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  • Nitrogen fixation  (56)
  • Springer  (56)
  • Cambridge University Press
  • Frontiers Media
  • Institute of Physics
  • 2020-2022
  • 1985-1989  (29)
  • 1980-1984  (27)
  • 1975-1979
  • 1970-1974
  • 1985  (29)
  • 1982  (27)
  • 1970
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Verlag/Herausgeber
  • Springer  (56)
  • Cambridge University Press
  • Frontiers Media
  • Institute of Physics
Erscheinungszeitraum
  • 2020-2022
  • 1985-1989  (29)
  • 1980-1984  (27)
  • 1975-1979
  • 1970-1974
Jahr
  • 1
    ISSN: 1432-2048
    Schlagwort(e): Alnus ; Ammonium ; Carbon translocation ; Endophyte damage ; Nitrogen fixation ; Root nodule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cloned plants of Alnus incana (L.) Moench were inoculated and grown without combined nitrogen for seven weeks. The effects of ammonium on the function and structure of the root nodules were studied by adding 20 mM NH4Cl (20 mM KCl=control) for four days. Nitrogenase activity decreased to ca. 50% after one day and to less than 10% after two days in ammonium treated plants, but was unaffected in control plants. The results were similar at photon flux densities of 200 and 50 μmol m-2 s-1. At the higher light level the effect was concentration dependent between 2 and 20 mM NH4Cl. The recovery was slow, and more than 11 d were needed for plants treated with 20 mM ammonium to reach initial activity. The distribution of 14C to the root nodules after assimilation of 14CO2 by the plants was not changed by the ammonium treatment. Microscopical studies of root nodules showed high frequencies of endophyte vesicles being visually damaged in nodules from ammonium-treated plants, but not in nodules from control plants. When nitrogenase activity was restored, visually damaged vesicles were again few, whereas young developing vesicles were numerous. The slow recovery, the 14C-translocation pattern, and the structural changes of the endophyte indicate a more complex mechanism of ammonium influence than simply a short-term reduction in supply of carbon compounds to the nodules.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-2048
    Schlagwort(e): Ammonium assimilation ; Glycine ; Nitrogen fixation ; Proplastid ; Purine synthesis ; Root nodule ; Ureide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Subcellular organelle fractionation of nitrogen-fixing nodules of soybean (Glycine max (L.) Merr.) indicates that a number of enzymes involved in the assimilation of ammonia into amino acids and purines are located in the proplastids. These include asparagine synthetase (EC 6.3.1.1), phosphoribosyl amidotransferase (EC 2.4.2.14), phosphoglycerate dehydrogenase (EC 1.1.1.95), serine hydroxymethylase (EC 2.1.2.1), and methylene-tetrahydrofolate dehydrogenase (EC 1.5.1.5). Of the two isoenzymes of asparate aminotransferase (EC 2.6.1.1) in the nodule, only one was located in the proplastid fraction. Both glutamate synthase (EC 1.4.1.14) and triosephosphate isomerase (EC 5.3.1.1) were associated at least in part with the proplastids. Glutamine synthetase (EC 6.3.1.2) and xanthine dehydrogenase (EC 1.2.1.37) were found in significant quantities only in the soluble fraction. Phosphoribosylpyrophosphate synthetase (EC 2.7.6.1) was found mostly in the soluble fraction, although small amounts of it were detected in other organelle fractions. These results together with recent organelle fractionation and electron microscopic studies form the basis for a model of the subcellular distribution of ammonium assimilation, amide synthesis and uredie biogenesis in the nodule.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-072X
    Schlagwort(e): Phototrophic bacteria ; Rhodospirillaceae ; Glutamine synthetase ; Nitrogen metabolism ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The phylogenetically related phototrophic bacteria Rhodospirillum tenue and Rhodocyclus purpureus modulate activity of their glutamine synthetases by adenylylation/deadenylylation. Evidence for covalent modification includes the inhibitory effect of Mg2+ on the activity of glutamine synthetase extracted from cells of either species grown on excess ammonia, and the lack of Mg2+ inhibition of activity of the enzyme isolated from N2-(R. tenue) or glutamine (R. purpureus)-grown cells. In addition, snake venom phosphodiesterase treatment of glutamine synthetase from either species grown on excess ammonia relieved Mg2+ inhibition of the enzyme (as measured via the γ-glutamyl transferase assay), and changed the cation specificity from Mn2+ to Mg2+ (in the biosynthetic assay).
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-072X
    Schlagwort(e): Ammonium assimilation ; Excretion ; Anabaena azollae ; Azolla caroliniana ; Cyanobacteria ; Glutamine ; Glutamate formation ; Nitrogen fixation ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Anabaena azollae was isolated fromAzolla caroliniana by the “gentle roller” method and differential centrifugation. Incubation of suchAnabaena preparations for 10 min with [13N]N2 resulted in the formation of four radioactive compounds; ammonium, glutamine, glutamate and alanine. Ammonium accounted for 66% of the total radioactivity recovered and 58% of the ammonium was in an extracellular fraction. Since essentially no extracellular13N-labeled organic compounds were found, it appears that ammonium is the compound most probably made available toAzolla during dinitrogen-dependent growth of the association. The kinetics of incorporation of exogenous13NH 4 + into glutamine and glutamate were characteristic of a precursor (glutamine)-product (glutamate) relationship and consistent with assimilation by the glutamine synthetase-glutamate synthase pathway. The results of experiments using the glutamine synthetase inhibitor, methionine sulfoximine, the glutamate synthase inhibitor, diazo-oxonorleucine, and increasing the ammonium concentration to greater than 1 mM, provided evidence for assimilation primarily by the glutamine synthetase-glutamate synthase pathway with little or no contribution from biosynthetic glutamate dehydrogenase. While showing that N2 fixation and NH 4 + assimilation were not tightly coupled metabolic processes in symbioticAnabaena, these results reflect a composite picture and do not indicate the extent to which ammonium assimilatory enzymes might be regulated in filaments associated with specific stages in theAzolla-Anabaena developmental profile.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 143 (1985), S. 72-76 
    ISSN: 1432-072X
    Schlagwort(e): Oscillatoria ; Cyanobacteria ; Nitrogen fixation ; Oxygen protection of N2-ase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Oscillatoria sp. strain 23 is a filamentous, non-heterocystous cyanobacterium that fixes nitrogen aerobically. Although, in this organism nitrogenase is inactivated by oxygen a high tolerance is observed. Up to a pO2 of 0.15 atm, oxygen does not have any measurable effects on acetylene reduction. Higher concentrations of oxygen inhibited the activity to a relatively high degree. Evidence for two mechanisms of oxygen protection of nitrogenase in this cyanobacterium was obtained. A high rate of synthesis of nitrogenase may allow the organism to maintain a certain amount of active enzyme under aerobic conditions. Secondly, a switch off/on mechanism may reversibly convert the active enzyme into a non-active form which is insensitive to oxygen inactivation after a sudden and short-term exposure to high oxygen concentrations. It is conceived that these mechanisms in addition to a temporal separation of nitrogen fixation from oxygenic photosynthesis sufficiently explain the regulation process of aerobic nitrogen fixation in this organism.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 143 (1985), S. 67-71 
    ISSN: 1432-072X
    Schlagwort(e): Oscillatoria ; Cyanobacteria ; Nitrogen fixation ; Light-dark cycles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The non-heterocystous cyanobacterium Oscillatoria sp. strain 23 fixes nitrogen under aerobic conditions. If nitrate-grown cultures were transferred to a medium free of combined nitrogen, nitrogenase was induced within about 1 day. The acetylene reduction showed a diurnal variation under conditions of continuous light. Maximum rates of acetylene reduction steadily increased during 8 successive days. When grown under alternating light-dark cycles, Oscillatoria sp. fixes nitrogen preferably in the dark period. For dark periods longer than 8 h, nitrogenase activity is only present during the dark period. For dark periods of 8 h and less, however, nitrogenase activity appears before the beginning of the dark period. This is most pronounced in cultures grown in a 20 h light – 4 h dark cycle. In that case, nitrogenase activity appears 3–4 h before the beginning of the dark period. According to the light-dark regime applied, nitrogenase activity was observed during 8–11 h. Oscillatoria sp. grown under 16 h light and 8 h dark cycle, also induced nitrogenase at the usual point of time, when suddenly transferred to conditions of continuous light. The activity appeared exactly at the point of time where the dark period used to begin. No nitrogenase activity was observed when chloramphenicol was added to the cultures 3 h before the onset of the dark period. This observation indicated that for each cycle, de novo nitrogenase synthesis is necessary.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 141 (1985), S. 40-43 
    ISSN: 1432-072X
    Schlagwort(e): Nitrogenase ; Nitrogen fixation ; Regulation ; Photosynthetic bacteria ; Chromatium ; Ammonia switch off
