Infl uence of rhisospheric bacteria on the productivity of wheat plants and the input of elements from polluted soils

Abstract

The results of a vegetation experiment on the humus horizon of soddy-podzolic sandy loamy soil (Albic Retisol),
which was contaminated with heavy metals as a re sult of sewage sludge as a fertilize r, are presented. Th e soil was
used for growing vegetables and forage grasses but has been abandoned for the last 10 years. In the experiment, the
eff ect of rhizospheric bacteria of the genus Pseudomonas on biomass and the entry of micro- and heavy metals into
the vegetative organs and root system of spring wheat plants was studied. Under the infl uence of inoculation with
bacteria, the biomass of wheat plants increased by 10–12% and the content of the main macro- and microelements
in plants changed. Th e content of Ca, K, Mg, Na and P decreased by 1,5–2 times in the vegetative part of wheat plants
inoculated with P. fl uorescens 21 and P. putida 23. The content of macroelements in wheat roots changed little, but the
ratio between the content of elements increased in roots and vegetative parts of plants. Th e distribution of the content
of trace elements and HMs was much more contrasting: the content of Cd in the roots of wheat plants exceeded that
in the vegetative part of plants by 9 times without treatment with bacteria and by 18 and 11 times aft er inoculation
with P. fl uorescens 21 and P. putida 23, and in variants with P. fl uorescens 20 by 7 times. A decrease in the content of
Cd in the vegetative part of wheat plants was noted, by 2 times upon inoculation with P. fl uorescens 21 and by 1,5
times for variants with P. putida 23. Th e content of Zn in the aerial parts of plants also decreased upon inoculation
with P. fl uorescens 21 and by 1,8 times for variants with and P. putida 23 by 1,4 times. An increase in the ratio of the
content of elements in the roots and vegetative mass of plants indicates an increase in the resistance of plants to the
toxic eff ect of heavy metals and the barrier function of the roots.