Phytoremediation Potential and Nutrient Status of Barringtonia acutangula Gaerth. Tree Seedlings Grown Under Different Chromium (CrVI) Treatments

To investigate the effect of different chromium (CrVI) treatments on seedlings of semi-aquatic plant Barringtonia acutangula, hydroponic experiments were conducted. Results revealed that B. acutangula could tolerate much higher CrVI concentration accumulated about 751–2,703 mg kg^?1 dry weight in roots and 50–1,101 mg kg^?1 dry weight in shoots, respectively, under 1.0, 2.0, 3.0, 4.0, and 5.0 mM chromium treatments. CrVI exposure at 1.0–4.0 mM does not exhibit toxicity signs; however, up to 4.0 mM CrVI exposure causes significant decline in growth parameters. Content of macronutrients such as Ca and K decreased under different Cr treatments in roots and shoots, while Mg content of roots and shoots did not influence at the range of 1.0–4.0 mM Cr; however, significant decrease at 5.0 mM Cr, besides P content, significantly shows increasing trends, respectively. Interestingly, sulfur content of roots and shoots show increasing trends at 1.0–2.0 mM Cr; however, severe decrease of up to 3.0–5.0 mM is shown in CrVI treatments. Furthermore, micronutrients content were enhanced under CrVI treatments excluding Cu and Fe since they show significant reduction in shoots as well as in roots. Bioaccumulation factor were also calculated on the basis of results obtained which shows the value of >1 without viewing chromium toxicity symptoms. This study demonstrated that B. acutangula could tolerate CrVI concentrations up to 1.0–4.0 mM Cr which may be useful in chromium phytoremediation programs.