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nitrogenase in Chromatium vinosum was rapidly, but reversibly inhibited by NH 4 + . Activity of the Fe protin component of nitrogenase required both Mn2+ and activating enzyme. Activating enzyme from Rhodospirillum rubrum could replace Chromatium chromatophores in activating the Chromatium Fe protein, and conversely, a protein fraction prepared from Chromatium chromatophores was effective in activating R. rubrum Fe protein. Inactive Chromatium Fe protein contained a peptide covalently modified by a phosphate-containing molecule, which migrated the same in SDS-polyacrylamide gels as the modified subunit of R. rubrum Fe protein. In sum, these observations suggest that Chromatium nitrogenase activity is regulated by a covalent modification of the Fe protein in a manner similar to that of R. rubrum.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 143 (1985), S. 185-191 
    ISSN: 1432-072X
    Schlagwort(e): Heterocyst ; Pyruvate: ferredoxin oxidoreductase ; Nitrogen fixation ; Electron transport to nitrogenase ; Ferredoxin ; Cyanobacteria ; Anabaena cylindrica ; Anabaena variabilis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Various electron donors were found to stimulate C2H2 reduction (N2 fixation) by isolated heterocysts from Anabaena variabilis and Anabaena cylindrica. Intermediates of glycolysis and the tricarboxylic acid cycle as well as unphosphorylated sugars like glucose, fructose and erythrose were among these electron donors. The transfer of electrons from donors like H2, NADH, glyoxylate and glycollate was strictly light-dependent, whereas others like NADPH or pyruvate plus coenzyme A supported C2H2 reduction also in the dark. In all cases, the overall activity was enhanced by light. The stimulation by light was more distinct with heterocysts from A. variabilis than with heterocysts from A. cylindrica. The present communication establishes that pyruvate supports C2H2 reduction by heterocysts from either A. variabilis or A. cylindrica with rates comparable to those with other electron donors. Pyruvate could, however, support C2H2 reduction only in the presence of coenzyme A, and the concentrations of both coenzyme A and pyruvate were crucial. A pyruvate-dependent reduction of ferredoxin by extracts from heterocysts was recorded spectrophotometrically. Glyoxylate, which is an inhibitor of thiamine pyrophosphate-dependent decarboxylations, inhibited pyruvate-dependent C2H2 reduction. This result supports the conclusion that pyruvate is metabolised by pyruvate: ferredoxin oxidoreductase in heterocysts. High concentrations of pyruvate and other electron donors inhibited C2H2 reduction which suggests that nitrogenase activity in heterocysts may be controlled by the availability of electron donors.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 132 (1982), S. 219-224 
    ISSN: 1432-072X
    Schlagwort(e): Rhizobium ; Nitrogen fixation ; Nodules ; Soybean
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Several mutants defective in nodulation were isolated from Rhizobium japonicum strains 3I1b110 and 61A 76. Mutants of class I do not form nodules after incubation with soybean [Glycine max (L.) Merrill] for 17 days, but will do so by 28 days. When host plants other than G. max are infected with several of these strains, there is no detectable difference in the time of nodulation or size of nodules as compared to the wild type. Two mutants of class I (i. e., SM1 and SM2) have been shown previously to be altered in the lipopolysaccharide portion of their cell wall. Mutants of class II are not slow to nodulate but form fewer nodules than the wild type on all the host plants tested. Mutants of class III are unable to form nodules. Some bacteriophage-resistant mutants, altered in cell surface structure, fall into this class. Two mutants of class III do not bind to soybean roots.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 133 (1982), S. 172-177 
    ISSN: 1432-072X
    Schlagwort(e): Beggiatoa ; Nitrogen fixation ; Acetylene reduction ; Nitrate assimilation ; Microaerobic ; Isolation of marine strains
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Four newly isolated marine strains of Beggiatoa and five freshwater strains were tested for nitrogen fixation in slush agar medium. All strains reduced acetylene when grown microaerobically in media containing a reduced sulfur source and lacking added combined nitrogen. The addition of 2 mmol N, as nitrate or ammonium salts, completely inhibited this reduction. Although not optimized for temperature or cell density, acetylene reduction rates ranged from 3.2 to 12 nmol·mg prot-1 min-1. Two freshwater strains did not grow well or reduce acetylene in medium lacking combined nitrogen if sulfide was replaced by thiosulfate. Two other strains grew well in liquid media lacking both combined nitrogen and reduced sulfur compounds but only under lowered concentrations of air. All freshwater strains grew well in medium containing nitrate as the combined nitrogen source. Since they did not reduce acetylene under these conditions, we infer that they can assimilate nitrate.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 133 (1982), S. 312-317 
    ISSN: 1432-072X
    Schlagwort(e): Rhizobium japonicum ; Rhizobium leguminosarum ; Formate metabolism ; Formate dehydrogenase ; Nitrogen fixation ; Nitrogenase ; Bacteroids ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Formate metabolism supported nitrogen-fixation activity in free-living cultures of Rhizobium japonicum. However, formate0dependent nitrogense activity was observed only in the presence of carbon sources such as glutamate, ribose or aspartate which by themselves were unable to support nitrogenase activity. Formate-dependent nitrogenase activity was not detected in the presence of carbon sources such as malate, gluconate or glycerol which by themselves supported nitrogenase activity. A mutant strain of R. japonicum was isolated that was unable to utilise formate and was shown to lack formate dehydrogenase activity. This mutant strain exhibited no formate-dependent nitrogenase activity. Both the wild-type and mutant strains nodulated soybean plants effectively and there were no significant differences in the plant dry weight or total nitrogen content of the respective plants. Furthermore pea bacteroids lacked formate dehydrogenase activity and exogenously added formate had no stimulatory effect on the endogenous oxygen uptake rate. The role of formate metabolism in symbiotic nitrogen fixation is discussed.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1432-072X
    Schlagwort(e): Alfalfa ; Conjugation ; Cross inoculation ; Host specificity ; Hydrogen uptake ; Nodulation ; Nitrogen fixation ; Rhizobium ; Plasmids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract pIJ1008, a Rhizobium leguminosarum plasmid which determines hydrogen uptake ability and symbiotic functions in pea was transferable to three of seven natural isolates of R. meliloti tested. In these three strains, pIJ1008 was maintained stably with the respective sym megaplasmid indigenous to each R. meliloti strain. These strains carrying both plasmids nodulated alfalfa but not pea. By reisolation and examination of the strains from alfalfa nodule tissue, it was shown that pIJ1008 continued to be maintained but that pea-nodulation ability was suppressed. In one strain of R. meliloti which carries a 200 kb cryptic plasmid (in addition to a megaplasmid), the transfer and selection for pIJ1008 resulted in the loss of the cryptic plasmid. In three separate plant growth experiments, alfalfa nodules induced by each of the R. meliloti strain carrying both sym plasmids were assayed for hydrogen uptake activity. The average activity was 40-, 3.5-and 2-fold higher than with the respective pIJ1008-free strains. However, this higher activity was not accompanied by an increase in plant biomass or nitrogen content of shoots.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 142 (1985), S. 289-294 
    ISSN: 1432-072X
    Schlagwort(e): Proteus mirabilis ; Nitrogen fixation ; nif genes ; nif plasmids ; Klebsiella pneumoniae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Self-transmissible plasmids carryinghis andnif genes fromKlebsiella pneumoniae have been introduced into threehis mutants ofProteus mirabilis: strains 5006-1, WR19 and WR20. Expression ofhis by the transconjugants was unequivocal, if slightly temperature-sensitive, but none was Nif+ when tested for acetylene reduction in anaerobic glucose medium using inocula from rich or glucose-minimal aerobic agar cultures. Succinate or pyruvate in place of glucose, low glucose, lower temperature or elevated Na2MoO4 did not allownif expression and no nitrogenase MoFe-protein peptide was detected immunologically after exposure to conditions in which diazotrophic enterobacteria, normal or genetically constructed, derepressnif. One strain,P. mirabilis WR19, carrying thehis nif Kmr plasmid pMF250 was examined in detail. Thenif activator genenifA was introduced on the plasmid pCK1. Such derivatives remained Nif- when tested, after aerobic growth on rich agar media, with normal or low glucose, with succinate or with elevated Mo. However, pre-conditioning by aerobic growth on glucose-minimal agar led to subsequent anaerobic expression ofnif in glucose medium from pMF250 in WR19 carrying pCK1. NH 4 + or proline could serve as N-source in the glucose-minimal agar. Maximum activity was about 5% of that ofK. pneumoniae in our assay conditions. Material cross-reacting with anti-serum to the nitrogenase MoFe protein was formed. Nitrogenase activity was not ‘switched off’ by NH 4 + .P. mirabilis WR19 (pCK1) showed NH 4 + -constitutive temperature-sensitive kanamycin resistance (anif-related phenotype of this plasmid) in aerobic glucose minimal medium. Expression ofnif inP. mirabilis WR19 (pCK1, pMF250) was NH 4 + -repressible despite the constitutivenifA character of pCK1 and introduction of thentrA + plasmid pMM17 did not alter this phenotype. However, pCK1 did not give rise to NH 4 + -constitutive diazotrophy in the wild-typeK. pneumoniae M5al. A construct of WR19 carrying pMF250 and constitutiventrC plasmid (pMD45) remained Nif- even after pre-growth on glucose-minimal media. We conclude (a) thatP. mirabilis forms a gene product functionally equivalent to that ofntrA inK. pneumoniae, (b) that it forms no functional equivalent of thentrC product in our growth conditions. The need for pre-conditioning on aerobic glucose media remains perplexing.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1432-072X
