Abstract
AbstractThe manner of salt entry into roots is discussed. Reasons are given for considering the plasmalemma of the epidermal cells as being the rate‐limiting barrier. The dependence of uptake on aeration is considered to arise from production of adenosine triphosphate (ATP) by oxidative phosphorylation in the mitochondria. Passage of the salt at the cellular membrane, however, is considered to depend on utilization of ATP. Partial processes involve H+ exchange for cations and OH‐ exchange for anions. The eventual charge balance within the root depends on production of carboxylic acids (initially oxaloacetic) by fixation of carbon dioxide. In salt accumulation, if transport from the roots is limited, an eventual equilibrium is reached with equal efflux and influx rates. Recent work indicating that the function of K+ in plants as chiefly one of determining protein configuration is cited.
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