Relationships between the Chloride and Iodide Uptake of Wheat Seedlings

Abstract

THE theory that plants absorb ions by the action of carriers has become general during the past decades. It is an intermediate labile complex, formed by a combination of the carrier and the ion, which traverses the membrane impermeable to free ions. Upon arriving at the inner surface, the complex breaks down and releases the ion carried by it. Epstein et al. ¹ suggest that different carriers are involved for different groups of ions. A common carrier mechanism is, for example, operative for chloride, bromide and iodide ions². It was demonstrated a few years ago that two separate systems of carriers act in the uptake of differently dissociated phosphate ions³, while, recently, likewise two separate carriers have been postulated for the absorption of monovalent cations⁴. It has thus become necessary to collect additional data concerning the uptake of monovalent anions.