3.3. Effect of dark preculture on in vitro germination
The seed germination percentage and protocorm development
were effected by dark preculture of seeds before transferring to
light, but the germination period were not significantly different
(Table 3). The seed germination percentage following dark
preculture for 45 days then transferring to a 16-h photoperiod
was significantly higher than in a 16-h photoperiod without dark
preculture, complete darkness, or preculture in the dark for 45 days
then transfer to a 16-h photoperiod for 120-day culture, but was
not significantly higher than preculture in the dark for 30 days followed
by transfer to a 16-h photoperiod. On the other hand, 53%
of protocorms developed into Stage 5 seedlings after preculture in
the dark for 45 days then transfer to a 16-h photoperiod; this was
significantly higher than other treatments.