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CHARACTERIZATION OF VARIABILITY IN Rhizoctonia solani CAUSING SHEATH BLIGHT OF RICE

KrishiKosh

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Title CHARACTERIZATION OF VARIABILITY IN Rhizoctonia solani CAUSING SHEATH BLIGHT OF RICE
 
Creator MEHI LAL
 
Contributor Janki Kandhari
 
Subject Unable to Generate Tags manish.pdf
 
Description t-8023
Sheath blight (
Rhizoctonia solani
Kühn) of rice is an important disease in
India. To determine variation on the basis of morphological, cultural, pathogenic and
genetic variability, 25 isolates of
R. solani
, incitant of sheath blight of rice were
collected from different agro-climatic zones of India. Pathogenicity test revealed that
all the isolates produced typical symptoms of sheath blight of rice on cultivar Pusa
Basmati-1. On the basis of cultural characters the isolates were categorized into
different groups: colony colour (5 groups), growth pattern (3 groups) and diameter
growth rate (3 groups). All the 25 isolates showed basic morphological
characteristics of
R. solani
. Hyphal width ranged from 4.75 μm to 7.43 μm. Based
on pigmentation of sclerotia, the isolates were classified into four groups and on the
basis of texture of sclerotia into two groups. Isolate RS-22 (New Delhi) produced no
sclerotia. Diameter of the sclerotia ranged from 1.13 (RS-9) to 2.03 mm (RS-18).
Based on the location and formation of sclerotia, the isolates were divided into three
groups each. Time taken for initiation of sclerotia formation ranged from 3-5 days in
different isolates. All isolates were taken for studying pathogenic variation on 6 rice
cultivars (Susceptible- PB-1, Annapurna, Swarna; Resistant- Pankaj, Manasarovar,
Sawarndhan). In Phytotron, on the basis of pathogenic variation on cultivar PB-1, all
isolates were categorized into two groups, moderately virulent and virulent group. In
glass house, all the isolates were pathogenic on all six cultivars except RS-25 on
cultivar Manasarovar and Swarnadhan. Maximum virulence index of 7.33 was at par
in RS-16 and RS-18 and maximum susceptibility index was found on cultivar
Annapurna (6.76). Four isolates viz, RS-16, RS-18, RS-20 and RS-21 which found
prominent can be used in future for screening resistance against sheath blight of rice.
RAPD–PCR was done with 23 primers, out of them 10 were found to give
reproducible and scorable bands with high percentage of polymorphism and the
fragments size ranged from 250-2500 bp. Two main primers viz.OPZ-20 and OPF-
06 can be used for differentiating
R. solani
isolates and non sclerotial isolates and
also maize isolates (RS-24 and RS-25). Genetic similarity ranged from 17% - 84%.
Maximum similarity (84%) was revealed between two isolates RS-14 and RS-15
and lowest similarity (17%) was observed between RS-25 and RS-20. On the basis
of Jaccard’s coefficient similarity 4 major groups were formed and 20 percent
isolates did not share any of the group which may be due to geographical variability.
 
Date 2017-01-06T15:06:24Z
2017-01-06T15:06:24Z
2009
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/94872
 
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