Interaction of Ni and Cu in accumulation in leaves of the Ni-hyper accumulator, Alyssum murale

Plants that can accumulate metals to exceptionally high concentrations in their shoots are so-called hyper-accumulators. To further quantify potential interactions between Ni and Cu, the Alyssuem murale grown in soils with factorial additions of NiSO4·6 H2O (0, 50, 250, 500 and 750 mg kg-1 Ni = Ni-T0, 50, 250 and 750) and/or CuSO4·H2O (0, 50, 250 and 500 mg kg-1 Cu = Cu-T0, 50, 250 and 500) salts were investigated. The experiments were carried out in pots in a greenhouse under controlled temperature, light conditions and ambient humidity. The test plants for biomass production were harvested three times; 30, 60 and 100 days after germination. Ni and Cu concentrations in the digests were determined by flame atomic absorption. The results showed that by each different levels of Ni, the maximum amount of absorbed Ni was achieved at 50 mg kg-1 Cu concentration. Also, with elevation of Cu concentration, Ni uptake decreased. These results indicated that the Ni-T750   and Cu-T50 at the third time period had the maximum average of 1585 µg kg-1 and was significantly different from the other treatments. The statistical analysis indicated that by the increased Ni levels from zero to 50 mg kg-1 in soil, the performance of the plant dry matter was significantly declined at the all Cu levels. In addition, by the Cu-T50   in the soil, the dry matter amount at the all Ni levels were higher than that of Cu-T0, although the differences were not significant (p < 0.05).