Nitrogen fixation associated with grasses in Oregon

1976 ◽  
Vol 22 (4) ◽  
pp. 523-530 ◽  
Author(s):  
Arthur D. Nelson ◽  
Lynn E. Barber ◽  
John Tjepkema ◽  
Sterling A. Russell ◽  
Robert Powelson ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Aerobic Bacteria ◽  
Bacillus Species ◽  
Natural Conditions ◽  
Wheat Roots ◽  
Natural Grasslands ◽  
Reduction Assay ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Root Surfaces

Nitrogen fixation associated with both natural grasslands and grain crops of Oregon was studied using the acetylene-reduction assay. A number of the grasses collected had some acetylene-reducing activity. Agrostis tenuis Sibth. had substantially greater activity than any of the other species, with a mean rate estimated at 37 g N2 fixed per hectare per day. Assuming 100 days of activity, about 3 kg of N2 would be fixed per hectare per year. This quantity of nitrogen may be important in the maintenance of this species under natural conditions. Nitrogen-fixing microorganisms were isolated from the root surfaces of some of the grasses. Cultures of Bacillus macerans, Bacillus polymyxa, and Enterobacter cloacae were isolated from wheat roots as were two cultures which have not been assigned a specific taxonomic classification. Strains of N2-fixing Bacillus species and Gram-negative aerobic bacteria were isolated from Festuca and Agrostis.

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.

Seasonal variation in nitrogen fixation, associated microbial populations, and carbohydrates in roots and rhizomes of Typha latifolia (Typhaceae)

1984 ◽  
Vol 62 (9) ◽  
pp. 1965-1967 ◽  
Author(s):  
David D. Biesboer
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Anaerobic Bacteria ◽  
Typha Latifolia ◽  
Root Surface ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Free Sugar ◽  
Fixation Rate ◽  
Reduction Assay

Seasonal changes in nitrogen fixation, numbers of nitrogen-fixing bacteria associated with the roots, and rhizome–root carbohydrates were studied for the broad-leaved cattail, Typha latifolia L. Populations of anaerobic and aerobic diazotrophic bacteria were present on the root surface. Anaerobic bacteria predominated in the diazotrophic association, were more active in the acetylene reduction assay, and generally outnumbered aerobic bacteria by 2 to 1 during maximum rates of seasonal nitrogen fixation. The observed maximum nitrogen fixation rate coincided closely with reproductive development in Typha and peak microbial populations. Starch levels in rhizomes were nearly depleted during the middle of the growing season, whereas free sugar concentrations remained stable. Sugar concentrations in the roots increased rapidly during rhizome–root growth and decreased rapidly prior to peak nitrogenase activity.

Use of spermosphere model for the screening of wheat cultivars and N2-fixing bacteria for N2 fixation

1986 ◽  
Vol 32 (4) ◽  
pp. 285-288 ◽  
Author(s):  
Devender K. Jain ◽  
R. J. Rennie
Keyword(s):  
Yeast Extract ◽  
N2 Fixation ◽  
Azospirillum Brasilense ◽  
Incubation Temperature ◽  
Wheat Cultivars ◽  
Wheat Roots ◽  
Naoh Solution ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Very High

The spermosphere model showed very high seedling-to-seedling variation in the ability to induce acetylene-reducing activity in bacteria associated with wheat roots. Several seedlings failed to induce nitrogenase in N2-flxing strains of Bacillus and Azospirillum brasilense. Increasing the concentration of yeast extract or the inoculum density, adding NaOH solution in the side arm of Pankhurst tubes to absorb CO2, and vernalizing the seeds did not increase the percentage of nitrogenase-positive tubes and did not decrease variation in acetylene-reducing activity. Increasing the incubation temperature from 25 to 27 °C induced nitrogenase in Bacillus, but not in Azospirillum strains; at 30 °C nitrogenase was also induced in Azospirillum strains. It appears that the spermosphere model is not a practical technique for screening nitrogenase induction by wheat, unless the use of genetic lines of unimpeachable uniformity can provide control of variability.

