Scholander P F, Bradstreet E D, Hammel H T, Hemmingsen E A
Plant Physiol. 1966 Mar;41(3):529-32. doi: 10.1104/pp.41.3.529.
Freezing point depression in xylem sap of mangroves was found to range from 0.05 to 0.5 degrees , in desert plants from 0.01 to 0.16 degrees . In crush juices from leaves of Batis and Salicornia, 90% or more of the freezing point depression was made up of sodium and chlorine ions; in mangroves they constituted 50 to 70%, the rest probably being organic solutes. Plants growing in seawater have -30 to -60 atmospheres pressure in the xylem sap. As shown earlier, at zero turgor pressure the intracellular freezing point of the parenchyma cells matches closely the negative pressure in the xylem sap. This agrees with the present data, that the fluid which exudes from the xylem by applying gas pressure on the leaves is practically pure water; freezing point is rarely above 0.01 to 0.02 degrees . To perform this ultrafiltration, the plasma membrane is subjected to a hydrostatic pressure gradient which in some cases may exceed 100 atmospheres.
发现红树林木质部汁液的冰点降低范围为0.05至0.5摄氏度，沙漠植物的为0.01至0.16摄氏度。在海蓬子属植物和盐角草属植物叶片的压榨汁液中，90%或更多的冰点降低是由钠离子和氯离子造成的；在红树林中，它们占50%至70%，其余可能是有机溶质。生长在海水中的植物，其木质部汁液的压力为-30至-60个大气压。如前所示，在零膨压时，薄壁细胞的细胞内冰点与木质部汁液中的负压密切匹配。这与目前的数据相符，即通过对叶片施加气压从木质部渗出的液体实际上是纯水；冰点很少高于0.01至0.02摄氏度。为了进行这种超滤，质膜承受着静水压力梯度，在某些情况下，该梯度可能超过100个大气压。
