Evaluation of bio-rational components and Induction of systemic resistance against collar rot of sunflower incited by Sclerotium rolfsii Sacc
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Date
2021-08
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CCSHAU, Hisar
Abstract
Collar rot disease incited by Sclerotium rolfii Sacc. is one of the most destructive soil borne
disease of Sunflower throughout the world (Helianthus annuus L). In Haryana state, the collar rot
caused has been recognized as most important limiting factor in reducing the yield. The collar rot
disease appears at every stage of the crop growth from seeding to maturity. Keeping in view the
enormous loss caused by the pathogen and its regular appearance in severe form the present
investigation has been devised on management and induction of systemic resistance under
laboratory, screen house and field conditions during 2020-2021 at Chaudhary Charan Singh Haryana
Agricultural University, Hisar. Salicylic acid was found the most effective in inhibition of mycelial
growth as compared to other treatments and completely inhibited mycelial growth at 200 ppm as
compare to 24.2% inhibition at 50 ppm concentration. Indole acetic acid was found least effective
among all non-conventional chemicals, as this chemical inhibited only 21.9 per cent of mycelial growth
even at 200 ppm concentration. A maximum control was also recorded by salicylic acid at 200 ppm
concentration after challenge inoculation by the pathogen followed by acetyl salicylic acid in both the
cultivars (HS-1 and Morden) under screen house conditions. SA has shown maximum induction in
peroxidase, polyphenol oxidase and catalase activity at three days after inoculation (DAI) in both the
cultivars at 200 ppm concentration followed by ASA. However, IAA has shown minimum induction
of these activities at three DAI in both the varieties. Among four botanicals Azadirachta indica was
found most effective with 59.5 per cent mycelial growth inhibition at 20% followed by Cannabis sativa
and Pongamia pinnata. Eucalyptus spp. found least effective in inhibition of mycelium growth (4.7%)
even at 20% concentration. Botanical also effective in reducing the sclerotial formation of S. rolfsii.
Minimum number of sclerotia 433.7 & 247.5 were also formed at 5% and 20% concentration with
Azadirachta indica as compare to other treatments. Among bio-agents Trichoderma harzianum showed
maximum antifungal activity with 85.6 per cent inhibition of mycelial growth followed by T.
harzianum (Darjeeling isolate) and T. viride. Coniothyrium sp. found least effective in inhibition
mycelial growth. One hundred germplasm lines were screened for their relative resistance to collar rot
disease under natural sick plot conditions in field. Out of these, none of the lines showed resistance
reaction (<10% disease incidence), forty-four lines showed moderately resistance reaction (10-20%
disease incidence) against collar rot disease.