Showing papers on "Nitrogen fixation published in 1970"
TL;DR: Although nitrogen fixation by plankton algae probably contributes less than 1% of the total nitrogen income of these lakes it may nevertheless be a major source of combined nitrogen for the plankton at particular times.
Abstract: Measurements of the fixation of molecular nitrogen have been made using 15 N as a tracer in the open waters of the north and south basins of Windermere and Esthwaite Water, English Lake District, at intervals of approximately 6 weeks over a period of 17 months. Fixation was light dependent (although occasionally appreciable in the dark) and correlated with the presence of heterocystous blue-green algae in the plankton. Examination of the data by multiple regression analysis showed a statistically significant positive correlation of rate of fixation with the concentration of organic nitrogen in the water. Although fixation was generally confined to periods when the concentration of nitrate nitrogen in the water was below 0.3 mg l -1 there was no statistically significant negative correlation of rate of fixation with nitrate concentration. The annual contribution of nitrogen fixation by planktonic blue-green algae is estimated as 0.037 to 0.287 g N m -2 , being greatest in the early stage of eutrophication represented by the south basin of Windermere. Although nitrogen fixation by plankton algae probably contributes less than 1% of the total nitrogen income of these lakes it may nevertheless be a major source of combined nitrogen for the plankton at particular times.
103 citations
TL;DR: Nitrogen fixation has been obained with strains of Desulfovibrio vulgaris and D. gigas, organisms hitherto believed to be incapable of using molecular nitrogen, andfixation of N2 may be widespread in this genus of the sulphate-reducing bacteria.
Abstract: SUMMARY: Nitrogen fixation has been obained with strains of Desulfovibrio vulgaris and D. gigas, organisms hitherto believed to be incapable of using molecular nitrogen. Fixation has been demonstrated by increases in total nitrogen and by uptake of 15N2. Fixation of N2 may be widespread in this genus of the sulphate-reducing bacteria.
73 citations
TL;DR: Compared to cells growing with ammonia, cells utilizing atmospheric nitrogen as the sole nitrogen source are smaller in size and volume, grow one-third slower, and lack detectable poly-beta-hydroxybutyrate.
Abstract: Azotobacter synthesizes an extensive internal membranous nework when grown with air (N(2)), i.e., under conditions when these bacteria fix nitrogen. Very slight quantities of internal membrane, concentrated mainly about the cell periphery, are formed when Azotobacter grows with fixed nitrogen, i.e., ammonia and amino acids. Compared to cells growing with ammonia, cells utilizing atmospheric nitrogen as the sole nitrogen source are smaller in size and volume, grow one-third slower, and lack detectable poly-beta-hydroxybutyrate.
72 citations
TL;DR: A wide taxonomic range of non-leguminous dicotyledonous plants bear root nodules and are able to fix atmospheric nitrogen, and the Alnus glutinosa endophyte has been isolated and grownin vitro in root-nodule callus tissue.
Abstract: A wide taxonomic range of non-leguminous dicotyledonous plants bear root nodules and are able to fix atmospheric nitrogen. These plants belong to the orders Casuarinales, Myricales, Fagales, Rhamnales, Coriariales, and Rosales. Actinomycetes are involved in the root-nodule symbiosis.
71 citations
TL;DR: A considerable proportion of the annual requirement for nitrogen by Douglas Fir may be provided by nitrogen-fixing bacteria on the leaves and in the soil.
67 citations
TL;DR: The correlation between the ability of a species to fix nitrogen and the possession of heterocysts has led to the suggestion that the heterocyst is the site of nitrogen fixation in blue–green algae.
Abstract: REPORTS of nitrogen fixation by blue–green algal species have, in the main, been restricted to members of the orders Nostocales and Stigonematales1 Unless they are grown in the presence of large concentrations of free ammonium ions, all the species produce characteristic types of cells called heterocysts The correlation between the ability of a species to fix nitrogen and the possession of heterocysts has led to the suggestion that the heterocyst is the site of nitrogen fixation in blue–green algae2
65 citations
TL;DR: The results indicated that vanadium will replace molybdenum in nitrogenase and that moly bdenum plays a role in the substrate binding and reduction site of the enzyme complex.
64 citations
TL;DR: In this paper, the capacity of an originally acid Norway spruce raw humus to fix isotopically labelled ammonium and amino nitrogen in a form resistant to cold 1N HCl treatment was studied.
