A mechanistic model for understanding root-induced chemical changes controlling phosphorus availability.
Ann Bot
; 105(7): 1183-97, 2010 Jun.
Article
em En
| MEDLINE
| ID: mdl-20495198
ABSTRACT
BACKGROUND AND AIMS:
Plant nutrition models do not properly account for the effects of root-induced chemical changes in the rhizosphere, e.g. pH changes, on the availability of nutrients such as phosphorus (P). As a result, they underestimate the actual P uptake, i.e. P bioavailability to the plant, in low-P soils. The present study aims at simulating root-induced chemical mechanisms controlling P nutrition in a P-limited soil.METHODS:
In this work a mechanistic description for the adsorption of cations and anions by soil constituents (1pK-Triple Plane Model, ion-exchange and Nica-Donnan) was used to simulate changes induced by durum wheat (Triticum durum turgidum) in the P availability of the soil, as measured by water and CaCl2 extraction. Calcium (Ca) availability was also measured and simulated. KEYRESULTS:
The simulations were found to be in close agreement with experimental data. In the rhizosphere, the goodness-of-fit required to account for the measured uptake of Ca by plants, in addition to the measured uptake of P and root-induced alkalization, were satisfactory. Calcium uptake significantly increased P availability, as assessed through water extraction, by decreasing the promoting effect of Ca adsorption on P adsorption. The study thus enabled P and Ca availability to be related to their bioavailability for durum wheat under experimental conditions. It was also shown that P was primarily adsorbed onto Fe oxides and clay minerals (kaolinite and illite) depending on soil pH. The major source of P for durum wheat nutrition was P desorbed from goethite and kaolinite.CONCLUSIONS:
In addition to confirming the validity of our approach to model P availability, the present investigation suggested that in the studied soil, a novel root-induced chemical process was controlling P nutrition under P-deficient conditions, namely the uptake of Ca.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fósforo
/
Triticum
/
Raízes de Plantas
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article