Interpopulation variation in nickel hyperaccumulation and potential for phytomining by Odontarrhena penjwinensis from Western Iran

Abstract

The Ni hyperaccumulator Odontarrhena penjwinensis (Brassicaceae) is a species endemic to the ultramafic soils of Western Iran. Seven ultramafic outcrops and the populations of O. penjwinensis they support were investigated for Ni and other elemental concentrations to assess their potential for future Ni agromining operations. Nickel hyperaccumulation was confirmed in at least one individual plant sampled from all seven populations. The highest and lowest concentrations of Ni in leaves were recorded for two sites (3270 and 660 mg kg−1, respectively). The highest concentrations of Mn, Cr, and Co were 3110, 79, and 193 mg kg−1, respectively. A positive relationship was found between the concentrations of Ni and Fe, and Mg and Ca in roots and shoots. Correlation analysis of edaphic factors also revealed positive correlations between Ni concentration in the shoots, water-holding capacity, and soil pH, whereas it was negatively correlated for soil organic matter. The highest Ni yield (c. 0.4 g per plant), biomass (115 g per plant) and maximum plant height (43 cm) were recorded for one population where the total soil Ni concentration was 2550 mg kg−1. This O. penjwinensis population is likely to be a promising candidate for the development of Ni agromining in the region.