Exploitation of Hypovirulence in Rhizoctonia solani kuhn for Management of Sheath Blight in Rice
By: Ranjit A.
Contributor(s): Girija A K (Guide).
Material type:
BookPublisher: Vellayani Department of Plant Pathology, College of Agriculture 2001DDC classification: 632.3 Online resources: Click here to access online Dissertation note: MSc Abstract: A study was conducted at Department of Plant Pathology,
College of Agriculture, Vellayani to explore the variability in Rhizoctonia
so/ani with a view to detect hypoviruient strains of the fungus, and evaluate
the efficacy of these isolates in management of sheath blight disease of rice.
Six hypovirulent isolates were selected after screerung 28 isolates obtained
from different rice growing tracts of Kerala. Screening for hypovirulence was .
based on cultural characters like mycelial growth rate and sclerotial
production under ill vitro conditions, and pathogenicity tests through cut stalk
assay. The hypovirulent isolates were non-sclerotial whereas the virulent
isolate produced profuse sclerotia. The hypovirulent isolates produced tan
mycelia appressed to the medium In Petri dishes. Antibiosis and
hyperparasitism were absent in the interaction between the hypovirulent and
virulent isolates in vitro. The character of hypovirulence could not be
transmitted from hypovirulent to the virulent isolate. The hypovirulent
isolates had no effect on the germination and seedling vigour of rice plants.
They did not produce symptoms of sheath blight on susceptible variety. Two
of the six hypovirulent isolates selected viz A 13 and GR23 which were
binucleate and did not anastomose with the selected virulent isolates, offered
the maximum protection to the rice plants from sheath blight. The plants
treated with GR23 showed immune reaction to challenge inoculation with
virulent isolate, showing no symptom production on challenge inoculation
with virulent isolate. The protective effect was found to be higher than that of
chemical and biological control treatments. The phenol oxidase activity in the
plants treated with the hypovirulent isolates was found to be significantly
higher than that of the plants treated with virulent isolate while the peroxidase
activity was higher in the plants treated with virulent isolate. Among the
different carrier materials tested for hypovirulent Rrsolani rice bran was
found to be good for long term storage and coirpith was found to be a cheap
indigenous material for its mass multiplication.
| Item type | Current location | Call number | Status | Date due | Barcode |
|---|---|---|---|---|---|
Theses
|
KAU Central Library, Thrissur Theses | 632.3 RAN/EX (Browse shelf) | Available | 171799 |
MSc
A study was conducted at Department of Plant Pathology,
College of Agriculture, Vellayani to explore the variability in Rhizoctonia
so/ani with a view to detect hypoviruient strains of the fungus, and evaluate
the efficacy of these isolates in management of sheath blight disease of rice.
Six hypovirulent isolates were selected after screerung 28 isolates obtained
from different rice growing tracts of Kerala. Screening for hypovirulence was .
based on cultural characters like mycelial growth rate and sclerotial
production under ill vitro conditions, and pathogenicity tests through cut stalk
assay. The hypovirulent isolates were non-sclerotial whereas the virulent
isolate produced profuse sclerotia. The hypovirulent isolates produced tan
mycelia appressed to the medium In Petri dishes. Antibiosis and
hyperparasitism were absent in the interaction between the hypovirulent and
virulent isolates in vitro. The character of hypovirulence could not be
transmitted from hypovirulent to the virulent isolate. The hypovirulent
isolates had no effect on the germination and seedling vigour of rice plants.
They did not produce symptoms of sheath blight on susceptible variety. Two
of the six hypovirulent isolates selected viz A 13 and GR23 which were
binucleate and did not anastomose with the selected virulent isolates, offered
the maximum protection to the rice plants from sheath blight. The plants
treated with GR23 showed immune reaction to challenge inoculation with
virulent isolate, showing no symptom production on challenge inoculation
with virulent isolate. The protective effect was found to be higher than that of
chemical and biological control treatments. The phenol oxidase activity in the
plants treated with the hypovirulent isolates was found to be significantly
higher than that of the plants treated with virulent isolate while the peroxidase
activity was higher in the plants treated with virulent isolate. Among the
different carrier materials tested for hypovirulent Rrsolani rice bran was
found to be good for long term storage and coirpith was found to be a cheap
indigenous material for its mass multiplication.
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