Evaluation for Resistance Levels of Newly-bred Rice Varieties(lines) to Brown Planthopper Nilaparvata lugens St(a)l in China

The resistance to brown planthopper (BPH-), Nilaparvata lugens Stal, in 3328 newly developed rice varieties (lines) bred by the National Rice Breeding Program (NRBP) and Zhejiang Provincial Rice Breeding Program (ZRBP) was evaluated using the Seedling Bulk Screening Test from 1986 to 2000. Results indicated that the rate of resistant rice variety in tested varieties from NRBP was 17.25% during the 7th Fiveyear Plan, and the rate rank from 11% to 13% was recorded in the 8th and 9th Five-year Plans. In the rice varieties from ZRBP, the rate of resistant variety in evaluated varieties were 11.54% and 18.96% in the 7th and 8th Five-year Plans, respectively, and the lowest rate of 5.51% was found in the 9th Five-year Plan.There was significant difference in the rate of resistant variety between rice varieties from NRBP and ZRBP in the 9th Five-year Plan. The fluctuation of the rate of resistant variety in different Five-year Plans was analyzed and the effective methods for breeding resistant rice varieties to BPH were discussed also.