Germination and storage behaviour of seeds of the subtropical evergreen tree Daphniphyllum glaucescens (Daphniphyllaceae)

Daphniphyllum glaucescens Blume ssp. oldhamii (Hemsl.) Huang is an important subtropical evergreen tree in Taiwan. Seeds of D. glaucescens have non-deep, simple, epicotyl morphophysiological dormancy, and a minimum of 10-12 weeks is required for the first step of seedling production, i.e. hypocotyl emergence. It is not known how to decrease the time for seedling production and how to store seeds for retention of viability. We determined the effects of (i) gibberellic acid and cold-stratification on germination (hypocotyl emergence) and (ii) storage temperature and seed moisture content (MC) on germinability. Exogenous application of GA₃ and of GA₄ promoted germination and increased the germination rate. Moist cold-stratification at 5°C also promoted germination; the longer the stratification period, the faster the rate of germination. More than 70% of seeds (fresh seeds, MC=37.6%) dried to an MC of 6.4%, 8.5% and 25.5% (fresh weight basis) retained germinability after a 1-month storage at 5°C, whereas germination percentage decreased to 0-2% after a 12-month storage at the same temperature. Germination percentage of seeds dried to the same MC and stored at 15°C decreased to 0% after 8 months, whereas seeds stored at -20°C did not germinate even after just 1 month of storage. The present evidence suggests that seeds of D. glaucescens have intermediate rather than orthodox or recalcitrant storage behaviour.