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  • Echinochloa polystachya  (1)
  • Hydrogen production  (1)
  • 1
    ISSN: 1432-2048
    Keywords: Anabaena(immobilization) ; Heterocyst frequency ; Hydrogen production ; Mucilage ; Nitrogenase (NH 4 + production) ; Polyurethane and polyvinyl foams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anabaena azollae, a presumptive isolate from Azolla filiculoides, was immobilized in polyurethane foam, hydrophilic polyvinyl foam and alginate. When viewed by low-temperature scanning electron microscopy a thick mucilage layer covered the surface of both cells and matrix; this closely resembles the mode of attachment of the symbiont Anabaena in the Azolla leaf cavity. The heterocyst frequency of the immobilized A. azollae doubled relative to free-living cells and reached a level of 14–17%. Immobilization induced increases in both hydrogen production via nitrogenase or hydrogenase and in the rates and stabilization of acetylene reduction (N2-fixation). Ammonia production by immobilized cells with L-methionine-D,L-sulfoximine (MSX) is greater than that of freeliving cells. Immobilized cells without MSX were, however, able to excrete ammonium at lower rates thus emulating the characteristic of the symbiotic cyanobacteria (A. azollae) in the leaf cavity of Azolla.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5036
    Keywords: biomass ; decomposition ; Distichlis spicata ; Echinochloa polystachya ; Eulalia trispicata ; Lophopogon intermedius ; Pennisetum mezianum ; primary production ; primary productivity ; Themeda triandra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Studies of net primary production in four contrasting tropical grasslands show that when full account is taken of losses of plant organs above- and below-ground these ecosystems are far more productive than earlier suggested. Previous values have mainly been provided by the International Biological Programme (IBP), where estimates of production were based on a change in vegetation mass alone and would not necessarily have taken full account of organ losses and turnover. Calculation at three of our sites based on estblished methodology using changes in plant mass alone (i.e. that used by the International Biological Programme, IBP) proved to be serious underestimates of when acount was taken of losses simultaneously with measurement of change in plant mass. Accounting for the turnover of material at these three sites resulted in productivities up to five times higher than were obtained using the standard IBP procedure. An emergent C4 grass stand at a fourth site in the Amazon achieved a productivity which approached the maximum recorded for agricultural crops. In this case, productivity values, when organ losses were taken into account, only slightly exceeded that obtained with IBP methods. The findings reported here have wider implications, in prediction of global carbon cycling, remote sensing of plant productivity and impact assessment of conversion to arable cropping systems.
    Type of Medium: Electronic Resource
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