Department of Botany, University of Florida, Gainesville, Florida 32611.
Plant Physiol. 1979 Jan;63(1):163-8. doi: 10.1104/pp.63.1.163.
Apical segments of roots of corn (Zea mays, L.) were excised and mounted in experimental salt solutions containing (86)RbCl and CaCl(2). Xylem exudates were collected hourly beginning at the 21st hour. At the 24th hour, experimental solutions were replaced with solutions of other chlorides (nonlabeled) of Ca(2+) +/- some monovalent cation.Following replacement of the labeled solutions, the rate of (86)Rb(+) release to the exudates from root segments declined by about the same proportional amount regardless of the initial steady-state output rate or the kinds of salts used to replace the RbCl. The content of (86)Rb(+) in the roots also declined with time, but to a relatively less degree. Loss of accumulated (86)Rb(+) to the various external solutions following replacement was less than 6% in 6 hours. It is concluded that movement of accumulated Rb(+) to the exudate is dependent on the concentration of Rb(+) in the root but is largely independent of exchange between accumulated ions and other ions in transit across the root.
玉米（Zea mays，L.）根的根尖被切除并安装在含有（86）RbCl 和 CaCl（2）的实验盐溶液中。从第 21 小时开始，每小时收集木质部渗出液。在第 24 小时，用其他氯化物（未标记）的 Ca（2+）和一些单价阳离子替换标记的溶液。在替换标记的溶液后，无论初始稳态输出率或用于替换 RbCl 的盐的种类如何，（86）Rb（+）从根段渗出物中的释放速率都以相同的比例下降。根中的（86）Rb（+）含量也随时间下降，但相对程度较小。在 6 小时内，更换后积累的（86）Rb（+）损失到各种外部溶液中的量不到 6%。结论是，积累的 Rb（+）向渗出物的移动取决于根中 Rb（+）的浓度，但在很大程度上独立于积累离子与穿过根的其他离子之间的交换。
