Browsing by Author "REETA, DEVI"
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ThesisItem Open Access STUDIES ON VIRUS DISEASE(S) OF CHRYSANTHEMUM (Dendranthema grandiflora Tzvelev)(UHF,NAUNI, 2017) REETA, DEVI; HANDA, ANILABSTRACT Surveys conducted during cropping season of 2016 in 24 chrysanthemum locations of Solan and Sirmour districts of Himachal Pradesh revealed viral incidence ranging between 5.33 to 54.48 per cent. The characteristic symptoms exhibited by present isolate were severe mosaic, vein clearing, vein banding to mild mosaic on leaves along with stunted growth of plants. The strongest reaction to Chrysanthemum virus B antibody was shown by C2 isolate from Khundidhar in DAS-ELISA tests. The isolate was then further selected for partial characterization. The isolate was found to infect the test indicator plant species viz. Nicotiana glutinosa L., N. tabacum var. White Burley, Chenopodium album L., C. amaranticolor Coaste and Reyn, C. quinoa Wild, Datura metel L., D. stramonium L., Phaseolus vulgaris L. and D. metel var. festuosa. The isolate was easily transmissible through sap as well as by aphid vectors Myzus persicae and Macrosiphoniella sanborni. The host range studies revealed that the virus isolate could infect the plants of the families Chenopodiaceae, Leguminosae, Compositae (Asteraceae) and Solanaceae. The isolate could not infect the test plants belonging to the families Amaranthaceae, Cruciferae and Polemoniaceae. Biophysical properties of the virus isolate included TIP of 70-75°C, DEP of 10-3-10-4 and LIV of 6 days at room temperature (22-26°C) and 8 days under refrigeration (4+1oC). Serological identification of virus isolate through DAS-ELISA showed strong positive serological relationship with CVB antiserum. Serological detection of Chrysanthemum virus B in different chrysanthemum cultivars indicated that cultivar Ajay showing characteristic symptoms of severe mosaic and vein banding resulted in highest O.D. value followed by Purnima. Hence, based on the results of identification parameters particularly host range, transmission and serological detection, the present virus isolate had been identified to be Chrysanthemum virus B belonging to the Carlavirus genus of family Betaflexiviridae. Screening of fifty one cultivars/collections of chrysanthemum under field conditions revealed that six cultivars of chrysanthemum were immune to the present virus isolate as no symptoms were observed on these collections.