Effects of simulated frost condition on growth and antioxidant enzyme activity of cucumber seedlings

ObjectiveTo provide technical support for the application and popularization of frost-prevention for cu-cumber,the effects of frost-prevention technique on morphology,antioxidant enzyme activity and cell membrane permea-bility of cucumber seedlings were analyzed under simulated frost condition.MethodCucumber seedlings were treated with frost-prevention technique(TR)under simulated frost condition,and then plant height,stem diameter,leaf length, leaf width and index of chilling injury were investigated at different times after temperature drop treatment.Antioxidant enzyme activity and other physiological indexes were measured 1 d before temperature dropped to 10 ℃/5 ℃(-1 d)and 1,3,5 d after temperature dropped to 10 ℃/5 ℃.ResultUnder simulated natural frost conditions,the relative plant height of cucumber seedlings after 3 d of TR group was 106.00%,which was significantly higher than that of CK 95.50% (P<0.05,the same below).There was no significant difference in relative stem diameter,relative leaf length,and relative leaf between TR and CK(P>0.05,the same below).The chilling injury indexes of TR group was 40.67% after 5 d tempera-ture drop treatment,which was significantly lower than that of CK.Superoxide dismutase(SOD)and catalase(CAT)ac-tivities of cucumber seedlings were significantly higher than those of CK after TR group for-1 d.The activities of SOD and CAT showed an upward trend after 1-3 d of treatment and were higher than those of CK,but the difference was not significant.Peroxidase(POD)activity of TR during-1-2 d of treatment was higher than CK,and it was lower than CK 3-5 d after treatment,but the difference was not significant.The content of hydrogen peroxide(H2O2)in TR group and CK group increased during-1-5 d of temperature drop treatment.The content of H2O2was lower than that of CK after treat-ment.Malondialdehyde contents(MDA)of TR group did not change greatly before and after temperature drop treatment, but it was significantly lower than that of CK on day 1 and day 5 after treatment.ConclusionApplying frost-prevention technique before the frost can improve the tolerance of cucumber seedlings against frost,and reduce the chilling injury of cucumber seedlings.