    Schlagwort(e): Evolution ; Nif genes ; Nitrogen fixation ; Nitrogenase ; Nucleotide sequence ; Phylogeny ; Rhizobium ; 16S rRNA cataloguing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract It was known that nitrogenase genes and proteins are well conserved even though they are present in a large variety of phylogenetically diverse nitrogen fixing bacteria. This has lead to the speculation, among others, that nitrogen fixation (nif) genes were spread by lateral gene transfer relatively late in evolution. Here we report an attempt to test this hypothesis. We had previously established the complete nucleotide sequences of the three nitrogenase genes from Bradyrhizobium japonicum, and have now analyzed their homologies (or the amino acid sequence homologies of their gene products) with corresponding genes (and proteins) from other nitrogen fixing bacteria. There was a considerable sequence conservation which certainly reflects the strict structural requirements of the nitrogenase iron-sulfur proteins for catalytic functioning. Despite this, the sequences were divergent enough to classify them into an evolutionary scheme that was conceptually not different from the phylogenetic positions, based on 16S rRNA homology, of the species or genera harboring these genes. Only the relation of nif genes of slow-growing rhizobia (to which B. japonicum belongs) and fast-growing rhizobia was unexpectedly distant. We have, therefore, performed oligonucleotide cataloguing of their 16S rRNA, and found that there was indeed only a similarity of S AB=0.53 between fast- and slowgrowing rhizobia. In conclusion, the results suggest that nif genes may have evolved to a large degree in a similar fashion as the bacteria which carry them. This interpretation would speak against the idea of a recent lateral distribution of nif genes among microorganisms.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 132 (1982), S. 333-337 
    ISSN: 1432-072X
    Schlagwort(e): Anabaena variabilis Kütz ; 14C-prelabeled blue-green algae ; Interaction respiration/photosynthesis ; CO2 exchange ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Prelabeled Anabaena variabilis Kütz. evolves 14CO2 in the light with KCN and DCMU (2,4-dichlorophenyl-1,1-dimethylurea) present, comparable to the dark control without inhibitors added. Double-reciprocal plots of CO2 release vs. light intensity with either KCN or KCN+DCMU present result in two straight lines intersecting at the ordinate. Apparently, reducing equivalents originating from carbohydrate catabolism are channeled into the photosynthetic electron-transport chain, competing for electrons from photosystem II. Under these conditions, the CO2 release is accompanied by a light-dependent oxygen uptake, presumably due to oxygen-reducing photosystem-I activity while ribulose-bisphosphate carboxylase is inhibited by KCN. Comparing nine blue-green algae it was shown that only nitrogen-fixing species release substantial amounts of CO2 in the light with KCN or KCN+DCMU present. This release is particularly obvious with Anabaena variabilis Kütz. under nitrogen-fixing conditions, but small when the alga is grown with combined nitrogen. We conclude that nitrogen-fixing species share a common link between respiratory and photosynthetic electron transport. The physiological role may be electron supply of nitrogenase by photosystem I.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 133 (1982), S. 6-10 
    ISSN: 1432-072X
    Schlagwort(e): Rhodospirillaceae ; Rhodopseudomonas globiformis ; Nitrogen metabolism ; Nitrogen fixation ; Glutamine synthetase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Rhodopseudomonas globiformis strain 7950 grew with a variety of amino acids, urea, or N2 as sole nitrogen sources. Cultures grown on N2 reduced acetylene to ethylene; this activity was absent from cells grown on nonlimiting NH 4 + . Glutamate dehydrogenase could not be detected in extracts of cells of strain 7950, although low levels of an alanine dehydrogenase were present. Growth ofR. globiformis on NH 4 + was severely inhibited by the glutamate analogue and glutamine synthetase inhibitor, methionine sulfoximine. High levels of glutamine synthetase (as measured in the γ-glutamyl transferase assay) were observed in cell extracts of strain 7950 regardless of the nitrogen source, although N2 and amino acid grown cells contained somewhat higher glutamine synthetase contents than cells grown on excess NH 4 + . Levels of glutamate synthase inR. globiformis were consistent with that reported from other phototrophic bacteria. Both glutamate synthase and alanine dehydrogenase were linked to NADH as coenzyme. We conclude thatR. globiformis is capable of fixing N2, and assimilates NH 4 + primarily via the glutamine synthetase/glutamate synthase pathway.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 141 (1985), S. 105-111 
    ISSN: 1432-072X
    Schlagwort(e): Ammonia ; Anabaena ; Cyanobacteria ; Nitrogen fixation ; Nitrogenase ; Nostoc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Incubation in the dark of photoautotrophically grown N2-fixing heterocystous cyanobacteria leads to a loss of nitrogenase activity. Original levels of nitrogenase activity are rapidly regained upon re-illumination of the filaments, in a process dependent on de novo protein synthesis. Ammonia, acting indirectly through some of its metabolic derivatives, inhibits the light-promoted development of nitrogenase activity in filaments of Anabaena sp. ATCC 33047 and several other cyanobacteria containing mature heterocysts. The ammonia-mediated control system is also operative in N2-fixing filaments in the absence of any added source of combined nitrogen, with the ammonia resulting from N2-fixation already partially inhibiting full expression of nitrogenase. High nitrogenase levels, about two-fold higher than those in normal N2-fixing Anabaena sp. ATCC 33047, are found in cell suspensions which have been treated with the glutamine synthetase inhibitor l-methionine-d,l-sulfoximine or subjected to nitrogen starvation. Filaments treated in either way are insensitive to the ammonia-promoted inhibition of nitrogenase development, although this insensitivity is only transitory for the nitrogen-starved filaments, which become ammonia-sensitive once they regain their normal nitrogen status.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 141 (1985), S. 244-248 
    ISSN: 1432-072X
    Schlagwort(e): Ammonia analogues ; Anabaena variabilis ; Cyanobacteria ; Ethylenediamine ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The cyanobacterium Anabaena variabilis showed a pH dependent uptake of ethylenediamine. No uptake of ethylenediamine was detected at pH 7.0. At higher pH values (e.g. pH 8.0 and pH 9.0) accumulation did occur and was attributed to diffusion of uncharged ethylenediamine in response to a pH gradient. A biphasic pattern of uptake was observed at these higher pH values. Treatment with l-methionine-d,l-sulphoximine (MSX) to inactivate glutamine synthetase (GS) inhibited the second slower phase of uptake without any significant alteration of the initial uptake. Therefore for sustained uptake, metabolism of ethylenediamine via GS was required. NH 4 + did not alter the uptake of ethylenediamine. Ethylenediamine was converted in the second phase of uptake to an analogue of glutamine which could not be detected in uptake experiments at pH 7.0 or in uptake experiments at pH 9.0 following pretreatment of cells with MSX. Ethylenediamine treatment inhibited nitrogenase activity and this inhibition was greatest at high pH values.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 141 (1985), S. 364-370 
    ISSN: 1432-072X
    Schlagwort(e): Nitrogen fixation ; Denitrification ; Associative symbiosis ; Acetylene reduction ; Nitrous oxide formation ; Azospirillum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A model system is described where Azospirillum and germinated wheat seeds were grown in association for a week and then assayed for nitrogen fixation (C2H2-reduction) and denitrification (N2O-formation) activities. The association performed C2H2-reduction and N2O-formation under microaerobic conditions. Both activities were measurable after already 3–5 h of incubation with substantial rates and were strictly dependent on the presence of both plants and bacteria. During the week of the growth of the association, the bacteria had lived exclusively from the carbon compounds supplied by the roots of the plants. C2H2-reduction activity by the association was more or less the same with all the Azospirillum brasilense strains, but lower with A. lipoferum and with the A. amazonense strains tested. Two nitrogenase negative mutants of Azospirillum brasilense showed virtually no activity in the association. C2H2-reduction activity was strongly dependent on the growth temperature of the association. Denitrification (N2O-formation) was high also at higher temperatures and at pH-values in the medium around 7.8 but not at neutrality and was strictly dependent on nitrate. The Azospirillum strain used strongly determined the rate of the N2O-formation in the association. It is suggested that Azospirillum may be beneficial to crops particularly under tropical conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 60 (1982), S. 579-587 
    ISSN: 1432-2234
    Schlagwort(e): Nitrogen fixation ; Nitrogen complexes ; Carbon monoxide complexes ; Electronic effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract MNDO method is used to study the interaction of nitrogen and carbon monoxide molecules with a proton, hydrogen atom, hydride ion, hydrogen molecule ion and hydrogen molecule. Predicted geometries and heats of reaction of different complexes are presented. The wave functions are analyzed in terms of ground state charge distributions and overlap populations. Electronic effects accompanying complexation are also discussed.
