Durable resistance to rice tungro virus disease: Estimation of components of tungro resistance among rice cultivars

摘要

Components of resistance to tungro in rice cultivars (CVS) for their subsequent utilization in durable resistance programme was worked out during wet season under controlled net house conditions. Sixteen rice cvs. having tungro field tolerance score ranging from 1 to 9 were tested under high disease pressure. "Jaladhi" having tolerance score of 2 recorded 7% of infection, which is the lowest among 16 CVS. tested. "Swarnaprabha" "Biraj", "Kshitish", "Hiwalaya-2" and "Padmini" recorded 40-50% tungro infection. Incubation period in cases of Annapurna, Tara, Kshira, Vikas, Sattari, Kalinga-II and Taighung Native-1 was 6-8 days whereas in "Swarnaprabha", "Banaprabha" and other tolerant cvs. incubation period ranged 10-12 days. Percent reduction in heightand tiller numbers were lowest (10-15%) in "Swarnaprabha" and "Banaprabha" compared to tungro susceptible Taichung Native-1 (80-95%). Eventhough the percentage of infection in "Banaprabha" was 8% compared to 4% in "Swarnaprabha", both recovered quicklyshowing less percentage reduction in height and tiller numbers.