Effect of Exchangeable Cations on Lateral Movement of Sulfate in Excised Roots1
- R. E. Franklin2
Autoradiographs of histologic sections from excised corn (Zea mays) roots exposed to 35S labeled SO42- after pretreatment with K+, Ca2+, or Al3+ are shown. The autoradiographs indicate that the permeability of the epidermal layer to sulfate is severely restricted when pretreated with K+ but not when pretreated with Ca2+ or Al3+. Apparently this effect is associated with the cation exchange sites located in or near the epidermal layer and results from the electrostatic repulsive forces opposing anions which approach the epidermis, where the negatively charged sites are first encountered. The repulsive force would be an inverse function of the degree neutralization of the exchange sites by adsorbed cations which is in the order Al3+ > Ca2+ > K+.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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