Trace enrichment of cytokinins from Douglas-fir xylem extrudate.

Quantitative trace-enrichment of cytokinins from a plant source (xylem sap from the Douglasfir, Pseudotsuga menziesii (Mirb.) Franco) has been achieved by adsorption onto octadecyl-silica columns followed by elution with ethanol. Adsorption is rapid and efficient and allows complete recovery of cytokinins at the nanomolar level. Douglas-fir sap contains at least four compounds having cytokinin activity, one of which co-elutes with zeatin and another with ribosylzeatin.