Effect of Rice Tungro Disease on Yield and Yield Attributes of Rice

Six rice cvs. T(N)1 and Tapaswini (susceptible), IR 20 and IR67406-6-3-2-3 (moderately resistant), TKM-6 and Vikramarya (resistant) were tested against the rice tungro disease on yield parameters. The results revealed that the resistant cv. Vikramarya was less affected in terms of plant height when inoculated with RTV at 60 DAS with 0.4% increase and 0.9% reduction in plant height at 50 DAS. Moderately resistant rice cvs. IR 20 and IR67406-6-3-2-3 showed less reduction in terms of plant height as compared to susceptible rice cvs. T(N)1 and Tapaswini. Reduction in number of panicles per plant was found less in Vikramarya inoculated with RTV at 60 DAS (1.5%) and 40 DAS (1.9%). A significant decrease of 15.5% in number of grains per panicle was observed in cv. Vikramarya when inoculated with RTV at 20 DAS while a decrease of 16.3% was noticed in TKM-6 plants when inoculated with RTV at 20 DAS. However, rice cvs. TKM-6 and Vikramarya when inoculated with RTV at 60 DAS had almost no significant effect on number of grains per panicle. In terms of grain yield per plant, Vikramarya, TKM-6 and IR 20 was less affected when inoculated with RTV at 60 DAS with increase of 0.5% and decrease of 3.4, 3.4%, respectively. The most affected cultivar in terms of hundred-grain weight was T(N)1 when inoculated at 20 DAS as the inoculated plants did not reach the flowering phase to produce panicles while rice cv. Vikramarya showed an increase of 0.4 and 1.3% in hundred-grain weight when inoculated at 50 DAS and 60 DAS. The effect of RTV infection on all quality parameters was high when cultivars were inoculated with RTV at 20 DAS and it was found less when inoculated at 30, 40, 50 and 60 DAS, respectively.