Nodal sections of the winter-hardy 'John Franklin' rose cultivar from field-grown plants were cultured on a modified Murashige and Skoog (MS) nutrient medium. Very high levels of contamination from the surface of the initial sections required that plants be grown under greenhouse conditions. Rose plantlets obtained from subsequent subcultures were used for the first time in a radiotracer experiment with $ sp{32}$P to study the kinetics of phosphorus (P) uptake as a function of temperature of the nutrient medium. P uptake increased with time for rooted and non-rooted plantlets in a linear fashion that did not reach an equilibrium value even after 96 hours of exposure. An analysis of variance revealed that the plantlets with roots absorbed significantly greater amounts of P at the 0.01 level compared with non-rooted plantlets at 22$ sp circ$C. P uptake was significantly higher at the 0.05 level, for rooted versus non-rooted plantlets at 33$ sp circ$C. There was no significant difference in P uptake by rooted and non-rooted plantlets at 3$ sp circ$C. Interaction between time of exposures and rooting was found to be significant at 22$ sp circ$C and 33$ sp circ$C at the 0.01 level. The results indicated that the root system, previously thought to be inefficient in the nutrient absorption, played a key role in absorbing P from the nutrient medium at optimum temperature.

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