Abstract: The capacity of an originally acid Norway spruce raw humus to fix isotopically labelled ammonium and amino nitrogen in a form resistant to cold 1N HCl treatment was studied. The amount fixed was determined after a reaction period of 24 hours (the humus pretreated with propylene oxide), using the amount of labelled N in the HCl-leached humus residue as a basis for calculating the amount of added N fixed. The nitrogen sources used were ammonium chloride, glycine and cyanamide. It was found that the fixation of added ammonium and glycine N was exceedingly low in the H+-saturated raw humus (pH 3.3–3.4), but the fixation rate was rapidly increased by increasing the pH during the aerobic incubation. Maximum fixation was obtained at a final pH of 10–11. Within the acid range the fixation was constantly higher for added glycine-N than ammonium-N. On the alkaline side of the neutral point the amount of fixation tended to be similar for ammonium and glycine. In treatments with N15-labelled ammonium, it was shown that small but fully detectable amount of added N were present in the soluble organic N fraction of the HCl extract, the quantities increasing with increasing soil pH during the incubation. The fixation was increased by increasing temperature and decreased by oxidative pretreatment of the humus before the addition of N. In the nitrogen gas atmosphere the fixation figures were 40 to 50 per cent lower than for corresponding treatments in air atmosphere. When various N compounds were added in equimolar concentrations the highest fixation was recorded for cyanamide. In studying the stability of fixed N to acid hydrolysis, it was found that 54 per cent of the fixed N resisted eight hours' refluxing with 6N HCl, the corresponding figure for the native raw humus N being 19 per cent. About one third of the fixed N was liberated as ammonia during the acid hydrolysis.
TL;DR: The rate of nitrogen fixation by soil samples from various California environments was determined at monthly intervals for a period of one year by comparing direct isotopic observations of fixation rates with rates determined by the acetyleneethylene method.
Abstract: The rate of nitrogen fixation by soil samples from various California environments was determined at monthly intervals for a period of one year by comparing direct isotopic observations of fixation rates with rates determined by the acetyleneethylene method. Annual fixation rates of approximately 5 kg. nitrogen per hectare per year were observed in the most favorable environment examined, and rates as low as 2 kg. per year were observed on a more arid site with native vegetation. Observations made by direct isotopic methods compared reasonably well with those obtained with useof theacetylene-ethylene method, but some variability between the two occurred. Limiting factors in the fixation reaction are reported and the significance of observed rates is discussed.
TL;DR: The overall data imply that in situ nitrogen fixation contributes to the productivity of Yellowstone hot spring regions and that Mastigocladus and Calothrix are the most important nitrogen-fixing blue-green algae.
Abstract: Potential nitrogen-fixing blue-green algae were common in three hot spring streams studied in Yellowstone National Park. In two streams, where the dominant nitrogen-fixing algae were species of Calothrix, nitrogen fixation, as measured by uptake of 15N2, was detected in situ in the temperature range 28–46 C. At higher temperatures nitrogen fixation was not detected, although the algae may have received fixed nitrogen from a growth of Calothrix, Nostoc, and unicellular algae which occurred at lower temperatures on the sides of the streams. In the third stream, where Mastigocladus was abundant, nitrogen fixation was detected at temperatures up to 54 C, although the optimum for fixation was near 42.5 C. The overall data imply that in situ nitrogen fixation contributes to the productivity of Yellowstone hot spring regions and that Mastigocladus and Calothrix are the most important nitrogen-fixing blue-green algae.
TL;DR: Well-nodulated plants of Glycine wightii grown in sand culture were subjected to 14 days of salinity ranging from nil to 148 m-equiv.
Abstract: Well-nodulated plants of Glycine wightii (formerly G. javanica) grown in sand culture were subjected to 14 days of salinity ranging from nil to 148 m-equiv. sodium chloride per litre of nutrient solution, and the response compared with that of similarly treated nitrogen-fertilized plants. The latter showed less tissue injury and a smaller reduction in growth rate at high salinity than the inoculated plants. During salinity treatment the development of new nodules, and nitrogen fixation by the existing nodules, were greatly inhibited, with a resulting marked decline in plant nitrogen concentration, especially in the laminae and nodules. Despite the severity of the salt effect on the inoculated plants, the nodules developed prior to salt treatment appeared remarkably resistant to stress, and rapidly regained pigmentation and efficiency of nitrogen fixation when the sodium chloride was removed from the culture solutions. Salt accumulation in the nodules was limited and the sensitivity of the symbiosis to salinity appeared primarily dependent on the host. These factors indicate the adaptability of the symbiosis to increases in substrate salinity.
