ISOLATION, CHARACTERIZATION AND SCREENING OF PGPR FROM SALINE SOILS OF TELANGANA AND FIELD EVALUATION OF EFFICIENT ISOLATES ON GREENGRAM UNDER SALINE STRESS CONDITIONS
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Date
2018
Authors
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
Salinity is one of the major abiotic stress limiting the productivity of agriculture in
India, successful remediation of salt degraded areas for crop production is based on
sustainable management practices which involves the use of salt tolerant microorganisms
which are of low cost and easily adaptable method by the farmers. Present investigation
was focussed towards isolation of salinity tolerant bacteria from the saline rhizospheric
soils of Telangana and in vitro screening of the isolates for NaCl tolerance and field
evaluation of the efficient isolates on greengram crop under saline stress conditions.
Eighty salt tolerant bacteria were isolated from 20 villages of Mahabubnagar,
Nalgonda and Rangareddy districts of Telangana, as the districts are prone to saline soils.
The isolates were culturally, morphologically and biochemically characterized, among 80
isolates 35 were identified as Bacillus sp., 22 as Pseudomonas sp., 16 as Azotobacter sp.,
and 7 as Rhizobium sp. according to the Bergey’s manual of Systemic Bacteriology. The
isolates were screened in vitro for salinity tolerance and 40 isolates which tolerated 15 per
cent NaCl were further evaluated for drought tolerance, ACC deaminase activity, EPS
production and plant growth promoting attributes like phosphorous, potassium and zinc
solubilization, siderophore, HCN and IAA production. Results revealed that among the 40
isolates 42.5 per cent isolates showed tolerance at - 0.73 MPa, 22.5 per cent isolates utilized
ACC as a sole nitrogen source, 55 per cent isolates produced EPS, phosphorous was
solubilized by 40 per cent isolates, potassium by 22.5 per cent, zinc by 82.5 per cent
isolates, siderophores was produced by 27.5 per cent isolates, HCN was produced by 70 per
cent and IAA was produced by 50 per cent isolates.
Six efficient isolates were selected and identified by 16S rRNA gene sequencing.
BLAST search results through NCBI revealed 98 per cent similarity of the isolate PJ 21
with Bacillus licheniformis, 99 per cent similarity of PJ 23 with Pseudomonas syringae, 98
per cent similarity of PJ 37 with Pseudomonas fluorescens, 99 per cent similarity of PJ 19
with Pseudomonas alcaligenes, 97 per cent similarity of PJ 70 with Azotobacter sp. and 98
per cent similarity of PJ 71 with Bacillus subtilis.
Two pot culture experiments were conducted during Kharif and Rabi, 2017. The
results revealed the Rabi data was superior over Kharif data due to residual effect of
microbial consortium which influenced crop production. Plant height at 60 DAS was found
significantly highest in T9 with 28.67 cm in Rabi, fresh weight at 60 DAS was registered
significantly highest in T9 with 14.33 g and dry weight was found significantly highest in
the consortium treatment with 5.08 g. Total bacterial population was enumerated and found
to be significantly highest in T9 (T1 + Seed treatment with consortium) with 4.28 x 107
, 7.42
x 107 and 5.82 x 107 CFU g-1
of soil at 20, 40 and 60 DAS respectively. Influence of salinity
tolerant strains on nodulation was assessed and found highest in the consortium treated pots
with 19.67 nodule number, 46.24 mg p-1
of nodule fresh weight and 38.87 mg p-1
of nodule
dry weight. Influence on enzyme activity at flowering stage was assessed with the enzymes
urease, dehydrogenase and phosphatase and found significantly highest in T9 with 32.6 µg
NH4 N g-1
d
-1
, 8.2 µg TPF g-1
d
-1
and 128.4 µg of PNP g-1
h
-1
activity respectively. Number
of pods per plant was measured at harvest and found highest in seed treatment with
consortium with 14.8, seed yield of plants was also found to be highest in T9 with 6.8 q ha-1
.
Soil analysis was carried out for NPK at harvest and showed highest in consortium
treatment with 2 - 3 per cent increase over control.
In the field experiment, plant height, fresh weight and dry weight at 60 DAS was
found significantly highest in T9 and increased two fold over control. Total bacterial
population was enumerated and found to be significantly highest in T9 (T1 + Seed treatment
with consortium) with 3 - 4 fold population over control. Influence of strains on nodulation
was measured and consortium treated plants improved nodule number by 30 per cent,
nodule fresh weight by 35 per cent and nodule dry weight by 45 per cent. Soil enzymes like
urease, dehydrogenase and phosphatase activity was found significantly more in T9 with 35
per cent, 80 per cent and 45 per cent increase respectively over control. Number of pods per
plant was measured at harvest and found highest in consortium treatment with two fold
increase and seed yield of plants was found to increase by 47 per cent over control. Soil
analysis was carried out for NPK at harvest and found 2 -3 fold increase of consortium
treatment when compared with control.
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D10,350