EFFECT OF FLOODING ON ANNUAL DORMANCY CYCLES IN BURIED SEEDS OF 2 WETLAND CAREX SPECIES

Buried seeds of Carer comosa and C. stricta were exposed to nonflooded and flooded conditions and natural seasonal temperature changes for 3 0.5 and 33 mo, respectively. At 1-, 2- or 6-mo intervals, exhumed seed s were tested for germination in light and darkness over a range of da ily thermoperiods. Freshly-matured seeds of both species were conditio nally dormant; maximum germination was at 35/20 degrees C, in light. D ormancy decreased in nonflooded and flooded seeds of C, comosa during late autumn and winter but the decrease was greater in flooded than in nonflooded seeds. Nonflooded and flooded seeds of C, stricta gained t he ability to germinate in light during the first summer of burial and in darkness during the following winter. Seeds of neither species ger minated while they were buried in pots of soil under either nonflooded or flooded conditions in the nonheated greenhouse. Nonflooded and flo oded seeds of both species incubated in light and flooded seeds of C. comosa incubated in darkness had an annual conditional dormancy/nondor mancy cycle, being conditionally dormant in summer and autumn and nond ormant in spring. However, nonflooded seeds of C comosa incubated in d arkness remained dormant, germinating to only 1%. Most nonflooded and flooded seeds of C stricta incubated in darkness had an annual dormanc y/nondormancy cycle, being dormant in summer and nondormant in spring. Thus, flooding influenced the annual changes in dormancy states of bu ried seeds of C. comosa, but it had no effect on seeds of C. stricta.