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Researcher Lekhashree
Advisor Dantre, R. K.
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Master of Science (M.Sc.)
Publisher Indira Gandhi Krishi Vishwavidyalaya
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Plants (Botany) ♦ Specific topics in natural history ♦ Technology ♦ Management & auxiliary services ♦ General management
Subject Keyword Rhizoctonia Solani Kã¼hn ♦ Disease ♦ Soybean ♦ Management ♦ Plant Pathology
Abstract The present investigation “VARIABILITY IN Rhizoctonia solani Kühn CAUSAL AGENT OF WEB BLIGHT DISEASE OF SOYBEAN AND IT’S MANAGEMENT†was carried out in the laboratory and field of Dept. of Plant Pathology and Plant Pathology Research Farm , I.G.K.V Raipur (C.G.). The sample of web blight of soybean, were collected and identified as Rhizoctonia solani on the basis of in vitro studies. The symptoms of web blight were observed under natural field conditions on leaves, stems, petioles and pods as water soaked at first but soon taken on a greenish brown to reddish brown appearance and later become tan, brown, or black. Koch's postulates were proved by detached leaf method. Survey was performed in different soybean growing areas of Chhattisgarh to record the incidence of web blight of soybean. Maximum disease incidence (58.33%) was observed in Dharsiwa block, followed by Kawardha (48.33%) and Durg (46.66%).The minimum disease incidence (30%) was observed in Khairagarh block. The average percent disease incidence was recorded as 39.89%.In cultural and morphological variability studies of 17 isolates of Rhizoctonia solani, all the isolates covered the entire plate (90mm) after 48 hours except RS 13 (86.30 mm).The highest mycelial growth after 24 hours was observed in RS 15(53mm). Eight isolates were found pale white, five isolates light brown and four isolates were ivory in colony colour. Seven isolates were sparse fluffy , six isolates were sparse , two isolates were cottony and two were cottony fluffy in colony texture. Seven isolates showed sclerotia initiation after 48 hours while nine isolates showed sclerotia initiation after 72 hours. The highest sclerotial weight (27.87 mg) was recorded for RS 17. The highest number of sclerotia(112) were observed in RS 14,followed by RS 8(110). Eight isolates were found to be rough pitted, three were smooth pitted, four were smooth and one was rough in terms of sclerotial texture. Seven isolates were dark brown, four isolates were light brown, four isolates were brown and one was grey in terms of sclerotia colour. The sclerotial arrangement pattern of seven , three, five and one isolate was peripheral , central ,scattered and ring in middle respectively. Honeydew formation was not observed in the isolates except RS 17. The highest hyphal width (4.38μm) was recorded in case of RS 14. The highest angle of branching was observed for RS 5(95.743˚). Forty different varieties of soybean were screened under natural field conditions for resistance of Rhizoctonia web blight of soybean. Among the tested varieties only 2 varieties (ASB 22 and PS 1521) were observed as absolutely resistant. Under in vitro condition , ashok leaf extract was most effective in inhibiting the growth of R. solani. Under in vivo conditions, seed treatment with garlic extract was most effective in reducing disease severity over control(35.61%) followed by karanj oil(34.79%). Various organic amendments were also tested under field conditions for reduction in disease severity. The highest reduction in disease severity over control was observed in mustard cake (56.81%) followed by neem cake(53.6%).Saaf was found to be 100 percent effective in inhibiting the radial growth of R. solani under in vitro condition. Minimum inhibition was recorded in Nativo. Under in vivo conditions, seed treatment with propiconazole was found to be the most effective in reducing the disease severity over control. Under in vivo conditions, seed treatment with biocontrol agents was also quite effective in reducing the disease severity over control. The highest reduction in disease severity over control was observed in case T. viride (44.47%). In vitro evaluation of antagonistic activity of T. viride against R. solani was done by dual culture technique and the percent growth inhibition of R. solani was found to be 75 percent. Under in vivo conditions, foliar spray with propiconazole recorded least severity (14.68%) closely followed by carbendazim+mancozeb(14.84%).
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Publisher Place Raipur
Owner Khare, N. ♦ Awadhiya, G.K. ♦ Nag, Chandrakar S.
Size (in Bytes) 6.42 MB
Page Count 130