关键词: 序贯抽样。, 序贯抽样。

Abstract: Researching into starch content of stem apex in leaf-vegetable sweet potato, providing the theory basis for its rational use. Using leaf-vegetable sweet potato variety ‘Baishu No.1’ as materials, research on the change rules of starch content in different parts of stem apex of sweet potato and different harvesting period. The results showed that: there were significant difference of starch content in stem apex, leaf, stem and petiole in different picking time. The average starch content in different parts from big to small order was stem > leaf > petiole. The coefficient of variation descending order was leaf > stem > petiole. The highest the starch content of leaf occurred in first picking stage, and the lowest starch content occurred in the second picking stage. From first to fourth picking stage, starch content in leaves showed high → low → high → low trend. After the fourth stage, gradually increasing trend. The maximum of starch content in stem was occurred in seventh picking stage, the third picking stage was the lowest. Starch content of petiole in the picking stage of 1 to 3 was a slow downward trend as well as the stage of 4 to 6. The highest starch content of petiole was at 6 picking stage; the lowest was at 3 picking stage. Starch content of petiole in the picking stage 1 to 3 decreased slowly; but at stage 3 to 6, the starch content increased gradually; at stage 6 to 7, the starch content showed a rapid downward trend. There was a complex relationship between the change trend of starch content in leaves, stems and petiole, but showed a part of correlation.