Effect of Adsorbed Cations on Phosphorus Absorption by Various Plant Species¹

Abstract

P uptake by excised roots of 10 different plant species was found to be stimulated by a short pretreatment with polyvalent cations, or by raising the ionic strength of the absorbing solution. The pretreatment consisted of a l‐min rinse with 10−3 N chloride salt solutions prior to exposure to 2 × 10−5 M KH2PO4. Also, the root CEC was estimated by isotopic exchange using a labeled CaCl2 solution. The stimulation of P uptake by the polyvalent cation pretreatments was significantly correlated with the amount of P taken up by the control and the root cation exchange capacities. The results supported the hypothesis that the cell wall can act act as a negatively charged membrane regulating P uptake.

Aluminium toxicity and induced nutrient disorders involving the uptake and transport of P, K, Ca and Mg inZea maysL.

“…It is therefore probable that a major requirement for these nutrient cations in the root involves a nonspecific charge neutralization role. This idea accords with observations regarding the stability of root ( +ve) charge and is compatible with the established non-specific stimulatory effect of some polyvalent cations on anion uptake (Viets, 1944;Franklin, 1970).…”

Influence of Temperature on Proton Secretion and Hexacyanoferrate (III) Reduction of Zea mays L. Roots

“…This stimulation has been attributed to screening of the negative membrane surface charge by cations (Federico and Giartosio, 1983;Rubinstein et al, 1984). A similar effect of cations has been observed by Franklin (1970), who found cation stimulation of phosphorous uptake. It has been assumed that anion movement within the apoplast is limited by negatively charged acidic residues in the cell wall matrix, thus resulting in increased diffusional resistance for the anion, which is decreased by cations screening the fixed negative charges of the cell wall.…”

“…It has been assumed that anion movement within the apoplast is limited by negatively charged acidic residues in the cell wall matrix, thus resulting in increased diffusional resistance for the anion, which is decreased by cations screening the fixed negative charges of the cell wall. (Franklin, 1970;Sentenac and Grignon, 1981;Richter and Dainty, 1989). This model holds true for the 3-fold negatively charged HCF(II1) molecule.…”

Influence of aluminium on phosphate and calcium uptake in beech (Fagus sylvatica) grown in nutrient solution and soil solution

“…On the other hand. Franklin (1970) pointed out that the negative charges at the cell walls are implicated and that polyvalent cations such as AP"^ are very effective in promoting phosphate uptake of roots (Viets effect; Viets 1944). A low concentration of Al probably stimulates transport of phosphate and other anions across membranes (Viets 1944, Clarkson andSanderson 1971).…”