Studies on characterization of important viral diseases of onion and their management

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dc.contributor.advisorDhawan, Poonam
dc.contributor.authorPawan Kumar
dc.date.accessioned2016-11-15T14:33:16Z
dc.date.available2016-11-15T14:33:16Z
dc.date.issued2009
dc.description.abstractThe present investigations on symptomatology, transmission, host range, host reaction, detection and eco-friendly management of onion yellow dwarf virus (OYDV) and iris yellow spot virus (IYSV) diseases were conducted on onion crop cv. Hisar-2 during Rabi seasons 2007-08 and 2008-09 at the experimental farm, Department of Plant Pathology, CCS Haryana Agricultural University, Hisar. OYDV disease appeared in the form of crinkling and faint chlorotic stripes on the leaves of the bulb as well as seed crop. Some plants showed prominent yellow stripes on leaves and scapes of seed crop. Later on the scapes showed twisting and bending and this incidence reached at 68% in seed crop. Iris yellow spot virus showed hay coloured and water soaked spots on the leaves of bulb as well as the seed crop. The spots were found in different shapes and sizes such as diamond-shaped and irregular spots on the scapes of seed crop. These spots coalesced and led to drying. The mechanical transmission of OYDV (68.88%) and IYSV (62.5%) were successfully achieved. Nymphs of aphids such as Aphid craccivora, A. gossypii and Myzus persicae could transmit OYDV to 46.87, 53.31 and 62.5 per cent, respectively. IYSV was transmitted upto 54.17% by nymphs of Thrips tabaci. Host range of OYDV was found to be very narrow only to onion and garlic cultivars whereas, IYSV had a wide host range. OYDV and IYSV were detected by DAS-ELISA in infected onion plants. The incidence of OYDV (83.22%) and IYSV (89.97%) were recorded in bulb crop which caused losses of 14.62% and 9.85% in bulb weight due to OYDV and IYSV, respectively. A high incidence of OYDV (90.65%), IYSV (88.25%) and lodging (75.68%) was recorded in seed crop. The reduction in seed yield (53.84%) was observed maximum in plants infected with OYDV grade A and least (6.6%) in OYDV grade D. A reduction of 50% in seed yield was recorded with IYSV disease with a substantial reduction in seed quality. None of the management strategies tried was effective for reducing OYDV incidence whereas incidence of IYSV (67.24%) and lodging (40.27%) was reduced in late planted crop i.e. 12th Nov., 2009. But at the same time seed yield was also reduced 34.22% due to late planting. None of the varieties/collections was found resistant to onion yellow dwarf virus and iris yellow spot virus diseases. All the varieties/collections were found highly susceptible to both diseases. There is a need to screen more germplasm lines to find sources of resistance to these viral diseases.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/85655
dc.language.isoenen_US
dc.publisherCCSHAUen_US
dc.subPlant Pathology
dc.subjectDiseases, Crops, Onions, Planting, Biological phenomena, Sowing, Fruits, Iris, Application methods, Gradingen_US
dc.these.typeM.Sc
dc.titleStudies on characterization of important viral diseases of onion and their managementen_US
dc.typeThesisen_US
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