scholarly journals Physical Environment and Symbiotic Nitrogen Fixation. V. Effect of Time of Exposure to Unfavourable Root Temperatures

1967 ◽  
Vol 20 (6) ◽  
pp. 1105 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Rhizobium Trifolii ◽  
Optimal Temperature ◽  
Three Stages

Symbiotic nitrogen fixation by Trifolium subterraneum L., inoculated with three strains of Rhizobium trifolii Dang., was examined over the range of root temperatures 8-28�0. The plants were transferred from an optimal temperature for nitrogen fixation (23�0) to other temperatures at three stages, namely (1) immediately after inoculation, 3 days after germination, (2) 14 days after germ� ination, when nitrogen fixation had commenced, and (3) 21 days after germination, when the plants had been fixing nitrogen for at least 7 days. Nitrogen increase and dry weight accumulation were determined for two growth periods-days 14-21 (I) and days 21-28 (II)

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation

1963 ◽  
Vol 16 (1) ◽  
pp. 28 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Rhizobium Trifolii

The effect of root temperatures (5-30�0) on the growth and symbiotic nitrogen fixation by nodulated plants of four varieties of Trifolium subterraneum L., inoculated with each of two strains of Rhizobium trifolii, was examined.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation II. Root Temperature Effects on the Relative Nitrogen Assimilation Rate

1965 ◽  
Vol 18 (2) ◽  
pp. 295 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Temperature Effects ◽  
Nitrogen Assimilation ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Bacterial Strains ◽  
Root Temperature ◽  
Relative Growth ◽  
Relative Growth Rates

Nitrogen fixation by six varieties of Trifolium subterraneum L., each inoculated with a number of strains of Rhizobium trifolii, was examined over a range of root temperatures. Significant differences in the rate of nodule establishment and early nitrogen fixation were found between varieties, and between bacterial strains. In order to minimize the effect of such differences, relative nitrogen assimilation rates (RN) and relative growth rates (R w) were used to compare the different legume-bacteria associations.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation VI. Nitrogen Retention Within the Nodules of Trifolium Subterraneum L

1969 ◽  
Vol 22 (4) ◽  
pp. 829 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Effective Strain ◽  
Nitrogen Retention ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Root Temperature ◽  
Protein Nitrogen ◽  
The Difference ◽  
Nodule Tissue

The effect of bacterial strain and root temperature on the retention of nitrogen in the root system of Trifolium Bubterraneum plants was re-examined. The root systems of plants nodulated by the moderately effective Rhizobium trifolii strain NA30 possessed a higher percentage nitrogen than those nodulated by the fully effective strain TAl, although the number of nodules formed by each strain was similar. The difference was due to a greater weight of nodule tissue on the NA30-nodulated plants, and also to a higher percentage nitrogen in the NA30 nodules; this latter effect was due to a higher concentration of non-protein nitrogen. The overall effect of these differences was to reduce the amount of nitrogen translocated to the shoots of the NA30 plants, in both absolute terms and as a proportion of the total amount of nitrogen fixed. Another difference between the two strains was the rate of nitrogen fixation per unit (dry weight or leghaemoglobin content) of nodule tissue.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation VII. Effect of Fluctuating Root Temperature on Nitrogen Fixation

1969 ◽  
Vol 22 (4) ◽  
pp. 839 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Dark Period ◽  
Light Period ◽  
Continuous Illumination ◽  
Continuous Exposure ◽  
Rhizobium Trifolii ◽  
Symbiotic System ◽  
Root Temperature

The effect of exposing nodulated plants to daily periods of high, moderate, or low root temperatures was examined, using Trifolium 8ubterraneum and three strains of Rhizobium trifolii. With strains whose nitrogen fixation was severely retarded by continuous exposure to high root temperatures, the results from treatments involving exposure of 4, 8, 12, and 20 hr/day to 30�C and continuous illumination were consistent with the effect being on the rate of nitrogen fixation, without any permanent impairment to the symbiotic system. With a 12 hr/day light period, a daily 12-hr exposure to 30�C during the dark period reduced total nitrogen fixation as much as exposure to 30�C during the light period. This indicated that the rate of nitrogen fixation during normal dark periods could be as high as that during periods of illumination. Similar conclusions were drawn from the same type of experiments involving daily exposure to moderate (14 and 16�C) root temperatures.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation III. Root Temperature Effects on Shoot and Root Development and Nitrogen Distribution In Trifolium Subterraneum

1966 ◽  
Vol 19 (2) ◽  
pp. 219 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Temperature Effects ◽  
Shoot Growth ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Trifolium Subterraneum ◽  
Root Temperature ◽  
Nitrogen Distribution ◽  
Root And Shoot Growth

Root and shoot growth, and the distribution of nitrogen to the roots and shoots, were examined in five varieties of Trifolium subterraneum. The plants were grown between 5 and 30�0 root temperature, and received their nitrogen from root nodules, or as ammonium nitrate.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation. IV. Faotors Affecting the Early Stages of Nodulation

