山杨叶片相对水分含量的日变化

DAILY CHANGE OF RELATIVE WATER CONTENT (RWC) IN POPULUS DAVIDIANA LEAF

本文应用β射线吸收方法研究了山杨（Ｐｏｐｕｌｕｓｄａｖｉｄｉａｎａ）叶片相对水分含量（ＲＷＣ）的日变化，具有快速、简单、准确及不离体等优点。结果表明：叶片的ＲＷＣ既可以反映植株立地条件的土壤水分状态，又对环境因子强度的变化较为敏感。植株处于严重的水分胁迫且受较强的太阳辐射时，叶片的ＲＷＣ值较低，但气孔的关闭起到保水的作用，反之亦然。

The paper used gβrays absorbed by leaf to study daily change of RWC of Populus davidiana under greenhouse conditions. The method is simple, rapid,accurate and the leaf needn't be cut from the plant. The result showed that the RWC can reflect the soil water state of the site condition and is sensitive to the intensity change of environmental factors. When the plant is at serious water stress stage and the sunlight is very strong, the RWC is lower, but stomatal closure plays an important role in preventing water further loss, and vice versa.