ISOLATION AND CHARACTERIZATION OF STRESS TOLERANT PLANT GROWTH PROMOTING RHIZOBACTERIA AND THEIR INFLUENCE ON BLACKGRAM (Vigna mungo L.)
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Date
2017
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Acharya N.G. Ranga Agricultural University
Abstract
Stress tolerant Plant Growth Promoting Rhizobacteria (PGPR) are the
rhizosphere bacteria that can enhance plant growth under stress condition by production
of ACC deaminase enzymes. In the present study 32 stress tolerant PGPR were isolated
from rhizospheric soils of drought prone areas and were tested for different plant
growth promoting activities. Out of 32 bacterial strains (8 Rhizobium isolates, 8
pseudomonas isolates, 8 potassium releasing bacterial isolates and 8 zinc solubilizing
bacterial isolates) isolated from blackgram soils, four efficient PGPR strains, one each
of Rhizobium (KUR1), pseudomonas (KCP1), potassium releasing bacterial (KGK1)
isolate and zinc solubilizing bacterial (STZ1) isolate were selected for further studies.
These four isolates contain higher ACC deaminase activity KUR1 (+++), KCP1 (+++),
KGK1 (+++), STZ1 (+++) and produce higher exopolysaccharide KUR1 (34.6 mg
ml-1), KCP1 (30.6 mg ml-1), KGK1 (20.3 mg ml-1), STZ1 (24.6 mg ml-1). All isolates
were positive for siderophore production, IAA production and also phosphate
solubilization efficiency.
All the isolates were further screened in vitro for antagonistic activity against the
fungal pathogen Rhizoctonia solani and found that all these isolates inhibited the fungal
pathogen and highest inhibition was found with the isolates KUR1 (37.6%), KCP1
(39.53%), KGK1 (36.47%), STZ1 (36.07%).
The selected strains were tested in soil to assess their effectiveness against stress
tolerance by improving growth of blackgram under water stress conditions. Pot culture
experiment was conducted with blackgram crop at different water holding capacity
(80%, 60%, 40% and 20%).
The results revealed that reduced soil moisture levels significantly decreased the
growth of blackgram. However inoculation of blackgram with stress tolerant
rhizobacteria containing ACC deaminase, isolated from the soils collected from drought
prone areas significantly increased the drought tolerance in blackgram and increases the
growth and yields.
These stress tolerant PGPR improved the growth parameters like plant height
(13.3 cm, 31.6 cm and 39.0 cm at 30 DAS, 60 DAS and75 DAS respectively), Number
of branches plant-1 (4.73, 9.60, 11.60 at 30 DAS, 60 DAS and75 DAS respectively) and
number of leaves plant-1 (13.3, 31.6, 39.0 at 30 DAS, 60 DAS and75 DAS respectively)
increases. Number of pods plant-1 (32.3), number of seeds pod-1 (5.0), seed yield
(2815.0 kg ha-1), 100 seed weight (4.98 gm) also increases.
Other physico chemical properties of soil like pH (7.97), EC (0.98 dSm-1),
Organic carbon (0.75%), N (283.40 kg ha-1), P (98.99 kg ha-1), K (324.73 kg ha-1) and
enzymes like dehydrogenase (233.4 μg TPF formed g-1 d-1), phosphatase (Acidic 130.00
μg pNP g-1 h-1, Alkaline 148.00 μg pNP g-1 h-1), urease (121.62 ug urea g-1 h-1) also
improved at flowering stage of blackgram. Proline content of plant was increases under
stress condition. i.e., at 20% WHC, it was recorded as 64.33 μ moles g-1. N (0.55%), P
(0.32%), K (2.21%) content of plant samples also increases. These results revealed that
combined inoculation of stress tolerant PGPR significantly increased growth and yield
of blackgram 42 percent more compared to control under moisture stress conditions.
Description
D5541
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