The presence of Rhizobium meliloti on pods of Medicago tribuloides

1965 ◽  
Vol 5 (17) ◽  
pp. 141
Author(s):  
J Brockwell
Keyword(s):  
Rhizobium Meliloti ◽  
Single Line ◽  
Nodule Bacteria ◽  
Barrel Medic

Pods of a single line of barrel medic (Medicago tribuloides Desr.) collected from the field were examined for the presence of Rhizobium meliloti. It was found that 99 per cent of pods carried 15 nodule bacteria or less. The ability of such low numbers of Rh. meliloti to promote nodulation of seedlings from sown pods is doubtful, and inoculation of pods may be necessary where soil populations of appropriate Rh. meliloti are low.

Protozoa and the decline of Rhizobium populations added to soil

1975 ◽  
Vol 21 (6) ◽  
pp. 884-895 ◽  
Author(s):  
S. K. A. Danso ◽  
S. O. Keya ◽  
M. Alexander
Keyword(s):  
Root Nodule ◽  
Rhizobium Meliloti ◽  
Rhizobium Strain ◽  
Nodule Bacteria ◽  
Sterile Soil ◽  
Rapid Multiplication ◽  
Nonsterile Soil ◽  
Root Nodule Bacteria ◽  
Large Numbers ◽  
Soil Protozoa

A fall in Rhizobium abundance occurred in nonsterile soil inoculated with large numbers of the root-nodule bacteria, but many of the rhizobia still survived. No such decline was evident in sterile soil. Protozoa feeding on these bacteria were isolated from soil and other environments. As the abundance of Rhizobium meliloti and a cowpea Rhizobium strain in soil decreased, the protozoan density increased. The inability of the predators to eliminate their prey from soil was not the result of the presence of organisms feeding on the protozoa because many rhizobia survived in sterile soil inoculated with the prey and cultures of individual protozoa, nor was it the result of the rapid multiplication of the bacteria to replace those consumed because survivors were still numerous in essentially organic matter free soil in which the bacteria did not grow appreciably. The lack of elimination also was not associated with a protective effect of soil particles because survivors were still abundant in solutions inoculated with protozoa and bacteria. It is suggested that the size of the prey population diminishes until a density is attained at which the energy used by the predator in hunting for the survivors equals that obtained from the feeding.

scholarly journals Nodulation Studies in Legumes III. The Effects of Delaying Inoculation on the Seedling Symbiosis of Barrel Medic, Medicago Tribuloides Desr.

1959 ◽  
Vol 12 (4) ◽  
pp. 427 ◽  
Author(s):  
PJ Dart ◽  
JS Pate
Keyword(s):  
Sand Culture ◽  
Nodule Bacteria ◽  
Barrel Medic ◽  
Ineffective Nodule

The technique of delayed inoculation with effective, ineffective, or mixtures of effective + ineffective nodule bacteria was used to study seedling symbiosis of barrel medic, M. tribuloides, in sand culture.

scholarly journals Diversity of root nodule bacteria from leguminous crops

2016 ◽  
Vol 68 (1) ◽  
pp. 195-205 ◽  
Author(s):  
Pooja Agrawal ◽  
Shruti Shukla
Keyword(s):  
Rhizobium Meliloti ◽  
Restriction Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Salt Content ◽  
Culture Conditions ◽  
Water Soluble ◽  
Differential Staining ◽  
Nodule Bacteria ◽  
Biochemical Tests ◽  
Acetic Acid Production

In the present study, a total of 353 nodule-associated bacteria were isolated from 220 legume plant samples belonging to Cicer arietinum (85), Glycine max (74), Vigna radiata (21) and Cajanus cajan (40). A total of 224 bacteria were identified as fast-growing Rhizobium spp. on the basis of differential staining (Gram staining and carbol fuchsin staining) and biochemical tests. All the isolates were tested for indole acetic acid production (IAA), phosphate solubilization and siderophore production on plate assay. To examine the effect of volatile organic metabolites (VOM) and water soluble soil components (WSSC) on nodule bacteria, culture conditions were optimized by observing the effects of various parameters such as pH, salt content and temperatures on the growth of bacteria. Selected rhizobia were subjected to random amplified polymorphic DNA (RAPD) and amplified ribosomal DNA restriction analysis (ARDRA) analysis to identify their species. On the basis of RAPD and ARDRA, 10 isolates were identified as Rhizobium meliloti. In this study, Rhizobium GO4, G16, G20, G77, S43, S81, M07, M37, A15 and A55 were observed as the best candidates among the tested bacteria and can be further used as potent bioinoculants.

