Physiological behaviour of four rapeseed cultivar (Brassica napus L.) submitted to metal stress.

Eliminating heavy metals in the environment by phytoremediation is a method that uses, generally, plants with a low biomass yielded and feeble depth of root system. For the purpose of improving this technique, we have tested four varieties of productive specie with high yields, the rapeseed (Brassica napus L.). In particular, we have studied metal stress effect on biomass, growth, and endogenous Zn and Cd content. Metal treatment caused significant dry weight differences between metal-treated and control plants. A significant genotypic difference has been noticed between the four cv. For two varieties, Jumbo and Drakkar, the accumulation is more important in the stems and petioles, whereas, this accumulation is at a maximum level in the root system for the two varieties, Cossair and Pactol. Chlorophyll and carotenoïd content, as well as lipid peroxidation, known as stress markers, were also evaluated. Metal treatment led to an increase in the amount of malondialdehyde (MDA) in the leaves. However, the increase of Zn and Cd levels in the tissue culture was followed by a decrease in the photosynthetic pigments.