Variability in Response of Selected Traditional and IRRI Rices to Tungro

Abstract

Six traditional and six IRRI rices with known genetic background for resistance to the green leafhopper Nephotettix virescens were planted in five locations in the Philippines for four seasons. Ten-day seedlings were planted at 25 x 25 cm spacing in 2 rows 5 m long alternated with two rows of susceptible TNl replicated four times every season. At 30 and 60 days after transplanting, tungro-infected hills were counted. The data for both traditional and cultivated rices were subjected to ANOVA. Results showed variability in response of the rices to tungro from locality to locality and from season to season. There was a negative correlation between the number of GLH collected and the frequency of infection on different rices. Population genetic studies on selected GLH populations revealed genetic differences even on populations which are geographically close These results indicate that variation in response of the rices to tungro was due to differences in virulence of the vectors.