Abstract
SUMMARY: When 8‐day seedlings were exposed to14CO2in light, approximately 2 hours were required for14C to reach the apices of the roots. One method used to detect the progress of14C down the root was to scan the root with a radiochromatogram strip scanner. At this stage most14C in aqueous ethanol extracts of roots was present as sucrose, equally labelled in glucose and fructose. This was converted only slowly to other components of the soluble fraction so that after 12 hours almost 50% of14C was still retained in sucrose.14C exuded from intact roots into surrounding solutions was present in both volatile and non‐volatile compounds. In the non‐volatile fraction glutamine, glutamic and aspartic acids were the main14C‐amino acids. Exudation of14C was not affected by changing the inorganic composition of the collecting solution. A change in pH of collecting solution from 6.4 to 5.9 increased exudation. Exudation also increased markedly when 2,4‐dinitrophenol or potassium cyanide was present in the collecting solution.