PERONI, PATRICIA A.*, JAMES W. WHITE, ALLISON A. CALDWELL, LAURAN HALPIN, AND ADAH WALKER. Department of Biology, Davidson College, Davidson, NC 28036-1719. - Dark induced secondary dormancy in seeds from a Silene latifolia meta population.
Habitat heterogeneity may influence the germination phenology of seed
crops if the environments that seeds experience upon dispersal differ
in their ability to induce secondary dormancy. We initiated
germination trials for seeds from two populations of Silene
latifolia in light (14 hr photoperiod) and dark conditions at 22
C in growth chambers (2 chambers per light treatment), and found
significantly lower percent germination in the dark environment than
the light treatment after 1 wk. When we subsequently exposed
ungerminated seeds from the dark treatment to a 14 hr photoperiod,
mean cumulative percent germination for these replicates after two wk
(1wk dark, 1 wk light) was lower than the mean percent germination of
seeds in the light treatment after 1 wk. Cumulative percent
germination for seeds initially exposed to dark conditions plateaued
after 2 wk in the light. At this time, cumulative percent germination
of these seeds was significantly lower than that recorded for
replicates that entered germination trials in the light at the same
time the dark treated seeds were exposed to light. We conclude that
our dark treatment initiated secondary physiological dormancy in a
large percentage of seeds. Treatment with gibberellin (100 ppm)
failed to break this dormancy. Stratification at 4 C for 1 mo broke
dormancy for a fraction of the viable seeds that remained
ungerminated. These results suggest that a large percentage of buried
S. latifolia seeds may be unable to germinate immediately upon
exhumation, although field investigations will be necessary to fully
explore this potential effect of seed burial.
Key words: dark, germination, secondary dormancy, seeds, Silene latifolia