Effects of Forms and Rates of Zinc Fertilizers on Cadmium Concentrations in Two Cultivars of Maize

Abstract

A pot experiment was conducted to investigate the effects of three soluble zinc (Zn) fertilizers on cadmium (Cd) concentrations in two genotypes of maize (Zea mays): Jidan 209 and Changdan 374. Zinc fertilizers were added to soil at four levels: 0, 80, 160, and 240 mg kg−1 soil as nitrate [Zn(NO3)2], chloride (ZnCl2), and sulfate (ZnSO4). Cadmium nitrate [Cd(NO3)2] was added to all the treatments at a uniform rate equivalent to 10 mg kg−1 soil. The biomass of maize plants was increased with the application of three zinc fertilizers, of which Zn(NO3)2 yielded more than others. Under ZnCl2 treatment, plant growth was promoted at the lower level and depressed at the higher one. All the three fertilizers decreased Cd concentration in shoots in comparison with treatments without Zn, but there were variations with different forms, especially in plants treated with Zn(NO3)2, which had the minimal value. The orders of average Cd concentration in shoots with different zinc fertilizers were ZnSO4>ZnCl2>Zn(NO3)2 for Jidan 209 and ZnCl2>ZnSO4>Zn(NO3)2 for Changdan 374, respectively (P<0.001). There was no significant difference between ZnSO4 and ZnCl2 treatments. The lowest Cd concentration in shoots was found in the 80‐mg‐kg−1 soil or 160‐mg‐kg−1 soil treatment. Cadmium concentration in roots in the presence of ZnCl2 was the lowest and under ZnSO4 the highest. The mechanism involved needs to be studied to elucidate the characteristics of complexation of Cl− and SO4 2− with Cd in plants and their influence on transfer from roots to shoots.