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  • Articles  (643)
  • Springer  (412)
  • Springer Nature  (231)
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  • 1
    ISSN: 1432-2137
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Fetusca arundinacea Schreber) is rapidly gaining popularity as a turfgrass. Limited information is available on seed yield response of turf-type cultivars to seed production management practices. We tested effects of four management variables on seed yield of Bonanza (late-maturing turf type), Rebel (mid-maturing turf type), Falcon (early-maturing turf type), and Fawn (forage type) tall fescue cultivars. Variables were spring-applied N rates (100, 145, and 190 kg ha-1), N application timing (double-ridge stage, spikelet initiation, and equally split between the two), row spacing (0.3 and 0.6 m), and post-harvest residue managements after removing the straw (flail-chopping or burning the stubble). Seed yields of the second through fifth crops were measured. Nitrogen application timing did not affect seed yield of any cultivar. Effects of the other three variables on seed yield interacted with each other. For both Fawn and Rebel, high seed yields were achieved when 100 kg N ha-1 was applied and residue was burned, irrespective of row spacing. Bonanza produced high seed yields with 145 kg N ha-1 , 0.6-m row spacing, and flail-chopping. In contrast, 0.3-m row spacing and residue burning was required for maximum seed yield in Falcon, whereas N rates did not have an effect. We conclude that seed yield responses of Fawn and rebel to management practices are similar. Results further suggest that, compared with Fawn, the optimum spring N rate was higher for Bonanza seed production, and the optimum row spacing was narrower for Falcon seed production. Also, residue burning was needed for maintaining high seed yield in Fawn, Rebel, and Falcon, whereas, at optimum row spacing and N rate, mechanical removal of post-harvest residue was as effective as burning for Bonanza seed production.
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  • 2
    ISSN: 1432-2137
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Fetusca arundinacea Schreber) cultivars is needed to improve cultural practices for seed production. We tested factorial combinations of two post-harvest residue managements (flail-chopping or burning the stubble), two row spacing (0.3 and 0.6 m), three spring-applied N rates (100, 145, and 190 kg ha-1), and three N application timings (double-ridge, spikelet initiation, and equally split between the two) on seed yield components of turf-type cultivars Falcon, Rebel, and Bonanza, and the forage cultivar Fawn. Seed yields of all cultivars were closely correlated with the number of seeds produced per unit area (m2), but yields were weakly and negatively correlated with weight per seed. Compared with flail-chopping, burning the residue increased the number of fertile tillers, floret sites, and seeds per unit area in all cultivars. The number of seeds per unit area was not affected by row spacing in Fawn and Bonanza, but was increased at 0.3-m row spacing in Falcon when the residue was burned, and was greater at 0.6-m in Rebel when the residue was flail-chopped. Increasing N rate above 100 kg ha-1 decreased floret site utilization and seeds per unit area in Fawn, but did not affect these components in Falcon and Rebel. Seeds per unit area in Bonanza was the greatest at 145 kg N ha-1. For all cultivars, N application timing had little effect on seeds per unit area. We conclude that management practices for the turf-type cultivars should focus on maintaining a high number of fertile tillers throughout the stand life by burning post-harvest residue. Using narrower row spacings for early- and mid-maturing turf-type cultivars also could increase the number of fertile tillers per unit area when the post-harvest residue is burned. The optimum spring-applied N rate for seed production is apparently greater for the late-maturing turf types than for forage cultivars.
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  • 3
    ISSN: 1432-1424
    Keywords: plasma membrane ; lung ; histamine receptors ; 5′ nucleotidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A simple and rapid method of isolating plasma membranes from human peripheral lung tissue is described. The method involves homogenization of tissue in 0.25m sucrose-buffered medium followed by differential and sucrose density gradient centrifugation. Enzymatic and morphological characterization of the plasma membrane fraction revealed minimal contamination by nonplasma membrane fragments. The isolated plasma membranes showed an 18-fold purification of 5′-nucleotidase activity compared to the original homogenate. Electronmicroscopic studies of the plasma membrane fraction revealed the presence of small membrane vesicles having a trilaminar membrane structure. To further examine the purity of the plasma membrane preparation, the binding of the H1 receptor antagonist,3H pyrilamine, to the plasma membrane-enriched fraction was compared to the binding to crude membrane preparations. Both the plasma membrane-enriched fraction and the crude membrane preparation had similar Kd's for the histamine antagonist, but the plasma membrane-enriched fraction had a threefold greater binding capacity, reflecting the relative enrichment of plasma membranes of the preparation. Thus, a method has been developed for the isolation of plasma membranes from human peripheral lung which should provide material for a variety of biochemical and pharmacological studies.
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  • 4
    ISSN: 1432-2048
    Keywords: Avena (phytochrome) ; Immunological discrimination ; Monoclonal antibody ; Phytochrome (red-, far-red absorbing forms)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A set of rat monoclonal antibodies (ARC MAC 48 to 52 and 54 to 56), raised to phytochrome from dark-grown seedlings of Avena sativa L. was tested for the ability to discriminate between the red-absorbing (Pr) and far-red-absorbing (Pfr) forms of phytochrome by indirect enzyme-linked immunosorbent assay. MAC 50 bound more strongly to Pfr and MAC 49 and 52 showed preferential binding to Pr from extracts of dark-grown Avena seedlings; MAC 50 also bound more strongly to Pfr from brushite-purified phytochrome. The remainder of the monoclonal antibodies and a rabbit polyclonal antiphytochrome preparation did not discriminate between Pr and Pfr. The results provide evidence for conformational changes in defined regions of the phytochrome apoprotein upon photoconversion.
