Inoculating Helianthus annuus (sunflower) grown in zinc and cadmium contaminated soils with plant growth promoting bacteria : Effects on phytoremediation strategies

摘要

Plant growth promoting bacteria (PGPR) may help reducing the toxicity of heavy metals to plants in pol-luted environments. In this work the effects of inoculating metal resistant and plant growth promoting bacterial strains on the growth of Helianthus annuus grown in Zn and Cd spiked soils were assessed. The PCPR strains Ralstonia eutropha (B1) and Chrysiobacterium humi (B2) reduced losses of weight in metal exposed plants and induced changes in metal bioaccumulation and bioconcentration - with strain B2 decreasing up to 67% Zn accumulation and by 20% Zn bioconcentration factor (BCF) in the shoots, up to 64% Zn uptake and 38% Zn BCF in the roots, and up to 27% Cd uptake and 27% Cd BCF in plant roots. The impact of inoculation on the bacterial communities in the rhizosphere of the plant was also assessed. Bac-terial community diversity decreased with increasing levels of metal contamination in the soil, but in rhi-zosphere soil of plants inoculated with the PCPR strains, a higher bacterial diversity was kept throughout the experimental period. Inoculation of sunflower, particularly with C humi (B2), appears to be an effec-tive way of enhancing the short term stabilization potential of the plant in metal contaminated land, low-ering losses in plant biomass and decreasing aboveground tissue contamination.