Benzylaminopurine [8-14C [carbon isotope]] translocation in Phaseolus vulgaris [kidney beans]

[8-14C]Benzylaminopurine (BA) translocation was studied in whole plants of Phaseolus vulgaris L. under three different light regimes (continuous light, 8-hour light + 16-hour dark, dark). Applications were made to the apex, to a cotyledonary leaf, or to the root system. Results showed that no BA basipetal translocation occurred, however BA is easily absorbed by the root system and is translocated acropetally. The amount of BA absorbed and its acropetal translocation rate depend on the light regime. The hypothesis of a passive cytokinin transport through the xylem, regulated by the transpiration stream, is discussed.