TL;DR: In this paper, the authors studied nitrogen fixation in the aerobic-anaerobic interfacial area in flooded, cellulose enriched media and the utilization of the products of anaerobic decomposition of cellulose by nitrogenfixing organisms when these products are brought under aerobic conditions by processes such as diffusion, mixing, and drying.
Abstract: Flooded soils usually consist of a surface aerobic phase a few millimeters thick (in contact with the atmosphere or oxygenated solution) underlain by an anaerobic phase. The objective of this research was to study nitrogen fixation in the aerobic-anaerobic interfacial area in flooded, cellulose enriched media and the utilization of the products of anaerobic decomposition of cellulose by nitrogen-fixing organisms when these products are brought under aerobic conditions by processes such as diffusion, mixing, and drying. The medium used for these studies was basically a sand matrix supplemented with a small amount of soil and mineral nutrients. When columns of medium enriched with cellulose were sectioned after incubation in the dark under flooded conditions, the increase in content of nitrogen per gram medium in the top 2 to 3 mm of the column was as much as 10 to 15 times the increase in nitrogen content of the lower portions of the column. Periodic mixing of flooded media, alternation of shaking in nitrogen and air atmospheres, and alternate flooding and drying all enhanced fixation relative to undisturbed, continuously flooded media incubated in air. Fixation during incubation under a nitrogen atmosphere was less than fixation under air atmospheres. The results of numerous experiments are consistent with the hypothesis that nitrogen fixation is enhanced when the products of anaerobic decomposition of cellulose are brought under aerobic conditions by any of several processes.
TL;DR: The growth patterns of Vigna sinesis and Vicia atopurpurea are differentially affected by nitrogen level, and are both considerably different from that of unnodulated plants given combined nitrogen as mentioned in this paper.
Abstract: Nitrogen fixation by Vigna sinesis nodulated effectively either by Rhizobium strain QA323 or by strain CB441 is little restricted by applications at sowing of ammonium nitrate up to 24 mg nitrogen per plant. The growth patterns of these two associations are differentially affected by nitrogen level, and are both considerably different from that of unnodulated plants given combined nitrogen. Nitrogen fixation by V. sinensis-strain SU318 may be stimulated by small doses of combined nitrogen at sowing, but for Vicia atvopurpurea all the combined nitrogen levels used in these experiments depressed fixation. Primary root nodulation of V. atropurpurea by the effective Rhizobium strain V27E and the ineffective strain NA6, and of V. sinensis by the effective Rhizobium strain SU318, is influenced by the form and amount of the nitrogen compound applied (ammonium nitrate, potassium nitrate, ammonium sulphate, or urea), and that of V. atropurpurea is also influenced by the Rhizobium strain. These forms of combined nitrogen restrict primary root nodulation on both hosts similarly except that urea has little effect on V. atuopurpurea. In both species many more nodules formed on the secondary roots than on the primary, but numbers of secondary root nodules are little affected by the combined nitrogen. Immersion of the first leaves of V. sinensis seedlings in solutions of combined nitrogen depressed nodulation, but urea slightly increased the dry weight of tops.
TL;DR: Nitrogen-fixing activity occurred from June through November suggesting that it is significant over the extremes of seasonal variation in light, temperature, and nutrients.
Abstract: Biological nitrogen fixation, as determined by acetylene reduction, occurs in Lake Erie Fixation potential by blue-green algae in situ in water and by bacteria in collected sediments was demonstrated Nitrogen-fixing activity occurred from June through November suggesting that it is significant over the extremes of seasonal variation in light, temperature, and nutrients
TL;DR: In this paper, the authors discuss the role of N2-f ixing algae in natural ecosysterns and discuss the use of N 2 -finite oxygen isotopes as a reductio-factors for N 2-f ing algae in soils.