NITROGEN FIXATION AND CARBON METABOLISM IN VICIA FABA ROOT NODULES OVER ONTOGENY

1999 ◽  
Vol 47 (1) ◽  
pp. 35-41 ◽  
Author(s):  
Antonio Ocaña ◽  
Juan Manuel Caba ◽  
Francisco Ligero ◽  
Carmen Lluch
Keyword(s):  
Nitrogen Fixation ◽  
Vicia Faba ◽  
Carbon Metabolism ◽  
Sucrose Synthase ◽  
Root Nodule ◽  
Vegetative Period ◽  
Complete Life Cycle ◽  
Reducing Activity ◽  
Alkaline Invertase ◽  
Acetylene Reducing Activity

The evolution of growth, nodulation, nitrogen fixation, and activities of root-nodule enzymes related to sucrose breakdown (sucrose synthase, alkaline invertase), pentose phosphate pathway (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase), malate dehydrogenase, phosphoenolpyruvate carboxylase, and NADP-dependent isocitrate dehydrogenase, were followed over the complete life-cycle of faba bean in a growth chamber. The aim was to study the ontogenic changes of these parameters to obtain information on the carbon metabolism in nodules ofVicia faba, an amide-exporting legume. The maximum values of the relative growth rate and the specific acetylene-reducing activity were registered during the vegetative period. At pod-filling, the specific and total acetylene-reducing activity per plant declined in parallel with the enzyme activities of carbon metabolism. Contrary to reports for other legume species, inV. fabaroot nodule activity of sucrose synthase exceeded alkaline invertase values by 2-fold or more during the vegetative period. The activity of the two enzymes was similar at flowering and pod formation. The enzymes of carbon metabolism registered two maxima, one before and one after a trough (day 32), which marked the change from the vegetative to the reproductive period.

Temperature sensitivity of nitrogen fixation in Azospirillum spp.

1992 ◽  
Vol 38 (12) ◽  
pp. 1238-1241 ◽  
Author(s):  
Anil K. Tripathi ◽  
Walter Klingmüller
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Lacz Fusion ◽  
Optimum Growth ◽  
Azospirillum Lipoferum ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
The Impact ◽  
Key Words Temperature

Azospirillum brasilense and Azospirillum lipoferum showed optimum acetylene-reducing activity at 25 and 30 °C, respectively, although both the bacteria grew optimally at 35 °C. Azospirillum halopraeferens displayed optimum growth and acetylene-reducing activity at 40–41 °C. Our experiments indicated that expression of nif genes was generally more sensitive to temperature than was nitrogenase activity. The NifA-dependent activation of a heterologous nifH–lacZ fusion was used to assess the impact of temperature on native NifA activity of A. brasilense and A. lipoferum. Maximum NifA activity was observed at 25 °C in A. brasilense and at 30 °C in A. lipoferum. Key words: temperature, nitrogen fixation, nifH–lacZ fusion, NifA activity, Azospirillum.

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.

Kinetics of first-cutting regrowth of alfalfa plants and nitrogenase activity in a controlled environment with and without added nitrate

1983 ◽  
Vol 61 (9) ◽  
pp. 2405-2409 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Dry Matter ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Radical Change ◽  
N Nutrition ◽  
Meliloti Strain ◽  
Medicago Sativa L ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Kinetics Of

Seedlings of Medicago sativa L. cv. Algonquin were grown in vermiculite and nodulated by Rhizobium meliloti strain 102F70 at two lower levels of N, until flowering when the tops were cut off to leave about 10% shoot stubble. Residual shoot dry matter immediately resumed first-order growth and maintained it throughout regrowth to second flowering. The rate constants of shoot regrowth were 34% lower (at 15 mM NO3−), 25% lower (at 1.5 mM NO3− symbiotically), or 220% higher (at zero NO3− symbiotically) than the values for 1 to 4-week-old seedlings, which indicated a radical change in physiology. Root dry matter resumed exponential growth after a 7-day recession and its recovery and yields were independent of N nutrition. The most pronounced minima occurred in the acetylene-reducing activity of nitrogenase, the kinetics of which paralleled root dry matter except that its redevelopment stopped after two-thirds of the regrowth time. The rate coefficient for the redevelopment of nitrogenase activity equalled that for its development during the seedling stage, which suggested unchanged limitations on that process until its redevelopment stopped.

Acetylene-reducing activity of detached root nodules ofMyrica faya ait

1974 ◽  
Vol 41 (3) ◽  
pp. 521-526 ◽  
Author(s):  
C. Miguel ◽  
C. Rodriguez-Barrueco
Keyword(s):  
Root Nodules ◽  
Reducing Activity ◽  
Acetylene Reducing Activity
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