Effect of toxic concentrations of Ni and Zn on growth and accumulation of these metals on six species from flora of Azarbijan

The effect of toxic concentrations of Ni and Zn (up to 100μM) on growth and metal accumulation was studied in some species from flora of Azerbaijan (Northwest of Iran) in a hydroponic experiment. Plant species including Cichorium intybus, Secale montanum, Dactylis glomerata, Salvia sclarea, Alyssum strigosum and Silene compacta are either from important elements of heavy-metal rich soils of Azerbaijan or are excluded from these areas. Growth data of shoot and root showed that Secale montanum is an extreme tolerant species to toxic concentrations of Ni, but Cichorium intybus and Silene compacta are highly susceptible species with growth inhibition of up to 90%. Shoot concentration of Ni in Alyssum strigosum and Silene compacta reached up to 2 mg g-1 DW being lower than the standard value of Ni-hyperaccumulation, but indicating a high accumulating potential for Ni in these species. Growth of Secale montanum and Salvia sclarea was not inhibited by Zn concentration of 100 µM in the medium, in contrast Silene compacta was the most susceptible species for Zn with 80% reduction of shoot growth. Similar with Ni, Alyssum strigosum and Silene compacta showed the highest accumulation of Zn in leaves (up to 1.1-1.7 mg g-1 DW), however, this amount was much lower than critical value for Zn hyperaccumulators (10 mg g-1 DW). In this work, no relationship was found between growth response of plants and heavy metal accumulation in leaves, so that, exclusion and inclusion were observed in both tolerant and susceptible species to Ni and Zn.