    Materialart: Digitale Medien
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  • 21
    ISSN: 1432-2048
    Schlagwort(e): Ammonia/ammonium (assimilation, excretion) ; Anthoceros ; Bryophyta ; Cyanobacteria ; Nitrogen fixation ; Nostoc ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The initial product of fixation of [13N]N2 by pure cultures of the reconstituted symbiotic association between Anthoceros punctatus L. and Nostoc sp. strain ac 7801 was ammonium; it accounted for 75% of the total radioactivity recovered in methanolic extracts after 0.5 min and 14% after 10 min of incubation. Glutamine and glutamate were the primary organic products synthesized from [13N]N2 after incubation times of 0.5–10 min. The kinetics of labeling of these two amino acids were characteristic of a precursor (glutamine) and product (glutamate) relationship. Results of inhibition experiments with methionine sulfoximine (MSX) and diazo-oxonorleucine were also consistent with the assimilation of N2-derived NH 4 + by Anthoceros-Nostoc through the sequential activities of glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.7.1), with little or no assimilation by glutamate dehydrogenase (EC 1.3.1.3). Isolated symbiotic Nostoc assimilated exogenous 13NH 4 + into glutamine and glutamate and their formation was inhibited by MSX, indicating operation of the glutamine synthetase-glutamate synthase (GS-GOGAT) pathway: However, relative to free-living cultures, isolated symbiotic Nostoc assimilated 80% less exogenous ammonium into glutamine and glutamate, implying that symbiotic Nostoc could assimilate only a fraction of N2-derived NH 4 + . This implication was tested by using Anthoceros associations reconstituted with wild-type or MSX-resistant strains of Nostoc incubated with [13N]N2 in the presence of MSX. The results of these experiments indicated that, in situ, symbiotic Nostoc assimilated about 10% of the N2-derived NH 4 + and that NH 4 + was made available to Anthoceros tissue where it was apparently assimilated by the GS-GOGAT pathway. Since less than 1% of the fixed N2 was lost to the suspension medium, it appears that transfer of NH 4 + from symbiont to host tissue was very efficient in this extracellular symbiotic association.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 125 (1985), S. 1-12 
    ISSN: 1615-6102
    Schlagwort(e): Glycine max ; Root nodule ultrastructure ; Nitrogen fixation ; Peroxisomes (microbodies) ; Uninfected (interstitial) cells ; Ureides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Ultrastructural studies were conducted on root nodules of soybean (Glycine max) inoculated as seeds withRhizobium japonicum. The development of the large peroxisomes and abundant tubular endoplasmic reticulum (ER) characteristic of the uninfected interstitial cells was followed during nodule growth and maturation. Quantitative data on differences between the uninfected and infected cells in volumes and numbers of peroxisomes, plastids and mitochondria were analyzed statistically. The peroxisomes are 60 times greater in volume per unit cytoplasm in the uninfected cells than the small presumptive peroxisomes in the infected cells. Plastids are about equal in volume in the two types of cells. Mitochondria have 4 × the volume and 3 × the number of profiles per unit cytoplasm in the infected cells than in the uninfected. The observations are discussed in relation to published evidence that several enzymes involved in ureide production are localized in organelles of the uninfected cells. The uninfected cells are viewed as essential components in the symbiotic relationship between host and bacterium.
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  • 23
    ISSN: 1615-6102
    Schlagwort(e): Azolla ; Anabaena ; Symbiosis ; Nitrogen fixation ; Trichome ; Transfer cell ; Ontogeny ; Ultrastructure ; Gland ; Metabolite exchange
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Anabaena azollae is associated with two types of multicellular epidermal trichomes inAzolla leaf cavities, the simple and branched hairs. The observation of transfer cell ultrastructure in some hair cells led to speculation that the cavity hairs might participate in metabolite exchange between the symbionts. The developmental ontogeny of cavity trichomes is described here, using transmission electron microscopy, with a goal of improving our understanding of possible functions of these structures in the symbiosis. The observations have established that all cells of simple and branched hairs develop the structural characteristics of transfer cells, but not simultaneously. Rather, there is an acropetal succession of transfer cell ultrastructure beginning in terminal cells, moving to body cells where present, and ending in stalk cells. The transfer cell stage is followed immediately by senescence in all hair cells. The timing of transfer cell differentiation, considered together with information from other studies, suggests that branched hairs may be involved in exchange of fixed nitrogen between the symbionts, while simple hairs may participate in exchange of fixed carbon fromAzolla toAnabaena.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1573-5036
    Schlagwort(e): Drought stress ; Nitrogen fixation ; Nodulation ; Prosopis spp ; Semi-arid ; Tree legumes ; Water potential
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The literature does not contain a field report of nodulation for the xerophytic tree legumes of the genus Prosopis despite their widespread occurrence in semi-arid regions of the world. A phraetophytically simulated greenhouse experiment was conducted with mesquite in a 3m deep soil column to determine if nodules would form in deper depths where moisture is more abundant. The upper 0.5m in the soil column was allowed to dry to 2200 kPa but the 3.2 m depth was maintained at soil moistures more positive than 70 kPa by water additions to the bottom of the soil column. Over 100 nodules and an acetylene reduction rate of 1.9 mg/h were observed at the 3.2m depth. Nodulation or acetylene reduction were not observed closer than 2.7m from the surface. Air temperatures during these assays exceeded 45°C. Leaf xylem water potentials were in the 2800–3500 kPa range.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 65 (1982), S. 383-396 
    ISSN: 1573-5036
    Schlagwort(e): Frankia ; Microbial ecology ; Nitrogen fixation ; Purshia ; Revegetation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Nitrogen fixing trees and shrubs may be useful in revegetation efforts. Speculation that insufficient endophyte populations in surface soils may limit non-leguminous symbiotic nitrogen fixation in marginal land was explored.Purshia tridentata andP. glandulosa seedlings were grown in greenhouse trials using ten soils from nativePurshia sites. Treatments include a control, an inoculated treatment, and six mmole nitrogen amendment. When inoculated with aP.tridentata crushed nodule inoculum, two of five non-nodulating soils and three sparsely nodulating soils produced well nodulated plants. Inoculation also increased nodule mass, total nitrogen, nitrogen content and shoot dry mass in plants from some of the soils. Of the three soils failing to produce nodulated plants when inoculated, one produced plants that responded well to nitrogen additions but failed to nodulate under low nitrogen conditions; another produced severely stunted plants indicating nutritional limitations on the host; and the third produced plants that were not nitrogen deficient. An application of nitrogen completely suppressed nodulation in all but one soil. The twoPurshia species were similar in nodulation, nitrogen fixation and growth, although important exceptions exist that indicate species may differ in adaptability to certain soil conditions.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1573-5036
    Schlagwort(e): Acridine orange ; Cochliobolus sativus ; Common root rot ; Nitrogen fixation ; Nuclear staining ; Roots ; Senescence ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Natural senescence of the root cortex was assessed by nuclear staining, for cultivars and chromosome substitution lines of spring wheat known to differ in (1) susceptibility to common root rot, (2) total rhizosphere populations and (3) ability to support growth of a free-living nitrogen-fixing bacterium. Together, three root rot susceptible wheat lines showed significantly more cortical senescence than did three resistant lines; the susceptible lines also support larger rhizosphere populations. The wheat line that supports growth of a nitrogen-fixing bacterium showed significantly less cortical death than did any other line. Substitution of chromosome pairs 5B or 5D between the parent cultivars Rescue and Cadet substantially altered the amount of root cortex death, which is thus genetically determined. It is suggested thatCochliobolus sativus and other weak parasites benefit from early natural senescence of the root cortex, and that the degree of susceptibility or resistance of wheat lines to common root rot is at least partly determined by differences in cortical senescence.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 68 (1982), S. 55-67 
    ISSN: 1573-5036
