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SCREENING OF LOCAL PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) ISOLATES FOR THEIR MULTIPLE BENEFICIAL ACTIVITIES AND FOR COMPATIBILITY WITH PESTICIDE MOLECULES

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Title SCREENING OF LOCAL PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) ISOLATES FOR THEIR MULTIPLE BENEFICIAL ACTIVITIES AND FOR COMPATIBILITY WITH PESTICIDE MOLECULES
 
Creator SAI PRASAD, J
 
Contributor Narayan Reddy, P
 
Subject bacteria, fungi, planting, biological development, productivity, inorganic acid salts, growth promoters, rhizobium, developmental stages, diseases
 
Description Plant Growth Promoting Rhizobacteria has gained worldwide importance and
acceptance for sustainable agriculture with cleaner environment. One of those strategies is
utilization of the soil microbiota to induce plant growth, control of plant diseases and
biodegradation of xenobiotic compounds. Keeping in view the importance of PGPR and such
biodiversity available an experiment entitled “Screening of local Plant Growth Promoting
Rhizobacteria (PGPR) isolates for their multiple beneficial activities and for compatibility with
pesticide molecules” was conducted at Department of Agricultural Microbiology and
Bioenergy, College of Agriculture, Rajendranagar, Hyderabad for characterizing efficient PGPR
isolates with multiple beneficial activities. One hundred and three bacterial isolates were
isolated from the rhizospheric soils of groundnut, black gram / non rhizospheric soils of
Rajendranagar and three pure isolates from Amaravathi were identified as Bacillus (24)
Pseudomonas (26), Azotobacter (24), Rhizobium (23) and Azospirillum (12) isolates. These
isolates were screened in vitro for Plant growth promoting attributes like phosphate
solubilization, production of Indole acetic acid (IAA), ammonia, hydrogen cyanide (HCN),
siderophores and were further studied for their antagonism against two soil borne pathogens viz.,
Rhizoctonia solani and Sclerotium rolfsii. These isolates were further tested for their
compatibility with the commonly used agrochemicals, i.e. fungicides (Tebuconazole,
Azoxystribin, Carbendazim and Captan), insecticides (Spiromecifin, Thiacloprid, Imidacloprid
and Flubendiamide) and herbicides (Metribuzin, Propaquizafop, Pretilachlor and
Pendimethalin).
The results revealed that 50% of the Bacillus isolates showed positive results for
phosphate solubilization, 100% for ammonia, 91.6% for IAA, 70.83% for siderophores and
58.33% isolates showed for HCN productions. All the Pseudomonas isolates positive for IAA
production, 76.9% for phosphate solubilization, 92.3% for ammonia, 88.46% for siderophores
and 80.76% for HCN productions. Among Azotobacter isolates 91.66% isolates were showed
positive for ammonia production, 58.3% phosphate solubilization, 83.33% for siderophores,
54.16% for HCN and 29.16% for IAA productions. All the Rhizobium isolates showed
nodulation on ground nut, black gram and soybean crops, 82.60% of isolates showed phosphate
solubilization, 91.3% for ammonia, 47.82% for IAA, 70.83% for siderophores and 52.17% for
HCN productions. Regarding Azospirillum isolates 66.66% isolates showed positive results for
phosphate solubilization, 75% for ammonia, 91.66% for IAA, 58.33% for siderophore and 50%
isolates showed HCN production.
All the 109 PGPR isolates were examined for the potential to inhibit two fungal
pathogens viz., Rhizoctonia solani and Sclerotium rolfsii under in vitro conditions. Out of 109
isolates, 88 isolates exhibited inhibition potential against one or the other phytopathogen, while
the remaining 21 isolates did not show inhibitory activity against any of the pathogens tested.
Out of 88 antagonistic isolates, 43 were inhibitory to Rhizoctonia solani and 45 were inhibitory
to Sclerotium rolfsii. Twenty isolates showed inhibition potential against both Sclerotium rolfsii
and Rhizoctonia solani.
All the 109 isolates tested for compatibility with fungicides, insecticides and herbicides.
Among the fungicides tested Azoxystrobin was found to be inhibit Bacillus, Pseudomonas,
Azotobacter while Tebuconazole inhibited Rhizobium and Azospirillum at recommended / half
recommended dosage. However other fungicides were compatible with all the isolates tested.
Among the insecticides tested Flubendiamide was found to inhibit Bacillus, Pseudomonas,
while Imidacloprid inhibited Azotobacter, Azospirillum, and Rhizobium was inhibited by
Thiacloprid at recommended / half recommended dosage. However other insecticides were
compatible with all the isolates tested. Among the herbicides tested Pretilachlor was found to be
inhibit Pseudomonas, Rhizobium while Propaquizafop inhibited Bacillus at recommended / half
recommended dosage. However other herbicides were compatible with all the isolates tested and
all the Azotobacter, Azospirillum isolates were also compatible with all herbicides.
From the present investigation, it can be inferred that PGPR due to their multiple
beneficial activities increase the plant growth and soil fertility by direct and indirect means. The
direct means of action could be through N2 fixation, solubilization of insoluble phosphorus,
sequestering of iron by production of siderophores, production of phytohormones such as
auxins, cytokinins, gibberellins and lowering of ethylene concentration. The indirect means
could be through biocontrol activity by production of siderophores, HCN, antibiotic production,
synthesis of antifungal metabolites, production of fungal cell wall lysing enzymes, competition
for sites on roots and induced systemic resistance. These PGPR are eco-friendly in nature, lowcost
effectiveness, certainly help in improving profitability and livelihoods of small and
marginal farmers. Therefore their use in crop production makes agriculture profitable and sustainable.
 
Date 2016-06-22T14:47:31Z
2016-06-22T14:47:31Z
2013
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67730
 
Language en
 
Relation D9424;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY