Dj. Metcalfe, GERMINATION OF SMALL-SEEDED TROPICAL RAIN-FOREST PLANTS EXPOSED TO DIFFERENT SPECTRAL COMPOSITIONS, Canadian journal of botany, 74(4), 1996, pp. 516-520
Seeds of 11 very small-seeded species with different degrees of shade
tolerance as juveniles were tested for their response to neutral shade
(6% daylight), green shade (3%), and darkness. Germination was monito
red over 46 weeks. All species germinated in daylight to some extent.
Species of Pternandra and Urophyllum, commonly found as juveniles in d
eep shade, germinated to the same percentage in green shade as in dayl
ight, although over a longer time period, and to a lower percentage in
the dark. Percentage germination of Gynotroches axillaris and Pellaca
lyx saccardianus, also found as juveniles in deep shade, was similar i
n all treatments, but much faster in daylight. Species of Ficus, which
are found commonly as seedlings in deep shade but require higher irra
diance for onward growth, germinated rapidly in daylight, and to a low
er percentage and after a longer time in green shade than in the dark.
Melastoma, which establishes in large gaps, germinated only in daylig
ht. As most species can germinate under a spectral composition similar
to canopy shade it is likely that they can germinate under a closed c
anopy in nature and may become established without the formation of ev
en a transient canopy gap provided leaf litter is absent.