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 (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Surface Sterilization ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.

Nitrogen fixation activity by white clover pastures during flood irrigation cycles

1988 ◽  
Vol 39 (3) ◽  
pp. 409 ◽  
Author(s):  
GN Mundy ◽  
HR Jones ◽  
WK Mason
Keyword(s):  
Nitrogen Fixation ◽  
Water Stress ◽  
White Clover ◽  
Nitrogen Fertilizer ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Acetylene Reduction Activity ◽  
Flood Irrigation ◽  
Reduction Activity ◽  
Nitrogen Fixation Activity

The effect of flood irrigation on clover nitrogen fixation (acetylene reduction activity) was investigated in unfertilized pastures and pastures fertilized with 100 kg N/ha as NH4N03. During the experiment acetylene reduction activities were monitored between successive flood irrigations. The rate of ethylene production increased with decreasing soil water content, peaking 13 days after irrigation. Measured nodule activity then declined, possibly owing to water stress. Nitrogen fertilizer reduced acetylene reduction activities to about half that of the unfertilized pastures. For most of the irrigation cycle acetylene reduction by the pasture was below the measured maximum.

Nitrogen fixation by naturally occurring duckweed–cyanobacterial associations

1985 ◽  
Vol 31 (4) ◽  
pp. 327-330 ◽  
Author(s):  
Tran Phuoc Duong ◽  
James M. Tiedje
Keyword(s):  
Nitrogen Fixation ◽  
Annual Cycle ◽  
Acetylene Reduction ◽  
Acetylene Reduction Activity ◽  
Lower Epidermis ◽  
Reduction Activity ◽  
Naturally Occurring ◽  
Favorable Environment ◽  
Nitrogen Inputs

Nitrogen fixation as measured by acetylene conversion to ethylene was found to be common for duckweed blooms on ponds, lakes, and streams in Michigan. Twenty-six of 29 sites with duckweed sampled over a 2-year period showed acetylene reduction activity (ARA). These activities corresponded to N inputs of 3.7–7.5 kg N∙ha−1 per annual cycle for typical blooms but dense Lemna trisulca blooms could be 10 times greater. The ARA was stimulated five- to six-fold by light, was not removed when plants were shaken in water, and was usually associated with the leaves and not the roots. Colonies of heterocyst-bearing cyanobacteria of the genera Nostoc, Gloeotrichia, Anabaena, Calothrix, and Cylindrospermum were observed attached to the lower epidermis or in the reproductive pockets of leaves of Spirodela and Lemna plants but not on Wolffia plants. The ARA correlated reasonably well with the density of cyanobacterial colonies observed. The duckweed appeared to provide a more favorable environment for the cyanobacteria which should result in enhanced nitrogen inputs to aquatic and sediment environments harboring duckweed. The N2 fixation was not sufficient, however, to meet all the nitrogen needs of the duckweed bloom.

Corrigendum - Nitrogen fixation activity by white clover pastures during flood irrigation cycles

1988 ◽  
Vol 39 (3) ◽  
pp. 409
Author(s):  
GN Mundy ◽  
HR Jones ◽  
WK Mason
Keyword(s):  
Nitrogen Fixation ◽  
Water Stress ◽  
White Clover ◽  
Nitrogen Fertilizer ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Acetylene Reduction Activity ◽  
Flood Irrigation ◽  
Reduction Activity ◽  
Nitrogen Fixation Activity

The effect of flood irrigation on clover nitrogen fixation (acetylene reduction activity) was investigated in unfertilized pastures and pastures fertilized with 100 kg N/ha as NH4N03. During the experiment acetylene reduction activities were monitored between successive flood irrigations. The rate of ethylene production increased with decreasing soil water content, peaking 13 days after irrigation. Measured nodule activity then declined, possibly owing to water stress. Nitrogen fertilizer reduced acetylene reduction activities to about half that of the unfertilized pastures. For most of the irrigation cycle acetylene reduction by the pasture was below the measured maximum.

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