中文摘要：

采用液体培养方法研究了水杨酸诱导桉树抗青枯病的作用。在液体培养中，用0．5mM或1．0mM的水杨酸浸泡按树幼苗，可以显著地提高幼苗对青枯病的抗性，诱导抗病效果分别为30．4％和60．2％。幼苗浸泡1d后，即表现较强的抗病性，但以预处理3～5d适宜。当水杨酸浓度超过3．0mM或浸泡时间达7d以上时，幼苗死亡率明显增加。因此，过量的水杨酸对桉树幼苗有毒害作用。液体培养系统操作简单，苗木发病时间仪为盆栽苗木发病时间的1／3或1／2，且容易观察苗木发病情况，可以代替土壤盆栽系统测定水杨酸对桉树苗的诱导抗病效果，也可应用于筛选大量外源物质和生物制剂的诱导抗病作用。

英文摘要：

This study focused on induction of systemic acquired resistance against bacterial wih by salicyhc acid in hydroponic growth system. Enhanced disease resistance against bacterial wilt was demonstrated by root dipping of eucalypt seedlings in 0. 5 mmol/L or 1.0 mmol/L salicylic acid solution for 3 - 5 days before being transferred to hydroponic system infected with Ralstortia solanacearum .The percentage of wilted seedlings in treatments dipped in solution of 0.5 mmol/L or 1.0 mmol/L salicylic acid decreased by 17.5% and 34.6% ,compared with control,and the induced efficacy of disease resistance was 30.4%and 60.2 % ,respectively. When the concentration of salicylic acid exceeded 3.0 mmol/L and dipping time was over 7 days, the percentage of wilted eucalypt seedlings increased sharply, indicating that high dose of salicyhc acid was toxic to eucalypt seedlings. Since the hydroponic system was convenient to observe the development of eucalypt bacterial wilt, it could be used as a replacement for soil potting system to examine the inducing effects of salicylic acid and to screen other potential abiotic or biotic inducing agents against bacterial wilt in E. urophylla.