Localization of the ca-mediated apparent ion selectivity in the cross sectional volume of soybean roots.

A major portion of the calcium in a soybean root appears to be in less than 10% of the root volume. Specifically, Ca is considered to be almost entirely localized in the epidermal cell layer. This relationship was established from consideration of rates and extent of ion absorption and ion interactions during the absorption process.Presence of calcium at the root-solution interface was associated with a change in the apparent selectivity of K over Mg by soybean roots. Accumulation of calcium by soybean roots was negligible.