Garden pansy (Viola × wittrockiana Gams.) – a good candidate for the revitalisation of polluted areas

Abstract

In the current studies, heavy metal tolerance level, accumulation efficiency and sexual reproduction were determined in Viola × wittrockiana, a non-metallophytic ornamental cultivar in comparison to V. tricolor, a metallophyte, after zinc (Zn) or lead (Pb) treatment (0, 10, 100 and 1 000 ppm) in pot experiments. The seed germination frequency that was not reduced in comparison to the control, the effective Zn absorption from the soil and exclusion strategy for Pb, as well as the regular sexual reproduction of V. × wittrockiana treated with heavy metals all indicate the tolerance of this plant to heavy metals. The lack of a seed set under experimental conditions of V. × wittrockiana was due to the absence of pollinators, rather than the negative impact of heavy metals, as pollen viability and ovule  development were normal under the treatments. The results indicate that V. × wittrockiana represents similar tolerance to Viola metallophytes and could be considered as a good material for the reclamation of polluted areas. The exceptional tolerance to heavy metals, the ability to initiate new generations in heavy-metal-burdened soil, which are additionally coupled with the unique beauty, make the garden pansy a good candidate to be potentially used in the future for phytoremediation purposes.