Zinc Extraction potential of two common crop plants, Nicotiana tabacum and Zea mays

A field study was conducted to investigate the efficiency of Zn phytoextraction by Nicotiana tabacum and Zea mays from a soil that had been artificially contaminated by different amounts of ZnSO4 (0, 50, 150, 350, 750 and 1550 mg kg−1 soil) 10 years prior to the present cropping. Increased NaNO3-extractable Zn in soil translated well into shoot concentrations (dry matter) in plants. Zn uptake by Z. mays increased linearly with increasing NaNO3-extractable Zn in soil, while for N. tabacum the increase could be described by a Langmuir isotherm. While Z. mays showed no significant decrease in biomass production up to the highest contamination level in soil, N. tabacum responded with a reduction of plant growth of about 50% compared with control plants at the highest Zn concentrations in soil. Maximum removal of Zn was 13 kg ha−1 y−1 with Z. mays and 11 kg ha−1 y−1 with N. tabacum. Calculated time required to reduce soil Zn from 350 to 150 mg kg−1 was about 55 years for N. tabacum and about 63 years for Z. mays at a soil pH of 4.8. At higher soil pH of 6.0 calculated decontamination time was about 87 years for N. tabacum and more than 200 years for Z. mays. Only small amounts of Zn were translocated into the seeds of N. tabacum and cobs of Z. mays. Therefore, corn cobs of Z. mays could be safely used for fodder and the seeds of N. tabacum, which are rich in oil, for industrial purposes, e.g. in the paint industr