EFFECT OF LIMING ON TRACE-ELEMENT INTERACTIONS IN PLANTS

Abstract

Corn (Zea mays L. cv. Golden Cross N. C.) and soybeans (Glycine max L. Merr. Bragg iron-inefficient cv. PI 54619–5–1 or T203) were grown in soil contaminated with combinations of Co, Ni, Cd, Li, Zn, and Cu in Yolo loam soil with and without lime amendment. The objective was to further test the ability of lime (increased soil pH) to protect plants against additive and synergistic effects of excesses of combinations of multiple trace elements applied simultaneously. With soybeans, the liming changed some additive and synergistic effects to those of protective, but not in all cases. With one combination of trace elements the effect was protective with or without liming. With corn, the interactions tended to be protective without the liming, but liming tended to decrease the protective nature of the interactions. The effect of protection was characterized by one of the various trace elements causing an antagonism against the other, and not necessarily due to the decreased uptake resulting from liming. The combinations of various trace metals tended to decrease Mn uptake, which ameliorated a slight Mn toxicity. This was one mechanism of protection. The trace elements, especially in combination, decreased considerably Fe concentration of soybean leaves; but the effects were different for corn. Some of the combinations of multiple trace elements resulted in decreased Ca concentrations in leaves of plants. Cadmium and often Zn concentrations in corn were higher with liming than without, contrary to most published results. Without liming, the high Mn hindered Cd and Zn uptake; liming decreased Mn uptake and also the interaction with Cd.