胡杨对渗透胁迫和盐分胁迫的不同响应

用等渗透势的ＮａＣｌ和ＰＥＧ溶液处理胡杨发现：（１）处理后１ｄ，－２４ｂａｒ渗透势的ＮａＣｌ胁迫使胡杨根ＡＢＡ含量上升为对照的２７倍，而ＰＥＧ处理没有影响．处理后７ｄ，－２４ｂａｒ渗透势的ＮａＣｌ胁迫的胡杨叶腐胺含量是群众杨的３３倍，渗透势胁迫加强到－９６ｂａｒ时腐胺含量扩大到４４倍．说明ＮａＣｌ胁迫由渗透胁迫和专性离子胁迫两部分构成，两者有加合性．这一方面进一步说明在这种情况下ＡＢＡ的增加基本上归咎于专性离子胁迫，另一方面暗示胡杨根系能感知环境中低浓度的专性离子而增加ＡＢＡ合成，ＡＢＡ是前胁迫反应产生的化学信号，作为一种调控剂诱导植株各部分进行代谢调节．

The Defferent Respone of P euphratica to Peg and NaCL

P euphratica was treated respectively with NaCl and PEG solutions with isomotic potential Under isomotic potential,ABA and Polyamine contents increased earlier under NaCl treatments than that under PEG treatment,and increments were higher under NaCl treatments than that under PEG treatment,indicating that P euphratica was more sensitive to specific ion toxicity than to non-specific osmotic stress Thus it can be postulated that salt stress signal is a complex signal composed by non-specific osmotic stress signal and specific ion toxicity signal,and those two signals are additive. Therefore,under isomotic potential,stress intensity caused by NaCl was higher than that caused by PEG. In the processes of stress communication,ABA is a signal substance Difference of stress intensity induces difference in ABA contents which will further induce the difference in metabolic adjustment and growth adjustment