    Schlagwort(e): Klebsiella ; Nitrogen fixation ; Oryza sativa ; Phyllosphere ; Rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The beneficial effect of spraying some highly active phyllosphere N2-fixing microorganisms on high and low yielding cultivars of rice plants as compared with that of urea applied at different doses are described. The dry weight, N-content, 1000 grain weight, and yield were remarkably increased in all cases with the application of phyllosphere microorganisms. The performance of two isolates KUP4 and KUPBR2 with IR-8 and IR-26 rice, was better than that of 52 kg urea-N per hectare. IR-579 rice leaves in association with some phyllosphere bacteria reduced acetylene at the rate of 664–816 nmoles/g leaf/h. In IR-26 rice the effect of application of bacterial suspension at three phases of plant growth corresponded very well with that of urea application in three split doses under identical conditions. Recommended fertilizer rates produced the same yield as the half dose plus bacterial spray in the cultivars Pankaj and Rupsail. Fertilizer application in Pankaj and Rupsail rice reduced nitrogenase activity and the beneficial effects of phyllosphere N2-fixation was reduced by 40–55%.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 233-238 
    ISSN: 1573-5036
    Schlagwort(e): Nitrogen fixation ; Azospirillum spp. ; Azospirillum lipoferum ; Wheat yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Seven isolates belonged toA. brasilense and 3 belonged toA. lipoferum. Isolates having more denitrifying capacity fixed less nitrogen in nitrogen free semi-solid malate medium. One strain ofA. lipoferum having high nitrogen fixing capacity with negative test for denitrification was tested as inoculant to supplement the nitrogen need of a wheat crop in field condition with different doses of N with and without the inoculant. While control without nitrogen yielded 1260 kg/ha the yield in inoculated treatment was 2070 kg/ha resulting in significant increase. In a treatment receiving 40 kg N/ha the grain yield was 2370 kg/ha as against yield of 3110 kg/ha in a similar treatment receiving fertiliser plus inoculant. Thus increase in yield was about 30%. Further the treatment receiving 80 kg N/ha yielded 2970 kg/ha as against yield of 4150 kg/ha in a treatment receiving inoculant alongwith the above dose of the fertiliser. Thus increase in yield due to application of inoculant was about 36%. Similarly, the uptake of N in different treatments was augmented due to inoculation of seeds with the culture.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 293-297 
    ISSN: 1573-5036
    Schlagwort(e): Ecology ; Frankia ; Nitrogen fixation ; Water potential
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Growth responses of Frankia isolates to decreasing water potential were monitored in systems where potentials were controlled by KCl, NaCl and Polyethylene glycol. The highest potential tested was −2 bar (basal medium). The general pattern emerging was that isolates fromAlnus glutinosa, A. viridis andComptonia peregrina showed declining growth at potentials below −2 to −5 bar. AMyrica gale isolate showed declining growth with decreasing potential. All isolates were more sensitive to decreases in potential in a matric controlled than an osmotic controlled system. They all showed approximately 50 percent growth reduction at −5 to −8 bar, and meagre growth at −16 bar after 35 days. The Comptonia isolate was the most vigorous at low potentials. Nitrogen fixation ability was monitored for two isolates. Highest specific activities were observed between −3 and −5 bar for the Myrica isolate and between −5 and −7.5 bar for theA. glutinosa isolate.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 341-352 
    ISSN: 1573-5036
    Schlagwort(e): Barley ; Nitrogen fixation ; Rhizoplane ; Rhizosphere
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Aerobic and anaerobic N2-fixing bacteria developed in the rhizosphere of barley seedlings and exhibited N2ase activity when seedlings were grown in sterilized sand-nutrient cultures containing low levels of combined nitrogen. The source of the N2-fixing bacteria appeared to be the seed. Average daily rates up to 0.9 μmoles C2H4 h−1 g−1 dry root tissue were measured, but the intensity of the activity was affected by moisture levels and concentration of combined N in the rhizosphere. Removal and washing of the roots did not remove the activity, and roots remained active even after surface-sterilization. An unidentified aerobic N2-fixing bacterium was isolated from the rhizoplane of active barley roots. Inoculation of barley seedlings with the aerobic N2-fixing bacterium enhanced N2ase activity of excised roots 10-fold, with average rates of 0.9, 1.1 and 1.3 μmoles h−1 g−1 dry root assayed under pO2 of 0.01, 0.02 and 0.04 atm respectively. The aerobic N2-fixing bacterium also exhibited N2ase activity when inoculated into the rhizosphere of oat, rice and wheat seedlings. Microscopic observations of sterilized live and stained barley roots suggest that the aerobic N2-fixing bacterium is an endophyte which infects root tissue and metamorphoses into vesicle-like structures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 64 (1982), S. 251-253 
    ISSN: 1573-5036
    Schlagwort(e): Competition of Rhizobium ; Nitrogen fixation ; Nodulation ; Vigna radiata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Competition of five strains of Rhizobium of the cowpea group, onVigna radiata (L) Wilcjeck variety ML 5, was tested in loamy clay and loamy sand soils. Strains RM 6 and RM 5 were effective nodulators in loamy clay soil, and strains MNH, M 20 and RM 6 were effective nodulators in loamy sand soil. Strains RM 6 and MNH predominated nodule formation in loamy clay and loamy sand soils respectively.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 64 (1982), S. 263-266 
    ISSN: 1573-5036
    Schlagwort(e): Blue-green algae ; Nitrogen fertilisers ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The effects of ammonium or nitrate-nitrogen on biological nitrogen fixation by an algal crust are compared. Nitrate-nitrogen up to 3.0 μmoles N g−1 sand/algal crust at 60% water holding capacity did not affect fixation, whereas an ammonium-nitrogen concentration of 0.2 μmoles N g−1 crust markedly depressed fixation. Consequences of these differential effects are considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 66 (1982), S. 21-28 
    ISSN: 1573-5036
    Schlagwort(e): Agro-forestry ; Acetylene reduction ; Leucaena leucocephala ; Nematode root knots ; Nitrogen fixation ; Nodule biomass ; Woody legume
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The nitrogen fixation rate in a 4-year-old stand of the woody legumeLeucaena leucocephala (Lam.) de Wit. was estimated in the field at a rather dry site in Tanzania by use of an acetylene reduction technique. The diurnal mean value during April–May was 35 nmol C2H4 mg−1 (dry weight) nodules h−1, with a variation between 22±8 and 48±12 nmol C2H4 mg−1 (dry weight) nodules h−1 in early morning and at midday, respectively. The nodule biomass was determined by auger sampling to be 51±16 kg (dry weight) ha−1. Most of the nodules were found at the 10–30 cm soil depth level. A rough calculation of the amount of nitrogen fixed annually arrived at 110±30 kg ha−1. The results give strong support for the use ofL. leucocephala for soil enrichment in less humid areas of tropical Africa.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 66 (1982), S. 125-127 
    ISSN: 1573-5036
    Schlagwort(e): Charcoal ; Garden pea ; Inoculation ; Nitrogen fertilisation ; Nitrogen fixation ; Nodulation ; Pisum sativum ; Wood charcoal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In a factorial pot experiment on garden peas investigating the effect of growing medium, inoculation, nitrogen fertilisation and charcoal addition, shoot growth was significantly better in John Innes potting compost than in 50/50 peat/sand compost and when receiving nitrogen fertilisation but was depressed by the presence of wood charcoal. In the peat/sand medium, root systems were smaller but carried more and larger nodules. The number of nodules was increased by inoculation but the addition of carbon decreased root size, nodule number and nodule size.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    ISSN: 1573-5036
    Schlagwort(e): Aluminium toxicity ; Nitrogen fixation ; Nodulation ; Stylosanthes hamata ; Stylosanthes humilis ; Stylosanthes scabra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Effects of three solution aluminium concentrations (0, 25, and 100μM) on nitrogen fixation by well-nodulated plants ofStylosanthes hamata, Stylosanthes humilis andStylosanthes scabra are reported. Plants were inoculated with Rhizobium CB756 and grown for 21 days in an aluminium-free nutrient solution at pH 5.3 before imposition of the aluminium treatments. Nitrogen fixation was measured both by the increase in total nitrogen content of the plants and acetylene reduction in roots of plants harvested at 10 and 20 days after imposition of the aluminium treatments. Solution aluminium concentrations as high as 100μM, had no detrimental effect on nitrogen fixation in any species.
