Host selection for effective Rhizobium trifolii by red clover and subterranean clover in the field

1969 ◽  
Vol 20 (6) ◽  
pp. 1053 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Host Selection ◽  
Root Nodule ◽  
Red Clover ◽  
Subterranean Clover ◽  
Mixed Population ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Heterologous Host ◽  
Selection For ◽  
Test Plants

Cultures of root-nodule bacteria, from the nodules of red clover and subterranean clover growing closely together in the field, were tested for comparative symbiotic ability (effectiveness) with both red clover and subterranean clover. It was found that test plants of either host species nodulated faster and more effectively when inoculated with cultures isolated from the homologous host growing in the field than did test plants inoculated with cultures isolated from the heterologous host. Because the hosts had originally been nodulated in the presence of the same field populations of Rhizobium trifolii, it is concluded that the host legume exerts a selective effect in accepting infections from a mixed population.

scholarly journals Quantitative evaluation of acidity tolerance of root nodule bacteria

1999 ◽  
Vol 30 (3) ◽  
pp. 203-208 ◽  
Author(s):  
Luiz Antonio de Oliveira ◽  
Hélio Paracaima de Magalhães
Keyword(s):  
Root Nodule ◽  
Maximum Growth ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Soil Persistence ◽  
Statistical Precision ◽  
Visible Growth ◽  
Selection For ◽  
Growth Scores ◽  
Selection Of

Quantification of acidity tolerance in the laboratory may be the first step in rhizobial strain selection for the Amazon region. The present method evaluated rhizobia in Petri dishes with YMA medium at pH 6.5 (control) and 4.5, using scores of 1.0 (sensitive, "no visible" growth) to 4.0 (tolerant, maximum growth). Growth evaluations were done at 6, 9, 12, 15 and 18 day periods. This method permits preliminary selection of root nodule bacteria from Amazonian soils with statistical precision. Among the 31 rhizobia strains initially tested, the INPA strains 048, 078, and 671 presented scores of 4.0 at both pHs after 9 days of growth. Strain analyses using a less rigorous criterion (growth scores higher than 3.0) included in this highly tolerant group the INPA strains 511, 565, 576, 632, 649, and 658, which grew on the most diluted zone (zone 4) after 9 days. Tolerant strains still must be tested for nitrogen fixation effectiveness, competitiveness for nodule sites, and soil persistence before their recommendation as inoculants.

scholarly journals The Symbiotic Synthesis of Auxin by Legumes and Nodule Bacteria and its Eole in Nodule Development

1960 ◽  
Vol 13 (4) ◽  
pp. 456 ◽  
Author(s):  
NP Kefford ◽  
J Brockwell ◽  
JA Zwar
Keyword(s):  
Acetic Acid ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Nodule Development ◽  
Distilled Water ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Root Medium ◽  
Growth Properties ◽  
Indole 3 Acetic Acid

When subterranean clover (Trifolium subterraneum L.) plants were grown for 3 weeks over distilled water, tryptophan could be detected in the root medium of both sterile cultures and those inoculated with Rhizobium trifolii 3 days earlier. Auxin could be detected only in the inoculated medium. The auxin had the chromatographic and growth properties of indole�3-acetic acid (IAA). Since nodule bacteria produce auxin only in the presence of tryptophan, which is a probable precursor of lAA, it is suggested that the tryptophan exuded by clover roots is converted to lAA by nodule bacteria. Auxin was still produced in the root medium when strains of Rhizobium which do not nodulate subterranean olover roots were used as inooulant, or when nitrate, which delays nodulation, was present in the medium.

Competition between effective and ineffective strains of Rhizobium trifolii in the nodulation of Trifolium subterraneum

1969 ◽  
Vol 20 (5) ◽  
pp. 827 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Competitive Ability ◽  
Root Nodule ◽  
Effective Strain ◽  
Substantial Reduction ◽  
Trifolium Subterraneum ◽  
Bacterial Cells ◽  
Rhizobium Trifolii ◽  
Parallel Study ◽  
Nodule Bacteria ◽  
Tube Culture

The competitive ability of effective and ineffective strains of Rhizobium trifolii to form nodules on two cultivars of Trifolium subterraneum was examined under bacteriologically controlled conditions in tube culture. Seedlings were inoculated with mixtures of known numbers each of effective and of ineffective strains and the strains forming the nodules subsequently determined. In all instances, the effective strains formed a much greater proportion of nodules than would be expected from the relative numbers of each strain in the inoculum. Moreover, a reduction in the numbers of an effective strain relative to the numbers of an ineffective strain failed to result in a corresponding increase in the proportion of nodules formed by an ineffective strain. Instead, the ratio of ineffective to effective strains had to be of the order of 108/104 or wider (c. 10,000/1) before there was a substantial reduction in the number of nodules formed by the effective strains. Even when this ratio was of the order of 108/102, the effective strains still produced some of the nodules. A parallel study of the rates of nodulation of seedlings inoculated with mixtures of strains showed that these rates were characteristic of the proportions of nodules being formed by each strain. Subsequently seedlings were inoculated with mixtures of effective and ineffective strains, and after 66, 90, and 114 hr the roots were surface-sterilized and their contents isolated and identified. Independently of the mixture of strains used, most of the bacterial cells were identified as the effective strains. Because the strains of effective and ineffective bacteria used produce nodules freely when inoculated separately onto these hosts, it is postulated that the hosts distinguished between effective and ineffective strains, and that this recognition is related to compatibility in association with the host. The significance of the results in relation to studies of the root-nodule bacteria is discussed.

