Effect of phosphate supply and competition from grasses on growth and nitrogen fixation of Medicago trunculata

1981 ◽  
Vol 32 (5) ◽  
pp. 761 ◽  
Author(s):  
ABK Dahmane ◽  
RD Graham
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Acetylene Reduction ◽  
Pure Culture ◽  
Dry Matter ◽  
Considerable Variability ◽  
Fixed Nitrogen ◽  
Intact Plants ◽  
Medicago Trunculata ◽  
Phosphate Supply

Medic plants and ryegrass were grown in small pots in a glasshouse in monoculture (six plants per pot) or in mixture (three plants of each species) at eight rates of phosphate application. After 10 weeks, the rate of nitrogen fixation was estimated by the acetylene reduction (AR) technique on the intact plants in soil, after which the plants were harvested, both shoots and roots. The yield of medic, in both monoculture and mixture, increased with increasing rate of phosphate application to an optimum at a level of 160 ppm phosphorus and then decreased again at higher phosphate levels. AR activity was similarly dependent on phosphate application and was optimal at the same phosphate level as was yield. AR activity was extremely low in the ryegrass monocultures, the yield of which was optimized at only 10 ppm phosphorus. The community x phosphate interaction on AR activity per plant of medic was not statistically significant, there being considerable variability in this measurement; the suppression of nitrogen fixation by competition from ryegrass near its own phosphate optimum was not therefore established in this study, but remains a possibility. Ryegrass plants benefited individually from growing in mixed culture with the legume, producing as much shoot dry matter from three plants in mixture as from six in monoculture. The advantage in mixture was due either to reduced competition offered by medic or to transfer of fixed nitrogen from legume to grass. Higher concentrations and contents of nitrogen per plant in mixture provided circumstantial evidence for the latter. However, on a pot basis, nitrogen content of ryegrass was similar in pure culture and in mixture. The relevance of the data to the results of a survey of farmers' fields is discussed.

The effect of Inoculation and cobalt application on the growth of and nitrogen fixation by sweet lupins

1978 ◽  
Vol 29 (6) ◽  
pp. 1191 ◽  
Author(s):  
DL Chatel ◽  
AD Robson ◽  
JW Gartrell ◽  
MJ Dilworth
Keyword(s):  
Nitrogen Fixation ◽  
Cell Division ◽  
Plant Growth ◽  
Nitrogen Content ◽  
Lupinus Angustifolius ◽  
Fixed Nitrogen ◽  
Soil Application ◽  
Seed Inoculation

The response of sweet lupins, Lupinus angustifolius L., to a soil application of cobalt and to seed inoculation was examined in both field and glasshouse experiments. Plant growth was dependent on nodule-fixed nitrogen, and the addition of cobalt increased the nitrogen content and the growth of the lupins in the absence of inoculation. Bacteroids in the nodules of inoculated plants without cobalt were found to be fewer and longer than those with cobalt, which suggests that cobalt is involved in the mechanism of rhizobial cell division.

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.

Nitrogen fixation in the high arctic tundra at Sarcpa Lake, Northwest Territories

1985 ◽  
Vol 63 (5) ◽  
pp. 974-979 ◽  
Author(s):  
Jim D. Karagatzides ◽  
Martin C. Lewis ◽  
Herbert M. Schulman
Keyword(s):  
Nitrogen Fixation ◽  
Northwest Territories ◽  
Acetylene Reduction ◽  
Biological Nitrogen Fixation ◽  
Arctic Tundra ◽  
High Arctic ◽  
Fixed Nitrogen ◽  
Free Living ◽  
Blue Green Algae ◽  
Biological Nitrogen

The acetylene reduction assay was used to examine biological nitrogen fixation in the high arctic tundra at Sarcpa Lake, Northwest Territories (68°32′ N, 83°19′ W). The highest rates of acetylene reduction (9.37 ± 3.19 μmol C2H4 m−2 h−1) were in habitats that had a high density of the legumes Oxytropis maydelliana, O. arctobia, and Astragalus alpinus. Nitrogen fixation in the wet soils along the shore of a small lake was similar (8.87 ± 4.35 μmol C2H4 m−2 h−1) because of the blue-green alga Nostoc, which associates with mosses. Free-living blue-green algae and lichens made insignificant contributions to the total nitrogen fixation budget because they were uncommon and fixed nitrogen at a slower rate. Nitrogen-fixing lichens in the area included Stereocaulon arenarium and S. rivulorum. It is concluded that legumes have a significant input to the biological nitrogen fixation budget at Sarcpa Lake.

