diatoms, especially Cyclostephanos dubius and Stephanodiscus parvus. Epilimnetic phosphorus concentrations were inferred using weighted averaging; at Væng Sø the diatom-inferred TP (DI-TP) concentrations were close to observed values in the early 1980s, but failed to record the post-biomanipulation decrease to 55 μg l-1 after 1988, presumably due to the smoothing of the sediment record by resuspension and mixing. At Langesø two increases in DI-TP suggest a two-phase enrichment of the lake, initial eutrophication ∼ 1880, and hypertrophy after 1950. The recent DI-TP values are lower than the annual observed values, and reasons for this are discussed. Despite problems associated with sediment mixing, the sediment records of these shallow systems can still be used for monitoring and for environmental reconstructions.
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    High resolution measurements of sediment resuspension above an accumulation bottom in a stratified lake (1994)
    Springer
    Hydrobiologia 284 (1994), S. 43-57 
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    ISSN: 1573-5117
    Keywords: sediment ; resuspension ; lakes ; optical measurements ; transmissometer ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed record of suspended particulate matter (SPM) concentrations in the benthic boundary layer (BBL) 1.5 m above an accumulation bottom and 13.5 m below the surface was obtained from frequent (30 min interval) beam attenuation measurements made with a Sea Tech transmissometer in the main basin of Lake Erken, a moderately deep (mean depth 9 m, maximum depth 21 m) dimictic lake in central Sweden. Concentrations of SPM (g m−3) were not as strongly correlated to the beam attenuation coefficient (c, [m−1]), as were concentrations of the inorganic SPM fraction. Apparently, this was caused by large optically inactive organic particles which significantly affected the measurements of SPM, but had little effect on the attenuation of light. When the water column was thermally stratified, SPM concentrations in the BBL showed a seasonal increase which was related to an increase in the thermocline depth. As the epilimnion deepened, there was also a marked increase in the occurrence of rapid and large changes in SPM concentration. After the loss of stratification, the amount of SPM and the temporal variability in its concentration was reduced. Since surface waves could not influence sediment resuspension at the depth of measurement, these data show the importance of internal waves in promoting sediment resuspension in areas of sediment accumulation. The relatively short period in each summer, when the thermocline reaches a sufficient depth to allow for resuspension over accumulation bottoms, can have important consequences for both the redistribution of lake sediments and the internal loading of phosphorus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005730
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    Hydrologic control of litter decomposition in seasonally flooded prairie marshes (1994)
    Springer
    Hydrobiologia 286 (1994), S. 155-165 
    Details
    ISSN: 1573-5117
    Keywords: decomposition ; marsh ; litter ; nitrogen ; Scolochloa festucacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of seasonal inundation on the decomposition of emergent macrophyte litter (Scolochloa festucacea) was examined under experimental flooding regimes in a northern prairie marsh. Stem and leaf litter was subjected to six aboveground inundation treatments (ranging from never flooded to flooded April through October) and two belowground treatments (nonflooded and flooded April to August). Flooding increased the rate of mass loss from litter aboveground but retarded decay belowground. Aboveground, N concentration decreased and subsequently increased earlier in the longer flooded treatments, indicating that flooding decreased the time that litter remained in the leaching and immobilization phases of decay. Belowground, both flooded and nonflooded litter showed an initial rapid loss of N, but concentration and percent of original N remaining were greater in the nonflooded marsh throughout the first year. This suggested that more N was immobilized on litter under the nonflooded, more oxidizing soil conditions. Both N concentration and percent N remaining of belowground litter were greater in the flooded than the nonflooded marsh the second year, suggesting that N immobilization was enhanced after water-level drawdown. These results suggest different mechanisms by which flooding affects decomposition in different wetland environments. On the soil surface where oxygen is readily available, flooding accelerates decomposition by increasing moisture. Belowground, flooding creates anoxic conditions that slow decay. The typical hydrologic pattern in seasonally flooded prairie marshes of spring flooding followed by water-level drawdown in summer may maximize system decomposition rates by allowing rapid decomposition aboveground in standing water and by annually alleviating soil anoxia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006247
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