An Anomaly in Potassium Accumulation by Barley Roots

Excised barley roots accumulated 40 to 50% more K(+) from 0.04 mm than from 0.06 mm KCl when incubated for 24 hours in KCl solutions containing 0.2 mm CaSO(4). This phenomenon was not markedly influenced by the rate of absorption of the counteranion. The presence of Na(+) in the treatment solutions decreased total K accumulation but did not alter the K(+) concentration at which the accumulation peak occurred. Short interval studies indicated that this phenomenon is easily observable after 4 hours and begins to become apparent within 2 hours. In comparison with barley, accumulation of K(+) by excised wheat roots decreased as KCl concentration was increased from 0.02 to 0.06 mm; but K(+) accumulation curve for corn roots showed no peaks or depressions in the concentration range of 0.01 to 0.1 mm. A normal hyperbolic curve was noted for the accumulation of Na(+) from 0.01 to 1 mm NaCl by barley roots.