    Materialart: Digitale Medien
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 66 (1982), S. 413-416 
    ISSN: 1573-5036
    Schlagwort(e): Growth ; Nematicide ; Nitrogen fixation ; Nodulation ; Peanut ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The effect of two granular nematicidesviz. oxamyl and fenamiphos, on the nodulation and growth of Rhizobium inoculatedArachis hypogaea L. was studied in glasshouse and field trials. In the glasshouse trial at the suggested rates of application shoot fresh weight was significantly reduced by oxamyl whilst root fresh weight was similarly affected by fenamiphos. In the field trial vegetative growth and plant emergence were significantly reduced by both nematicides. Nodulation at the higher rates of application was increased by both oxamyl and fenamiphos whilst oxamyl caused a significant increase in pod number at the highest rate of application.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 68 (1982), S. 321-329 
    ISSN: 1573-5036
    Schlagwort(e): Alginate ; A value ; Endomycorrhiza ; Glomus mosseae ; Inoculant ; Nitrogen fixation ; Rhizobium japonicum ; Soybean
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary This field study was undertaken to determine the effect of inoculation withGlomus mosseae on N2 fixation and P uptake by soybean. The inoculation withGlomus mosseae was achieved using a new type of inoculant, alginate-entrapped (AE) endomycorrhizal fungus. N2 fixation was assessed using the A value method. In P-fertilized plots, inoculation with AEGlomus mosseae increased the harvest index based on dry weight (+20%) and N content of seeds (+17%), the A value (+31%) and %N derived from fixation (+75%). Inoculation with AEGlomus mosseae decreased the coefficient of variation for the A value and for the dry weights of the different plant parts.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 265-273 
    ISSN: 1573-5036
    Schlagwort(e): Azotobacter chroococcum ; Fertilizers ; Farmyard manure ; Nitrogen ; Nitrogen fixation ; Potassium ; Phosphorus ; Yields of grain stover ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Field trials were conducted during theKharif seasons of 1979 and 1980 to examine the effect of the nitrogen-fixing bacteriumAzotobacter chroococcum (isolate M4) on yields of maize and N-economy. Different levels of nitrogen and farmyard manure (FYM) were supplied to assess their interaction with Azotobacter inoculation. Seed inoculation without fertilization raised grain and stover yields significantly. FYM coupled with inoculation gave higher yields than either could singly. The financial gain due to an increase in grain yield upon applying per ha 80 kg N, 10×103 kg FYM and Azotobacter over the treatment 40N + FYM + Azotobacter was offset by the cost of the additional N; thus, the higher N-application was not economical. Azotobacter inoculation was economically most efficient at lower doses of fertilizer nitrogen which not only increased yields but resulted in a saving of fertilizer N when applied in combination with FYM.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 275-280 
    ISSN: 1573-5036
    Schlagwort(e): Azotobacter chroococcum ; Fertilizers ; Farmyard manure ; Zea mays ; Maize ; Nitrogen ; Nitrogen fixation ; Phosphorus ; Potassium ; Total nitrogen uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The economic feasibility of using cultures of nitrogen fixing microorganisms in programmes to increase crop production, as a selfgenerating source of nitrogen, has been proved beyond doubtviz. Legume-Rhizobium symbiosis and blue green algal ‘fertilizer’ for rice. The extent to which the free living, N-fixing, aerobic, heterotropicAzotobacter chroococcum could replace the application of nitrogenous fertilizer to maize was investigatedin vivo. Total nitrogen uptake (kg ha−1) by maize after inoculation with Azotobacter combined with moderate applications of nitrogen fertilizer and farmyard manure was influenced significantly and resulted in a higher nitrogen concentration in grain and stover along with a higher yield.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 391-399 
    ISSN: 1573-5036
    Schlagwort(e): Associative nitrogen fixation ; Inoculation ; Nitrogen fixation ; Root exudate ; Soil bacteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Organic components leaked fromSorghum bicolor seedlings (‘root exudates’) were examined by recovering14C labelled compounds from root solutions of seedlings inoculated withAzospirillum brasilense, Azotobacter vinelandii orKlebsiella pneumoniae nif-. Up to 3.5% of the total14C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of14C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of14C in the solutions did not occur. Quantities of14C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with14CO2, about 15% of the total14C recovered within 48 hours exposure was found in soil leachates.
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  • 41
    ISSN: 1573-5036
    Schlagwort(e): Isotope techniques ; Nitrogen-15 ; Nitrogen fixation ; Nitrogen utilization ; Phaseolus vulgaris ; Rhizobium ; Varietal comparison
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Differences in N2-fixation byPhaseolus vulgaris bean cultivars were successfully evaluated in the field using15N isotope dilution technique with a non-fixing test crop of a different species (wheat). The Phaseolus cultivars could have been similarly ranked for N2-fixation capacity from either seed yield or total nitrogen yield, but the isotope method provided a direct measure of N2-fixation and made it possible to estimate the proportion of fixed to total nitrogen in the crop and in plant parts. Amounts of nitrogen fixed varied between 24.59 kg N/ha for the 60-day cultivar Goiano precoce to 64.91 kg N/ha for the 90-day cultivar Carioca. The per cent of plant nitrogen due to fixation was 57–68% for the 90-day cultivars and 37% for Goiano precoce (60-day cultivar). Fertilizer utilization was 17–30% of a 20 kg N/ha fertilizer application. 100 kg N/ha fertilizer application decreased N2-fixation without suppressing it totally. Differences in yield between the highest yielding (Carioca) and the lowest (Moruna) 90-day cultivars were also due apparently to varietal differences in efficiency of conversion of nitrogen to economic matteri.e. seed, as well as to differences in capacity of genotypes for N2-fixation.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 68 (1982), S. 217-222 
    ISSN: 1573-5036
    Schlagwort(e): Nitrogen fixation ; Oryza sativa ; Phragmites communis ; Reed ; Rhizosphere ; Rice ; Roots ; Soil temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The relation of nitrogenase activity (ethylene evolution) to soil temperature or incubation temperature of roots was determined on two genera of swamp plants, namely rice (Oryza sativa) cultivated in tropical climate and reed (Phragmites communis) grown in temperate regions. For both intact rice plants and excised rice roots the optimum temperature was 35°C. On excised roots nitrogenase activity responded more sensitivity to changes in temperature. In contrast to intact rice plants no ethylene evolution occurred on excised roots at 17 and 44°C. On reed roots temperature optimum was between 26 and 30°C which is clearly lower than on rice (35°C). The temperature range in which nitrogen fixation occurred was, however, similar to that of rice, although on a lower level. The results suggest a higher potential of the tropics for associative N2 fixation, while in cooler climates the lower temperatures appear to be a major limiting factor.
