Effect of iron level on trace metal stress in bush bean plants grown in solution culture

Bush beans (Phaseolus vulgaris L. cv. Improved Tendergreen) were grown in nutrient solutions with levels of Cu, Zn, Ni, Cd, Co, and Mn at or near the stress point and with a high and a low level of Fe supplied as the chelate Fe EDDHA. No Fe deficiency was present on the control plants at the low Fe level. The Cu resulted in severe stress at low Fe and none at high Fe. The Zn resulted in severe stress at the low Fe level and in considerable stress at the high Fe level. The Ni resulted in a slight stress at the low Fe level and in no stress at the high Fe level. The Cd resulted in severe stress at both Fe levels. The Co resulted in severe stress at low Fe and in moderate stress at the high Fe level. The Mn resulted in considerable stress at the low Fe level and in no stress at the high Fe level. Thus no two metals behaved similarly at the levels used. The Cu, Zn, Cd, and Co resulted in low Fe concentrations in trifoliate leaves on plants supplied low Fe but only Cd resulted in low Fe concentrations in plants grown with high Fe. These results with Fe were also quite similar for primary leaves. The high Fe level suppressed Ni, Cd, Cu, and Mn concentrations in leaves but not those of Co and Zn. Manganese was the only element in excess which accumulated in primary leaves to a large extent. Trace metals often decreased Ca levels in leaves which resulted in some increase in K.