<正>采用 4种质量分数的PEG 60 0 0 ( 1 0 %～ 30 % )对银杏幼苗进行根际渗透胁迫处理。结果表明 ,银杏体内脯氨酸含量、POD活性、膜相对透性及MDA含量对渗透胁迫做出了不同的反应。POD在第 2天出现高峰 ( 1 0 %除外 )后下降 ;脯氨酸含量的显著增加出现 2d之后 (特别是PEG2 0 %～ 30 %强度下 )上升幅度很大 ;膜相对透性增加在脯氨酸含量变化之后。脯氨酸含量与膜相对透性相关显著 (r=0 .97) ,与MDA呈一般的相关。 4种胁迫强度可划分为 3种类型 :1 0 %～1 5 %PEG处理时为轻度胁迫型 ,1 5 %～ 2 0 %处理为中度胁迫型 ,2 0 %～ 30 %处理为严重胁迫型。银杏能较长时间地忍受 2 0 %PEG处理以下的水分胁迫 ,超过此胁迫强度则出现伤害

The content of free proline,peroxidase(POD)and the relative permeability of plasma membrane(RPM)in seedlings of Ginkgo biloba were studied under different levels of osmotic stress by PEG(6000,10%～30%).The results showed that the POD activity increased in first two days(except 10%),then decreased proline content increased from the second day to the sixth day especially under 20%～30% it increased sharply,while RPM increased greatly from the forth day.In the three indications,the peak of POD activity appeared most early,then proline content and RPM last.There was significant correlation between proline content and RPM( r =0.97)and a general correlation between proline content and MDA.As a result,three categories were classified in the four levels of osmotic stress.Ginkgo seedlings was able to endure the 20%PEG(6 000)level of water stress and would be harmed above that of level.