Substrate flow in the rhizosphere

The major source of substrates for microbial activity in the ectorhizosphere and on the rhizoplane are rhizodeposition products. They are composed of exudates, lysates, mucilage, secretions and dead cell material, as well as gases including respiratory CO2. Depending on plant species, age and environmental conditions, these can account for up to 40% (or more) of the dry matter produced by plants. The microbial populations colonizing the endorhizosphere, including mycorrhizae, pathogens and symbiotic N2-fixers have greater access to the total pool of carbon including that recently derived from photosynthesis. Utilization of rhizodeposition products induces at least a transient increase in soil biomass but a sustained increase depends on the state of the native soil biomass, the flow of other metabolites from the soil to the rhizosphere and the water relations of the soil. In addition, the phenomena of oligotrophy, cryptic growth, plasmolysis, dormancy and arrested metabolism can all influence the longevity of rhizosphere organisms. With this background, microbial growth in the rhizosphere will be discussed.

[1]  C. E. Powell,et al.  The Respiratory Costs of Nitrogen Fixation in Soyabean, Cowpea, and White Clover II. COMPARISONS OF THE COST OF NITROGEN FIXATION AND THE UTILIZATION OF COMBINED NITROGEN , 1979 .

[2]  C. E. Powell,et al.  Comparisons of the Respiratory Effluxes of Nodules and Roots in Six Temperate Legumes , 1983 .

[3]  E. H. Roberts,et al.  Carbon and nitrogen nutrition of nodulated roots of grain legumes , 1981 .

[4]  H. Lappin-Scott,et al.  Starvation and nutrient resuscitation of Klebsiella pneumoniae isolated from oil well waters. , 1988, The Journal of applied bacteriology.

[5]  J F Artusio.  A method of study. , 1969, Clinical anesthesia.

[6]  H. Castorph,et al.  The rhizosphere microflora of wheat and barley with special reference to gram-negative bacteria , 1983, Archives of Microbiology.

[7]  S. A. Ekwebelam,et al.  Nitrogen nutrition, photosynthesis and carbon allocation in ectomycorrhizal pine , 1983 .

[8]  L. D. Moore,et al.  Factors Affecting Root Exudation Ii: 1970–1978 , 1980 .

[9]  J. Lynch,et al.  Cultivation and the soil biomass , 1980 .

[10]  J. Lynch.  Products of soil microorganisms in relation to plant growth. , 1976, CRC critical reviews in microbiology.

[11]  S. J. Pirt,et al.  Principles of microbe and cell cultivation , 1975 .

[12]  S. J. Chapman,et al.  Endogenous metabolism and macromolecular composition of Arthrobacter globiformis , 1981 .

[13]  J. Whipps.  Effect of CO2 Concentration on Growth, Carbon Distribution and Loss of Carbon from the Roots of Maize , 1985 .

[14]  H. Keith,et al.  Input of carbon to soil from wheat plants , 1986 .

[15]  J. K. Martin,et al.  Extraction of microbial biomass components from rhizosphere soils , 1987 .

[16]  M. Wainwright.  Metabolic diversity of fungi in relation to growth and mineral cycling in soil — A review , 1988 .

[17]  D. Sauerbeck,et al.  Method to study turnover processes in soil layers of different proximity to roots , 1983 .

[18]  K. Koch,et al.  Photosynthate partitioning in split-root citrus seedlings with mycorrhizal and nonmycorrhizal root systems. , 1984, Plant physiology.

[19]  E. Newman.  The rhizosphere: carbon sources and microbial populations. , 1985 .

[20]  J. Lynch,et al.  Measurement of the microbial biomass in intact cores of soil , 1981, Microbial Ecology.

[21]  Ingrid Kraffczyk,et al.  Soluble root exudates of maize: Influence of potassium supply and rhizosphere microorganisms. , 1984 .

[22]  K. Domsch,et al.  Determination of ecophysiological maintenance carbon requirements of soil microorganisms in a dormant state , 1985, Biology and Fertility of Soils.

[23]  A. Microbiology.  Survival of Starved Bacteria , 1967, Nature.

[24]  J. Postgate,et al.  The survival of starved bacteria. , 1962 .

[25]  Peter J. Gregory,et al.  Water relations of winter wheat: 1. Growth of the root system , 1978, The Journal of Agricultural Science.

[26]  J. Lynch,et al.  The Influence of the Rhizosphere on Crop Productivity , 1986 .

[27]  J. Lynch,et al.  Substrate flow and utilization in the rhizosphere of cereals , 1983 .

[28]  E. Nelson,et al.  Attachment of Enterobacter cloacae to hyphae of Pythium ultimum: possible role in the biological control of Pythium preemergence damping-off , 1986 .

[29]  C. E. McClelen,et al.  A MORPHOMETRIC ANALYSIS OF CELLULAR DIFFERENTIATION IN THE ROOT CAP OF ZEA MAYS , 1983 .

[30]  F. Paneth.  Tracer Technique , 1951, Nature.

[31]  G. Sparling,et al.  Interference from plant roots in the estimation of soil microbial ATP, C, N and P , 1985 .

[32]  M. G. Hale,et al.  Factors Affecting Root Exudation , 1971 .

[33]  R. K. Dixon,et al.  GROWTH, NUTRITION AND GAS EXCHANGE OF BROMUS INERMIS INOCULATED WITH GLOMUS FASCICULA TUM , 1986 .

[34]  S. A. Barber.  Effect of Tillage Practice on Corn (Zea mays L.) Root Distribution and Morphology1 , 1971 .