Annual nitrogen fixation in grazed dairy pastures in south-western Victoria

1999 ◽  
Vol 50 (2) ◽  
pp. 273 ◽  
Author(s):  
Penny A. Riffkin ◽  
Paul E. Quigley ◽  
Fiona J. Cameron ◽  
Mark B. Peoples ◽  
Janice E. Thies
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Dry Matter ◽  
Experimental Studies ◽  
15N Natural Abundance ◽  
N Fixation ◽  
Botanical Composition ◽  
Fixed Nitrogen ◽  
Western Victoria ◽  
On Farm

Amounts of biologically fixed nitrogen (kg N/ha) were determined in grazed dairy pastures in 3 different areas of south-western Victoria over 12 months between October 1995 and 1996 using measurements of pasture growth, botanical composition, and the 15N natural abundance of white clover (Trifolium repens) and non-legume components. Estimates of the amounts of N fixed, based on N in clover shoots, were similar in each pasture (11, 16, and 18 kg N/ha.year), despite different environmental and management conditions. These on-farm determinations were low compared with experimental studies on N fixation by white clover undertaken in New Zealand (224–291 kg N/ha.year) and elsewhere in Australia (44–135 kg N/ha). Low fixation levels were attributed to low pasture yields (average 8.2 t dry matter (DM)/ha.year) and poor legume content in the swards (average 8%). Despite this, most of the white clover N was derived from atmospheric N2 (65%), and therefore, N fixation could potentially be playing an important role in the N economy of milk production on these farms.

The influence of soil nitrogen status and previous crop on nitrogen fixation (acetylene reduction) in Barrel Medic, Medicago truncatula Gaertn

Soil Research ◽  
1982 ◽  
Vol 20 (1) ◽  
pp. 51 ◽  
Author(s):  
AM Alston ◽  
RD Graham
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Medicago Truncatula ◽  
Total Nitrogen ◽  
Acetylene Reduction ◽  
Mineral Nitrogen ◽  
Total Nitrogen Content ◽  
Soil Mineral Nitrogen ◽  
Nitrogen Status ◽  
Barrel Medic

Barrel medic (Medicago truncatula Gaertn.) was grown in a glasshouse in pots containing solonized brown soils with total nitrogen contents ranging from 1.2 to 2.7 g kg-1. The dry weight and nitrogen content of the plants were determined on three occasions, and the acetylene reduction technique was used to estimate the rate of nitrogen fixation. All soils had been subjected to rotations of cereal and annual pasture, but half were sampled following pasture, while the others were collected after cereal. Both groups of soils had similar ranges of total nitrogen content, but the pasture soils contained higher concentrations of mineral nitrogen at the time of sowing the experiment and produced more mineral nitrogen on incubation. Correlations among these three indices of nitrogen status were exceedingly low for such a collection of similar soils, and only mineral plus mineralizable nitrogen correlated reasonably well with nitrogen uptake by wheat plants grown on the soils for 9 weeks. Medic on the pasture soils generally had higher dry weights and contained more nitrogen than plants on soils which were cropped with cereal, but rates of acetylene reduction were lower. These differences, which diminished as the season progressed, were closely related to the mineral nitrogen but not the total nitrogen content of the soils. Thus, the rate of accretion of nitrogen in the soils from nitrogen fixation, as estimated in this study, was independent of the existing soil total nitrogen content but was decreased by soil mineral nitrogen when the latter was high. The results have implications for the maintenance of the nitrogen status of soils under cereal-pasture rotations.

YIELD AND NITROGEN UPTAKE OF FORAGE SEEDINGS AS AFFECTED BY NITROGEN FERTILIZATION

1961 ◽  
Vol 41 (1) ◽  
pp. 176-187 ◽  
Author(s):  
E. A. Grant ◽  
C. S. Brown
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Nitrogen Uptake ◽  
Nitrogen Fertilization ◽  
Dry Matter ◽  
Total Yield ◽  
Yield Increase ◽  
Significant Yield ◽  
Second Year ◽  
Nitrogen Treatment

Over 2 tons of dry matter per acre were obtained from pure seedings of timothy and of brome in the seeding year with an application of 100 pounds of nitrogen per acre. Nitrogen at 200 and 400 pounds per acre produced no further significant yield increase. In the second year, yields were significantly increased by each increment of nitrogen applied in the seeding year up to and including 400 pounds per acre with brome and 200 pounds per acre with timothy. Nitrogen content of grasses increased with each increment of nitrogen in the seeding year but this effect was not consistent in the second year. Over the 2-year period grasses recovered approximately 65 per cent of the applied nitrogen at the 100- and 200-pound levels and about 40 per cent at the 400-pound level.Red clover and alfalfa seeded in mixture with timothy and with brome were about equal in yield to grass alone plus 100 pounds of nitrogen in the seeding year and were much superior in the second year. Application of 100 pounds of nitrogen to grass-legume mixtures increased both yield and nitrogen content in the first cutting. In subsequent cuttings, total yield and legume fraction of the yield were often depressed by nitrogen treatment; exceptions were noted where legume stands were weak.Apparent nitrogen fixation by the legumes was consistently reduced by nitrogen treatment. Vigorous legume stands had an apparent nitrogen fixation of 60 pounds per acre in the seeding year and up to 200 pounds in the second year.

