Background : Recently new breeding goal setting is required to develop new boxthorn variety with superior treats of bigger fruits, higher yield in fruits and sprout, pest tolerance, higher medicinal functionality, and self-compatiblity. Various genetic resources also should be retained for this goal. This study was carried out to obtain boxthorn tetraploid for breeding resource. Methods and Results : Colchicine concentration and treatment time for polyploid induction were 0.1, 0.2, 0.4, 0.6% and 12, 24, 36, 48hours respectively. Polyploid was identified by chromosome numbering of individuals by aceto-carmine stain which were examined for polyploid by flow cytomertry(Partec, PA-1) in advance. Conclusion : When cuttings of Cheongyang-jaerae were treated by colchicine to induce tetraploid, survival rate decreased as colchicine concentration and treatment time increased. Rate of individuals having over 30 chloroplast number of stomata guard cell was highest as 37.5% in colchine 0.1% and 48 hours treatment. 8 of them were identified as polyploid by flow cytometry and tetraploid induction efficiency was highest as 6.0% in colchine 0.1% and 48 hours treatment. According to chromosome number examination, 3 of 8 individuals were aneuploid and 5 were tetraploid.

The effect of colchicine treatment on the agronomic performance and polyploid formation of Bupleurum falcatum using flow cytometry technique was investigated. The roots of 4-leaf stage plants were treated with colchicine (0.5%) for 3, 6, 12, and 24 hours and then transplanted in the field. Agronomic characters (survival rate, plant height, chlorophyll content, bolting rate) were recorded at 4 weeks and 6 months after transplanting while flow cytometry technique was conducted for determination of polyploid formation. Flow cytometry technique revealed polyploid nuclear DNA formation in colchicine treated plants. The highest number of polyploids was obtained at the shortest colchicine treatment time indicating an inverse relationship between colchicine treatment time and polyploid formation. Results also showed that survival and bolting rates were inversely related with the treatment time while plant height and chlorophyll were not significantly affected by the treatment. This study showed a convenient method for determination of colchicine-induced polyploid in B. falcatum and its superior agronomic performance at shorter treatment time.