You are not currently logged in.
Access JSTOR through your library or other institution:
Carboxylate release of wheat, canola and 11 grain legume species as affected by phosphorus status
Stuart J. Pearse, Erik J. Veneklaas, Greg R. Cawthray, Mike D. A. Bolland and Hans Lambers
Plant and Soil
Vol. 288, No. 1/2 (2006), pp. 127-139
Published by: Springer
Stable URL: http://www.jstor.org/stable/24125442
Page Count: 13
You can always find the topics here!Topics: Plants, Carboxylates, Acid soils, Agricultural soils, Rhizosphere, Plant roots, Phosphorus, Exudation, Brasses, Citrates
Were these topics helpful?See something inaccurate? Let us know!
Select the topics that are inaccurate.
Preview not available
Preview not available
The capacity of plant roots to increase their carboxylate exudation at a low plant phosphorus (P) status is an adaptation to acquire sufficient P at low soil P availability. Our objective was to compare crop species in their adaptive response to a low-P availability, in order to gain knowledge to be used for improving crop P-acquisition efficiency from soils that are low in P or that have a high capacity to retain P. In the present screening study we compared 13 crop species, grown in sand at either 3 or 300 μM of P, and measured root mass ratio, cluster-root development, rhizosphere pH and carboxylate composition of root exudates. Root mass ratio decreased with increasing P supply for Triticum aestivum L., Brassica napus L., Cicer arietinum L. and Lens culinaris Medik., and increased only for Pisum sativum L., while the Lupinus species and Vicia faba L. were not responsive. Lupinus species that had the potential to produce root clusters either increased or decreased biomass allocation to clusters at 300 μM of P compared with allocation at 3 μM of P. All Lupinus species acidified their rhizosphere more than other species did, with average pH decreasing from 6.7 (control) to 4.3 for Lupinus pilosus L. and 5.9 for Lupinus atlanticus L.; B. napus maintained the most alkaline rhizosphere, averaging 7.4 at 300 μM of P. Rhizosphere carboxylate concentrations were lowest for T. aestivum, B. napus, V. faba, and L. culinaris than for the other species. Exuded carboxylates were mainly citrate and malate for all species, with the exception of L. culinaris and C. arietinum, which produced mainly citrate and malonate. Considerable variation in the concentration of exuded carboxylates and protons was found, even with a genus. Cluster-root forming species did not invariably have the highest concentrations of rhizosphere carboxylates. Lupinus species varied both in P-uptake and in the sensitivity of their cluster-root development to external P supply. Given the carbon cost of cluster roots, a greater plasticity in their formation and exudation (i.e. reduced investment in cluster roots and exudation at higher soil P, a negative feedback response) is a desirable trait for agricultural species that may have variable access to readily available P.
Plant and Soil © 2006 Springer