Abstract: page 1, The p r e p a r a t i o n of un ia lga l bac te r i a f ree cu l tu res of b lue -green algae 556 2. Tes t ing a n algal cu l tu re for a capac i ty to fix N~ . . . . . . . . . 558 (a) Measur ing gains in t o t a l n i t r o g e n b y K j e l d a h l ana lys i s . . . . . 558 (b) T h e use of n i t r ogen isotopes in m e a s u r i n g for N2-f ixa t ion . . . . 558 (c) The use of ace ty l ene reduct ior t as a n i ndex of n i t r o g e n f i x a t i o n . 559 3. Growth , Ne-I ixa t ion , a n d t he p r o d u c t i o n of ex t ra -ce l lu la r n i t r ogen . 562 4. The m e c h a n i s m oI Nef ixa t ion . . . . . . . . . . . . . . . . . 566 5. The role of N2-f ixing algae in r~atural ecosysterns . . . . . . . . 568 (a) N i t r o g e n f ixa t ion in soils . . . . . . . . . . . . . . . . . 568 (b) N i t r o g e n f ixa t ion in a q u a t i c h a b i t a t s . . . . . . . . . . . . 573 6. Associa t ions of b lue-green algae w i t h o t h e r plart ts . . . . . . . . 578 7. Refe rences . . . . . . . . . . . . . . . . . . . . . . . . . 580
TL;DR: Native rhizobia associated with Trifolium albopurpureum and T. tridentatum nodulate subterranean clover but are ineffective in nitrogen fixation with this host.
Abstract: Native rhizobia associated withTrifolium albopurpureum, T. bifidum, T. ciliolatum, T. depauperatum, T. dichotomum, T. flavulum, T. melanthum, T. microcephalum, T. microdon, T. oliganthum andT. tridentatum were found in Northern California range soils. These rhizobia nodulate subterranean clover but are ineffective in nitrogen fixation with this host. Native rhizobia compet with those in commercial inoculants to form nodules. To ensure effective nodulation by nitrogen fixing rhizobia, commercial inoculants should be applied at rates greater than those recommended by the manufacturerse Effective nodulation was achieved by an application of 7.5×104 rhizobia per seed, four times the recommended rate.
TL;DR: The dependence of the nitrogen fixing system in the root nodules of pea plants (Pisum sativum) L. cv.
Abstract: The dependence of the nitrogen fixing system in the root nodules of pea plants (Pisum sativum) L. cv. Torsdag II) on light induced reactions was studied. The pots of the inoculated pea plants, after the nolules had fixed nitrogen for a fornight, were transferred to a dark room. The control plants were kept under normal lighting conditions.
The decay of leghemoglobin was measured after photosynthesis had ceased. In the dark the red nodules turned green in three days, when about half of the haem had been broken down. The plants in normal lighting conditions had maintained the red nodules. The appearence of leghemoglobin and bacteroids was simultaneouos. In normal lighting conditions the number of bacteroids was about 1.6 × 108 per g fresh nodules. The appearance of leghemoglobin and bacteroids was simultaneous. In normal lighting conditons the number of bacteroids was bout 1.6 × 108 per g fresh nodules. At the same time as the nodules turned green in the dark most of the bacteroids disappeared and the number of rod-shaped bacteria increased. After five days int the dark thenumber of bacteria of the green nodules was 2.2 × 108 per g fresh nodules. A large increase of of bacteria in the nodules is one of the results after the termination of effective symbiosis.
Quantitative estimations were made with an automatic amino acid analysator of the amino acid composition in the root nodules of pea plants grown in the light and of pea plants grown in the dark. Altogether 27 amino acids and amides and 3 unknown ninhydrin positive compounds were found in the free amino acid fraction. In the red N-fixing nodules asparagine, the amide of aspartic acid, was the most prominent (more than 50 per cent of the total amino acid fraction), indicating the energy charge of the nitrogen fixation. 5 days in the dark affected the proportions of the amino acids as follows. Asparagine, homoserine, γ-aminobutyric acid and ethanolamine were decreased and the most of the others increased.
In the hydrolysate of the non-soluble protein fraction 25 amino acids could be detected. The proportions of the amino acids in the root nodules of light-grown and dark-grown pea plants were very similar. Hydroxyproline and α, γ-diaminopimelic acid (DAP) were found in these fraction. Most of the DAP was contained in the peptide fraction. Also hydroxyproline was found to a small extent. It was assumed that the amino acids in this fraction were derived from the peptides of both plant cells and rhizobia.
TL;DR: The Chromatium nitrogenase complex was found to have the typical properties of other nitrogenases, i.e., reduction of N2 to ammonia, and of acetylene to ethylene, ATP-dependent H2 evolution and reductant-dependent ATP hydrolysis.
TL;DR: Evidence for fixation by type strains of mesophilic, spore-forming, sulphate-reducing bacteria, genus Desulfotomaculum is reported, including strains originating from the rumens of hay-fed sheep.
