Soil Microorganisms and Plant Roots

Clark, Francis E.

doi:10.1016/s0065-2113(08)60750-6

Cited by 158 publications

(41 citation statements)

References 123 publications

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“…Clark [8], Krasilnikov [22], Wardle [44], and Whitford [46] argued about the extent of the significance of plant rhizosphere on microbial quantity, emphasizing the magnitude of the abovementioned community. However, our data obtained for a xeric environment showed a significant …”

Section: Discussionmentioning

confidence: 99%

Vertical Distribution of a Soil Microbial Community as Affected by Plant Ecophysiological Adaptation in a Desert System

Barness

Rodrı́guez-Zaragoza²,

Shmueli

et al. 2008

Microb Ecol

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The spatial and temporal patterns of resource distribution in a desert system have been shown to influence a number of soil biota components and processes. The pattern of possible different resources supplied by two typical halophyte shrubs with different ecophysiological adaptations, Atriplex halimus and Hammada scoparia, was found to be the trigger in the present study on the microbial community temporal and spatial (vertical) scale. The uniqueness of A. halimus, a saltbush plant, is in the creation of 'islands of salinity' in its rhizosphere system and the relatively high percentage of organic matter beneath its canopy, whereas the H. scoparia shrub has a leafless stem with a relatively lower amount of organic matter accumulation beneath its canopy. Soil samples from 0 to 50 cm depths were collected at 10-cm intervals during each of the four seasons. The vertical distribution of the microbial community was measured in the vicinity of the above plant shrubs and in the open spaces between them. The results obtained from the field study demonstrated that plant ecophysiological adaptation played an important role in the temporal and spatial distribution of abiotic conditions and microbial community levels such as microbial biomass, CO 2 evolution, and colony-forming units (CFUs) of both bacteria and fungi. However, we did not find consistency in the positive effect of plant cover on the microbial community. The shrub effect was observed to have a major outcome on microbial variables not only on a temporal but also on a spatial (vertical) basis. This contributed to the understanding of the controversy regarding the difference between the shrubs.

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Section: Discussionmentioning

confidence: 99%

Vertical Distribution of a Soil Microbial Community as Affected by Plant Ecophysiological Adaptation in a Desert System

Barness

Rodrı́guez-Zaragoza²,

Shmueli

et al. 2008

Microb Ecol

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“…The marked stimulation of bacterial numbers in soil immediately adjacent to plant roots and the variation with plant age have been well documented (Clark 1949;Rovira 1965). However, there are limitations to the conventional method of expressing the rhizosphere effect.…”

Section: Introductionmentioning

confidence: 99%

Influence of Plant Species and Plant Age on the Rhizosphere Microflora

Martin¹

1971

Aust. Jnl. Of Bio. Sci.

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Significant differences were observed in the number of bacteria present in water leachates from pots containing different plant species (wheat, subterranean clover, ryegrass), and within a plant species, during growth from seedlings to the formation of mature seed. Bactel·ial numbels in the leachates reached a peak which coincided with flowering for each plant species. The peak values for wheat, clover, and ryegrass, respectively, were 33, 77, and 99 times the number of bacteria present in leachates from control pots without plants. Subsequently, the number of bacteria in leachates from wheat pots decreased until they were not significantly different from the controls. There was a lesser decrease for the clover and no significant decrease for the ryegrass treatments.In all cases, the numbers of bacteria leached from the pots were less than 1 % of the total bacteria present in the soil as estimated by counts of bacteria growing on soil extract agar. In contrast, fluorescent pseudomonads were readily displaced and were present in leachates in numbers corresponding to 5-1600% of the numbers remaining in the soil.

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“…However, in all of these studies the plant material was present as a solid mass of chopped or ground air-dried leaves, stems, or roots and was not distributed through soil. It seemed possible that the marked immobilization of the plant phosphorus resulting from its incorporation into microbial cells was largely a consequence of the experimental conditions, since microbial populations in decomposing green manure may be 10 times higher than the normal population on root surfaces (Clark 1949). It seemed desirable to determine the degree to which the inorganic and organic phosphorus components contained in plant roots are released into solution with decomposition conditions simulating those existing in undisturbed arable and pasture soils.…”

Section: Introductionmentioning

confidence: 99%

Factors Controlling the Release of Phosphorus From Decomposing Wheat Roots

Martin¹,

Cunningham²

1973

Aust. Jnl. Of Bio. Sci.

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An increase in incubation temperature from 5 to 45°C significantly (P 90 % of total radioactivity into solution, mainly as orthophosphate, showing an extensive dephosphorylation of organic phosphorus components by plant enzymes. Factors favouring microbial growth around the dead roots caused a slight reduction in 32p activity in solution. Air-drying at 20-40°C prior to incubation resulted in a rapid release of 32p activity from the roots which was independent of the incubation temperature.It is concluded that root phosphorus can be released directly into soil solution, mainly as orthophosphate, as the result of autolysis and does not necessarily become incorporated into the organisms decomposing the roots.The amounts of phosphorus contained in different components of the total soil biomass were estimated and the conditions favouring release of this phosphorus into soil solution are discussed.

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Soil Microorganisms and Plant Roots

Cited by 158 publications

References 123 publications

Vertical Distribution of a Soil Microbial Community as Affected by Plant Ecophysiological Adaptation in a Desert System

Vertical Distribution of a Soil Microbial Community as Affected by Plant Ecophysiological Adaptation in a Desert System

Influence of Plant Species and Plant Age on the Rhizosphere Microflora

Factors Controlling the Release of Phosphorus From Decomposing Wheat Roots

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