Neighbourhood effect of genotypes of Rhizobium leguminosarum biovar trifolii, Trifolium repens and Lolium perenne

1997 ◽  
Vol 94 (3-4) ◽  
pp. 486-492 ◽  
Author(s):  
J. M. Expert ◽  
P. Jacquard ◽  
M. Obaton ◽  
A. Lu¨scher
Keyword(s):  
Lolium Perenne ◽  
Trifolium Repens ◽  
Rhizobium Leguminosarum ◽  
Rhizobium Leguminosarum Biovar Trifolii

Specificity of association between Bacillus isolates and genotypes of Lolium perenne and Trifolium repens from a grass – legume pasture

1990 ◽  
Vol 68 (5) ◽  
pp. 1126-1130 ◽  
Author(s):  
C. P. Chanway ◽  
F. B. Holl ◽  
R. Turkington
Keyword(s):  
Lolium Perenne ◽  
Trifolium Repens ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Permanent Pasture ◽  
Trifolium Repens L ◽  
Shoot Weight ◽  
Genotypic Mixtures ◽  
Rhizobium Leguminosarum Biovar Trifolii ◽  
Pasture Plants

Specificity between plants and associated rhizosphere bacteria was investigated using species and genotypic mixtures of Lolium perenne L. (perennial ryegrass) and Trifolium repens L. (white clover) inoculated with Bacillus strains isolated from rhizosphere soil of the pasture plants. The genotypic identity of plants was controlled by using stolon tips (Trifolium) and tillers (Lolium) of three genotypes of each species collected from a 45-year-old permanent pasture. Inoculation of plants in the greenhouse with Bacillus isolates that had coexisted in the field with the Lolium component of a Lolium–Trifolium mixture increased Lolium root and shoot weight. Root and nodule weight of Trifolium in mixture regardless of its genotype was also higher when coexistent Bacillus–Lolium combinations were present. The presence of other coexistent Bacillus–plant or plant–plant combinations did not enhance performance of either pasture species. The identity of the Rhizobium leguminosarum biovar trifolii strains that formed Trifolium root nodules was unaffected by inoculation with Bacillus. Key words: Trifolium repens, Lolium perenne, Bacillus, specificity, rhizosphere, yield.

The influence of Rhizobium leguminosarum biovar. trifolii on the growth and neighbour relationships of Trifolium repens and three grasses

1990 ◽  
Vol 68 (2) ◽  
pp. 296-303 ◽  
Author(s):  
J. D. Thompson ◽  
R. Turkington ◽  
F. B. Holl
Keyword(s):  
Trifolium Repens ◽  
Rhizobium Leguminosarum ◽  
Polyacrylamide Gel Electrophoresis ◽  
Strain Differences ◽  
Grass Species ◽  
Single Strain ◽  
Rhizobium Inoculation ◽  
Cell Extracts ◽  
Rhizobium Strains ◽  
Rhizobium Leguminosarum Biovar Trifolii

Trifolium repens was sampled from 10 areas dominated by each of Dactylis glomerata, Holcus lanatus, and Lolium perenne in each of three different-aged pastures. Cell extracts of nodule isolates of Rhizobium leguminosarum biovar. trifolii were compared using polyacrylamide gel electrophoresis. Each pasture contained a range of Rhizobium strains as defined by the protein profiles. No single strain was common to Trifolium sampled from the same grass species neighbourhood. The diversity of Rhizobium strains encountered was negatively correlated (r = −0.67; n = 9) with pasture age; old pastures showed a decrease in strain diversity. In addition, in the oldest pasture (45-year-old), tillers of the associated grasses were also sampled. In a glasshouse, ramets from each Trifolium clone and each of the three grass species were grown in all possible combinations with each of the three Rhizobium strains, plus Trifolium monocultures and an uninoculated control. All Trifolium clones gave increased yield in mixture with Lolium compared with yields with Dactylis and Holcus. Trifolium from the Holcus patches, in most cases, had higher yield than Trifolium from other grass patches. Rhizobium inoculation did not consistently increase Trifolium yield; it actually caused a decrease in yield when in mixture with Lolium. A significant Rhizobium × Trifolium interaction indicated a variable performance of each Trifolium genotype with different Rhizobium strains. The identity of the Trifolium clone had a significant effect on the yield of Holcus and Lolium, but not Dactylis. Total mixture yields were highest when Trifolium from a Lolium patch was part of the mixture. These results are discussed in the context of the hypothesis that Trifolium–grass coexistence is significantly influenced by Rhizobium strain differences.

Slow rehydration improves the recovery of dried bacterial populations

1992 ◽  
Vol 38 (6) ◽  
pp. 520-525 ◽  
Author(s):  
J. W. Kosanke ◽  
R. M. Osburn ◽  
G. I. Shuppe ◽  
R. S. Smith
Keyword(s):  
Relative Humidity ◽  
Rhizobium Leguminosarum ◽  
Moisture Absorption ◽  
Rhizobium Meliloti ◽  
Bacterial Populations ◽  
Bulk Powder ◽  
Alfalfa Seed ◽  
Powder Samples ◽  
Cellular Stresses ◽  
Rhizobium Leguminosarum Biovar Trifolii

Slow rehydration of bacteria from dried inoculant formulations provided higher viable counts than did rapid rehydration. Estimates were higher when clay and peat powder formulations of Rhizobium meliloti, Rhizobium leguminosarum biovar trifolii, and Pseudomonas putida, with water activities between 0.280 and 0.650, were slowly rehydrated to water activities of approximately 0.992 before continuing the dilution plating sequence. Rhizobium meliloti populations averaged 6.8 × 108 cfu/g and 1328 cfu/alfalfa seed greater when slowly rehydrated from bulk powder and preinoculated seeds, respectively. Bulk powder samples were slowly rehydrated to 0.992 water activity by the gradual addition of diluent, followed by a 10-min period for moisture equilibration. Preinoculated seed samples were placed in an environmental chamber at 24 °C with relative humidity greater than 80% for 1 h to allow moisture absorption. "Upshock," osmotic cellular stresses that occur during rehydration, was reduced when dried microbial formulations were slowly rehydrated and equilibrated before becoming fully hydrated in the dilution plating sequence. These procedures may also be applicable when estimating total viable bacterial populations from dried soil or other dry formulations. Key words: rehydration procedure, microbial rehydration, desiccation, Rhizobium, Pseudomonas.

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