Abstract:
Plant growth-promoting rhizobacteria or PGPR are a group of bacteria that
aggressively colonize the roots of plants and exert beneficial effects on
plant growth and development. Rhizobia are a group of PGPR that fix
nitrogen in symbiosis with legumes. Studies have been reported on the
association of bacteria and legumes for possible remediation of heavy
metal-contaminated soil. To examine the possible use of PGPR and
legume in bioremediation, experiments were conducted to study the effect
of PGPR and rhizobia on the growth of Stylosanthes guianensis in a
copper-contaminated soil. S. guianensis seeds were inoculated with PGPR
strains B4B (Klebsiella pneumoniae) and BTToRe (Enterobacter spp.)
alone and in combination with CB 756 (Bradyrhizobium spp.) under
sterile conditions in a growth room and non-sterile conditions in a screen
house. After twelve weeks, growth of the plants was evaluated based on
parameters such as plant height, number of trifoliate leaves, number of
lateral branches, total length of lateral branches, shoot dry weight, root dry
weight, nodule dry weight and nodule number. Dried shoots from the nonsterile
setup were analyzed for plant copper uptake. Results of the
experiment showed that PGPR and .rhizobial inoculation did not
significantly increase the growth of S. guianensis plants in copper-contaminated
soil based on the growth parameters measured. The
inoculation of PGPR strains also did not significantly enhance the uptake
of copper from the soil by the plant. Further studies are needed to fully
explore the potential of PGPR in the remediation of contaminated soils.
