Toxicity symptom of micronutrients copper, magnesium and zinc were investigated for geranium, marigold, vinca and zinnia. Plants were grown in peat-lite mix in 11 cm plastic pots and watered with nutrient solutions containing 0.05, 0.5, 1, 5, 10 mM concentrations of Cu2+, Mg2+ and Zn2+. In most species, the concentrations of these micronutrients higher than 5 mM greatly reduced plant growth and induced stem and foliar toxicity symptoms. Toxic levels of Cu2+ and Zn2+ reduced plant and leaf sizes without producing leaf spots in all species tested. Toxicity symptom of Mn2+ were characterized by numerous chlorotic or brown leaf spots. Visual leaf toxicity symptoms of these 3 micronutrients in each species are illustrated.
If the inline PDF is not rendering correctly, you can download the PDF file here.