This study was conducted to obtain some fundamental informations concerning inheritance, physiology and breaking of seed dormancy in Raphanus sativus L. Three cultivars different in the degree of dormancy were crossed in all possible combinations including reciprocals and the intensity of dormancy of each combination was checked.
To obtain an effective method of dormancy breaking, the dormant seeds were treated with several alkalic, acidic solutions and a few regulators. The results were as follows;
1. Germination percentage of three varieties used, shown immediately after harvest, was following; Joongkook Moo (A): no germination, Minongjosyeng Moo(B): 60% germination, Jinjoo-daipyong Moo(C): 80% germination.
2. The degree of dormancy was markedly affected by maternal factors; the degree of dormancy of combinations Joongkook Moo x Minongjosyeng Moo, Joongkook Moo x Jinjoodaipyong Moo were deeper than combinations of Minongjosyeng Moo x Joongkook Moo, Jinjoodaipyong Moo x Joongkook Moo.
3. The dormancy period after harvest varied according to combinations; the dormancy period for combinations of Joongkook Moo x Minongjosyeng Moo, Mingjosyeng Moo x Joongkook Moo were longer than those of Joongkook Moo x Jinjoodaipyong Moo and Jinjoodaipyong Moo x Joongkook Moo. Selfed seeds of Joongkook Moo had about three months dormancy period.
4. Radish seed dormancy occured as a combinations of such parts of seed; seed coat, cotyledon and embryonic axis.
5. Embryo dormancy appeared from early embryo stage (10 days after pollination) and genetically shown incomplete dominance.
6. Except thiourea, all chemicals (hydrochloric acid, sulferic acid, potassium phosphate, potassium hydroxide, sodium hydroxide) were effective on breaking seed dormancy at 0.01 and 0.001N levels. Among growth regulators tested (GA₃, NAA, IAA) only gibberellin had prominent effect in breaking the dormancy of radish seeds regardless its concentration.
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