Changes in Desiccation Tolerance During Imbibition of Zea mays L.Relate to Activity of Reactive-Oxygen-Scavenging Enzymes

Maize ( Zea mays L.) seeds were used as experimental material. Changes in desiccation tolerance of seeds during imbibition, and changes of viability, rate of electrolyte leakage,MDA content and activity of reactive-oxygen-scavenging enzymes(SOD,POD,CAT) in maize embryos of different desiccation tolerance during dehydration were studied. At 25 ℃ the critical imbibition time of desiccation tolerance loss of maize seeds was 24 h. After imbibition of 58h, it totally lost desiccation tolerance. The loss of desiccation tolerance of imbibed maize seeds was a quantitative feature. It progressively lost during imbibition, and was not a all_or_nothing response. As imbibing more time , desiccation tolerance was lost more seriously, and the activity of reactive_oxygen_scavenging enzymes was easier to decrease during dehydration. The change pattern of activity of reactive_oxygen_scavenging enzymes in desiccation_intolerant maize embryos (imbibed 58 h) during dehydration was similar to that of the recalcitrant seeds, however, for as partial_desiccation_tolerant maize axes (imbibed 35 h), they were not as similar with each other. The change tendency of MDA content in as partial_desiccation_tolerant or desiccation_tolerant maize embryos during dehydration was decreased_increased_decreased, but for desiccation_intolerant maize axes,it increased at the early desiccation stage, then it decreased with dehydration.