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  • 5
    ISSN: 1432-2048
    Keywords: Action spectrum ; Light-grown plants ; Photoperiodism ; Phytochrome (type I) ; Triticum (photoperiodism)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluence-rate response curves for wavelengths from 640 nm to 730 nm were constructed for the day-extension promotion of flowering in green, light-grown, wheat (Triticum aestivum L., cv. Alexandria), a long-day plant. The resultant action spectrum had action maxima at 660 nm and 716 nm and resembles spectra for the high-irradiance reaction (HIR) seen in etiolated plants. Because, the HIR is thought to be controlled by type I pytochrome (that which is most abundant in etiolated tissue) our results indicate the involvement of type I phytochrome in the photomorphogenesis of a light-grown, green plant.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Planta 192 (1993), S. 104-109 
    ISSN: 1432-2048
    Keywords: Aluminum toxicity ; Calcium displacement ; Electrical potential ; Root ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several mineral rhizotoxicities, including those induced by Al3+, H+, and Na+, can be relieved by elevated Ca2+ in the rooting medium. This leads to the hypothesis that the toxic cations displace Ca2+ from transport channels or surface ligands that must be occupied by Ca2+ in order for root elongation to occur. In this study with wheat (Triticum aestivum L.) seedlings, we have determined, in the case of Al3+, that (i) Ca2+, Mg2+, and Sr2+ are equally ameliorative, (ii) that root elongation does not increase as Ca2+ replaces Mg2+ or Sr2+ in the rooting media, and (iii) that rhizotoxicity is a function solely of Al3+ activity at the root-cell membrane surface as computed by a Gouy-Chapman-Stern model. The rhizotoxicity was indifferent to the computed membrane-surface Ca2+ activity. The rhizotoxicity induced by high levels of tris(ethylenediamine)cobaltic ion (TEC3+), in contrast to Al3+, was specifically relieved by Ca2+ at the membrane surface. The rhizotoxicity induced by H+ exhibited a weak specific response to Ca2+ at the membrane surface. We conclude that the Ca2+-displacement hypothesis fails in the case of Al3+ rhizotoxicity and that amelioration by cations (including monovalent cations) occurs because of decreased membrane-surface negativity and the consequent decrease in the membrane-surface activity of Al3+. However, TEC3+, but not Al3+, may be toxic because it inhibits Ca2+ uptake. The nature of the specific H+-Ca2+ interaction is uncertain.
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  • 7
    ISSN: 1432-2048
    Keywords: Gibberellin and protoplast swelling ; Phytochrome ; Protoplast (swelling) ; Triticum (protoplast swelling)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of light on the size of intact protoplasts isolated from the primary leaves of etiolated Triticum aestivum was studied. A 2-min red-light irradiation in the presence of 1 mM KCl was sufficient to cause a swelling of protoplasts compared with those maintained in darkness. The effect was photoreversible by far-red light over two light cycles, indicating the involvement of phytochrome. At 4°C, escape from reversibility occurred between 2 and 5 min after the exposure to red light. In exposure-response experiments, 20 s red light at 27 μmol m-2s-1 was sufficient to saturate the response. Exogenous gibberellic acid added in darkness in the presence of KCl also induced protoplast swelling. Gibberellins may act as an intermediate in the phytochrome-induced swelling of protoplasts.
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  • 8
    ISSN: 1432-2048
    Keywords: Light and plant growth ; Photoperiodism ; Phytochrome (type 1) ; Triticum (phytochrome)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetics of type 1 phytochrome were investigated in green, light-grown wheat. Phytochrome was measured by a quantitative sandwich enzyme-linked immunosorbent assay using monoclonal antibodies. The assay was capable of detecting down to 150 pg of phytochrome. In red light, rapid first-order destruction of the far-red-light-absorbing form of phytochrome (Pfr) with a half-life of 15 min was observed. Following white light terminated by red, phytochrome synthesis was delayed in darkness by about 15 h compared to plants given a terminal far-red treatment. Synthesis of the red-light-absorbing form of phytochrome (Pr) was zero-order in these experiments. Phytochrome synthesis in far-red light was approximately equal to synthesis in darkness in wheat although net destruction occurred in light-grown Avena sativa tissues in continuous far-red light, as has been reported for other monocotyledons. In wheat, destruction of Pfr apparently did not occur below a certain threshold level of Pfr or Pfr/total phytochrome. These results are consistent with an involvement of type 1 phytochrome in the photoperiodic control of flowering in wheat and other long-day plants.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and computational fluid dynamics 5 (1993), S. 139-139 
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 10
    ISSN: 1432-1939
    Keywords: Seed dispersal Seed shadow Hornbills Telemetry Tropical frugivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. We studied two species of Ceratogymna hornbills, the black-casqued hornbill, C. atrata, and the white-thighed hornbill, C. cylindricus, in the tropical forests of Cameroon, to understand their movement patterns and evaluate their effectiveness as seed dispersers. To estimate hornbill contribution to a particular tree species' seed shadow we combined data from movements, determined by radio-tracking, with data from seed passage trials. For 13 individuals tracked over 12 months, home range varied between 925 and 4,472 ha, a much larger area than reported for other African avian frugivores. Seed passage times ranged from 51 to 765 min, with C. atrata showing longer passage times than C. cylindricus, and larger seeds having longer gut retention times than smaller seeds. Combining these data, we estimated that seed shadows were extensive for the eight tree species examined, with approximately 80% of seeds moved more than 500 m from the parent plant. Maximum estimated dispersal distances for larger seeds were 6,919 and 3,558 m for C. atrata and C. cylindricus, respectively. The extent of hornbill seed shadows suggests that their influence in determining forest structure will likely increase as other larger mammalian dispersers are exterminated.
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