Agriculture Reference
In-Depth Information
11.6 PGPR Consortium Application in Plants Growing
in Stressed Soils
11.6.1 Drought Stress
The consortia of
Paenibacillus polymyxa
(DSM 36) and
P. polymyxa
Loutit
(L) along with
Rhizobium tropici
(CIAT 899) significantly increased growth, N
content, and nodulation of common bean (
Phaseolus vulgaris
) growing under
drought stress conditions (Figueiredo et al.
2008
) compared to plants inoculated
only with
Rhizobium
. However, negative effects of drought stress on the measured
parameters were observed suggesting that the mixture of bacteria had a positive
mitigating impact on stressor. Single and multiple inoculations with different
Pseudomonas
sp. were carried out to study the effect on Asparagus (
Asparagus
officinalis
) cultivars (Guelph millennium and Jersey giant) under both drought and
flood stress up to 8 weeks. The results so obtained were significantly convincing in
one of the cultivars in case of both single and multiple inoculation (Liddycoat
et al.
2009
). Five drought-tolerant bacterial strains, namely,
Pseudomonas
entomophila
strain BV-P13,
P. monteillii
strain WAPP53,
P. putida
strain
GAP-P45,
P. stutzeri
strain GRFHAP-P14, and
P. syringae
strain GRFHYTP52,
were used to inoculate maize grown under water-deficit conditions. The PGPR
inoculation reduced the drought stress damage and improved plant biomass, leaf
water potential, relative water content, aggregation stability, sugars, amino acids,
and proline content. The effects also included decreased electrolyte leakage and
water loss from leaves (Sandhya et al.
2010
). In other experiment, three plant
growth-promoting strains—
B. cereus AR
156,
B. subtilis
SM21, and
Serratia
sp
.
XY21—decreased wilting symptoms and leaf monodehydroascorbate in cucumber
(
Cucumis sativus
) plant, while they showed 3.45-fold increase in proline content
along with increased SOD activity, supporting the hypothesis of induced systemic
tolerance in drought stress (Wang et al.
2012
). The combined application of PGPR
(
A. brasilense
,
B. lentus
, and
Pseudomonades
sp.) improved antioxidant activity
and also indicated better photosynthetic capacity and improved photosynthetic
pigments in Basil (
Ocimum basilicum
) (Heidari and Golpayengani
2012
), while
the combined inoculation of different PGPR strains increased superoxide dismutase
and peroxidase activity along with better chlorophyll content and transpiration in
runner bean plants (
Phaseolus coccineus
L.) (Stefan et al.
2013
).
11.6.2 Salt Stress
Effects of dual inoculation of
Serratia
sp. and
Rhizobium
sp. on the growth and
other parameters of lettuce plant grown under salt stress were variable. PGPR
negated the effects of salt stress on the antioxidant enzymes and on photosynthesis,
