Abstract:
The rice tungro disease is a composite disease caused by two viruses, the rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). It is transmitted in a semi-persistent transitory manner by an insect pest, the green leafhopper (GLH). In this study, the reaction of hybrid rice and component lines to the virus and its vector was evaluated with four Matatag Lines and Taichung Native 1 (TNI) as the resistant and susceptible checks, respectively. A total of 71 hybrid rice lines were inoculated with the virus and green leafhopper and were allowed to develop tungro symptoms in the screen house. Tungro scoring was done a month after inoculation The percent reduction in height, the degree of leaf discoloration and the final scores based on the Standard Evaluation System (SES) for rice were determined and used to identify the specific reaction of each line to tungro. The tungro scores were analyzed using IRRISTAT. Results showed that rice tungro virus greatly reduced the height of infected plants and produced a high degree of yellowing which means that all hybrid rice and component lines were susceptible to the disease except for Matatag 1. All lines were also found to be susceptible to the vector, which further increased the degree of infection in all the lines, except Matatag 1. Since all the entries have parents that were susceptible to both rice tungro virus and its vector only, 68 lines showed susceptible reaction, 22 lines showed tolerance reaction and only Matatag 1 exhibited resistance reaction out of the 71 test entries.
