GROWTH OF RYE GRASS AND FESCUE AS AFFECTED BY LEAD-CADMIUM-FERTILIZER INTERACTION

Rye grass (Lolium perenne L.) and red fescue (Festuca rubra L.) were grown from seed in fertilized (NPK, 12:6:6) and unfertilized Flanagan silt loam soil treated with Pb (0, 10, 100, 1.000, 5.000, 10.000 μg g-1), Cd (0, 0.1, 1, 10, 50, 100 μg g-1), or a combination of Pb plus Cd at a ratio of 100 Pb:1 Cd. Plant growth and heavy metal content of plants were measured at the end of 3, consecutive, 10-day periods. Growth of Pb-treated plants did not begin to decrease until treatment concentrations reached 1.000 μg g-1 Pb or above. Above a treatment concentration of 1.000 μg g-1 Pb with or without added Cd, growth was reduced sharply in a log-linear fashion with increasing treatment concentrations. Some reduction in growth of plants treated with Cd alone occurred for fertilized fescue above 10 μg g-1 Cd but not for rye until treatments above 50 μg g-1. No reduction in growth was found for nonfertilized plants treated with Cd alone at the highest soil concentration (100 μg g-1). Reduction in growth for plants treated with Pb + Cd was no lower than that of plants treated with Pb alone. While fertilization stimulated growth at treatment concentrations < 1.000 μg g-1, it did not ameliorate the effects of Pb at higher concentrations. Fertilization reduced Pb content and uptake in rye (P < 0.001) but not in fescue. The Cd content of fertilized plants was greater (P < 0.05) than that of nonfertilized plants. Cadmium content of plants treated with Pb + Cd was greater (P < 0.05) than that of plants treated with Cd alone, while there was no difference in Pb content between Pb and Pb + Cd treatments.