Implications of natural ethylene cycling processes for forest soil acetylene reduction assays

1989 ◽  
Vol 35 (7) ◽  
pp. 713-718 ◽  
Author(s):  
O. Q. Hendrickson
Keyword(s):  
Carbon Monoxide ◽  
Forest Soil ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Forest Floor ◽  
Nitrogenase Activity ◽  
Mineral Soil ◽  
Ethylene Oxidation ◽  
Acetylene Reduction Activity ◽  
Oxidation Rates

Under aerobic conditions, ethylene production and oxidation occurred simultaneously in organic and mineral horizons of a northern hardwood forest. Ethylene oxidation rates in mineral soil were high (up to 25 nmol∙g−1∙day−1) relative to other forest soils, and exceeded production rates unless moisture contents were raised above saturation. Acetylene inhibits ethylene oxidation while allowing ethylene production to proceed; control samples for acetylene reduction assays should therefore contain acetylene plus a nitrogenase inhibitor such as carbon monoxide if forest soil nitrogenase activity is to be accurately quantified. A level of 7 kPa carbon monoxide gave complete nitrogenase inhibition in active forest floor samples in the presence of acetylene; carbon monoxide was applied 2 h in advance of acetylene to compensate for its lower solubility in water. Use of this methodology revealed a strong inhibitory effect of saturated water contents on forest floor acetylene reduction activity, suggesting that aerobic N2-fixing activity predominated in unamended forest soil samples.Key words: nitrogenase, acetylene reduction, ethylene formation, forest soil.

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.

Investigations of nitrogenase activity in rheotrophic peat

1976 ◽  
Vol 22 (10) ◽  
pp. 1561-1566 ◽  
Author(s):  
George John Waughman
Keyword(s):  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Anaerobic Bacteria ◽  
Organic Soils ◽  
Nitrogen Fixing ◽  
Anaerobic Conditions ◽  
Time Courses ◽  
Aerobic And Anaerobic ◽  
Stimulation Of

Acetylene reduction by the peat microflora was unaffected by light, but was sensitive to temperature, with an optimum of about 30 °C. The nitrogenase was inactivated by exposure to temperatures above about 35 °C. Activity occurred in completely anaerobic conditions; the rate of ethylene production was of the order of 0.5 nmol C2H4 ml−1h−1. Experiments with time courses indicated that exposure to oxygen caused an initial inhibition of activity followed by a period in which ethylene production was stimulated to rates much higher than in the anaerobic tests; both the inhibition and stimulation appeared to be related to the level of oxygenation. It is suggested that these results could be explained by the existence of nitrogen-fixing associations of aerobic and anaerobic bacteria in the peat. The stimulation of activity caused by exposure to air indicates that care must be taken when interpreting results of the assay obtained from waterlogged organic soils.

A survey of angiosperms in Nova Scotia for rhizosphere nitrogenase (acetylene-reduction) activity

1978 ◽  
Vol 56 (18) ◽  
pp. 2218-2223 ◽  
Author(s):  
D. Smith ◽  
D. G. Patriquin
Keyword(s):  
Nova Scotia ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Reduction Technique ◽  
Acetylene Reduction Activity ◽  
Forage Grasses ◽  
Reduction Activity ◽  
Tropical Forage ◽  
Poorly Drained Soils

Excised root samples from 901 plants, representing 130 species of nonnodulated angiosperms largely in upland, pioneering habitats, were assayed for nitrogenase activity by the acetylene-reduction technique after overnight preincubation of the samples under low pO2. Most samples and most species exhibited very low excised root acetylene-reducing activities, but for 19 species, maximum values were greater than 50 nmol C2H4∙g−1∙h−1. In situ C2H2 assays, conducted on 10 species which had exhibited maximum excised root activities greater than 10 nmol C2H4∙g−1∙h−1, indicated average belowground N2-fixation rates of 3 to 92 g N∙ha−1∙day−1 and maxima greater than 100 g N∙ha−1∙day−1 for 3 of the 10 species. The highest values were for grasses characteristic of poorly drained soils and for some dicotyledonous weeds. It is concluded that the potential of temperate-zone angiosperms for nitrogenase activity by 'associative symbioses' approaches that of tropical forage grasses.

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.

Invasion of clear-cuttings by the actinorhizal plant Comptoniaperegrina

1986 ◽  
Vol 16 (4) ◽  
pp. 872-874 ◽  
Author(s):  
O. Q. Hendrickson
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Dry Weight ◽  
Significant Negative Correlation ◽  
Acetylene Reduction Activity ◽  
Total N ◽  
Reduction Activity ◽  
Site Disturbance ◽  
Harvest Site ◽  
Whole Tree

Three years after harvesting a mixed conifer–hardwood forest in Ontario, the density of sweet fern (Comptoniaperegrina (L.) Coult.) was far greater on a whole-tree harvest site (logging slash removed) than on an adjacent conventional harvest site (logging slash present). These differences were related to the degree of site disturbance, particularly forest floor removal. Nodule fixation rates also appeared to reflect the degree of disturbance, being highest in plants growing along a logging road where the sandy, nitrogen-poor mineral soil was exposed, and exceptionally low on the conventional harvest site (0.67 μmol C2H4 g dry weight−1 h−1). Overall, acetylene reduction activity showed a significant negative correlation (r = −0.77, p < 0.001) with total N.

