High levels of four heavy metals on the iron status of plants

Abstract
Bush beans (Phaseolus vulgaris L. cultivar Improved Teadergreen) were grown for three weeks in a simulated calcareous soil (Yolo loam + 2% CaCO3) with Co, Ni, Zn, and Cu applied as sulfates at the rate of 1000 ppm metal on the dry soil basis. Iron at 5 ppm as FeEDDHA (ethylenediamine di(o‐hydroxyphenylacetic acid)) was applied to half the plants to test its ability to overcome any of the apparent Fe deficiency induced by heavy metals. Cobalt and Ni were the most toxic of the four metals; Cu was next with only mild effects due to Zn. Copper decreased Fe concentration in shoots while Ni increased it. Nickel decreased Mn in shoots; Zn and Co increased Mn in shoots. The FeEDDHA overcame none of these toxic effects of heavy metals even though the symptoms were similar to those of Fe deficiency. Nickel decreased the total quantity of cations in leaves.