Potassium and storage root development: focusing on photosynthesis, metabolites and soluble carbohydrates in cassava.

The linkage between K and the development of storage roots in root crops is partially understood, hence this experiment determined some of the mechanisms involved in cassava. The effects of 10, 40, 70, 100, 150 and 200 mg K l^-1 fertigation on photosynthetic attributes, soluble carbohydrates, starch, metabolites, growth and yield were studied in a greenhouse. Storage root yield, number of storage roots, stomatal conductance and net photosynthesis reached maximum at 150 mg K l^-1 . However, soluble carbohydrates and starch in the leaves significantly declined with concentration of K solution. Similar to the trend of glycerol in the leaves. Conversely, malic acid, citric acid and propionic acid gradually increased reaching maximum at 150, 150 and 70 mg K l^-1 respectively. Combined the results suggest that these sugars were transported from the leaves to a stronger sink - the bulking storage roots. This and the increase of intermediate metabolites of TCA cycle provided the energy required for the bulking process and the development of the storage roots. Although the measured parameters link K indirectly to storage root development, they nonetheless form a basis for extensive studies into direct interactions. This article is protected by copyright. All rights reserved.