Effects of forms and rates of potassium fertilizers on cadmium uptake by two cultivars of spring wheat (<italic>Triticum aestivum</italic>, L.): Fid-Bau Portal

Effects of forms and rates of potassium fertilizers on cadmium uptake by two cultivars of spring wheat (Triticum aestivum, L.)

Zhao, Zhong-Qiu / Zhu, Yong-Guan / Li, Hui-Ying / Smith, Sally E. / Smith, F.Andrew

Abstract

AbstractA greenhouse pot experiment was conducted to study the influence of potassium fertilizers in different forms and rates on cadmium (Cd) uptake by two cultivars of spring wheat (Triticum aestivum, L.): Brookton and Krichauff. Potassium fertilizers were added to soil at four levels: 0, 55, 110 and 166 mg K kg⁻¹ soil as KNO3 (N), KCl (C) or K2SO4 (S). CdCl2 was added to all the treatments at a uniform rate equivalent to 15 mg Cd kg⁻¹ soil. Plant shoot and root dry weights (DW) of both cultivars were reduced significantly by the addition of K-fertilizer in C and S treatments but there were only marginal changes in the N treatments. The Cd concentrations in shoots and whole plants increased significantly (P<.001) with increasing K addition, from 37.5 to 81.4 mg kg⁻¹ and from 42.9 to 86.8 mg kg⁻¹ for Brookton and Krichauff, respectively. However, no obvious effect was observed in the N treatments, except for the highest K level (K3) where there was a sharp increase in Cd concentration compared to the lower additions. Forms of K-fertilizers significantly influenced the Cd concentrations in plant shoots and roots (P<.001), but there was no significant difference between C and S treatments. This experiment showed that anions Cl⁻ and SO4²⁻ increase Cd uptake by plants, which can be interpreted as Cl⁻ and SO4²⁻ complexing readily with Cd²⁺ and thereby increasing the bioavailability of Cd²⁺ in soils. The effect of potassium itself on plant uptake of Cd was also observed. We suggest that when applying potassium fertilizer to Cd-contaminated soils, the forms and rates should be considered.