Figure 3. Sucrose (a), fructose (b) and glucose(c) in the dry matter of cassava leaves; sucrose (d), fructose(e) and glucose (f) in the sap of cassava stem phloem; and sucrose (g), fructose (h) and glucose (i) in the dry matter of cassava roots.

Plants of the same size were chosen. Leaf tissue samples (not including petioles) from the sixth leaf down from the top of each plant were used. For assay of sugars in the sap of stem phloem, stems within 10–20 cm above the ground were ring-cut at 10 a.m. with a scalpel, and the phloem sap flowing from the wound was collected with a pre-chilled plastic syringe of a syringe needle. The roots were fibrous roots at the first two growth stages of ‘seedling’ and formation of root system, and the storage roots at the other two growth stages of root bulking and starch maturity. For analysis, root tissues were taken from whole fibrous roots or from the middle sections of the storage roots. Each datum was the mean ± SD from three individual plants. Different letters on the columns indicate the statistical difference at p < 0.05. F01, cassava cultivar Fuxuan 01. H124, cassava cultivar Huanan 124.