Abstract: | Plants were allowed to assimilate 14CO2 for 30 min at 5, 15,25, and 35 °C. The changes in 14C content of a mature expandedleaf (Leaf 4), young apical leaves, and storage root, were sequentiallyfollowed over a subsequent period of 24 h in continuous light.In a second experiment plants were transferred after 14CO2 assimilationto temperatures of 10, 18, 26, and 34 °C, and the partitionof 14C between the ethanol-soluble and ethanol-insoluble fractionsof the roots and leaves was followed over a period of 72 h. The specific activities of the apical leaves and of the storageroot increased to a maximum 2 h after labelling at 25 °C,4 h at 15 and 35 °C, and 6 h at 5 °C suggesting thatthe optimum temperature for translocation of photosynthate wasabout 25 °C. The 14C partition to ethanol-soluble and ethanol-insoluble fractionsof the roots and leaves was largely attained in. 9 h. Littlerepartition of 14C assimilate fractions occurred as a resultof temperature change or growth. Root ethanol-insoluble activity,however, did increase significantly over the 72-h period : possiblecauses of this slow incorporation and their relevance to themechanism of sugar storage are discussed. |