木本植物枝条导水率的季节变化

Comparative Studies on Measurements of Plant Water Potentials with an Air Chamber and an Oil Chamber 

用“冲洗法”测定了维也纳农业大学校园内１４种树木枝条导水率的季节变化。一年中针叶树枝条的相对导水率高于阔叶树，欧洲光叶榆的相对导水率最低，浆果紫杉的相对导水率最高，在阔叶树中欧洲柔毛桦的相对导水率最高，大多数树种在春天导水率最低。一般树木枝条导水率在生长季较高，但欧洲山毛榉例外，其３月和４月份的枝条导水率大于生长季。针叶树枝条导水率的季节变化不明显，甚至在冬季导水率仍然较高。长叶前导水率最低，时间随树种不同而异。冬季导水率降低愈厉害，树木发芽愈晚。环孔材树木的相对导水率低于其它树种。柔毛栎２月份的相对导水率很低（１．１％）。

Leaves and twigs of 12 species were sampled at the campus of Agricultural University Vienna for parallel determinations of water potential with an air chamber and an oil chamber. The results indicated that there was no significant difference between the water potentials determined with the air chamber and with the oil chamber. Therefore, it is suggested that the oil chamber could be used with advantage for field work in situations where weight of equipment or a continuous supply of compressed air are matters of concern.