CADMIUM UPTAKE AND TRANSLOCATION DURING REPRODUCTIVE DEVELOPMENT OF PEANUT (ARACHIS-HYPOGAEA L)

The uptake and translocation of cadmium (Cd) by roots and below-ground developing reproductive structures of peanut (Arachis hypogaea L.) we re examined under controlled growth conditions. Specially designed pot s allowed separate Cd treatments of the root and fruit media to study uptake in both compartments. Results indicated uptake and translocatio n of Cd to various vegetative plant parts, reaching values close to 2. 0 mu g . g(-1) DW in roots, leaves, and petioles. Values recorded for seed of Cd-treated plants remained on average slightly lower (1.7 mu g . g(-1) DW). Only 18 % and 32 % of the Cd found in seeds and pod wall s, respectively, were directly taken up by the developing fruits. Upta ke also occurred via below-ground portions of gynophores with some Cd even entering above-ground portions of this plant organ. However, seed s and pod walls received 82 % and 68 %, respectively, of their Cd from roots via gynophores. Since gynophores and peanut fruits have an extr emely reduced xylem and a very large phloem, and since peanut fruits a re hardly capable of transpiration, it is suggested that the majority of Cd translocated to the fruits was transported in the phloem.