Comparison of soil and foliar zinc application for enhancing grain zinc content of wheat when grown on potentially zinc-deficient calcareous soils.

BACKGROUND: The concentration of Zn and phytic acid in wheat grain has important implications for human health. We conducted field and greenhouse experiments to compare the efficacy of soil and foliar Zn fertilisation in improving grain Zn concentration and bioavailability in wheat (Triticum aestivum L.) grain grown on potentially Zn-deficient calcareous soil. RESULTS: Results from the 2-year field experiment indicated that soil Zn application increased soil DTPA-Zn by an average of 174%, but had no significant effect on grain Zn concentration. In contrast, foliar Zn application increased grain Zn concentration by an average of 61%, and Zn bioavailability by an average of 36%. Soil DTPA-Zn concentrations varied depending on wheat cultivars. There were also significant differences in grain phytic acid concentration among the cultivars. A laboratory experiment indicated that Zn (from ZnSO4 ) had a low diffusion coefficient in this calcareous soil. CONCLUSION: Compared to soil Zn application, foliar Zn application is more effective in improving grain Zn content of wheat grown in potentially Zn-deficient calcareous soils.

Impacts of phosphorus and zinc levels on phosphorus and zinc nutrition and phytic acid concentration in wheat (Triticum aestivum L.).

BACKGROUND: Zinc (Zn) and phytic acid content in grain crops are directly related to their nutritional quality and therefore human health. To investigate the nutritional influences of phosphorus (P) and Zn levels on wheat (Triticum aestivum L.), plants were grown hydroponically to maturity in chelator-buffered solutions. RESULTS: Appropriate amounts of P, coupled with sufficient Zn, increased P and Zn concentrations in wheat grain. The Zn supply decreased both phytic acid and the molar ratios of phytic acid to Zn in wheat grain with respect to the Zn(0) treatment. Furthermore, proportions of Zn and P content in the grain relative to that of the whole plant were improved. With increasing P, the proportion of Zn and P content in the grain relative to the whole plant decreased. P and Zn acted antagonistically in roots. Excess P inhibited Zn uptake in roots, while Zn decreased the transfer of P from roots to shoots. For P that had been transported to the shoots, supplemental Zn facilitated its transfer to the grain. CONCLUSION: Excess P decreased the distribution of Zn in grain, while Zn enhanced the uptake of Zn and P in grain, The combined application of Zn fertilizer with the extensive use of P fertilizer can effectively increase the P and Zn concentration and Zn bioavailability of wheat grain, and hence Zn nutritional quality.