STUDIES ON UPTAKE OF TRIVALENT AND HEXAVALENT CHROMIUM BY MAIZE (ZEA-MAYS)

Pot culture experiments were carried out to study the uptake and trans location of chromium from irrigation water when supplied in its trival ent and hexavalent states to maize plants grown in soil and sand cultu re. The uptake of chromium was observed to increase with increase in t he concentration for both oxidation states of chromium. For the root, the observed order of uptake was CrIII sand > CrVI sand > CrIII soil > CrVI soil, whereas in the lower shoot, upper shoot and fruit the orde r was CrVI sand > CrVI soil > CrIII sand > CrIII soil. Significantly h igh uptake of chromium by roots in the sand culture (CrIII treatment) is attributed to the effect of root exudates and degradation products on the mobilization of CrIII. In aerial parts of the plants a higher u ptake was observed when the initial supply was CrVI. The trends observ ed are explained on the basis of the redox behaviour of chromium.