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 86 (1985), S. 57-67 
    ISSN: 1573-5036
    Schlagwort(e): Azolla ; N2-fixing efficiency ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The productivity of three species of Azolla (A. pinnata, A. filiculoides andA. caroliniana) in outdoor culture has been evaluated at different planting densities. The highest yields were obtained with biomass concentration ranging from 40 to 70g d.w. m−2. The mean productivity over a 90 days period (from May 10th to August 10th) ranged from 10g d.w. m−2 day−1 forA. filiculoides up to 11.5 g d.w. m−2 day−1 forA. caroliniana. The nitrogen content of the dried biomasses was 48.3 mg (g d.w.)−1 forA. pinnata, 51.5mg (g d.w.)−1 forA. filiculoides and 52.3 mg (g d.w.)−1 forA. caroliniana. Very little variations of the nitrogen content of the ferns during the experimental period were observed. The nitrogen-fixing efficiency of the Azolla-Anabaena azollae symbiosis grown in outdoor conditions was evaluated both by direct measurement of the amount of N2 fixed by the culture and by the C2H2-reduction and H2-evolution tests in an air atmosphere. These tests were performed outdoor under the same environmental conditions as the growing cultures. For all the species the ratios of C2H2-reduced to N2-fixed were unexpectedly low, ranging from 2.04 (A. pinnata) to 1.50 (A. caroliniana). The results suggest that the reliability of the C2H2-reduction assay, particularly when applied to complex biological N2-fixing systems, must be re-examined.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 87 (1985), S. 49-60 
    ISSN: 1573-5036
    Schlagwort(e): Actinorhizae ; Alnus ; Frankia ; Nitrogen fixation ; Plasmids ; Restriction analysis ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary After the initial screening of more than 200Frankia strains, the plasmid DNA observed in eight Frankiae was analyzed.In situ lysis was performed to obtain an estimate of their copy number and molecular weight. Four plasmid classes were distinguished, 7–9, 18–20, 30–35 and 50–55 kb. Twelve plasmids were thus analysed with restriction enzymes to determine their plasmid restriction patterns. While someFrankia plasmids with comparable molecular weights were found to be heterologous in their restriction enzyme pattern, an 8 kb plasmid found in bothFrankia sp. ArI3, isolated fromAlnus rubra andFrankia sp. CpI1 isolated fromComptonia peregrina showed undistinguishable ‘fingerprints’. Furthermore, an 18 kb plasmid found in the same two strains, also showed homologous restriction enzyme patterns. However, the copy numbers of the two ArI3 plasmids were higher than those of the CpI1 plasmids. Similarly, strains ACN1AG, $$TX41_{b^--- }^{AC} and TX38_{b^--- }^{AC} $$ , isolated fromAlnus crispa all contained a 50 kb plasmid, and the three plasmids were found upon restriction analysis to be undistinguishable. In one strain, ARgX17c isolated fromAlnus rugosa, it was found through restriction enzyme analysis that two plasmids of a similar molecular weight were in fact heterologous. The possible origin of the homologous plasmids and their potential as specificFrankia markers to be used in ecological studies are discussed.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 87 (1985), S. 143-152 
    ISSN: 1573-5036
    Schlagwort(e): Actinorhizae ; Elaeagnus angustifolia ; Frankia ; In vitro propagation ; Nitrogen fixation ; Nodulation ; Russian Olive ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Following the evaluation of the nutritional requirements for thein vitro propagation ofElaeagnus angustifolia, this actinorhizal species was routinely multiplied on MS, supplemented with 100 mM sucrose and 5 μM kinetin. On this medium, at a 3 week-interval, a multiplication rate of 5–10 was observed. A morphological variant occurred in culture (wet type) but it was converted into the normal type (pubescent type) by a passage on 1/2 macro MS and 1.5% agar. One hundred percent rooting was achieved in liquid medium containing 1/2 MS without growth regulators. The plantlets were transferred aseptically to a nitrogen-free artificial soil substrate and inoculated with pure cultures of differentFrankia strains which had been isolated from Elaeagnus, Shepherdia and Hippophae host plants. We thus ascertained that afterin vitro propagation, the plants retained their capacity to nodulate and sustain nitrogen fixation.
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  • 46
    ISSN: 1573-5036
    Schlagwort(e): Azospirillum ; Mustard ; Nitrogen fixation ; Rhizosphere soil ; Root association ; Seed inoculation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A microplot field experiment was conducted in the presence or absence of P and N application to evaluate the influence of the seed inoculation of mustard (cv. Baruna T59) withAzospirillum lipoferum on N2-fixation in rhizosphere, association of the bacteria with the roots and grain yield and N uptake. Inoculation significantly increased the N content in rhizosphere soil particularly at early stage (40 days) of plant growth, which was accompanied by the increased association of the bacteria (A. lipoferum) in rhizosphere soil, root surface washing and surface-sterilized macerated root. A significant increase in grain yield and N uptake was also observed due to inoculation. Application of P particularly at the 20 kg. ha−1 level further enhanced the beneficial effect ofAzospirillum lipoferum inoculation, while N addition markedly reduced such an effect.
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  • 47
    ISSN: 1573-5036
    Schlagwort(e): Nitrate nitrogen ; Nitrate tolerance ; Nitrogen fixation ; Nodulation ; Trifolium repens ; Symbiotic variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The variability in nodulation and nitrogen fixation traits ofTrifolium repens (cv. S. 100) supplied with abundant nitrate nitrogen was examined using an aseptic tube culture technique. Nodule numbers varied from 0 to 20 per plant and acetylene reduction activity from 0 to 49 nmol C2H4/plant per h. Plants were selected from this variable population for high, low and zero nodule numbers. Plants within groups were intercrossed and progeny used to establish high, low and zero nodule families. These were subsequently tested for nodulation and acetylene reduction activity in the presence and absence of combined nitrogen. When grown with nitrate the control populations (unselected S. 100 and Pronitro) averaged 3.05 nodules per plant, the high family averaged 4 per plant while the low line averaged 1 nodule per plant (P〈0.05). Nodule numbers were strongly correlated with acetylene reduction activity (r= +0.92) but C2H4 production was generally low, averaging respectively 4.9 and 3.1 nmol/plant per h in the high and low lines. In the absence of nitrate nodule numbers increased to an average of 50 per plant and acetylene reduction activity rose to 175.5 nmol/plant per h. There was no correlation between ability of selection lines to nodulate in the presence and absence of nitrate. The results demonstrate the existence of heritable genetic factors controlling nodulation and nitrogenase activity in the presence of nitrate, but the phenotypic expression of these characters is so strongly inhibited by nitrate that increases in nitrogen fixation in the presence of combined nitrogen which are likely to be of agricultural significance would require much greater genetic improvements than those demonstrated here. The possibilities for such improvements are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    ISSN: 1573-5036
    Schlagwort(e): Acetylene reduction ; Bean cultivars ; Harvest index ; 15N dilution ; Nitrogen fixation ; Nodulation ; Phaseolus vulgaris ; Rhizobium inoculation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A field experiment was performed to assess the effects of Rhizobium inoculation and nitrogen fertilizer (100 kg N ha−1) on four cultivars of Phaseolus beans; Carioca, Negro Argel, Venezuela 350 and Rio Tibagi. In the inoculated treatment 2.5 kg N ha−1 of15N labelled fertilizer was added in order to apply the isotope dilution technique to quantify the contribution of N2 fixation to the nutrition of these cultivars. Nodulation of all cultivars in the uninoculated treatments was poor, but the cultivars Carioca and Negro Argel were well nodulated when inoculated. Even when inoculated, nodulation of the cultivars Venezuela 350 and Rio Tibagi was poor and these cultivars showed little response to inoculation in terms of nitrogen accumulation or grain yield. The estimates of the contribution of N2 fixation estimated using the isotope dilution technique, for the Carioca and Negro Argel cultivars, amounted to 31.7 and 18.4 kg N ha−1 respectively. These two cultivars produced 991 and 883 kg ha−1 of grain, respectively, when inoculated and 663 and 620 kg ha−1 with the addition of 100 kg N ha−1 of N fertilizer. The response to nitrogen was particularly poor due to high leaching losses in the very sandy soil at the experimental site. The Venezuela 350 and Rio Tibagi cultivars only responded to N fertilizer and not to inoculation with Rhizobium which stresses the great importance of selecting plant cultivars for nitrogen fixation in the field.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    ISSN: 1573-5036
    Schlagwort(e): Acetylene reduction ; Minesoil ; Nitrogen fixation ; Nitrogen source ; Reclamation ; Sericea lespedeza ; Surface mining
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Two growth chamber experiments were conducted to determine the response ofLespedeza cuneata (Dumont) G. Don. (sericea lespedeza) to delayed inoculation and low levels of nitrogen fertilization. Nitrogen was supplied either as NH 4 + or as NO 3 − in solution. At 0.5 and 5.0 ppm nitrogen early growth and N2(C2H2) fixation was inhibited by NH 4 + and promoted by NO 3 − . Inoculation at seeding did not negatively affect growth prior to the onset of N2(C2H2) fixation. Delayed inoculation until the trifoliate stage thus did not increase growth or N2 fixation during the first 40 days of growth. After 40 days, specific nitrogenase activity was highest for plants inoculated at the first trifoliate stage of growth. In contrast, growth and total shoot nitrogen accumulation were higher in plants inoculated at planting. The experimental results suggest that delaying inoculation is not a useful technique for improving early growth ofL. cuneata for surface mine reclamation.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 87 (1985), S. 1-16 
