Secondary dormancy imposition in pre-chilled, dried seeds of Douglas fir (Pseudotsuga menziesii) during storage

摘要

The aim of this study was to determine whether the benefits of pre-chilling were lost during drying at different temperatures and subsequent storage of Douglas fir (Pseudotsuga menziesii) seeds. Seeds were pre-chilled at the target moisture content (30-32%) for 32 weeks, dried down to storage moisture content (5-8%) in desiccators at a range of temperatures, and then stored at 4 degrees C for various intervals (0 to 64 weeks). At each storage interval, cohorts of seeds were incubated at a sub-optimal temperature (15 degrees C) to track the onset of secondary dormancy. After 8-weeks storage, most seeds germinated successfully without significant loss of pre-chilling benefits. Thereafter, germination decreased with increasing storage duration, that is, secondary dormancy was imposed during storage. Secondary dormancy imposition, however, coincided with increasing storage moisture content during storage. Storage moisture content, therefore, appeared to be the critical factor for the successful storage of pre-chilled, re-dried seeds.