The results of exposure to ethylene on ethylene
production in D. ‘Darren Glory’, D. ‘Jaquelyne Concert’ ×
D. ‘Rinappa’ and D. ‘Sonia Bom’ showed that their
ethylene production on day 3 was higher than nonexposed
to ethylene (Figure 5). These findings confirm
the results of Ketsa and Rugkong (1999) that exogenous
ethylene resulted in autocatalytic increase in endogenous
ethylene of the cut Dendrobium 'Pompadour' flowers.
However, there were no significant differences on day 3
in other orchid hybrids either exposed or non-exposed to
ethylene. This could be due to level of ethylene sensitivity.
Interaction between hybrids and ethylene
production on day 1, 3 and 5 showed that the trend of
ethylene production depending of hybrids is different.
Furthermore, with exposure to ethylene occurred a burst
in ethylene production and early senescence, especially
in sensitive cut orchids. More also, ethylene production
had a negative correlation with vase life and positive
correlation with weight loss and anthocyanin degradation with and without exogenous ethylene and this was similar
with the results of Bartoli et al. (1997) for chrysanthemum flowers.
Finally, responses among the cut Dendrobium hybrids
to exogenous ethylene were different. Thus, based on
sensitivity to ethylene, the hybrids could be divided into
two groups, ethylene sensitive and less ethylene
sensitive. The hybrids in the sensitive group are: D.
‘Darren Glory’ and D. ‘Jacqueline Concert’ × D. ‘Rinappa’
because these hybrids were more prone to floret epinasty
in addition to bud drop, floret wilting and reduced vase
life, while the other hybrids could be considered less
ethylene sensitive.