Background : Tetraploid plants are bigger in the size of fruits, leaves, stems, and roots than diploid plants due to bigger cells attributed to chromosome multiplication. The advantage of tetraploid plants includes breakdown of self-incompatibility and increase of disease resistance. This study was carried out to gain tetraploid resources for breeding of new boxthorn varieties having pest resistance, higher yield, and self-compatibility. Methods and Results : Tetraploid lines for this study were C0148-10 and C0412-1 from Cheongyang-jaerae (CJ), M0148-94 and M0148-120 from Myongan (MA), B0148-43 and B0148-78 from Bulro (BL), D0148-62 and D0148-72 from Cheongdae (CD), and Y0148-2 and Y0148-24 from Youngha (YH). Flower width ranged 13.2～17.4mm. Flower, pollen and anther were bigger than the mother plants. Pollen germination rate of the tetraploid lines ranging 36.1～58.8% was lower than mother plants (46.5～67.6%). Self-fertilization rate in 4 varieties, MA, BL, CD and YH was low as 1.3%, 4.0%, 1.4% and 4.7% respectively indicating that mother plants are self-incompatible. Self-fertilization rate in tetraploid lines was higher as 58.1～87.5% and B0148-43, M0148-120, and D0148-72 showed the highest self-fertilization rate over 80%. Conclusion : Tetraploid lines showed higer self-fertilization rate than mother plants that they were expected as valuable resources for new boxthorn variety having self-compatibility.

고감미 다수성 계통인 자가수정 스테비아의 hypocotyl 절편체를 이용하여 대량증식방법 개발에 대한 결과는 다음과 같다. 선발된 자가수정개체는 초장이 72.0~120.7 cm로 분포되어 있었고, 분지수는 4.9~56.6개로 분포되어 있었다. HPLC 분석을 통하여 rebaudioside-A(RA)성분이 평균함량 55.2%이상 함유된 자가수정 개체를 선발하였다. 스테비아의 hypocotyl 절편체를 이용하여 MS배지에 1.5 mg/L BA와 0.5 mg