Virulence analysis of Rhizoctonia solani Kuhn and evaluation of resistance in Rice

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dc.contributor.advisorUpmanyu, Sachin
dc.contributor.authorRathi, Monika
dc.date.accessioned2022-03-07T05:27:31Z
dc.date.available2022-03-07T05:27:31Z
dc.date.issued2021-12-18
dc.description.abstractSheath blight of rice caused by Rhizoctonia solani is the second most important production constraint after blast in rice-growing regions of India. The investigation on “Virulence analysis of Rhizoctonia solani Kuhn and evaluation of resistance in rice” was undertaken during 2020-2021 in the Department of Plant Pathology, CSKHPKV, Palampur and RWRC, Malan. The fungal organism was confirmed as Rhizoctonia solani on the basis of its morphological and cultural characteristics. In all, twenty isolates were collected from different rice growing areas of Himachal Pradesh. Among twenty isolates studied, colony colour varied from cream to dark brown while hyphal cell size ranged from 102.90 x 4.20 µm to 220.50 x 5.95 µm. All the isolates except RS-2 produced light to dark brown, small to large sclerotia of varying intensity ranging from low to high. Isolates were placed into different groups based on colony colour, sclerotial colour, sclerotial size and sclerotial intensity. Growth rate of isolates ranged from 0.10 to 2.08 mm/h and 1.20 to 2.98 mm/h at 25⁰C and 30⁰C, respectively with maximum rate (2.98 mm/h) exhibited by isolate RS-5 and the least by RS-2 at both the temperatures. Isolates were further grouped into slow, medium and fast growing groups based on growth rate at 30⁰C temperature. Studies on pathogenic variability among R. solani isolates carried out on seven different rice cultivars showed that incubation period of all the isolates on the cultivars varied from two to four days. The relative lesion height (RLH) caused by the isolates also varied as in cultivar HPR 2880, it ranged from 26.83 to 55.71per cent, in TN1 from 23.44 to 54.76 per cent, in HPR 2612 from 27.27 to 54.69 per cent, in IR50 from 31.63 to 54.76 per cent, in HPR 1068 from 23.10 to 53.73 per cent, in HPR 2143 from 15.38 to 54.10 and in HPU 2216 from 32.38 to 52.82 per cent. On the basis of RLH induced on different cultivars, ten R. solani isolates were classified as highly virulent (>45 % RLH), seven as moderately virulent (35-45% RLH) and three as less virulent (<35% RLH). Out of sixty seven genotypes evaluated, seven genotypes showed resistant, seventeen moderately resistant, twenty nine moderately susceptible and fourteen genotypes showed susceptible reaction on the basis of disease severity while, no genotype was found immune.en_US
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810183085
dc.keywordsgenotypes,cultivars ,isolates,temperature.en_US
dc.language.isoEnglishen_US
dc.pages61en_US
dc.publisherPalampuren_US
dc.subGenetics and Plant Breedingen_US
dc.themeTo study the virulence spectrum of Rhizoctonia solani Kuhn and to identify resistant sources against sheath blight of riceen_US
dc.these.typeM.Scen_US
dc.titleVirulence analysis of Rhizoctonia solani Kuhn and evaluation of resistance in Riceen_US
dc.typeThesisen_US
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