ISSN:
1573-5036
Keywords:
agarose
;
aluminium
;
Al-hydroxyde
;
Al toxicity
;
H+ release
;
nitrogen nutrition
;
rhizosphere acidification
;
Zea mays L
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The object of this study was to analyze the dynamics of Al and protons in the rhizosphere of maize cultivated in a simple acid substrate, so as to allow the use of a dynamic model of the functioning of a rhizosphere consisting of an organic phase (an agarose gel) and a mineral phase (an amorphous aluminium hydroxide). Two cultivars of maize (Zea mays L.), one Al-sensitive and the other Al-tolerant, were cultivated on this substrate in the presence of different proportions of NH 4 + and NO 3 - , which served to acidify the rhizosphere to a greater or lesser extent. The state of the agarose gel and of the cell walls of the roots were monitored using an ion exchange model which had previously been calibrated for each substrate. The experiment showed that Al and protons reduce root growth and the Ca and Mg content in the root, while relative growth varies little between pH 4.0 and pH 4.5. The model showed that competition between Al and protons for the binding sites of the cell walls might account for these results. The sensitivity of the model to the rate of Al(OH)3 dissolution and to the cation exchange capacity of the culture substrate was tested by numerical simulation. When roots release protons and dissolve Al(OH)3 in the rhizosphere, there is little possibility of Al desorption by protons on the cell walls at pHs compatible with good root growth of maize, plant specie sensitive to Al and H. Furthermore, the phytotoxicity of the different forms of Al hydroxides should be considered only in taking into account the dynamics of the whole system, in particular the solubilisation of Al in the rhizosphere.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004515815446
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