Zinc (Zn)-phosphorus (P) Interactions in Two Cultivars of Spring Wheat (Triticum aestivum L.) Differing in P Uptake Efficiency

Abstract

Zinc-phosphorus (Zn-P) interactions were investigated in two wheat cultivars (Brookton and Krichauff) differing in P uptake efficiency. The experiment was carried out in a growth chamber. Rock phosphate or CaHPO4were used as P sources, and ammonium nitrate or nitrate only as nitrogen sources. Two Zn levels were used: 0.22 and 2.2mg ZnSO4.5H2Okg−1. The results confirmed that Brookton had a higher P uptake efficiency than Krichauff under low P conditions, irrespective of nitrogen and Zn supply. Zn supply had little effect on tissue P concentration and P uptake per unit of root weight in either cultivar, irrespective of nitrogen supply. An increase in P availability caused a significant reduction in Zn uptake per unit of root weight, and tissue concentration of Zn in both cultivars. The reduction in tissue Zn concentration cannot be explained entirely by a dilution effect. Zn uptake by, and Zn concentrations in, Brookton (with high P uptake efficiency) were significantly lower than those of Krichauff. Zn concentrations in Brookton were more sensitive to P uptake than those in Krichauff. It is suggested that high P uptake efficiency may depress plant uptake of Zn, and therefore cause a reduction in the concentration (density) of Zn in grains of wheats grown in low P (and possibly low Zn) soils.