Denitrification and nitrogen fixation in floodplain successional soils along the Tanana River, interior Alaska

1993 ◽  
Vol 23 (5) ◽  
pp. 956-963 ◽  
Author(s):  
K.M. Klingensmith ◽  
K. Van Cleve
Keyword(s):  
Nitrogen Fixation ◽  
Forest Floor ◽  
Nitrogenase Activity ◽  
Mineral Soil ◽  
White Spruce ◽  
Interactive Effects ◽  
Successional Stage ◽  
Alder Forest ◽  
Mineral Soils ◽  
Soil Interface

Forest floors and mineral soils from early (open willow), middle (poplar–alder), and late (white spruce) floodplain primary successional stages were examined for nitrogen fixation and denitrification. The acetylene-reduction and acetylene-inhibition techniques were used separately and in combination to measure nitrogenase and denitrification activities, both in laboratory and field studies. In situ N2O production was undetectable at all sites and during all sampling periods. Denitrifying activity measured in the field with acetylene amendments was low to undetectable, except after a brief flood in the open willow stand when N2O production ranged from undetectable to 34 ng N•cm−2•h−1 within the newly deposited alluvium–old mineral soil interface. Intact core assays also had low to undetectable denitrification activities; the highest activities (259 ng N•g−1 h−1) were measured in the poplar–alder forest floor in the fall. Laboratory studies showed that potential denitrification enzyme activity (DEA) was also greatest in the poplar–alder forest floor (4332 ng N•g−1•h−1), once again occurring in the fall. In early and midsuccessional stages, the interactive effects of temperature, carbon, and NO3− limited denitrification, yet even with the addition of the limiting amendments, low to undetectable DEA was observed in mineral soils. The later white spruce successional stage also had low to undetectable DEA, increasing only with the addition of the full DEA media and independent of temperature changes. Nonsymbiotic nitrogenase activities were highly variable, ranging from undetectable to 30 ng N•cm−2•h−1. Highest activities were seen in the open willow, newly deposited alluvium–old mineral soil interface immediately after a flood and approximately 1 month after the flood on the newly deposited silt surface. Only the white spruce forest floor had measurable nonsymbiotic nitrogenase activity at all sampling times. Alder root nodule nitrogenase activity showed no significant differences between sampling periods. The estimated annual nitrogen fixation rate of 164 kg N•ha−1 for alder root nodules is a substantial N contribution to the alder stand and to the floodplain ecosystem in general.

Relative contributions to nitrogenase (acetylene reducing) activity of stem and root nodules in Sesbania rostrata

1992 ◽  
Vol 38 (6) ◽  
pp. 577-583 ◽  
Author(s):  
J. K. Ladha ◽  
Minviluz Garcia ◽  
R. P. Pareek ◽  
G. Rarivoson
Keyword(s):  
Acetylene Reduction ◽  
Root Nodule ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Dry Weight ◽  
Acetylene Reduction Activity ◽  
Sesbania Rostrata ◽  
Reduction Activity ◽  
Acetylene Reducing Activity ◽  
Aerial Stem

Six experiments, two each in the phytotron, greenhouse, and field, were conducted to assess the contribution of nitrogenase activity (acetylene reduction) by stem nodules in the presence and absence of root nodules of Sesbania rostrata (Brem & Oberm). In a greenhouse experiment, the effect of detaching already formed aerial stem nodules on the restoration of root nodules and nitrogenase activity was studied. The field experiment compared nodulation and acetylene-reduction activity by dual-nodulating S. rostrata and root-nodulating Sesbania cannabina. Acetylene-reduction activity expressed per gram of nodule dry weight was higher for stem nodules than for root nodules. Root nodule dry weight and acetylene-reduction activity failed to increase after stem inoculation, but root nodule dry weight and acetylene-reduction activity increased several fold within 15 days of detachment of aerial stem nodules. Stem nodulation, which occurred without inoculation under lowland field condition, suppressed root nodulation, thus accounting for more than 75% of total nitrogenase activity. Sesbania rostrata showed higher acetylene-reduction activity than S. cannabina. In dual-nodulating plants, root and stem nodules appeared to strike a balance in competition for energy, which may be controlled by stem nodulation. Key words: Sesbania rostrata, Azorhizobium caulinodans, stem nodule, root nodule, acetylene-reducing activity.

Stomatal conductance, photosynthesis and acetylene reduction rate in soybean genotypes

1992 ◽  
Vol 72 (2) ◽  
pp. 383-390 ◽  
Author(s):  
A. Djekoun ◽  
C. Planchon
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Leaf Water ◽  
Acetylene Reduction Activity ◽  
Reduction Activity ◽  
Leaf Osmotic Potential ◽  
Glycine Max L

Yield limitation in soybean (Glycine max L. Merr.) can result from decreases in photosynthesis and N2 fixation during periods of water deficiency. In this study, the relationships among stomatal conductance, photosynthesis and N2 fixation were analyzed in connection with drought tolerance of genotypes. Plants were grown in pots and exposed to field conditions. Carbon dioxide exchange rate was measured by gas analysis and nodule activity by the acetylene reduction method. Leaf water status was determined with a pressure bomb, and nodule water potential and leaf osmotic potential were measured psychrometrically. The differing tolerances of the cultivars Kingsoy and Hodgson to leaf water deficit resulted in a more or less developed ability of the lower side of the leaf to maintain good stomatal conductance during water stress. Stomatal conductance affects photosynthetic rate directly and acetylene reduction activity indirectly. Early stomatal closure, by limiting H2O exchange, contributes to conservation of nitrogenase activity. On the contrary, maintenance of high conductance during a water stress decreases soil water availability and nodule water content, which in turn has a decisive and limiting effect on acetylene reduction activity. Thus, if tolerance at low leaf water potentials associated with osmotic adjustment is an important drought mechanism for maintaining photosynthetic processes under water-limited conditions, the result would be obtained at the expense of symbiotic N2 fixation.Key words: Glycine max L. Merr., nitrogenase activity, photosynthesis, drought stress, soybean

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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