TEMPERATURE AND SEED MOISTURE GOVERN STORAGE DURATION AND GERMINATIONOF PHLOX-DRUMMONDII

Phlox drummondii Hook seed germinated well over a wide range of consta nt or alternating temperatures. Germination percentages at constant te mperatures of 10 to 25C ranged from 94% to 98% for 'Light Salmon' and from 83% to 88% for 'Deep Salmon'. No seeds germinated at constant 30C . Total germination percentages at alternating temperatures ranged fro m 93% to 99% for 'Light Salmon' and 67% to 82% for 'Deep Salmon'. For both cultivars, the number of days to 50% of final germination (T50) a nd between 10% and 90% germination (T90 - T10) decreased as constant t emperatures or the median for alternating temperatures rose from 10 to 20C. The seeds had only limited desiccation tolerance. Reducing the m oisture content of stored seed from 9% to 5% did not reduce total germ ination significantly, but 5% to 6% seed moisture levels increased the days to T50 and T90 - T10 compared with higher moisture contents. The relative humidity and temperature that phlox seed received during lon g-term storage influenced germination. After seed was stored at 5C, ge rmination generally was higher, earlier, and more uniform than after s torage at 15 or 25C. The highest total germination percentages and sho rtest T50 and T90 - T10 occurred following storage for 12 months at 5C and 20% to 40% relative humidity.