Growth and mineral composition of nickel-stressed plants under conditions of supplementation with excessive amounts of calcium and iron.

This study investigated the effectiveness of excessive calcium (Ca) and iron (Fe) supplement nutrition in spinach Markiza F(1) cv. and sweet corn Zlota Karlowa cv. to alleviate nickel (Ni)-induced phytotoxicity. The following doses of the pollutant Ni were introduced: 0 (control), 40, or 60 mg Ni/kg growth medium. Two levels of calcium (Ca), 270 (basic) and 400 mg/kg (intensive), as well as two levels of iron (Fe), 10 (basic) and 20 mg/kg (intensive), respectively, were used. Intensive nutrition supplementation of Ni-stressed test plants species with Ca or Fe was beneficial as manifested by significantly increased maize shoots and roots biomass, lowered content of Ni in spinach and maize in above-ground parts, and decreased concentration of the pollutant in roots of intensive Ca-supplied maize plants grown in the environment containing 60 mg Ni/kg. Moreover there was significantly elevated Fe content in highly fertilized with iron spinach plants grown in the presence of 60 mg Ni/kg and in shoots of Ni-treated maize plants intensively supplied with Ca or Fe. Generally, high content of Ca or Fe in the growth medium significantly raised the content of free and bound Ca in shoots of Ni-stressed spinach plants. The same phenomenon was found in roots, but only in the presence of 60 mg Ni. Intensive nutrition supplementation of Ni-treated maize plants with Fe or Ca generally did not change the concentration of free Ca in plant organs, but elevated bound Ca levels in roots was observed. Increased bound Ca content was also found in leaves of maize plants intensive supplied with Ca. Thus, intensive Ca or Fe nutrition presents a promising potential for use in the conditions of Ni contamination by increasing plant growth, reducing Ni translocation from roots to shoots and raising the nutritive value of above-ground parts of spinach and maize plants.