Grain and shoot zinc accumulation in winter wheat affected by nitrogen management

Background and aims Nitrogen (N) nutrition is a critical factor in zinc (Zn) acquisition and its allocation into grain of wheat (Triticum aestivum L.). Most of the information collected about this topic is, however, derived from the pot experiments. It is also not known whether optimal N management by decreasing N input could affect the Zn status in grain and plant in the field. The aim of this research is to investigate the impact of N management on grain and shoot Zn status of winter wheat. Methods Field experiments were conducted in two cropping seasons. Results Results showed applying N at optimal rate (198 kg N ha(-1) in 2007-2008 and 195 kg N ha(-1) in 2008-2009) maintained or resulted in significantly higher grain Zn concentration and especially grain content of Zn compared to no or lower N treatments. For example, grain Zn concentration increased from 21.5 mg kg(-1) in the control to 30.9 mg kg(-1) with optimized N supply in 2007-2008 and from 24.7 mg kg(-1) in the control to 29.1 mg kg(-1) with optimized N supply in 2008-2009. Further increasing N supply from optimal to excessive N supply resulted in non-significant increases in grain Zn concentration and content. Generally, similar trends were also found in shoot Zn. Moreover, 72 % to 100 % of the shoot Zn requirement had been accumulated at anthesis, and accordingly 67 % to 100 % of grain Zn content was provided by Zn remobilization from pre-anthesis Zn uptake with N supply. Grain Zn accumulation mainly originates from Zn remobilization and the optimal N management would ensure better shoot Zn nutrition to contribute to increasing Zn remobilization from vegetative tissues and to maintain relatively higher grain Zn for better human nutrition