Effects of Ni stress on the uptake and translocation of Ni and other mineral nutrition elements in mature wheat grown in sierozems from northwest of China

Effects of heavy metal on uptake of mineral nutrition elements in plants have attracted widespread interest and been widely explored. This paper reports the translocation and accumulation behaviors of Ni in the organs of mature wheat plants by means of pot experiment using the sierozem collected from northwestern China as experimental soil. Effect of Ni on accumulation of Cu, Mn, Ca, and Mg is also demonstrated. It was found that influence of Ni on wheat plants differed greatly at different Ni levels. Ni content in the organs of wheat plants increased with the increase in Ni level, and the increasing rate decreased when the Ni level was higher than 400 mg/kg. Ni was mainly accumulated in the roots and less distributed in the shoots, shells, and grains. When the Ni level was lower than 400 mg/kg, the bioconcentration factor (BCF) of the roots was higher than 1, suggesting that Ni was taken in against a concentration gradient. The average translocation factor (TF) of wheat plants was 0.221, indicating the weak ability of wheat plants in translocating Ni toward the aboveground parts. Since Ni is readily accumulated in the grains of wheat plants at lower Ni level, concerns in health risks might be raised. Excess Ni in wheat plants could inhibit the transfer of Cu, Mn, and Mg to grains, leading to the accumulation of Ca, Mg, and Mn in the shoots and shells of wheat plants. The increase in Ni content can disturb the uptake and distribution of mineral nutrition elements in the organs of plants, resulting in the toxic effect of Ni on wheat plants. Results from this study provide a scientific support to prevent or control heavy metal pollution in an arid region.