Effect Of ABA On Cold-resistence Of Cucumber Seedlings

Effect of 0,50μmol·L^-1,150μmol·L^-1,250μmol·L^-1 abscisic acid(ABA) on defensive enzyme activity,proline and protein content,and carbohydrate metabolism in 'guonong 25' cucumber seedlings under low temperature stress were studied.The results showed that as follows1.Low temperature stress led to increase in MDA content in cucumber seedlings at the initial stage,SOD,POD,CAT,APX,DHAR activity,and proline,sugar and protein contents all as well as increased.6d later however, the MDA content continualy ascended,most of the above defensive enzyme activity and proline,protein content came to descended.2.50μmol·L^-1,150μmol·L^-1 ABA resulted in declined in MDA content, inhanced SOD,POD,CAT,APX,DHAR activity and proline and protein contents as compared with the control.When the seedlings were pretreated with 250μmol·L^-1ABA,the MDA content were higher than those of pretreated with water,While the defensive enzymes activty and proline,protein contents were lower than those of tretreated with water.3.Under low temperature stress,the totall sugar,fructose,sucrose,Stachyose, raffinose contents of cucumber seedlings which pretreated with 50μmol·L^-1 and 150μmol·L^-1 ABA all higher than those of the control.However,no significant difference between the seedlings pretreated with 250μmol·L^-1 ABA and the control in the above sugers at the begenning of stress days,as the stress time delaying,the total sugar and the most monose and寡糖content decreased,and lower than those of the control remarkably after 9 days.