Effect of EDTA chelating on bioccmulation of lead ion in alfalfa plant ( medicago astiva L.)

Abstract

The study was conducted at plant physiology laboratory, department of biology, college of education for pure sciences, university of Basrah, at the period from 2/6/2019 till 1/11/2019 in order to evaluate the efficiency of alfalfa plant (Medicago sativa L.) for bioaccumulation of lead ions and to study the role of the chelating agent ethylene diamine tetraacetic acid (EDTA) in the accumulation process.Seeds of local variety of alfalfa plant were planted in plastic pots (16x16) filled with a mixture of sand and peat moss at ratio of 1:1 on volume basis. Lead as lead nitrate (Pb(NO3)2) was added alone to the pots at concentrations of 0 (full strength Hoagland nutrient solution), 0.25, 0.5 and 0.75 mM or in interaction with EDTA at concentrations of 0, 5 and 10 mM. The experiment continued for sixteen weeks after which the following results were estimated:Increasing lead nitrate concentrations or its interactions with EDTA cased a significant increase in lead ions accumulation in alfalfa plant roots, the same results were estimated in plant shoots.There were no significant changes in chlorophyll a and b resulting from increasing lead nitrate concentrations or its interaction with EDTA. A significant increase in proline (free amino acid) concentrations were seen regarding to increasing lead nitrate concentrations or its interactions with EDTA, the highest proline concentration was at 0.5 mM of lead nitrate alone, and in interaction with 10mM EDTA x 0.5 lead nitrate. The results showed that increasing lead nitrate concentrations or its interactions with EDTA caused a significant increase in the values of translocation factor (TF) and in bio- concentration factor (BCF) comparing with control..