reported that the duration of the dark pretreatment significantly affected the germination percentage; 45 days of
dark pretreated seeds had the highest germination percentage. Other research has reported that the media can modulate
the influence of light on germination. Stimart and Ascher (1981) reported that modified Thomale GD medium in darkness
strongly promoted seed germination as well as protocorm survival of Paphiopedilum hybrids, while germination was best
in Burgeff EG-1 when seeds were given light, though these seeds later died. The study by Zeng et al. (2012) reported
that continuous dark treatment of seeds did not produce seedlings, suggesting that light is an important ecological cue in
seedling development, although it is not clear why the dark treatment promotes seed germination of terrestrial orchids. It is widely accepted that epiphytic orchids require light for seed germination while terrestrial species require dark conditions.
However, this is a complex phenomenon and our results and others show that the requirement for light for germination in
Paphiopedilum genus is species-specific as well as germination stage-specific.