A field screening method to evaluate rice breeding lines for resistance to the hoja blanca virus

Abstract

SUMMARYA method is presented for rearing large colonies of viruliferous Sogatodes oryzicola, vector of the rice hoja blanca virus (RHBV). These colonies were used for field screening up to 10 000 rice breeding lines per season for resistance to RHBV. Uniform infection of check varieties in the field indicated that the method was adequate. Field release of vectors when plants were 14 days old resulted in satisfactory disease incidence, after 21 days, to distinguish lines segregating for resistance from lines uniformly resistant or susceptible. Various sources of resistance identified earlier continued to be resistant under the screening conditions. Progeny of lines identified as non‐segregating resistant continued as non‐segregating resistant. Resistant plants from lines segregating for resistance produced progeny lines that were segregating and non‐segregating. Ratios of resistant to susceptible plants in F1 progeny of three‐way crosses were consistent with earlier observations that RHBV resistance is a dominant character. The susceptibility of the commercial checks indicates that rice production in RHBV areas of tropical Latin America continues to be at risk from the virus. Virus‐resistant commercial cultivars resulting from this method should be available in 2 years.