Corn grain yield is very responsive do Zn in Brazilian soils. A greenhouse experiment was conducted in the Crop Science Department of the Botucatu College of Agricultural Sciences to compare sources of Zn and their application to corn. Three plants were grown up to 45 days in 10 L pots filled with a Dark Red Latosol (Acrortox, 22% clay). The soil was limed to 70% of base saturation. Zinc was applied to corn seeds (90 g ha-1), in the seed furrow, blended with the basal fertilizers (5.3 kg ha-1) or incorporated to the soil (5.3 kg ha-1) as zinc oxide, zinc sulphate, EDTA-Zn and lignosulphonate-Zn. The seed treatment was effective in supplying Zn during early growth of corn. The incorporation, irrespective of Zn source, as well as the chelate sources led to higher Zn availability to the plants. The corn root system was decreased when Zn availability was too high. The 5.3 kg ha-1 rate of Zn as EDTA or lignosulphonate, when applied in the seed furrow, is phytotoxic to corn plants.
EDTA; lignosulphonate; micronutrients; root; zinc oxide; Zea mays; zinc sulphate