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Advisor(s)
Abstract(s)
The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic
bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from
a serpentine environment on the plant growth and the translocation and accumulation of Ni,
Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine
soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order
to obtain a range of heavy metal concentrations and used in microcosm experiments.
Regardless of inoculation with bacteria, the biomass of both plant species decreased with
increase of the proportion of SS. Inoculation of plants with bacteria significantly increased
the plant biomass and the heavy metal accumulation compared with non-inoculated control
in the presence of different proportion of SS, which was attributed to the production of plant
growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed
a maximum increase in the biomass of the test plants grown even in the treatment of
75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals
in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant
species exhibited low values of bioconcentration factor (<1) for Ni and Fe. The inoculation
of both bacterial strains significantly increased the translocation factor (TF) of Ni while
decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs
of all metals were <1, indicating that all studied bacteria–plant combinations are suitable
for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8
improved the growth of B. juncea and R. communis in SS soils and have a great potential
to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.
Description
Keywords
phytostabilization plant growth promoting bacteria serpentine soils heavy metals Brassica juncea Ricinus communis