抄録
1. The germination charctores of 29 kinds of herbaceous flower seeds were studied during the period of 1 to 5 months after harvests. According to their degree of dormancy, they were classified to the following three categories.
a) kinds which have no dormancy: Aster, Dianthus, Gaillardia, Gypsophila, Stock.
b) kinds which exhibit weak dormancy: Balsam, Calliopsis, Cosmos Orange Flare, Godetia, Helichrysum, Kochia, Pyrethrum, Sweet Willium, Vinca.
e) kinds which exhibit somewhat stronger dormancy: Amaranthus, Celosia, Cleome, Coleus, Cosmos late-flowered, Digitalis, Euphorbia, Pansy, Petunia, Phlox, Portulaca, Salvia, Snap-dragon, Torenia, Viola.
2. As the seeds awaked from the dormancy in dry storage conditions, both the germination percentage and germination speed became greater graduatedly. In general, freshly harvested seeds had a narrow requirement of temperature for their germination, but they were found to be able to germinate over a wide range of temperature with their aging.
3. The effective treatments for breaking the dormancy were alternative temperature (20°C, 16 hrs. and 30°C, 8 hrs.), prechilling, 0.2% potassium nitrate, 0.2% thiourea, light and their combination. The degree of their effectiveness varied with kinds and their seed age.
4. Among the treatments used, 0.2%, potassium nitrate was most effective for the most kinds of herbaceous flower seeds; 0.2% thiourea produced abnormal seedlings in many cases, and depressed the germination rate in some.
5. Light promoted the germination of Coleus, Digitalis, Helichrysum and Petunia seeds during their dormancy, while light depressed the germination rate of Amaranthus seeds. The degree of light sensitivity decreased graduatedly during their dry storage period in above both cases.
6. In general, treatments for breaking the dormancy were necessary only in the case of germination test and unnecessary in the seeding. However, Portulaca and Cleome remained dormant until the next seeding season.