Variation in the acidity of cropped and uncropped light-textured red soils of central western New South Wales

1999 ◽  
Vol 39 (8) ◽  
pp. 981 ◽  
Author(s):  
R. R. Young ◽  
C. L. Alston ◽  
C. J. Chartres
Keyword(s):  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Soil Surface ◽  
Aluminium Toxicity ◽  
Total Carbon ◽  
Agricultural Activity ◽  
Barrel Medic ◽  
South Wales

Summary. The light-textured, red, gradational and duplex soils in semi-arid central western New South Wales were found to be on a pH threshold for suitability for the traditional cultivars of barrel medic (Medicago truncatula), an important pasture legume in the region, and other acid sensitive species. However, there was little evidence that cropping over a long time increased soil acidity. Over the 38 sampling sites, mean pHCa in the soil surface 0–20 cm was significantly higher in cropped compared to contiguous uncropped and usually timbered control areas. The return of cations and associated alkali in standing timber to the soil surface when trees were pushed and burnt is a plausible explanation. In the surface (0–20 cm) layers of 10 of 38 cropped paddocks, mean pH in 0.01 mol CaCl2/L was <5, sufficient to severely obstruct growth and the nitrogen fixing capacity of barrel medic. All but 4 sites had pHCa <6, where some reduction in nitrogen fixation would be expected to occur. Variation in pH within transects within paddocks was large, which is consistent with the common observation of poor and patchy growth of barrel medic. Exchangeable calcium, important for Medicago–Rhizobium meliloti symbiosis function, decreased with increasing acidity. The potential for manganese toxicity appeared low with aluminium toxicity likely only at some sites with pHCa ≤4.5. Total carbon decreased with increasing soil acidity and was less under cropping at any pHCa. Although acidification of these soils due to agricultural activity was not apparent from paired sampling of cropped and contiguous uncropped transects, they seem likely to be prone to acidification.

Tandem scanning reflected light microscopy: How it works and applications

1986 ◽  
Vol 44 ◽  
pp. 84-87
Author(s):  
Alan Boyde ◽  
Milan Hadravský ◽  
Mojmír Petran ◽  
Timothy F. Watson ◽  
Sheila J. Jones ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Focal Plane ◽  
Central Symmetry ◽  
Single Line ◽  
Scanning Microscope ◽  
Reflected Light ◽  
Illuminating Light ◽  
Illuminating Beam

The principles of tandem scanning reflected light microscopy and the design of recent instruments are fully described elsewhere and here only briefly. The illuminating light is intercepted by a rotating aperture disc which lies in the intermediate focal plane of a standard LM objective. This device provides an array of separate scanning beams which light up corresponding patches in the plane of focus more intensely than out of focus layers. Reflected light from these patches is imaged on to a matching array of apertures on the opposite side of the same aperture disc and which are scanning in the focal plane of the eyepiece. An arrangement of mirrors converts the central symmetry of the disc into congruency, so that the array of apertures which chop the illuminating beam is identical with the array on the observation side. Thus both illumination and “detection” are scanned in tandem, giving rise to the name Tandem Scanning Microscope (TSM). The apertures are arranged on Archimedean spirals: each opposed pair scans a single line in the image.

More Tears in Achilles Tatius (7.4.3–6)

2018 ◽  
Author(s):  
G. O. Hutchinson
Keyword(s):  
Single Line ◽  
Delayed Effects ◽  
Vital Part ◽  
Achilles Tatius

A further passage shows the imagination and craft of Achilles Tatius taken to a still greater degree, as he depicts the hero Cleitophon at the terrible crisis of believing his beloved to be dead. The narrative is suspended as the writer develops, at remarkable length, a psychological and physiological observation on delayed effects. Where Heliodorus had heaped up imagery with abundance, Achilles develops with skilled organization a single line of thought and imagery, developing it and enriching it as he goes. Rhythm plays a vital part in this remarkable union of tight order and inventive imagination. The expansion and the deployment of science have a Plutarchan element; but the fantasy and the tautness create something quite different out of rhythm.

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