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Distribution of radiochromium at the plant and cellular levels varies with the chemical form added to the nutrient medium. Cr EDTA is less absorbed and metabolized by the roots than Cr +++ and CrO4--but its translocation rate is clearly higher.More than 99 percent of the Cr +++ and CrO4--absorbed remained bound in the roots and in the concentration range used absorption was proportional to the nutrient solution content.Protoplasmic fractions of roots contained the highest percentage of Cr +++ and CrO4--activities except when the level of Cr+++ added was 1 ppm (maximum permissible level for the cationic form). In that case cell wails constitute a serious barrier and like for Zn++ the mechanism of tolerance would reside in cation binding sites in the cell wall components.Cr is bound to the different proteins isolated from the protoplasm and the results obtained confirm the non-specificity of such a process.

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