Influence of root temperature on uptake and accumulation of Ni and Co in potato

The impact of root temperature on Ni and Co concentration and accumulation has been studied in organs (roots, tubers, stems and leaves) of Solanum tuberosum L. var. Spunta plants. The response of foliar- and root-urease activity was also determined under the same conditions. Four different polyethylene plastic covers were employed (T1: transparent; T2: white; T3: coextruded black+white; T4: black), using uncovered plants as control (T0). The different treatments had a significant effect on mean root zone temperatures (T0 = 16 °C, T1 = 20 °C, T2 = 23 °C, T3 = 27 °C and T4 = 30 °C) and induced a significantly different response in the Ni and Co distribution in potato organs, since T3 (27 °C) gave higher concentrations of Ni in roots, leaves and tubers. The T1 (20 °C) registered the greatest Co concentration in leaves and roots, while T3 gave higher Co concentrations in tubers. The tubers proved to be the organs with the highest biomass and also the highest Co and Ni accumulation. With respect to the response of the urease activity as Ni-bioindicator, the root urease activity was higher in T1, whereas the leaf urease activity was higher in T3 and T4, coinciding with higher concentrations of leaf Ni. It is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction (phytoremediation) of elements.