AbstractThe discrimination between strontium and calcium is not only conditioned by the Sr/Ca ratio of the nutrient solution but also by the total dose (Ca + Sr) of the medium. The variation of the observed ratio in relation to the total dose is closely related with the Sr/Ca ratio of the solution. Sr is preferentially fixed by the roots when the Sr/Ca ratio of the solution is low; such a result is observed in the shoots for higher ratios. For all the treatments, the OR of the leaves is lower than unity (discrimination against strontium). When the stable strontium concentration of the solution is not detectable, an increase in the calcium concentration reduces the radiostrontium retention by the roots.