Role of root derived organic acids in the mobilization of nutrients from the rhizosphere

The role of organic acids in the mobilization of plant nutrients from the rhizosphere was assessed in seven contrasting soil types. The results indicated that malate was poor at mobilizing micronutrients from all the test soils, whilst citrate was capable of mobilizing significant quantities. Citrate was also capable of mobilizing P from one soil which possessed a large Ca-P fraction. This mobilization of P was due to both the complexing action of the citrate anion and due to the dissolution properties of the protons released from citric acid upon equilibrium with the soil solution. The reaction of citrate with cations was found to be near instantaneous with significant absorption to the solid phase in some soils at low concentrations. Soil decomposition studies indicated that citrate was rapidly broken down in organic soils but was more resistant to degradation in subsoil horizons. It was concluded that organic acids can be expected to be of little consequence in nutrient mobilization from high pH soils, whilst in acid soils they may be involved both in a more general mechanism for micronutrient uptake or as a potential Al detoxification mechanism.

[1]  D. López-Hernández,et al.  Competitive Adsorption of Phosphate with Malate and Oxalate by Tropical Soils1 , 1986 .

[2]  B. W. Avery.  Soil classification in the soil survey of England and Wales , 1973 .

[3]  P. Darrah,et al.  Influx and efflux of organic acids across the soil-root interface of Zea mays L. and its implications in rhizosphere C flow , 1995, Plant and Soil.

[4]  D. A. Barber,et al.  The acquisition of phosphorus byLupinus albus L. , 1983, Plant and Soil.

[5]  D. H. Jennings.  MINERAL NUTRITION IN HIGHER PLANTS (Book). , 1988 .

[6]  D. Jones,et al.  Re-sorption of organic components by roots of Zea mays L. and its consequences in the rhizosphere , 1992, Plant and Soil.

[7]  P. Darrah.  Measuring the diffusion coefficients or rhizosphere exudates in soil. II. The diffusion of sorbing compounds , 1991 .

[8]  E. Hoffland,et al.  Solubilization of rock phosphate by rape , 2005, Plant and Soil.

[9]  U. Lundström.  The role of organic acids in the soil solution chemistry of a podzolized soil , 1993 .

[10]  D. Jones,et al.  Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere , 1993, Plant and Soil.

[11]  T. Takemoto,et al.  Physiological aspect of mugineic acid, a possible phytosiderophore of graminaceous plants , 1984 .

[12]  E. J. Kamprath,et al.  Soil Nutrient Bioavailability—A Mechanistic Approach , 1985 .

[13]  J. Syers,et al.  Origin of the Effects of Citrate, Tartrate, and Acetate on Phosphate Sorption by Soils and Synthetic Gels1 , 1979 .

[14]  L. Kochian,et al.  Induction of iron(III) and copper(II) reduction in pea (Pisum sativum L.) roots by Fe and Cu status: Does the root-cell plasmalemma Fe(III)-chelate reductase perform a general role in regulating cation uptake? , 1993, Planta.

[15]  N. Hue,et al.  Effect of Organic Acids on Aluminum Toxicity in Subsoils , 1986 .

[16]  A. Pohlman,et al.  Kinetics of Metal Dissolution from Forest Soils by Soluble Organic Acids , 1986 .

[17]  S. Mori,et al.  Why are young rice plants highly susceptible to iron deficiency , 1991 .

[18]  C. Foy,et al.  Mechanism of aluminum tolerance in snapbeans : root exudation of citric Acid. , 1991, Plant physiology.

[19]  E. Hoffland.  Quantitative evaluation of the role of organic acid exudation in the mobilization of rock phosphate by rape , 1992, Plant and Soil.

[20]  J. P. Riley,et al.  A modified single solution method for the determination of phosphate in natural waters , 1962 .

[21]  D. Jones,et al.  Role of proteinaceous amino acids released in root exudates in nutrient acquisition from the rhizosphere , 2004, Plant and Soil.

[22]  C. Reid,et al.  Comparison of the Abilities of Hydroxamic, Synthetic, and Other Natural Organic Acids to Chelate Iron and Other Ions in Nutrient Solution 1 , 1982 .

[23]  H. Majdi,et al.  Spatial distribution of fine roots, rhizosphere and bulk‐soil chemistry in an acidified Picea abies stand , 1993 .

[24]  R. Merckx,et al.  Plant-induced changes in the rhizosphere of maize and wheat , 1986, Plant and Soil.

[25]  Y. Hadar,et al.  Iron Nutrition and Interactions in Plants , 1991, Developments in Plant and Soil Sciences.

[26]  Volker Römheld,et al.  Citric acid excretion and precipitation of calcium citrate in the rhizosphere of white lupin (Lupinus albus L.) , 1989 .

[27]  W. W. McFee,et al.  Phosphorus and Aluminum Release from a Spodic Horizon Mediated by Organic Acids , 1990 .

[28]  W. Lindsay.  Chemical equilibria in soils , 1979 .

[29]  D. Jones,et al.  Amino-acid influx at the soil-root interface of Zea mays L. and its implications in the rhizosphere , 1994, Plant and Soil.