Abstract

A hydroponic greenhouse study was carried out to evaluate the effects of increasing cadmium (Cd) concentration on plant growth, mineral nutrition and Cd distribution of H-250 sunflower genotype. Exposure to increasing Cd concentrations reduced plant biomass by 40, 34, 47 and 42% of the total, leaves, stem and roots dry weights as compared to the control. Regardless of the treatment most of Cd uptake by the genotype was allocated in the root, followed by leaf and stem. The higher bioconcentration factors values in both above ground and underground plant tissues and low transfer factor value indicated that this genotype may be an alternative for use in phytostabilization programs. The results also showed that increasing Cd concentration disrupted plant homeostasis as it increased the concentration of some nutrients and had adverse effect on others, impacting plant growth. In this context, the results suggest that the low magnesium, iron and manganese concentrations in the leaves were the main cause for plant biomass reduction and leaf chlorosis and necrosis, as each one of these elements plays a key role on the chlorophyll molecule and on photosynthesis process.

Key words: Bioremediation, bioaccumulation factor, heavy metal stress, Helianthus annuus, transfer factor.