Growth, Nodulation and Nitrogen Fixation in Stylosanthes: Effect of Different Day/Night Root Temperatures

1989 ◽  
Vol 25 (4) ◽  
pp. 461-472 ◽  
Author(s):  
R. A. Date
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Constant Temperature ◽  
Dry Matter ◽  
Dry Weight ◽  
Strong Interactions ◽  
Controlled Environment ◽  
Harvest Time ◽  
Root Temperature ◽  
Lower Range

SUMMARYNodulated plants of six varieties of Stylosanthes were grown at a constant temperature of 30°C for 21 days in a controlled environment and then for a further 21 days at a range of day/night root temperatures. Dry matter and nitrogen content of S. hamata cv. Verano and CPI40264A were measured after growth at day/night root temperatures of 30/30, 40/30, 50/30, 60/30 and 60/35°C. Similarly, growth and nitrogen content were measured for Verano, CPI40264A, S. gvianensis cv. Oxley and cv. Cook, S. humilis cv. Lawson and S. scabra cv. Seca after growth at root temperatures of 25/20, 25/25, 30/25, 30/30, 35/30 and 40/30°C. There were strong interactions of root temperature with variety and harvest time (31 and 42 days) but all varieties grew well even at the highest temperatures (50–60°C) provided they were supplied with nitrogen. Symbiotically dependent plants of S. hamata cv. Verano were more tolerant of high root temperatures and maintained better growth and nitrogen fixation at 40/30°C than those of CPI40264A, especially after the 31 day harvest. All six varieties responded similarly, but to differing extents, to the lower range of root temperatures. Nitrogen fixation was more severely affected than dry weight by high root temperature.

Effects of Root Temperature on the Growth and Nitrogen Fixation of Trifolium semipilosum and Trifolium repens

1986 ◽  
Vol 22 (2) ◽  
pp. 133-147 ◽  
Author(s):  
R. A. Date ◽  
R. J. Roughley
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Dry Matter ◽  
Dry Weight ◽  
Root Systems ◽  
Root Temperature ◽  
Short Term ◽  
Weight Yield ◽  
Short Term Exposure ◽  
Diurnal Temperatures

SUMMARYChanges in plant dry weight and nitrogen content of Trifolium semipilosum cv. Safari and T. repens cv. Grasslands Huia were monitored when the root systems of effectively nodulated 28-day-old plants were exposed to a range of constant and diurnal temperatures for 21 days. Nitrogen fixation was more sensitive to high root temperatures than was dry weight accumulation, and T. semipilosum was relatively more tolerant of high root temperatures than T. repens for both dry weight and nitrogen content. The optimum temperatures for dry weight yield and nitrogen fixation (≡nitrogen content) were similar (21–23°C) for both species.Our data suggest that growth and nitrogen fixation in T. semipilosum are more tolerant of short-term exposure to increase in root temperature than in T. repens. In addition, both species accumulated more dry matter and fixed more nitrogen when night temperatures were reduced from either 30 or 35°C to 25°C. The increase was greater with T. semipilosum and may be a major factor in its adaptation to the humid subtropics and cooler (elevated) tropics.

An effective strain of Frankia from Casuarina sp.

1983 ◽  
Vol 61 (11) ◽  
pp. 2815-2821 ◽  
Author(s):  
H. G. Diem ◽  
D. Gauthier ◽  
Y. Dommergues
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Pure Culture ◽  
Root Nodules ◽  
Effective Strain ◽  
Root Hairs ◽  
Culture Conditions ◽  
Reduction Technique ◽  
Standard Culture

A strain of Frankia, designated Cj1-82, from root nodules of a hybrid of Casuarina junghuhniana and C. equisetifolia has been isolated in pure culture. When grown under standard culture conditions, Cj1-82 exhibited the following characteristics: cushionlike colonies with short, wide hyphae and, in addition to typical sporangia, intercalary elongated sporangialike structures (SLS) which could be disrupted into sporelike units. No vesicles were found. When inoculated into the rhizosphere of C. equisetifolia, Cj1-82 produced vesicles. Reinfection of seedlings of C. equisetifolia was achieved repeatedly with inocula prepared from a suspension of Cj1-82. Sequences of infection of root hairs were described. Fourteen days after inoculation, nodules were apparent on the roots. Nodules were shown to be effective in nitrogen fixation as assessed by the acetylene-reduction technique.

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