Our previous studies suggested that increases in carbohydrate content may directly induce anthocyanin biosynthesis in B.semperflorens (Zhang et al., 2013, 2016). To investigate whether the reduced anthocyanin biosynthesis in seedlings grown at low temperature under long-day conditions was determined by carbohydrate insufficiency, we measured the total soluble sugar, sucroseand starch contents of the plants. As shown in Fig. 1B, at normal temperature, the short-day condition significantly increas edonly the total soluble sugar content compared to the contentin the long-day plants. At low temperature, the long-day condition did not significantly influence carbohydrate levels, but plants grown under the short-day condition showed significant increasesin their total soluble sugar, sucrose and starch contents. Further more, compared with the effects of normal temperature and the short-day condition, low temperature and the short-day condition had a greater effect on the starch content than on the total soluble sugar and sucrose contents. The starch content was increased by approximately 87.51%, whereas the total soluble sugar and sucrose contents were increased by 78.77% and 65.50%, respectively.