Disease tolerance/resistance breeding depends on available genetic variability in the vast collection of germplasm as a source of disease tolerance/resistance. Rice varieties behave differently in tungro epidemic according to their susceptible and tolerant nature. From earlier investigations it was found that traditional rice varieties of West Bengal viz. Dumursail, Radhunipagol, Raghusail and Tulaipanja were tolerant varieties with zero yield loss. The genetics of tolerance in the traditional rice variety, Radhunipagol was investigated in this present study by crossing tolerant variety Radhunipagol with a susceptible variety Pusa Basmati-1. The F2 plants derived from this cross were evaluated in glasshouse and field experiments to determine the inheritance pattern of RTD resistance. A total of 14 F2 lines comprising of 683 F2 plants were evaluated for their reaction to rice tungro disease (RTD). A chi-square (χ2) analysis for assessing segregation from F2 led to the conclusion that the tolerance found in the F2 progeny of this cross is determined by a recessive gene. It indicates a typical monogenic recessive gene is governing resistance and susceptibility reaction against RTD in rice. The information obtained in this study could be valuable for rice tungro disease tolerance breeding using traditional rice varieties of West Bengal. Furthermore the data could be used in planning a systematic breeding programme to incorporate the RTD tolerance into the susceptible cultivars.

Keywords: Rice tungro disease (RTD); F2 segregating population; Chi-square (χ2) analysis; Goodness of fit; Inheritance.