Soil-water tension and the movement of rhizobia

Hamdi, Y.A.

doi:10.1016/0038-0717(71)90004-6

Cited by 76 publications

(24 citation statements)

References 11 publications

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“…Nevertheless, we suggest that increased soil moisture in elevated CO 2 is a plausible and simple explanation for the changes we observed, and that our ANCOVA analysis provides correlative support for this hypothesis. Increased soil moisture can enhance bacterial motility and accessibility to substrates (Hamdi 1971), stimulate protozoan grazing and associated N mineralization (Kuikman et al 1991), and increase substrate diffusion (Davidson et al 1990). Any one or combination of these could explain the results we observed.…”

Section: Resultsmentioning

confidence: 58%

Stimulation of grassland nitrogen cycling under carbon dioxide enrichment

et al. 1997

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Nitrogen (N) limits plant growth in many terrestrial ecosystems, potentially constraining terrestrial ecosystem response to elevated CO. In this study, elevated CO stimulated gross N mineralization and plant N uptake in two annual grasslands. In contrast to other studies that have invoked increased C input to soil as the mechanism altering soil N cycling in response to elevated CO, increased soil moisture, due to decreased plant transpiration in elevated CO, best explains the changes we observed. This study suggests that atmospheric CO concentration may influence ecosystem biogeochemistry through plant control of soil moisture.

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Section: Resultsmentioning

confidence: 58%

Stimulation of grassland nitrogen cycling under carbon dioxide enrichment

et al. 1997

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“…Bitton et al (1 974) found that water-mediated movement of Kfebsielfa aerogenes (K. pneumoniae) depended on the water content of the soil and on the surface properties of the bacteria. Hamdi (1974) concluded that vertical movement of R . trifolii was proportional to the amount of water applied to the soil.…”

Section: Discussionmentioning

confidence: 99%

“…Migration distances of several centimetres, and in some cases several tens of centimetres, have been recorded (Frazier & Fred, 1922;Hamdi, 1971Hamdi, , 1974Kellerman & Fawcett, 1907;Madsen & Alexander, 1982 ;McCoy & Hagedorn, 1979 ;Wong & Griffin, 1976). The migration distance of associative beneficial bacteria of the genus Azospirillum in natural soil has not yet been sufficiently evaluated.…”

Section: Introductionmentioning

confidence: 99%

Horizontal and Vertical Movement of Azospirillum brasilense Cd in the Soil and along the Rhizosphere of Wheat and Weeds in Controlled and Field Environments

Bashan¹,

Levanony²

1987

Microbiology

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Horizontal movement of Azospirillum brasilense Cd in soil and its vertical movement in the plant rhizosphere were studied. No movement was detected in the absence of living plants. In a controlled environment the bacteria moved horizontally at least 30 cm from the inoculation point to the first growing plant. Once the first root system was colonized, all the neighbouring plants became inhabited. Horizontal movement under field conditions was at least 160 cm-, and depended on the presence of live plant roots. Several weeds that grew in the passes betweenglots acted as efficient vectors. The numbers of A . brasilense Cd decreased with increasing distance from the inoculated plot. Vertical movement in soil columns in a controlled environment was up to 40 cm. Under field conditions, bacteria were detected as deep as 50 cm in the root systems of wheat plants in various types of soil. During the growing season bacteria were mostly found on and in young roots at a depth of 20-50 cm and near the soil surface. A map of depth distribution of A. brasilense Cd showed an uneven colonization pattern within the same root system or between adjacent plants. It was concluded that A . brasilense Cd moved horizontally and vertically in various soil types and that this movement was mainly dependent on the presence of plants.

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“…Like the motility of bacteria, motility of Actinoplunes zoospores would also be expected to vary with soil colloids (Goring & Hamker, 1972), soil moisture content (Wong & Griffin, 1976u) and the diameter and continuity of soil pores (Hamadi, 1971). Invariably, soil at a matric potential of 0 and -10 mbar was most suitable for active movement of zoospores.…”

Section: Discussionmentioning

confidence: 99%

Chemotaxis of Actinoplanes missouriensis Zoospores to Fungal Conidia, Chlamydospores and Sclerotia

Arora

1986

Microbiology

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The chemotactic response of Actinoplanes missouriensis zoospores to three different types of fungal spores (conidia of Curvularia lunata, chlamydospores of Fusarium solani and sclerotia of Macrophominaphaseolina) and their exudates was examined in vitro and in soil. Zoospores were attracted in vitro to substances exuded by fungal spores and to a number of organic compounds but not to sodium phosphate buffer solution. Numbers of zoospores attracted to spores of C . lunata, F. solani or M . phaseolina and their exudates, mixed in a sterilized soil, were significantly (P = 0.05) greater than to soil only supplemented with buffer. Movement of zoospores in an unsterilized soil to conidia, chlamydospores or sclerotia was significantly greater (P = 0.05) than background populations occurring in soil held at 0, -10 and -50 mbar matric potential. Attraction of zoospores to fungal spores and (or) their exudates was generally in the order of conidia > chlamydospores > sclerotia both in vitro and in soil. The results suggest that compounds exuded by living fungal spores may act as attractant for motile Actinoplanes zoospores.

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Soil-water tension and the movement of rhizobia

Cited by 76 publications

References 11 publications

Stimulation of grassland nitrogen cycling under carbon dioxide enrichment

Stimulation of grassland nitrogen cycling under carbon dioxide enrichment

Horizontal and Vertical Movement of Azospirillum brasilense Cd in the Soil and along the Rhizosphere of Wheat and Weeds in Controlled and Field Environments

Chemotaxis of Actinoplanes missouriensis Zoospores to Fungal Conidia, Chlamydospores and Sclerotia

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