Abstract: The effects of hydrogen peroxide on the increased cold tolerance of tomato by cold-shock treatment and metabolism of dynamic changes of antioxidant enzyme system were studied. Cold-shock treatment reduced the chilling injury rate and chilling injury index, enhanced the endogenous H2O2 content in the beginning of storage, postponed the increases of MDA and increased the activities of CAT and APX. The MDA content increased after pretreatment with dimethylthiourea before cold-shock treatment. Furthermore, the activities of CAT and APX were inhibited. These results indicated that cold-shock increases cold tolerance of tomato, reduces the effects on the injury of cell membrane and increases the activities of the antioxidant enzymes. Pretreatment with dimethylthiourea (a trap for H2O2) remarkably inhibits cold tolerance induced by cold-shock. All the results showed that endogenous H2O2 may improve the tolerance cold shock-enhanced tomatoes.

Key words: tomato, cold-shock, chilling injury, H2O2, antioxidant enzyme