Abstract:

Two sweet sorghum varieties (XT-2 and T601) with seven different planting densities of treatments, were need to analyze the reducing sugar, total sugar content, sucrose content, activities of SS and SPS at different growing stages. The total sugar content in two varieties had the same, increasing tendency with the highest value at mature period.The reducing sugar content changed in a tendency of increasing maintaining decreasing in XT-2, and in a tendency of increasing, reducing in T601. The sucrose contents of the two varieties showed the same increasing tendency with the highest value at mature period. In addition to the density treatment B6 (6170 plants ha^–1), SS activity showed a tendency of rising-decreasing-hiding in T601, and no obvious changing hale in XT-2. Except for density treatment B2 (11 110 plants ha^–1), B4 (7929 plants ha^–1), SPS activity showed a tendency of rising-reducing-rising in XT-2, and no obvious rule in T601.For XT-2, the optimal density was 9250 plants ha^–1, the total sugar content was 14.2% (on a fresh matter basis), for T601 the optimal density was 11 110 plants ha^–1, the total sugar content was 14.31% (on a fresh matter basis). The latter is the best choice for total sugar accumulation. Activity of SS is decline, SPS activity Declined and increased. SPS activity in the full ripening stage are favorable to sugar accumulation. In this care, it is the best time for harvest.

Key words: Sweet sorghum, Plant density, Saccharide, Sucrose synthase (SS), Sucrose phosphate synthase (SPS)