Abstract: Two-year-old Platycodon grandiflorum was used as materials to study the allocation characteristics of soluble sugar and starch during the flowering and fruiting stage. The results showed that the contents of starch and soluble sugar in root decreased gradually and reached the minimum at 25 d after
flowering. The soluble sugar content in branches declined gradually at first and reached the minimum at 15 d after flowering, lately increased. The content of starch in branches showed significantly difference between
branches with flower and flower cutted-off. The content of starch in branches with flower appeared the trend of rise at first then dropping, while the starch content in branches with flower cutted-off showed significantly rising trend. The total soluble sugar content was higher in the leaves with flower cutted-off than that in leaves with flower. Compared with that at 17：00 on the previous day, after one night consumption, the total soluble sugar content in the leaves with flower cutted-off decreased obviously at 8：00, but the change in the leaves with flower was not obvious. The starch content in leaves appeared opposite tendency comparing with soluble sugar content. It was shown that starch in the root decomposed into soluble sugar and transported to the stem for temporary storage to meet the need of leaves, flowers and fruits development within 25 d after flowering, then the contents of starch and soluble sugar in root were increased. It is well indicated that the organic material made by aerial parts of plant transported to root and promoted root development at this stage.

Key words: Platycodon grandiflorum, starch, soluble sugar, allocation characteristic