"Changes in specific activity and protein level of ascorbate peroxidase (EC 1.11.1.11) were studied in pansy (Viola wittrockiana) petals during anthesis. The activity of ascorbate peroxidase in pansy petals was already present at a high level in immature buds covered with sepals and decreased gradually during development of buds. Thereafter, it decreased rapidly at the start of flowering. The protein level of ascorbate peroxidase decreased rapidly prior to the start of flowering. The amounts of phenylpropanoid compounds in pansy petals also decreased at the start of flowering. It was suggested that phenylpropanoid compounds may play an important role in detoxicification of H_20_2 in pansy petals as well as ascorbate during anthesis.Changes in specific activity and protein level of ascorbate peroxidase (EC 1.11.1.11) were studied in pansy (Viola wittrockiana) petals during anthesis. The activity of ascorbate peroxidase in pansy petals was already present at a high level in immature buds covered with sepals and decreased gradually during development of buds. Thereafter, it decreased rapidly at the start of flowering. The protein level of ascorbate peroxidase decreased rapidly prior to the start of flowering. The amounts of phenylpropanoid compounds in pansy petals also decreased at the start of flowering. It was suggested that phenylpropanoid compounds may play an important role in detoxicification of H_20_2 in pansy petals as well as ascorbate during anthesis."