This deterioration and discoloration could be due to an increase of vacuole’s pH or enzyme effects such as
polyphenol oxidase and peroxidase on senescing flowers
as reported by Zhang et al. (2003, 2001). Except for D.
‘Sonia White’, the results of this experiment confirmed the
findings of Rebecca et al. (2008) who found that anthocyanin
content decreased in senescing cut orchid
flowers. However, for D. ‘Sonia White’, anthocyanin content
showed an increase trend because when the florets
start to senesce, their colour became darker due to
browning process (Figure 4). This suggests that the
browning of perianth was induced by a loss of water
through the sepal and petal via transpiration. The
resulting negative water status in the cells causes the
diffusion of anthocyanins and other flavonoids from the
vacuoles to the functional cytoplasma. Through enzymatic
and/or air oxidation, these substances become
brown especially in white hybrids and they are precipitated,
causing the browning phenomenon (Ferreira,
1983). Thus, absorbance at 530 nm for these flowers
increased through 5 days in vase solution. The
interaction between hybrids and days in vase solution on
anthocyanin content suggested that anthocyanin degradation
depended on the hybrids and their sensitivity to
ethylene.