Abstract: To investigate the relationship between the tolerance to water deficit stress and superoxide dismutases in postharvest cut rose, Samantha (Bridal Pink × Seedling), a cultivar with strong tolerance to water deficit, was pulsed with 12 h DDTC pretreatment and subjected to 12-48 h water deficit stress under controlled conditions, i.e. relative humidity of 35%-40%,12 h /12 h photoperiod with photosynthetic photon flux density of 80 E·m-2·s-1, and 20℃, then vased for observation. The results showed that SOD activity in petals was remarkably inhibited pulsed with 20 mmol·L-1 DDTC pretreatment and flower tolerance to water deficit was obviously decreased, which was evidenced by the obvious increase of bentneck rate, the significant decrease of rewater water recovery rate and flower water potential, and the dramatic shortness (reduction) of vase life. Three types of SOD were observed in the petals of control at the earlier stages of flowering, and FeSOD had three isoforms, Cu/ZnSOD two isoforms, and MnSOD one isoform, respectively. The turn of mobility of them was Cu/ZnSOD>FeSOD>MnSOD; and bands activity was FeSOD>Cu/ZnSOD>MnSOD. By water deficit stress, three new bands named as FeSOD4－6 were induced, and MnSOD disappeared simultaneously. However, the newly induced bands by water deficit stress mentioned above were inhibited by DDTC pretreatment. It is presumed that the tolerance to water deficit is highly related to SOD activity, and to newly induced FeSOD4－6 in the petals of postharvest cut rose Samantha.

Key words: Cut rose (Rosa hybrida), Water deficit stress, Superoxide dismutases (SODs), SOD isoenzymes, Diethyldithiocarbamate (DDTC)