Characterization of Tilletia barclayana causing kernel smut of rice and its management
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
Kernel smut of rice caused by Tilletia barclayana is a designated seed borne disease under Indian
minimum seed certification standards. The pathogen converts the grains into black powdery mass
resulting considerable loses in the yield as well as quality of the produce. The short duration rice
varieties are more susceptible to kernel smut as compared to the other varieties. The present studies
aimed at characterization of the populations of T. barclayana isolates obtained from different varieties
under cultivation in Punjab from different agro-climatic regions and to devise management of this
disease. A total of thirty three isolates of T. barclayana were obtained from thirteen districts and eight
different varieties for morphological and pathological characterization. Based on the morphological and
cultural characteristics, the isolates were grouped into 8 clusters, from each cluster representative
isolates were selected for their pathological characterization under field conditions. Fourteen isolates
were used for pathological characterization using spray inoculation technique at fifty per cent flower
opening and by syringe inoculation technique at late boot stage. Multivariate cluster analysis of the
pathogenicity data grouped the isolates into five and three clusters by spray and syringe inoculation
method respectively. Isolate Tb 24 obtained from variety PR 124 from district Ropar was the most
virulent isolate of T. barclayana whereas isolate Tb 31 obtained from variety PR 121 from district
Tarantaran was the least virulent among the isolates under study. The germinated teliospores obtained
from weed hosts, Dichanthium annulatum, Cyanodon dectylon were inoculated on variety PR 114 by
spray inoculation method to study the cross infectivity of T. barclayana from weeds to rice. Neither of
the isolate from any weed hosts were able to produce disease symptoms on rice. Six different
fungicides including Hexaconazole 75% WG, Propicinazole 13.9% + Difenconazole 13.9% EC,
Hexaconazole 4% + Zineb 68%, Tebuconazole 50% + Trifloxystrobin 25% WG, Azoxystrobin 23%
SC, Propiconazole 25% were evaluated against T. barclayana under lab conditions and for disease
control under the field conditions. Minimum ED 50 (3.57 ppm) and ED 90 (37.11 ppm) values were
recorded for Hexaconazole 75% WG. Maximum disease control under field conditions was achieved
in plots where two sprays of combination fungicide Hexaconazole 4% + Zineb 68% was given. The
results of two sprays of Propiconazole 25% EC and combination of Tebuconazole 50% +
Trifloxystrobin 25% WG @ 0.1 % and 0.04% respectively were equally effective for the management
of disease under field conditions Fifty advanced breeding lines of rice were screened for disease
reaction under natural conditions. Disease incidence and coefficient of infection was categorized into
different response of disease reaction on the fifty advanced breeding lines under study at Ludhiana and
Kapurthala. At PAU Ludhiana fourty six lines exhibited resistance response and four lines exhibited
highly resistance response. At RRS Kapurthala 41 lines exhibited resistance response, one of the line
was susceptible and seven lines were moderately susceptible to kernel smut under natural conditions.
The lines showing resistance response can further be evaluated under artificial inoculation conditions in
order to obtain resistance sources against the pathogen. The most virulent pathogen isolate Tb-24 may
be used for artificial screening of lines against T. barclayana.
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Citation
Babanpreet Singh (2020). Characterization of Tilletia barclayana causing kernel smut of rice and its management (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.