Zinc accumulation and remobilization in winter wheat as affected by phosphorus application

Abstract

Although the interaction between phosphorus (P) and zinc (Zn) in crop production has long been a focus of plant nutrition research, the effects of P on the Zn content of cereal crops remains unclear, especially in intensive agricultural systems with high rates of P application and low levels of available Zn. The current study of a high-yielding winter wheat system on the North China Plain compared the effects of P application (0, 25, 50, 100, 200, and 400kgha−1) on yield, biomass accumulation, Zn accumulation, Zn uptake during all crop stages, and Zn remobilization. In two growing seasons (2011–2012 and 2012–2013), the results indicated that P application significantly increased wheat grain yield and shoot biomass. Phosphorus application also significantly increased the P concentration and decreased the Zn concentration in shoots. Phosphorus application increased P accumulation (kg ha−1) throughout the growing season but the effect of P application on Zn accumulation (g ha−1) depended on crop stage. Zn accumulation increased with increasing P application rates at the jointing stage. Zn accumulation at the flowering and maturity stage increased with application of 25 and 50kgPha−1 but decreased with application of 100–400kgPha−1 in both cropping seasons. The Zn harvest index and the ratio of pre-anthesis to post-anthesis Zn accumulation were not greatly affected by P application rate. Zn remobilization into grain increased with application of 0–50kgPha−1 but then decreased with the further application of 50–400kgPha−1 in both cropping seasons. Overall, the effects of P application on Zn nutrition depended on P rate and crop stage. Lower P application rates (<50kgha−1) increased Zn accumulation especially after the flowering stage and increased Zn remobilization to grain. High rates of P (>50kgha−1), in contrast, significantly decreased Zn accumulation and remobilization in this high-yielding winter wheat system. The results indicate that optimal P management in intensive agricultural systems is needed to ensure both high wheat yields and high levels of Zn in grain required for human nutrition.