Effects of stratification, temperature and light on seed germination of Colchicum macrophyllum B. L. !Burtt

Colchicum macrophyllum (Colchicaceac), a protected hysteranthous geophyte is being investigated as a potential floricultural crop. In its natural habitat it exhibits seed dormancy and low germination. Dormancy and seed germination of C. macrophyllum were investigated by seeds pre-treated for 4 or 8 weeks in wet vermiculite at 5 degrees C, 20 degrees C or room temperature (R.T.) (20 +/- 5 degrees C). The seeds were then incubated at 10, 15 or 20 degrees C in 12 h photoperiod or in darkness for 8 weeks. Seeds pre-treated at 5 degrees C for 4 and 8 weeks did not germinate under any of the treatments. However, pre-treatment at 20 degrees C or at room temperature for 4 and 8 weeks accelerated germination at 10 and 15 degrees C. Best results were recorded when seeds were pre-treated for 8 weeks at 20 degrees C and incubated at 15 degrees C (76%) or 10 degrees C (67%) in darkness. Light decreased germination percentage compared to darkness in all incubation temperatures. A possible explanation is that the embryo was not fully developed at the time of seed dispersal and a higher temperature for the pre-treatment favours its growth.