Abstract: The acetylene test for nitrogen fixation has been an important tool in reassessing the ability of various groups of micro-organisms to fix nitrogen (Parejko & Wilson, 1968; Millbank, 1969; Hill & Postgate, 1969). As a result of this reassessment, it has been found that several aerobic genera such as Azotomonas, Pseudomonas, Nocardia, Pullularia and yeasts probably do not fix N2; on the other hand, nitrogen fixation has proved to be far more widespread among the sulphate-reducing bacteria of the genus Desulfovibrio than was earlier thought (Reiderer-Henderson & Wilson, 1970). This communication reports evidence for fixation by type strains of mesophilic, spore-forming, sulphate-reducing bacteria, genus Desulfotomaculum (Campbell & Postgate, 1965), including strains originating from the rumens of hay-fed sheep. Some data with type strains of Desulfovibrio are included to supplement the findings of Reiderer-Henderson & Wilson (1970).
TL;DR: InAlnus viridis nodule growth relative to plant growth was inversely related to the quantity of nitrate added to nutrient solutions, and rate of nitrogen fixation by nodules of plants growing in the field increased with increase in altitude, a reflection of the extent to which the field sites were nitrogen deficient.
Abstract: InAlnus viridis nodule growth relative to plant growth was inversely related to the quantity of nitrate added to nutrient solutions Nodulated plants showed maximum growth when grown independently of supplied nitrogen and made better growth in its absence than unnodulated plants at any level of added nitrogen Low levels of nitrate caused a depression of growth of nodulated plants, apparently by suppressing both nitrogen fixation and nodule growth Nodules in nitrogen-free sand culture fixed atmospheric nitrogen at a rate of 66 mg/day/g nodule Phosphorus deficiency was induced by low levels of phosphate and resulted in small plants with dark-green foliage
TL;DR: Humic acid in the form of sodium humate and fulvic acid markedly increased the growth and efficiency of nitrogen fixation of Azotobacter chroococcum and was more pronounced in increasing the number of cells than affecting the nitrogen fixation.
Abstract: Humic acid in the form of sodium humate and fulvic acid markedly increased the growth and efficiency of nitrogen fixation ofAzotobacter chroococcum. Fulvic acid proved more effective than the sodium humate. The effectiveness of these substances was more pronounced in increasing the number of cells than affecting the nitrogen fixation. The increases in growth and nitrogen fixation were in direct proportion to the quantities of sodium humate and fulvic acid applied up to 500 and 700 ppm respectively. Thereafter the growth was restricted, although it was not inhibited even at 1,400 ppm.
01 Jan 1970
TL;DR: It is concluded that the success of underplanting is due to a multiplicity of factors, including the role of nitrogen fixation in conjunction with Pinus and Araucaria; the increased availability of nitrogen as a consequence of changes in the soil—nitrogen cycle; and the effect of reduced light intensity on improving the carbohydrate/nitrogen balance in AraUCaria under conditions of low soil— Nitrogen availability.
Abstract: Hoop pine (Araucaria cunninghamii Ait.), a nitrogen—sensitive rain—forest species can be grown without fertilizers as an underplanting to established stands of Pinus, on soils which will not support open plantings of pure hoop pine without fertilizing with nitrogen at the rate of 112 kg/ha per year. Stem volume growth rates of 6.6 m3/ha per year representing 28% of total stand increment have been obtained in 15—year—old underplantings. Removal of the Pinuscomponent from mixed stands of Pinus and Araucaria led to chlorosis of the remaining hoop pine but no significant decline in foliar nitrogen levels nor loss in growth over the ensuing 3 years. In contrast, 2—year—old transplants of Araucaria established on a site from which mature Pinus had been clear felled exhibited extremely slow growth and chlorosis, which could be overcome either by shading or applying nitrogen fertilizers. Underplants responded only slightly to added nitrogen compared to open plantings. Nitrogen requirements of fertilized open plants and unfertilized underplants were similar, however, being approximately 0.005 g nitrogen/g dry matter produced. The rate of immobilization of nitrogen by 8—year—old underplants established at 1,160 trees/ha was only 3.4 kg/ha per year. The source of nitrogen for underplantings is discussed, and nitrogen requirements of hoop pine are considered in relation to light intensity. It is concluded that the success of underplanting is due to a multiplicity of factors,including (1) the role of nitrogen fixation in conjunction with Pinus and Araucaria; (2) the increased availability of nitrogen as a consequence of changes in the soil—nitrogen cycle; and (3) the effect of reduced light intensity on improving the carbohydrate/nitrogen balance in Araucaria under conditions of low soil—nitrogen availability.