Exposing Viburnum edule seeds to a sequence of temperatures affects the germination characteristics

For many species of Viburnum, exposure to two distinct stratification sequences -warm to cold or cold to warm -may break embryo dormancy to initiate significant germination. Seeds of Viburnum edule were collected and moved through a series of cold-warm (4/20 degrees C) or warm-cold (20/4 degrees C) stratification to better understand precisely which temperature sequences and duration improve germination percentage (GRP), mean germination time (MGT), germination synchrony (SYN) and uncertainty (UNC), and time for seeds to reach 50% germination (t50). Seeds kept in cold-warm temperature sequences, on average, improved GRP by 24%, reduced MGT by 216 days and t50 by 97 days compared with those in the warm-cold stratification sequence. The warm-cold temperature sequence was more advantageous in improving the SYN (0.94 vs. 0.51) and reducing the UNC (0.21 vs. 0.96) indices than the cold-warm temperature sequence.