Effet des métaux lourds dans les sols amendés en bentonite (Plomb) sur les caractéristiques biométriques et biochimiques chez quelques espèces d’Atriplex

Abstract

The objective of our work is to study the combined effect of lead and bentonite on the physiological and biochemical characteristics of two species of Atriplex: Atriplex halimus. L and Atriplex canéscens L. Sowing was carried out in plastic pots of 600g with a diameter of 10 cm. The gravel was deposited under the substrate ground of each pot in order to ensure a good drainage. The sandy substrate was treated with bentonite with amounts of 0%, 7% and 10%. The plant was stressed with lead amounts of 2000,5000 and 10000 ppm. The measured parameters are: chlorophyl, soluble sugars, the relative content water, the wet and dry biomass of the roots and shoots parts and accumulation of lead in the plants. The results obtained showed that the two studied species of Atriplex are resistant to lead with very high concentrations which can go up to 10000 ppm. It was also recorded that the metal stress involved physiological disturbances affecting chlorophyll. In addition the response of the plants to lead shows that soluble sugars and the relative water content not affected by the lead stress. The enrichment of the sandy grounds to amounts of bentonite 7% improves considerably the adaptation and the plants resistance against this abiotic constraint. The growth of the plant is very considerable in the amended sandy grounds with7% of bentonite. These two species have an important capacity of accumulation of lead in the roots and a weak translocation towards the air parts.