scholarly journals The Quantitative Relationship between Nitrogen Fixation and the Acetylene-Reduction Assay

1970 ◽  
Vol 23 (4) ◽  
pp. 1015 ◽  
Author(s):  
FJ Bergersen
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Host Plants ◽  
Quantitative Relationship ◽  
Root Systems ◽  
Mean Value ◽  
Reduction Assay ◽  
Nodulated Root ◽  
The Mean ◽  
Free Media

Acetylene.reduction activity of detached soybean nodules was positively correlated with the nitrogen content of the host plants grown in nitrogen-free media. Acetylene reduction by nodulated root systems was related to light intensity preceding sampling; activity of detached nodules was lower and less influenced by light. Comparison of acetylene reduction and 15N 2 uptake by detached soybean nodules gave ratios of acetylene reduced to nitrogen fixed (C2~: NHs ratio) ranging from 2�7 to 4�2 in different experiments. The mean value for four experiments was 3�3�0�6 (S.E.). Different effects of oxygen were obtained with detached soybean nodules when 0�1 atm nitrogen and 0�1 atm acetylene were used as substrates. When the acetylene concentration was reduced to 0�005 atm the effects upon both assays were similar but the ratio of the two assays was still affected by p02.

Nitrogen fixation associated with 'Park' Kentucky bluegrass (Poapratensis L.)

1979 ◽  
Vol 25 (10) ◽  
pp. 1197-1200 ◽  
Author(s):  
R. C. Shearman ◽  
W. L. Pedersen ◽  
R. V. Klucas ◽  
E. J. Kinbacher
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Acetylene Reduction Activity ◽  
Controlled Environment ◽  
Nitrogen Accumulation ◽  
Reduction Activity ◽  
Significant Difference ◽  
Reduction Assay

Associative nitrogen fixation in Kentucky bluegrass (Poa pratensis L.) turfs inoculated with five nitrogen-fixing bacterial isolates was evaluated using the acetylene reduction assay and nitrogen accumulation as indicators of fixation. 'Park' and 'Nugget' Kentucky bluegrass turfs were grown in controlled environment chambers and inoculated with Klebsiella pneumoniae (W-2, W-6, and W-14), Erwinia herbicola (W-8), and Enterobacter cloacae (W-11). 'Park' inoculated with K. pneumoniae (W-6) had significant acetylene reduction activity using undisturbed turfs. Other treatments including turfs treated with heat-killed cells had no significant difference in acetylene reduction. In a second study, 'Park' and 'South Dakota Certified' turfs were grown in a greenhouse and inoculated with K. pneumoniae (W-6) and E. herbicola (W-8). 'Park' inoculated with K. pneumoniae (W-6) had increased acetylene reduction activity rates and also a greater nitrogen accumulation in aerial tissues when compared to controls. Acetylene reduction activity was correlated (r = 0.92) to nitrogen accumulation. Other treatments did not effectively increase acetylene reduction activity or nitrogen accumulation.

Nitrogen Fixation and Phosphorus Turnover in a Hypertrophic Prairie Lake

1983 ◽  
Vol 40 (11) ◽  
pp. 1853-1860 ◽  
Author(s):  
B. G. Brownlee ◽  
T. P. Murphy
Keyword(s):  
Nitrogen Fixation ◽  
Light Intensity ◽  
Acetylene Reduction ◽  
Ammonia Volatilization ◽  
Molar Ratio ◽  
Short Term ◽  
Nitrogen Reduction ◽  
The Mean ◽  
Phosphorus Turnover

Nitrogen fixation by Aphanizomenon flos-aquae in a prairie lake in southwestern Manitoba was dependent on the light intensity and in situ oxygen concentrations. The mean molar ratio of acetylene reduction to nitrogen reduction was 5.8:1. High external ammonium concentrations did not appear to inhibit nitrogen fixation over the short term. Nitrogen fixation was not directly initiated by the bloom collapse. We propose that the coupled sequence of ammonia volatilization and nitrogen fixation was triggered by the bloom collapse and that the bloom collapse was caused by coprecipitation of orthophosphate with carbonates. 32PO4 turnover was most rapid during periods when the lake was opalescent, presumably due to carbonate precipitaton.

Fixation, accumulation, and distribution of nitrogen in a crop of Lupinus angustifolius cv. Unicrop

1977 ◽  
Vol 28 (2) ◽  
pp. 237
Author(s):  
P Farrington ◽  
EAN Greenwood ◽  
ZV Titmanis ◽  
MJ Trinick ◽  
DW Smith
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Acetylene Reduction ◽  
Grain Filling ◽  
Plant Nitrogen ◽  
Balance Sheets ◽  
Reduction Assay ◽  
Beginning Of Flowering ◽  
Proportional Distribution

A lupin crop was sampled each week to measure nitrogen fixation by acetylene reduction assay and for determination of the total nitrogen content on the organs on each axis of the plant. Nitrogen fixation started 5 weeks after sowing, reached its maximum rate per plant at the beginning of flowering on the main axis, and ceased during the period of rapid grain filling, which was 4 weeks before maturity. Plants did not accumulate measurable quantities of nitrogen until 2 weeks after the start of nodular fixation as indicated by acetylene reduction. In the vegetative phase within each order of axes most nitrogen went to the leaves before they senesced. During the first half of the period of rapid grain filling, both the weight and the concentration of nitrogen in the grain increased at the expense of the vegetative components. Balance sheets for nitrogen content and the current proportional distribution of nitrogen are presented for three occasions at weeks 8-9, weeks 15-16 and weeks 18–19. Waterlogging greatly decreased acetylene reduction and plant growth.

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