    ISSN: 1573-5036
    Schlagwort(e): Allocasuarina ; Casuarina ; Frankia ; Nitrogen fixation ; Nodulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Seedlings ofCasuarina spp. andAllocasuarina spp. were grown from seed in the greenhouse and inoculated with a nodule suspension fromC. equisetifolia. Plants ofCasuarina spp. nodulated regularly and were effective in nitrogen-fixation. Only one species ofAllocasuariona, A. lehmanniana formed root nodules. Using these plants as source of inoculum, the isolation of a newFrankia sp. HFPA11I1 (HFP022 801) was made and the strain was grown in pure culture.Frankia sp. HFPA11I1 grows well in a defined medium and shows typical morphological characteristics. In media lacking combined nitrogen, the filamentours bacterium forms terminal vesicles in abundance and differentiaties large intrahyphal or terminal sporangia containing numerous spores. This strain, used as inoculum, nodulates effectively seedlings ofC. equisietifolia andC. cunninghamiana, forming nodules with verically-growing nodule roots. Although effective in acetylene reduction, the endophyte within the nodules is filamentous and lacks veiscles. When used to inoculated seedlings ofA llocasuarina lehmanniana, Frankia sp. HFPA11I1 induces root nodules which are coralloid and lacking nodule roots. The nodules are effective in acetylene reduction and the filamentous hyphae ofFrankia within the nodule lobes lack vesicles. Effective nodulation inA. Lehmanniana depends upon environmental conditions of the seedlings and proceeds much more slowly than in Casuariana.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 87 (1985), S. 223-231 
    ISSN: 1573-5036
    Schlagwort(e): Nitrogen fixation ; Rhizobia ; Vigna unguiculata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Biological nitrogen fixation is considered an important trait of cowpeas (Vigna unguiculata (L.) Walp. var. ‘California Blackeye’ No. 5) for economical production yet the process does not alone provide the quantity of nitrogen required by the plant for maximum productivity. Two experiments were undertaken to determine the potential of an increase in nodule mass and number of bacteroids resulting in increased nitrogen fixation. Cowpeas were grown in a glasshouse for 7 weeks under conditions forcing near total dependence on biological nitrogen fixation for growth. Nodule mass on the roots was varied by inoculating seeds with various ratios of effective and ineffective rhizobia that could be identified serologically and by the color of nodule formed. The results of both experiments demonstrated a linear relationship between total nodule mass formed by the effective rhizobia and quantity of nitrogen fixed. The regression coefficients were high in both experiments (r=0.99** and 0.91**). The relationship between total nitrogen fixed and total number of bacteroids of the effective strain was not consistent. In one experiment the regression coefficient was 0.93** but in the other experiment it was 0.65**. From these results it appears that there is good potential for increasing nitrogen fixation in cowpeas by increasing nodule mass. An increase in nodule mass would also result in an increase in the number of bacteroids.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 87 (1985), S. 445-447 
    ISSN: 1573-5036
    Schlagwort(e): Glomus fasciculatum ; Lentil ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Responses of lentil in unsterile soils at low, medium and high levels of plant available soil P toGlomus fasciculatum inoculation were evaluated. It was observed that growth, dry matter accumulation, nodulation, and nitrogen fixation were considerably improved in VAM inoculated plants over uninoculated control at low and medium levels of plant available soil P.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 89 (1985), S. 57-67 
    ISSN: 1573-5036
    Schlagwort(e): Adaptation ; Carbon balance ; Carbon dioxide ; Environmental stress ; Heat stress ; Maintenance respiration ; Nitrogen fixation ; Salinity stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The fitter of two species that use different strategies to overcome the same stress may be the one that expends the least resources to cope with this stress. However, this concept has proven difficult to quantify. It is proposed here that the increase in maintenance respiration in response to stress factors such as high temperature, salinity or a high-oxygen atmosphere (one indirect effect of which is nitrogen deficiency) may provide a measure of the cost of adaptation, in terms of expenditure of assimilated carbon. A corrolary to this is that, where it can be shown that an adaptive strategy results in the expenditure of assimilates, adaptation may be enhanced by increasing carbon assimilation. Results are presented supporting the hypothesis and its corrolary.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 85 (1985), S. 145-148 
    ISSN: 1573-5036
    Schlagwort(e): Mutualism ; Nitrogen fixation ; Sorghum bicolor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Sorghum plants were inoculated withAzospirillum brasilense or received an N-amended nutrient solution. Azospirillum inoculation increased plant dry weight and nitrogen assimilation by 25%. Most plant growth responses to Azospirillum were comparable to application of 2.0 mM N. Increased scavenging of nutrients, altered root permeability or nitrogen fixation are possible explanations for these effects.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    ISSN: 1573-5036
    Schlagwort(e): Glycine max ; Isotope dilution ; 15N techniques ; Nitrogen availability ; Nitrogen fixation ; Plant breeding ; Varietal comparison
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Soybeans (Glycine max (L.) Merr.) have a high N requirement which is fulfilled by soil N uptake and N2-fixation. This study was concerned with the effects of past yield selection on N2-fixation in soybeans. The soybean cultivars, ‘Lincoln’, ‘Shelby’, and ‘Williams’, which represent successive improvements in the ‘Lincoln’ germplasm, and a non-nodulating control were planted in a soil containing15N labelled organic matter. Two replications occurred on soil previously cropped to alfalfa and two on soil previously cropped to soybeans. Plants were harvested at five growth stages and leaf area, plant weight, total N, and atom percent15N were determined. Mature grain was harvested and yield components were also determined, as well as the total N and15N content. Cultivar differences in total dry matter were only evident at physiological maturity, when Williams contained the greatest dry matter. Williams exhibited the longest period of seed formation and seed fill and also had the highest grain yield which resulted from a larger weight per seed. The N content of the cultivars did not vary until physiological maturity when Williams contained the highest percent N. The quantity of N fixed at physiological maturity was highest for Williams and lowest for Lincoln. Fixed N contained in the harvested grain was greater for Williams than for the other two cultivars. The fraction of the total plant N derived from fixation was not greatly affected by cultivar and all cultivars acquired an average of 50% of their total N through N2-fixation. Previous cropping history greatly affected the quantity of N fixed and the fraction of the total plant N derived from fixation. Soybeans following soybeans were more dependent upon N2-fixation than soybeans following alfalfa with the former deriving 65% of the total plant N from fixation and the latter only 32%. These soybean cultivars apparently utilized soil N first and then used N2-fixation to satisfy their N requirement. The past selection for higher yield has resulted in soybean cultivars with improved capacities to fix atmospheric N2 and an improved ability to take up available soil N.
    Materialart: Digitale Medien
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  • 56
    ISSN: 1573-5036
    Schlagwort(e): Breeding ; Nitrate nitrogen ; Nitrogen fixation ; Nodulation ; Trifolium repens ; White clover
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Sodium nitrate applications ranging from 0.36 to 22.84 mM N were shown to depress rates of nodule formation and reduce total nitrogen fixation (acetylene reduction) in white clover plants grown in aseptic test tube culture. Low nitrate levels gave an initial depression in symbiotic activity but the reduction was of short duration and these treatments were subsequently associated with enhanced rates of nodule formation and nitrogen fixation. As a result, phenotypic variation appeared to be strongly differentially affected by the amount of nitrate present. A subsequent experiment suggested that much of the variation was a consequence of early enhancement of plant growth rates by low levels of nitrate followed by rapid depletion thus giving a transitory inhibitory effect. This was confirmed in a third experiment in which the range of nitrate concentration was held constant. Differential effects on variability in nodule formation and nitrogen fixation were then greatly reduced but there was still a residual level of plant-to-plant variation. The results have clear implications for selecting genetic variants capable of fixing di-nitrogen in the presence of combined N. The provision of a single limiting dose of combined nitrogen to a population containing individuals with inherently different growth rates can bring about variations in the phenotypic expression of symbiotic characters. These variations are unlikely to be based on genetic factors which have a direct and stable effect on nodule development and nitrogenase activity. The implications of the results for plant breeding are discussed.
    Materialart: Digitale Medien
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