131
Plant-Microbe Associations
adaptation of host plants to suboptimal soil conditions during stressful conditions and increase the efficiency of phytoremediation (Hassan et al., 2017;
Oves et al., 2013).
The PGPR strain Agrobacterium sp. Zn1-18 was used as an inoculant to
increase the efficiency of phytoremediation of trace elements contaminated
soil using M. × giganteus plants. The strain was isolated during the germination period from the rhizosphere of M. × giganteus when crop was cultivated
in trace elements contaminated postindustrial soil (Table 7.2). Isolated strain
showed PGPR properties: the ability to fix atmospheric nitrogen, to dissolve
hard-to-reach phosphates, to synthesize siderophores, to produce phytohormone indolacetic acid (IAA), and ability to grow in medium that contains Zn
ions up to 4.0 mmol L −1 and Pb ions up to 2.5 mmol L −1 .
Agrobacterium sp. Zn1-18 showed a significant effect on the bioparameters
of M. × giganteus plants: the aboveground biomass of treated crop increased
by 50%; the biomass of roots decreased by 77.3% on comparison with control
untreated crop. Upon inoculation of M. × giganteus rhizome the roots’ dry
weight decreased by 34.8% while the dry weight of the aboveground biomass,
on the contrary, increased by 7.1%. When comparing M. × giganteus grown
on control and contaminated soils in the presence of PGPR, results revealed
that the Agrobacterium sp. Zn1-18 increased the productivity of aboveground
biomass by 7.1% while reduced the root dry weight. Thus, Agrobacterium sp.
Zn1-18 promoted the growth and development of M. × giganteus on trace
elements contaminated post-industrial soils.
TABLE 7.2
The Trace Element Concentrations in the Research Soils
Trace Element
MPC (mg kg −1 )
The Total Trace Element Concentration in
Soil (mg kg −1 )
Control Soil
Contaminated Soil
V
150
50.5 ± 3.5
60.0 ± 12.0
Cr
6
35.0 ± 2.8
44.0 ± 7.1
Mn
1500
690.0 ± 56.5
810.0 ± 42.4
Fe
n/a
19,600 ± 424
21,450 ± 2,757
Co
5
14.5 ± 0.7
18.0 ± 1.4
Ni
4
32.0 ± 5.6
39.2 ± 2.8
Cu
3
31.0 ± 2.8
31.5 ± 7.7
Zn
55
101.0 ± 12.7
180.0 ± 14.1
As
2
11.5 ± 0.7
22.5 ± 4.9
Sr
7
66.0 ± 1.4
81.3 ± 0.8
Ba
0.1
125.0 ± 21.2
210.1 ± 28.2
Pb
32
20.0 ± 21.2
230.0 ± 44.2
U
n/a
0.8 ± 0.1
1.3 ± 0.2
Depth of soil sampling: 0–60 cm.
MPC, maximum permissible concentration.
Plant-Microbe Associations
adaptation of host plants to suboptimal soil conditions during stressful conditions and increase the efficiency of phytoremediation (Hassan et al., 2017;
Oves et al., 2013).
The PGPR strain Agrobacterium sp. Zn1-18 was used as an inoculant to
increase the efficiency of phytoremediation of trace elements contaminated
soil using M. × giganteus plants. The strain was isolated during the germination period from the rhizosphere of M. × giganteus when crop was cultivated
in trace elements contaminated postindustrial soil (Table 7.2). Isolated strain
showed PGPR properties: the ability to fix atmospheric nitrogen, to dissolve
hard-to-reach phosphates, to synthesize siderophores, to produce phytohormone indolacetic acid (IAA), and ability to grow in medium that contains Zn
ions up to 4.0 mmol L −1 and Pb ions up to 2.5 mmol L −1 .
Agrobacterium sp. Zn1-18 showed a significant effect on the bioparameters
of M. × giganteus plants: the aboveground biomass of treated crop increased
by 50%; the biomass of roots decreased by 77.3% on comparison with control
untreated crop. Upon inoculation of M. × giganteus rhizome the roots’ dry
weight decreased by 34.8% while the dry weight of the aboveground biomass,
on the contrary, increased by 7.1%. When comparing M. × giganteus grown
on control and contaminated soils in the presence of PGPR, results revealed
that the Agrobacterium sp. Zn1-18 increased the productivity of aboveground
biomass by 7.1% while reduced the root dry weight. Thus, Agrobacterium sp.
Zn1-18 promoted the growth and development of M. × giganteus on trace
elements contaminated post-industrial soils.
TABLE 7.2
The Trace Element Concentrations in the Research Soils
Trace Element
MPC (mg kg −1 )
The Total Trace Element Concentration in
Soil (mg kg −1 )
Control Soil
Contaminated Soil
V
150
50.5 ± 3.5
60.0 ± 12.0
Cr
6
35.0 ± 2.8
44.0 ± 7.1
Mn
1500
690.0 ± 56.5
810.0 ± 42.4
Fe
n/a
19,600 ± 424
21,450 ± 2,757
Co
5
14.5 ± 0.7
18.0 ± 1.4
Ni
4
32.0 ± 5.6
39.2 ± 2.8
Cu
3
31.0 ± 2.8
31.5 ± 7.7
Zn
55
101.0 ± 12.7
180.0 ± 14.1
As
2
11.5 ± 0.7
22.5 ± 4.9
Sr
7
66.0 ± 1.4
81.3 ± 0.8
Ba
0.1
125.0 ± 21.2
210.1 ± 28.2
Pb
32
20.0 ± 21.2
230.0 ± 44.2
U
n/a
0.8 ± 0.1
1.3 ± 0.2
Depth of soil sampling: 0–60 cm.
MPC, maximum permissible concentration.