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STUDIES ON INTEGRATED MANAGEMENT OF Rhizoctonia bataticola (Taub.) Butler CAUSING DRY ROOT ROT OF CHICKPEA

KrishiKosh

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Title STUDIES ON INTEGRATED MANAGEMENT OF Rhizoctonia bataticola (Taub.) Butler CAUSING DRY ROOT ROT OF CHICKPEA
 
Creator AMRUTHA VEENA, G
 
Contributor ESWARA REDDY, N.P
 
Subject hybrids, cotton, genotypes, dna, diseases, planting, developmental stages, sowing, genetics, plant habit
 
Description Chickpea (Cicer arietinum L.) is an important pulse crop grown in tropical, subtropical and temperate regions of the world. Chickpea is affected by Rhizoctonia bataticola (Taub.) Butler causing dry root rot an important disease with yield losses ranging from 50 to 71 per cent.
A detailed study was carried on isolation of the pathogen and establishment of pathogenicity of Rhizoctonia bataticola. In vitro antagonism of fungal and bacterial antagonists isolated from rhizosphere and root habitats against Rhizoctonia bataticola and their compatibility with different fungicides was studied. In vitro evaluation of fungicides against pathogen, integrated disease management of Rhizoctonia bataticola and molecular characterization of potential biocontrol agents by using RAPD and 16S rDNA analysis was also carried.
The Pathogen was isolated from infected plant showing typical dry root rot symptoms viz., withering and drying of the plants, presence of dark tap root showing signs of rotting and devoid of its lateral and finer roots, purified by single hyphal tip method and identified as Rhizoctonia bataticola.
In vitro efficacy of four fungicides viz., copper oxychloride, captan, hexaconazole, tebuconazole and one antifungal antibiotic validamycin was
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evaluated against Rhizoctonia bataticola using poisoned food technique at different concentrations. Among the four fungicides and one antibiotic tested against the pathogen copper oxychloride, captan, hexaconazole and tebuconazole showed 100 per cent inhibiton of mycelial growth, whereas the antibiotic validamycin showed 91.66 per cent inhibition.
Among ten fungal antagonistic isolates, Trichoderma isoloate-7 (CT7) was found to be superior with highest per cent (83.33) inhibition of the growth of R. bataticola. Among 20 rhizosphere bacterial isolates CRB-13 showed highest inhibition (86.66 %). Regarding 20 root endophytes, the isolate CREB-13 showed maximum inhibition (95.55%) followed by CREB-6 (94.44 %) and CREB-16 (93.33 %).
In vitro compatibility of potential fungal and bacterial antagonists was tested against four fungicides and one antifungal antibiotic at different concentrations using poisoned food technique and spectrophotometry respectively. Trichoderma isolate-7 (CT7) was more compatible with validamycin (72.22 %), followed by copper oxychloride (61.12 %). Among CREB-6, CREB-13, CREB-16 and CRB-13 bacterial isolates, CREB-16 was found to be most compatible antagonistic bacteria with validamycin (84.14 %) followed by copper oxychloride (78.28 %) and least compatibility was recorded in case of tebuconazole (25.52 %) in spetrophotometry.
The in vitro mode of action of Trichoderma isolate-7 (CT7) against Rhizoctonia bataticola showed hyphal interaction between the antagonist and the pathogen.
The in vitro experimental results revealed that volatile metabolites produced by antagonistic bacteria inhibited the mycelial growth of Rhizoctonia bataticola to an extent of 77.77 per cent (CREB-16) over control. In the case of non-volatile test, culture filtrate of antagonistic bacteria did not show any inhibition on the growth of Rhizoctonia bataticola over control in vitro.
Trichoderma isolate-7 (CT7) showed highest compatibility with the bacterial isolate CREB-16 (72.22 %) in compatibility tests between antagonistic fungus and bacteria.
In blotter technique, 100 per cent seed germination was recorded in all the treatments under the present investigation.
The efficacy of potential fungal antagonist Trichoderma isolate-7 (CT7), bacterial antagonist CREB-16, fungicide copper oxychloride and organic amendments like FYM, vermicompost and neem cake were tested in pot culture against dry root of chickpea. The results revealed that treatment T8 i.e seed treatment with fungicide (Copper oxychloride) + soil application of potential fungal (Trichoderma isolate-7) and bacterial biocontrol agent
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(CREB-16) was found to be superior as it recorded the highest germination percentage, highest initial and final population of chickpea, least PDI, maximum plant height, root length and maximum shoot and root dry weights.
The population dynamics of both antagonists and pathogen were estimated at two different intervals initially at 7 DAS and then on 45 DAS in pot culture experiment. With the increase in antagonists population, the population dynamics of pathogen were significantly reduced from 7 DAS to 45 DAS over control in all the treatments with the maximum reduction in T8 treatment.
The RAPD banding profiles with random primers viz., OPA-12, OPA-18, OPD-4 and OPD-5 reflected the genetic diversity among the antagonistic bacterial isolates with formation of three main clusters. Amplified 16S rDNA with universal primers 63F and 1387R produced approximately 1300 bp fragments as expected. The amplified product was sent for sequencing to Eurofins Genomics Private Limited, Bangalore
 
Date 2016-06-17T14:08:50Z
2016-06-17T14:08:50Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67533
 
Language en
 
Relation D9363;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY