STUDIES ON DIVERSITY OF Sclerotium rolfsii Sacc. AND SCREENING OF GROUNDNUT COLLECTIONS AGAINST STEM ROT DISEASE
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Date
2019-09-06
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Studies on diversity of Sclerotium rolfsii Sacc. and screening of groundnut
collections against stem rot disease were carried out during 2018-19 at the Department
of Plant Pathology, University of Agricultural Sciences, Bangalore. Survey was
conducted in major groundnut growing districts of Karnataka to know the prevalence
of groundnut stem rot disease. The disease is prevalent in the entire groundnut growing
areas surveyed with maximum (18.65 %) and minimum (11.63 %) incidence recorded
in Bagalkot and Dharwad district, respectively. Ten isolates of Sclerotium rolfsii were
collected from different locations of Karnataka and its variability were studied. The
morphological and cultural characters of these isolates varied with respect to their
growth rate, time taken to initiate sclerotia, size and weight of sclerotial bodies.
Guledagudda isolate (SrB2) produced largest sclerotial body (2.33 mm) and Madhugiri
isolate (SrT2) proliferated much faster compared to other isolates (12 days). Variability
of these isolates were analyzed by amplifying and sequencing the ITS rDNA region.
Among the ten isolates, seven isolates viz., SrY1, SrY2, SrD1, SrD2, SrC1 and SrT1
shared more per cent identity with Athelia rolfsii, two (SrB2 and SrC2) share more
identity with Sclerotium delphini and two (SrB1 and SrT2) share identity with both
Athelia rolfsii and Sclerotium dolphini. The groundnut genotypes were screened
against the stem rot disease to identify the resistance source. Among the 31 genotypes
screened in disease sick plot, 15 genotypes were moderately resistant with disease
incidence ranging from 10.10-30.00 per cent, 15 genotypes were susceptible and one
genotype TMV-2, was highly susceptible.