Effect of various application rates of phosphorus combined with different zinc rates and time of zinc application on phytic acid concentration and zinc bioavailability in wheat

Abstract

Imbalance and improper time of application disturb the availability of zinc (Zn) to crops. Less Zn intake due to over-application of phosphorus (P) deteriorates cereal grain quality due to the accumulation of phytic acid. Phytic acid causes many human diseases, especially in children. Furthermore, impairments in linear growth, learning ability and improper immune functioning in humans are also major side effects of Zn deficiency. Phytic acid has been of interest regarding a balanced intake of Zn, but the influence of phosphatic fertilizers and the time of Zn application have not received considered attention. Therefore, the current experiment considered the hypothesis that the balanced use of P fertilizers and the time of Zn application would improve Zn availability for human consumption and reduce the phytic acid concentration. Two Zn rates (5 kg/ha, 10 kg/ha) were applied at the tillering stage (TS) and booting stage (BS) of wheat under three P rates (60 kg/ha, 90 kg/ha, 120 kg/ha). The results confirmed that relative to 5 kg/ha Zn, 10 kg/ha Zn application at TS significantly improved grain Zn concentration (22%) and grain yield (16%). The highest application of P (120 kg/ha) enhanced 33% and 27% grain phytic acid at TS and BS, respectively. The increased level of Zn and P decreased the grain concentration of Ca. It was concluded that 90 kg/ha P with 10 kg/ha Zn at TS was the best combination to achieve a sustainable wheat grain yield with a minimum phytic acid content.