Seed Dormancy of Viola mandshurica and V. albida and Their Germination Characteristics by Seed Storage

The purpose of this study was to determine the seed dormancy types of Viola mandshurica and V. albida, and to investigate their germination characteristics during seed storage. V. mandshurica seeds were incubated at 25/15, 20/10, and 15/6°C with final germination rates of 86%, 66%, and 66%, respectively, indicating that these seeds have no physiological dormancy (PD). However, V. albida seeds were found to have PD, since germination hardly occurred during the 4-week experiment, and the final germination rate was 50% or less. When the seeds of V. albida were treated with GA3 1000 mg･L-1, the final germination rate was 100%. Moreover, the germination rate increased as the period of cold stratification for V. albida seeds increased. The germination characteristics of Viola seeds were also examined from seeds harvested in 2019. V. mandshurica seeds germinated at 25/15°C in one week, but the mean germination time decreased compared to seeds that were stored for 4 years. This shows that V. mandshurica has reduced seed viability during storage. V. albida seeds that were harvested in 2019 hardly germinated within the 4-week experiment, and the germination rate increased through cold stratification. Therefore, the seeds of V. mandshurica and V. albida do not change the seed dormancy type, but the seed viability might be affected by the type of long-term storage used.