1967 ◽  
Vol 20 (6) ◽  
pp. 1087 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Light Period ◽  
Root Temperature ◽  
Early Stages ◽  
Temperature Conditions ◽  
General Decline ◽  
Effect Of Light

The influence of root temperature on the initial nodulation of Trifolium subterraneum L. was examined, and observations were made on the effect of light period and shoot temperature on this character. The maximum constant root temperature at which nodules would form was 33�0, and the minimum was in the vicinity of 7�0. The most rapid initial nodulation (2-3 days after inoculation) was observed at 30�0, and plants growing at this temperature had the highest rate of nodule appearance. Below 22�0, there was a marked increase in the "time to first visible nodule" and a general decline in the rate at which they appeared. Differences were observed in the time to first visible nodule, and in the rate of nodule appearance, between different cultivars of T. 8ubterraneum. There was an indication of a temperature X cultivar interaction for these characters. With the three strains of Rh. trifolii used, no differences in their ability to form nodules were observed, although it was known that their subsequent symbiotic behaviour differed under certain root temperature conditions.

Rhizosphere relationships of subterranean clover. I. Interactions between strains of Rhizobium trifolii.

1954 ◽  
Vol 5 (2) ◽  
pp. 247 ◽  
Author(s):  
JR Harris
Keyword(s):  
Nitrogen Fixation ◽  
Host Plant ◽  
Root Zone ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Rhizobium Trifolii ◽  
Rhizobial Strain ◽  
Susceptible Host ◽  
Active Elements ◽  
Indigenous Microflora

A study was made of a number of effective and ineffective strains of Rhizobium trifolii in association with subterranean clover (Trifolium subterraneum L.), variety Bacchus Marsh. Where these were inoculated singly into sterilized soils in pot experiments conducted in the greenhouse, typical effective, ineffective, or intermediate plant reactions were obtained. Where more than one strain was inoculated, competition between strains took place and was reflected in nodule pattern and plant reaction. Some strains consistently failed to produce appreciable nodules in the presence of other rhizobia, some showed modification to varying degrees, and some were unaffected. Such behaviour was found to be closely linked with the ability of the strain to proliferate in the rhizosphere of the host plant, and placement of inoculum was shown to influence plant reaction. The concept of "incursion" as a property of a rhizobial strain is suggested. An incursive strain is one able to migrate from the initial site of inoculation and establish an adequate population in the root zone of the susceptible host despite the presence of active elements of the indigenous microflora and microfauna, including antagonistic and predatory forms. The property of incursion is independent of considerations of efficiency of nitrogen fixation or virulence for the host plant. Strains of rhizobia which are poorly incursive may fail to infect the host upon which they have been inoculated if subject to competition from indigenous rhizobia already established in the soil. The necessity of assessing properties of virulence and incursion as well as efficiency of nitrogen fixation in selecting rhizobia for purposes of commercial inoculation is stressed, and the methods of making such tests are discussed.

scholarly journals EFFETS DES SOUCHES DE RHIZOBIUM MELILOTI ET DES COUPES SUCCESSIVES DE LA LUZERNE (MEDICAGO SATIVA) SUR LA FIXATION SYMBIOTIQUE D’AZOTE

1977 ◽  
Vol 57 (2) ◽  
pp. 433-439 ◽  
Author(s):  
L. M. BORDELEAU ◽  
H. ANTOUN ◽  
R. A. LACHANCE
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Sativa ◽  
Statistical Study ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Dry Weight ◽  
Indirect Measurement ◽  
Controlled Environment ◽  
Symbiotic Efficiency ◽  
Plant Yield

Symbiotic nitrogen fixation with 49 isolates of Rhizobium meliloti was studied under controlled environment with alfalfa cv. Saranac. It was shown that plant yield in dry weight can be used as an indirect measurement of nitrogen fixation, and as a criterion for selecting efficient strains of R. meliloti. Statistical study on yields of three cuttings has established that the second cutting gives the most necessary information to correctly evaluate the symbiotic efficiency of the isolates. Six very efficient strains were selected.

Phorate-resistant mutant strains of chick pea (Cicer arietinumL.)Rhizobiumsp. growth and their compatibility in symbiotic nitrogen fixation

1982 ◽  
Vol 98 (3) ◽  
pp. 547-551 ◽  
Author(s):  
R. Rai ◽  
R. B. Sinha ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
Grain Yield ◽  
Symbiotic Nitrogen Fixation ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Pyridine Nucleotides ◽  
Chick Pea ◽  
Active Iron ◽  
Mutant Strains

SUMMARYChick peaRhizobiumstrain RG3 was treated with 30 μg/ml of N-nitrosoguanidine and two mutants isolated were resistant to 2000 μg phorate/ml yet retained the capacity to form nodules. On the basis of number of nodules, their dry weight, N2ase activity, total pyridine nucleotides and active iron contents, mutant strains G11 and G26 were found to be equally effective with and without phorate and resulted in significantly greater grain yield.

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