Abstract: To understand the adaptation mechanism of mycorrhizal Rhododendron annae plant to severe drought stress, annual Rhododendron annaea seedlings inoculated with 2 kinds of Ericoid mycorrhizas(ERM) strains( TY29,TY35) and uninoculated seedlings(CK) were used as materials,the dynamic changes of physiology and biochemistry of mycorrhizal Rhododendron annae seedlings under severe drought stress by pot water control method were studied.The result showed that the Pro(proline)content and SOD(superoxide dismutase)activity of CK reached the maximum on day 7 after sever drought stress,MDA(malonaldehyde) content reached its maximum on day 14;Pro content,SOD activity of inoculation treatment reached the maximum on day 14, and MDA content reached the maximum on day 21; the inoculation of ERM strain significantly increased the Pro content and SOD activity of Rhododendron annae and delayed the production of MDA. Under the severe drought stress,the endogenous hormones IAA,ABA,GA₃,ZR contents of Rhododendron annae had different change;the inoculation of ERM significantly increased the contents of IAA,ABA,GA₃,and ZR in the leaves and roots of Rhododendron annae,and decreased the ratios of IAA to ABA,ZR to ABA,(IAA+ZR+GA₃) to ABA.It can be seen that,with the duration of stress, ERM can alleviate the damage of Rhododendron annae under severe drought by regulating the contents of Pro,MDA,endogenous hormones and SOD activity.The Rhododendron annae of inoculation treatment can better adapt to the long-term severe drought environment.

Key words: Ericoid mycorrhizas(ERM), Endogenous hormones, Severe drought stress, Rhododendron annae, Physiology and biochemistry

摘要： 为了解菌根化桃叶杜鹃（Rhododendron annae）幼苗对重度干旱胁迫的适应机制，以接种2种杜鹃花类菌根(ERM)菌株（TY29、TY35）及不接菌处理（CK）的1年生桃叶杜鹃幼苗为试材，采用盆栽控水法研究重度干旱胁迫下菌根化桃叶杜鹃幼苗生理生化特性的动态变化。结果表明，CK游离脯氨酸（Pro）含量、超氧化物歧化酶（SOD）活性在重度干旱7 d达到最大值，丙二醛(MDA)含量在重度干旱14 d达到最大值；接菌处理游离Pro含量、SOD活性则在重度干旱14 d达到最大值，MDA含量在重度干旱21 d达到最大值；接种ERM菌株处理总体上显著提高桃叶杜鹃游离Pro含量、SOD活性，延缓MDA生成。重度干旱下，桃叶杜鹃内源激素含量变化不一，接种ERM处理总体上显著增加桃叶杜鹃叶片和根系IAA、ABA、GA₃、ZR含量，降低IAA/ABA、ZR/ABA、（IAA+ZR+GA₃）/ABA值。可见，随着胁迫时间的持续，ERM可以通过调控游离Pro、MDA、内源激素含量及SOD活性缓解重度干旱对桃叶杜鹃的伤害，接菌处理桃叶杜鹃更能适应长时间的重度干旱胁迫环境。

关键词: 杜鹃花类菌根, 内源激素, 重度干旱, 桃叶杜鹃, 生理生化