Wheat breeding in China over the past 80 years has increased grain zinc but decreased grain iron concentration

•Field trials were conducted using 154 wheat cultivars and 138 landraces.•Yield dilution effect was strong for grain Fe but was relatively weak for grain Zn.•Cultivars bred since 1933 had similar grain Zn but lower grain Fe than landraces.•Wheat breeding in China since 1933 has enhanced grain Zn but reduced grain Fe.