Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706.
Plant Physiol. 1977 Dec;60(6):854-6. doi: 10.1104/pp.60.6.854.
Young cabbage plants (Brassica oleracea L. var. capitata) that were exposed to an atmosphere at 50% relative humidity transpired freely and accumulated significant quantities of (45)Ca in the leaves. Plants that were enclosed by plastic bags to stop transpiration from all leaves exhibited guttation with the development of root pressure and also accumulated significant quantities of (45)Ca in the leaves. (45)Ca accumulation increased in the leaves and tended to decrease in roots and stems with increasing quantities of water transpired or guttated by the plant. When plants were only partially enclosed so that some leaves were covered and the remainder exposed, only the exposed leaves that were transpiring accumulated significant quantities of (45)Ca. The covered leaves of partially enclosed plants exhibited no guttation and accumulated little (45)Ca with no measurable (45)Ca at the margins of the leaves. The results demonstrate that root pressure flow is required to transport adequate amounts of Ca to those tissues in plants that are not undergoing transpirational water loss.
年轻的白菜植株（甘蓝型油菜变种。白菜）在 50%相对湿度的大气中自由蒸腾，并在叶片中积累了大量的（45）Ca。用塑料袋将叶片的蒸腾作用封闭起来的植株，随着根压的发展，也会发生溢泌作用，并在叶片中积累大量的（45）Ca。（45）Ca 在叶片中的积累随着植物蒸腾或溢泌的水量增加而增加，并趋于在根和茎中减少。当植物仅部分封闭，使一些叶片被覆盖而其余叶片暴露时，只有暴露的正在蒸腾的叶片才会积累大量的（45）Ca。部分封闭植物的被覆盖叶片不发生溢泌作用，积累的（45）Ca 很少，叶片边缘也没有可测量的（45）Ca。结果表明，根压流是将足够数量的 Ca 运输到那些没有进行蒸腾失水的植物组织所必需的。
