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Subject: Plant Pathology × Author: Babanpreet Singh × End date: 2023 × Start date: 2020 ×
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    ThesisItemOpen Access
    Characterization of Tilletia barclayana causing kernel smut of rice and its management
    (Punjab Agricultural University, Ludhiana, 2020) Babanpreet Singh; Anju Bala
    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.