CADMIUM EFFECTS ON INFLUX AND TRANSPORT OF MINERAL NUTRIENTS IN PLANT-SPECIES

Solution culture experiments were conducted under controlled environme ntal conditions to determine the effects of cadmium(II) [Cd(II)I activ ity (0, 8, 14, 28, 42, and 54 mu M) on influx (IN) into roots and tran sport (?Ti) from roots to shoots of zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), calcium (Ca), magnesium (Mg), phosphorus (P), and sul fur (S) in ryegrass (Lolium perenne L.), maize (Zea mays L.), white cl over (Trifolium repens L.), and cabbage (Brassica oleracea var. capita ta L.). Shoot and root dry matter (DM) decreased with increased extern al Cd, and plant species differed extensively. Ryegrass and cabbage we re relatively tolerant to Cd toxicity compared to white clover and mai ze. Influx and TR of Cu, Zn, Fe, Mn, Ca, and Mg were lower with increa sing external Cd compared to controls, and species also differed. Infl ux and TR of P were enhanced in each species with up to 14 mu M Cd, de creased in white clover and cabbage at higher Cd levels, while in maiz e and ryegrass continued to increase as Cd increased. Influx and TR of S were high in white clover at 8 mu M Cd and decreased as Cd increase d. Influx of S was high in ryegrass, but TR of S remained relatively c onstant as Cd increased. Influx and TR of S did not significantly chan ge in maize, but decreased in cabbage as Cd increased. With Cd up to 1 4 mu M, decreases in both IN and TR of Zn, Fe, Mn, Ca, and Mg were gre ater in white clover than in cabbage. Sensitivity of the dicotyledonou s plant species to Cd toxicity might have been associated with Cd effe cts on IN and TR of Fe, Mn, Ca, and Mg. However, differences in plant sensitivities to Cd toxicity between ryegrass and maize were not refle cted in Cd effects on IN and TR of mineral nutrients.