Abstract

Iris dichotoma Pall. found on Daechung Island in Korea has been designated as an endangered species. To aid in conservation efforts of this species, this study investigated its germination characteristics and seed dormancy type. Four sets of seeds were incubated at different temperatures (4/1°C, 15/6°C, 20/10°C, and 25/15°C). One set of seeds was cold stratified (4 weeks at 4/1°C). The final germination rate and mean germination time showed that the optimal germination temperature was 25/15°C. Final germination rates were ~70%, showing no significant difference among temperature treatments. However, mean germination time were significantly different among all temperature treatments except for 4/1°C. Mean germination time for seeds with temperature treatments of 15/6°C, 20/10°C, and 25/15°C were 3.2, 2.1, and 1.5 weeks, respectively. At 25/15°C, the mean germination time was half of that at 15/6°C. Seeds of I. dichotoma had fully developed embryos at the time of dispersal. No additional growth of the embryo was observed. Cold stratification did not affect the final germination rate or the mean germination time. This study shows that seeds of I. dichotoma have no physiological or morphological dormancy, unlike other members of the Iris genus known to have seed dormancy that needs a relatively high incubation temperature (≥25/15°C) for mass propagation to occur. These results will be useful for understanding ecophysiological mechanisms related to the species’ habitat. They are also useful for mass propagation of I. dichotoma for the purpose of conserving this endangered species.