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20211
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Subject: Plant Pathology × Author: Ajit Singh × Start date: 2001 × Type: Thesis ×
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    ThesisItemOpen Access
    Evaluation of bio-rational components and Induction of systemic resistance against collar rot of sunflower incited by Sclerotium rolfsii Sacc
    (CCSHAU, Hisar, 2021-08) Ajit Singh; Rakesh
    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.