Comparative reaction of popular high yielding spanish and virginia bunch groundnut varieties to Tobacco streak virus.

Abstract

Reaction of five spanish (JL 24, TMV 2, Kadiri 6, Kadiri 9 and Anantha) and a virginia (Kadiri 7 Bold) groundnut cultivars was studied against Tobacco streak virus (TSV) by sap inoculation using different age group of plants [7-84days after sowing (DAS)]. Among different cultivars, incubation period varied from 4 to 28days and high incubation period recorded in Kadiri 7 Bold. The percent infection decreased with increase in the age of the plants in all the cultivars as it ranged up to 100% in both pre-flowering (7-21 DAS) and flowering stage (28-63 DAS) plants followed by 50-100% in maturity stage plants (70-84 DAS) except Kadiri 7 Bold. Similarly, 100% wilting was observed in pre flowering stage plants against no wilting in maturity stage plants. However, cultivars differed in per cent wilting of flowering stage plants by recording maximum wilting (100%) in JL24, Kadiri 6 and minimum (25.0%) in Kadiri 7 Bold. Both localized (necrotic spots, veinal necrosis) and systemic (petiole necrosis, necrotic spots on young leaves, top growing bud and stem necrosis, axillary shoot proliferation, stunting, peg necrosis, pod necrosis, wilting of plant) symptoms induced by TSV were similar among all cultivars without any new symptoms. Prolonged stage of axillary shoot proliferation was observed for the first time in all the cultivars. In maturity stage plants of Kadiri 7 Bold, Kadiri 9 and Anantha, systemic symptoms restricted to leaf and petiole necrosis only. Virus titer varied significantly with the age of plants and inoculum harvest at days post inoculation and least virus titer recorded by Kadiri 7 Bold at all stages of infection. Among different cultivars, Kadiri 7 Bold was least susceptible/tolerant to TSV by registering higher incubation period with less per cent infection, wilt and titer.