[35]  M. Shinitzky,et al.  Gross structural changes in isolated liver cell plasma membranes upon binding of insulin. , 1979, Biochemistry.

[36]  J. Whipps.  Environmental Factors Affecting the Loss of Carbon from the Roots of Wheat and Barley Seedlings , 1984 .

[37]  J. K. Martin,et al.  A model system for studying the biochemistry and biology of the root-soil interface , 1985 .

[38]  J. Lynch,et al.  Variations in the size of the soil biomass , 1980 .

[39]  D. Barber,et al.  Microbial growth in the rhizosphere , 1977 .

[40]  D. Barber,et al.  THE RELEASE OF ORGANIC SUBSTANCES BY CEREAL ROOTS INTO SOIL , 1976 .

[41]  E. Paul,et al.  CARBON ECONOMY OF SOYBEAN-RHIZOBIUM-GLOMUS ASSOCIATIONS. , 1985, The New phytologist.

[42]  J. W. Doran,et al.  Microbial biomass and mineralizable nitrogen distributions in no-tillage and plowed soils , 1987, Biology and Fertility of Soils.

[43]  H. Lambers.  The physiological significance of cyanide‐resistant respiration in higher plants , 2006 .

[44]  A. Neilson,et al.  Acetylene Reduction (Nitrogen Fixation) by Enterobacteriaceae Isolated from Paper Mill Process Waters , 1976, Applied and environmental microbiology.

[45]  Lynch Jm.  Products of Soil Microorganisms in Relation to Plant Growth , 1976 .

[46]  H. M. Taylor,et al.  Top and Root Relations of Field-Grown Soybeans 1 , 1977 .

[47]  G. Bethlenfalvay,et al.  Defoliation effects on mycorrhizal colonization, nitrogen fixation and photosynthesis in the Glycine-Glomus-Rhizobium symbiosis , 1984 .

[48]  J. Ares.  Dynamics of the Root System of Blue Grama , 1976 .

[49]  D. Coleman,et al.  Distribution of photo-assimilated 14 carbon in the root system of a shortgrass priarie , 1974 .

[50]  H. Ziegler,et al.  Exudation of Water-soluble Vitamins and of Some Carbohydrates by Intact Roots of Maize Seedlings (Zea mays L.) into a Mineral Nutrient Solution , 1982 .

[51]  J. Whipps.  Carbon loss from the roots of tomato and pea seedlings grown in soil , 1987, Plant and Soil.

[52]  David S. Powlson,et al.  The effects of biocidal treatments on metabolism in soil—V: A method for measuring soil biomass , 1976 .

[53]  R. Fogel.  Roots as primary producers in below-ground ecosystems , 1985 .

[54]  J. Lynch.  Rhizosphere Microbiology and its Manipulation , 1986 .

[55]  R. Fogel,et al.  Contribution of mycorrhizae and soil fungi to nutrient cycling in a Douglas-fir ecosystem , 1983 .

[56]  G. Billès,et al.  Root activity and carbon metabolism in soils , 1988, Biology and Fertility of Soils.

[57]  D. Powlson,et al.  Measurement of microbial biomass in intact soil cores and in sieved soil , 1980 .

[58]  M. H. Gaskins,et al.  Increased root exudation of14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria , 1982, Plant and Soil.

[59]  P. Bottner,et al.  Effect of wheat (Triticum aestivum) roots on mineralization rates of soil organic matter , 1988, Biology and Fertility of Soils.

[60]  E. Paul,et al.  Seasonal transfers of assimilated 14C in grassland: Plant production and turnover, soil and plant respiration , 1977 .

[61]  J. Pate,et al.  Economy of Carbon and Nitrogen in a Nodulated and Nonnodulated (NO(3)-grown) Legume. , 1979, Plant physiology.

[62]  J. Lynch,et al.  Some properties of polysaccharides of microorganisms from degraded straw , 1985 .

[63]  R. Leonard,et al.  Membrane-mediated decrease in root exudation responsible for phorphorus inhibition of vesicular-arbuscular mycorrhiza formation. , 1981, Plant physiology.

[64]  S. C. Geijn,et al.  Gas and ion exchanges in wheat roots after nitrogen supply , 1984 .

[65]  R. Martens.  Limitations in the application of the fumigation technique for biomass estimations in amended soils. , 1985 .

[66]  P. Tinker,et al.  THE DISTRIBUTION OF CARBON AND THE DEMAND OF THE FUNGAL SYMBIONT IN LEEK PLANTS WITH VESICULAR-ARBUSCULAR MYCORRHIZAS , 1982 .

[67]  D. Sauerbeck,et al.  Effect of plant roots on carbon metabolism of soil microbial biomass , 1986 .

[68]  A. Herold.  REGULATION OF PHOTOSYNTHESIS BY SINK ACTIVITY–THE MISSING LINK , 1980 .

[69]  J. A. Veen,et al.  Turnover of root-derived material and related microbial biomass formation in soils of different texture , 1985 .

[70]  J. F. Dormaar,et al.  Seasonal effects on photoassimilated carbon-14 in the root system of blue grama and associated soil organic matter , 1983 .

[71]  S. Beck,et al.  Role of wheat root exudates in associative nitrogen fixation , 1983 .

[72]  M. Koelling,et al.  TOTAL NET PRODUCTIVITY AND TURNOVER ON AN ENERGY BASIS FOR TALLGRASS PRAIRIE , 1967 .