Abstract:Changes in RWC, MDA content and the activities of SOD and POD in Opium Poppy were measured at the bud stage treated by different concentrations of 2,4-D. RWC was affected insignificantly by 1ml/L, 2ml/L and 4ml/L 2,4-D treatment, but RWC decreased significantly in 8ml/L treatment and RWC was 48.7% lower 4d post treatment than 1d post treatment. The changes in the MDA content and the cell membrane electrolyte leakage showed the same trend with different treatments. The MDA content and cell membrane electrolyte leakage decreased in the early stage then increased under 1ml/L, 2ml/L and 4ml/L treatment. In contrast, the MDA content and cell membrane electrolyte leakage increased in the early stage then decreased under the 8ml/L treatment. The activities of SOD and POD varied among treatments. POD activities increased at 2 or 4d post treatment except for the 8ml/L treatment, in which POD activities increased at 2d and decreased at 4d post treatment. SOD activities decreased in the early stage and increased in the later stage, and its activities were significantly higher in the treatments than in the CK. These results suggested that a high concentration (8ml/L) 2,4-D treatment caused damage to the Opium Poppy cells by lipid peroxidation, whereas lower concentrations were less effective.