Phytotoxicity of cobalt, vanadium, titanium, silver, and chromium

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Abstract
The phytotoxicity of 5 non-essential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. cv. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Co was one of the more mobile of the 5 trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10-5 M) and 142 (with 10-4 M) .mu.g Co/g dry wt in leaves resulted in severe chlorosis. V as 10-4 M vanadate resulted in smaller plants, but not in chlorosis. Leaf, stem and root V, respectively, were 13, 8 and 881 .mu.g/g dry wt. Ti was somewhat mobile with considerable yield decrease at 10-4 M; leaf, stem and root Ti concentrations, respectively, were 202, 48 and 2420 .mu.g/g. Symptoms were chlorosis, necrotic spots on leaves and stunting. Ag was very lethal at 10-4 M AgNO3; at 10-5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem and root concentrations of Ag for this treatment were, respectively, 5.8, 5.1 and 1760 .mu.g/g dry wt. Plants grown with 10-5 M Cr2O7 were decreased in yield by about 25% with or without EDTA; the same level of Cr2(SO4)3 was essentially without effect. For the 2 salts, the leaf, stem and root concentrations for Cr, respectively, were 2.2 and 1.3, 0.7 and 0.7, and 140 .mu.g/g. Most of the trace metals had interactions in the uptake and/or distribution of other elements.