Translocation at 0{degrees} C in Helianthus annuus

Potassium uptake by Helianthus annuus plants growing in waterculture was found to be closely dependent upon the translocationof sugar to the roots. This relationship was used to determinethe effect of cooling on the rate of translocation. A Q₁₀ ofapproximately 3 over the range 0–25° C was obtainedbut tracer experiments showed that translocation was not stoppedat 0° C. A complete recovery in translocation rate appeared to occurin some experiments after prolonged cooling. It is concludedthat this can only be satisfactorily explained on the assumptionthat carbohydrates move in the sieve tubes by mass flow. Thedriving force of such a mass flow is considered to be locatedin each sieve element.