The effect of anti-fungal antibiotics on the nodulation of Trifolium subterraneum and the estimation of Rhizobium trifolii populations

1968 ◽  
Vol 8 (32) ◽  
pp. 327 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Pure Culture ◽  
Culture Media ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Test Plant ◽  
Rhizobium Trifolii ◽  
Plant Infection ◽  
Micro Organisms ◽  
Anti Fungal ◽  
Test Plants

Three anti-fungal antibiotics (cycloheximide, griseofulvin, and mycostatin) were tested for their effects on inoculated Trifolium subterraneum (subterranean clover). All three influenced the growth and nodulation of the test plant, the effects being least with mycostatin. Mycostatin was further examined for its effect on a plant-infection technique for estimating Rhizobium numbers. The presence in culture media of mycostatin did not impair the accuracy of the plant-infection test for counting rhizobia in a pure culture. Moreover, when the plant-infection technique was used for counting rhizobia in soil, the antibiotic reduced the amount of infection of the test plant by miscellaneous soil micro-organisms, thereby improving nodulation. It is concluded that the incorporation of mycostatin into media (100 p.p.m.) used for growing test plants in plant-infection tests will improve the reliability of the method.

Ecological studies of root-nodule bacteria introduced into field environments. 3. Persistence of Rhizobium trifolii in association with white cover at high elevations

1972 ◽  
Vol 12 (57) ◽  
pp. 407 ◽  
Author(s):  
J Brockwell ◽  
WG Bryant ◽  
RR Gault
Keyword(s):  
White Clover ◽  
Root Nodule ◽  
New South ◽  
Single Step ◽  
Rhizobium Trifolii ◽  
Nodule Bacteria ◽  
Legume Seed ◽  
South Wales ◽  
Inoculant Strain ◽  
High Elevations

Eight strains of Rhizobium trifolii were tested for ability to persist in association with white clover (Trifolium repens) sown at three sites at different elevations in the Snowy Mountains region of New South Wales. The standard clover inoculant strain, TA1, persisted poorly. Five strains of Tasmanian origin (representing two distinct serotypes), all highly effective in nitrogen fixation in combination with white clover, were recovered from the soils at high frequency over a period of three years. A single-step technique of pelleting and seed inoculation was slightly but consistently superior to the more complicated method that has been employed routinely for inoculation of legume seed used in revegetation undertakings in the Snowy Mountains.

Corrigendum to: Boron deficiency in pasture based on subterranean clover (Trifolium subterraneum L.) is linked to symbiotic malfunction

2017 ◽  
Vol 68 (8) ◽  
pp. 805
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Boron Deficiency ◽  
Nodule Bacteria ◽  
Clover Root ◽  
Per Se ◽  
Clover Seed

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha–1 (P B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.

Ecological studies of root-nodule bacteria introduced into field environments. I. A survey of field performance of clover inoculants by gel immune diffusion serology

1968 ◽  
Vol 19 (5) ◽  
pp. 739 ◽  
Author(s):  
WF Dudman ◽  
J Brockwell
Keyword(s):  
Root Nodule ◽  
Natural Populations ◽  
Field Performance ◽  
The Other ◽  
Rhizobium Trifolii ◽  
Ecological Studies ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Seed Inoculation ◽  
Clover Seed

A gel immune diffusion procedure for identifying strains of rhizobia has been used to follow the persistence of two strains of Rhizobium trifolii introduced simultaneously into soil by clover seed inoculation. Isolations of rhizobia were obtained from nodulated clover at intervals between 3 and 42 months after sowing. Of 456 isolates examined, 53.3% were recognized as inoculum strains but one strain, TA1, was recovered more than 11 times as frequently as the other, UNZ29. At one place, the inoculum was recovered 30 months after sowing but at another it had disappeared after 18 months. There was a significant trend for the proportion of recoverable inoculum strains to diminish with Iapse of time between sowing and isolation. Even in places where natural populations of Rh. Trifolii were small or undetectable, there was no evidence to suggest that the strains introduced as seed inoculant were likely to become permanently established as a large proportion of the nodule bacteria in the soil.

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