Abstract
Water accumulation of the roots was reduced by enclosing them within an acrylic sleeve thereby restricting lateral growth. This study was carried out to investigate how restricting the uptake of water by fleshy turnip roots affects the accumulation and the concentration of sugars of that organ.
1. The sleeve reduced the volume of fleshy roots by 1/3 of that of the untreated roots. The dry matter, ethanol-insoluble solids, glucose and fructose contents expressed on a whole root basis were lower in the treated roots than in those of the control, but the level of sucrose in the treated and control roots was nearly equal. When the data are expressed on the ba-sis of water content in the roots, the growth restriction increased the concentrations of dry matter and sucrose but decreased those of glucose and fructose slightly. Hence, the total sugar concentrations of the treated and control roots were the same.
2. Sucrose concentrations were not different among the tissues outside (phloem) and just inside (outer xylem) the lateral cambium and the central cortex which indicate that the re-striction of root volume did not increase sucrose concentration in a particular tissue.
These results suggest that the accumulation of sugars depends on the accumulation of water in the fleshy turnip roots. Reasons why total sugar concentrations were not affected by the treatment are discussed in relation to sugar metabolism in the roots.
