Scholarly record

CADMIUM AND LEAD ACCUMULATION AND ANATOMICAL CHANGES IN ROOTS OF VICIA FABA UNDER HEAVY METAL CONTAMINATION

Vita Alle

Abstract

Nowadays, it is important to pay attention to soil contamination with heavy metals, especially in agricultural soils, because heavy metals taken up by crop plants can affect human health. The aim of this study was to investigate the impact of substrate contamination on cadmium and lead accumulation in field bean (Vicia faba L.) and to specify changes in root anatomical structures. The vegetation experiment was carried out under controlled conditions. Changes to the above mentioned parameters were investigated at 0, 10, 15, 20, 25 mg L-1 of cadmium added as Cd(NO3)2 · 4H2O solution in substrate and at 0, 200, 400, 600, 800, 1000 mg L-1 of lead at the first day of the experiment added as Pb(CH3COO)2 · 3H2O solution in substrate. Throughout the experiment lead level in substrate was gradually added after every sample collecting day, reaching the maximal content 2000 mg L-1. The level of cadmium and lead in the air-dry plant material were estimated by an atomic absorption spectrometer. To study changes in root anatomical structures cross sections were cut using microtome and stained with Astra Blue-Safranin for observations using a light microscope. Cadmium and lead were mainly accumulated in roots of V. faba: at the last day of the experiment (35th day) reaching cadmium 833 mg kg-1 (dry weight) and lead 13400 mg kg-1 at the highest level of pollutants in substrate (cadmium 25 mg L-1 and lead 2000 mg L-1, respectively). While on the same day the amount of cadmium in the leaves reached 23.5 mg kg-1 and lead 99.0 mg kg-1. Earlier development of root secondary structure of treatment variant plants compared to control variant plants was observed under the influence of cadmium and lead contamination in substrate. There was also lignification of pith cell walls observed due to heavy metals contamination. Thus, field beans could be used efficiently for greening and recovery of agricultural areas (soils), which are located close to roads/highways, as well as field beans could be used for remediation process as hyperaccumulants.

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