Department of Plant Sciences

The concentration of zinc (Zn) in wheat grain is frequently correlated with the concentration of sulphur (S). Many of the molecules that bind Zn or are involved in the acquisition and transport of Zn contain S or have the S-amino acid methionine as a precursor. However, the role of S nutrition on the deposition of Zn in wheat grain has not been examined. An experiment was conducted in which bread and durum wheat were grown at 2 levels of Zn (2.5 and 5.0 kg Zn kg-1) and 3 levels of S (15, 35 and 55 mg S kg-1). Biomass production and yield were not affected by the Zn and S treatments. Adding S increased the concentrations of Zn in the shoots and Zn in the grain and the concentrations of grain Zn and grain S were significantly correlated. Increasing S from 15 to 55 mg kg-1 raised grain Zn concentration by 40-50%. The S:Zn ratio in the grain did not vary with S (50, 47 and 50 at 15, 35 and 55 mg S kg-1, respectively), suggesting additional S increased Zn uptake and deposition in a proportional manner. Grain Zn concentrations were significantly correlated with the concentration of Zn in the vegetative tissue a month after sowing, which emphasises the importance of uptake as a foundation of high grain Zn. The experiment demonstrated for the first time that S can enhance the uptake of Zn under conditions when Zn is adequate for growth