NAGARAJA, A.SAVITHA, A. S.2020-10-072020-10-072019-12-14Th-12554https://krishikosh.egranth.ac.in/handle/1/5810152665False smut recently has become a threat for the successful production of rice. Roving survey of disease affected areas revealed that the disease severity ranged from 3.95 to 18.59 per cent and 3.89 to17.04 per cent during Kharif 2017 and 2018, respectively. Twenty isolates were obtained from five rice ecosystems of Karnataka and cultural variability of five selected representative isolates from each ecosystem revealed that the isolate Uv-12 recorded maximum colony diameter of 43.90 mm on potato sucrose agar (PSA) with typical yellowish white colony. Amongst 20 isolates of U. virens, isolate Uv-15 recorded maximum colony diameter of 70.00 mm on PSA media with raised flat, whitish to dark green colony and brown coloured chlamydospores. Maximum mycelial width of 6.37 μm was recorded in Uv-19 with the chlamydospore size of 28.82 to 90.16 μm. Scanning electron microscopy revealed hyaline, globose to irregularly rounded, ornamented chlamydospores with prominent spines. Among the ideal carbon and nitrogen sources, while Uv-1 recorded maximum growth on glycerol as carbon source, but Uv-12 did so on media supplemented with sodium nitrate. The higher number of chlamydospore germination was recorded in 2 per cent sucrose at 24 h of incubation. The DNA of 20 U. virens isolates was successfully amplified at 600-700 bp with ITS1 and ITS4 primers and the dendrogram drawn based on sequence data separated these isolates into two major clusters. The size of RAPD-PCR amplified products of U. virens isolates ranged from 290-3400 bp with Jaccard similarity coefficient values of 0.00 to 0.79. Foliar application of trifloxystrobin 25 % + tebuconazole 75 WG or tebuconozole 250 EC or azoxystrobin 25SC or propiconazole 25 EC at booting or at 50 % panicle emergence was effective for the management of false smut of rice.EnglishThesis