Department of Horticulture, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1967 Nov;42(11):1483-8. doi: 10.1104/pp.42.11.1483.
Calcium (or magnesium) sulfate or chloride was found to inhibit energy dependent potassium transport in excised corn roots. This Ca(2+) inhibition of K(+) transport was most pronounced during the initial phases of transport. As the absorption periods were lengthened the effect of Ca(2+) gradually changed from an inhibition to a typical promotion (after about 30-45 mins) of K(+) transport. Kinetic analysis indicated the inhibition to be of a non-competitive nature.Identical experiments with excised barley roots showed that CaSO(4) had no effect on K(+) absorption whereas CaCl(2) had a typical stimulatory effect on K(+) absorption. Kinetic analysis indicated that both corn and barley have efficient K(+) transporting systems but barley roots are approximately 5 times more active (on a fr wt basis) than corn roots.These results illustrate the hazards involved in applying results obtained with 1 (or even several) plant species to all species.
钙（或镁）硫酸盐或氯化物被发现可抑制离体玉米根中能量依赖的钾转运。这种 Ca（2+）对 K+转运的抑制在转运的初始阶段最为明显。随着吸收时间的延长，Ca（2+）的作用逐渐由抑制转变为典型的促进（约 30-45 分钟后）。动力学分析表明，这种抑制是非竞争性的。对离体大麦根进行的相同实验表明，CaSO4 对 K+吸收没有影响，而 CaCl2 对 K+吸收有典型的刺激作用。动力学分析表明，玉米和大麦都有高效的 K+转运系统，但大麦根的活性（按鲜重基础计算）约为玉米根的 5 倍。这些结果说明了将从 1 种（甚至几种）植物物种获得的结果应用于所有物种所涉及的风险。
