Effect of copper carbonate and zinc oxide applied to seeds on copper and zinc uptake by maize seedlings

Abstract

Seed treatment is an interesting alternative to deliver micronutrients to field crops. The aim of this study was to investigate the uptake of Cu and Zn by maize seedlings, with the application of the water-insoluble sources copper carbonate and zinc oxide as seed treatment. Treatments were composed of a control (untreated seeds), five doses of copper (0.14, 0.28, 0.56, 1.12 and 2.24 mg Cu∙seed–1) and zinc (0.55, 1.10, 2.20, 4.40 and 8.80 mg Zn∙seed–1) as well as five doses of copper and zinc combined (0.14, 0.28, 0.56, 1.12 and 2.24 mg Cu∙seed–1; 0.55, 1.10, 2.20, 4.40 and 8.80 mg Zn∙seed–1). Plants were cultivated in sand, under greenhouse conditions and, at the two-leaf stage (15 days), the root and shoot tissues dry mass and concentration of Cu and Zn were determined, which allowed to calculate accumulation and uptake efficiency of these micronutrients by maize plants. Seed treatment with copper carbonate and zinc oxide increased both root and shoot concentration and accumulation of Cu and Zn in maize seedlings, with two fully expanded leaves. Cu tended to accumulate in roots, while Zn was more evenly distributed among roots and shoots. Combined application of copper carbonate and zinc oxide resulted in lower uptake of both Cu and Zn by maize if compared to individual applications, with Cu uptake reduced in a higher extent.