Phenotypic evaluation of Ptb 33 introgressed rice lines for resistance to brown planthopper, Nilaparvata lugens (Stål)

Brown planthopper (BPH), Nilaparvata lugens (Stal) continues its dominantce as an important pest in rice and cause considerable yield loss. Ptb 33 is a well-known source of resistance to BPH. Introgressed lines from Ptb 33 were evaluated against BPH using various parameters of resistant mechanisms. Initial screening was done by protray and modified seedbox screening tests. Eight entries illustrate resistance to BPH in mass screening. Further experiments assessed the mechanisms viz., antibiosis, antixenosis and tolerance in selected resistant entries. Antibiosis studies revealed reduced honeydew excretion, lower nymphal survival rates and prolonged developmental periods in resistant lines compared to the susceptible check. Antixenosis was evaluated through nymphal settling preference tests, with resistant entries showing reduced BPH attraction over time. Tolerance parameters, including Functional Plant Loss Index (FPLI) and Plant Dry Weight Loss Index (PDWLI), indicated varying levels of resistance among the introgressed lines. Among the entries identified as resistant through screening, FSR-3 exhibited strong resistance across all three mechanisms, while X21302-145 showed excellent antibiosis but poor tolerance character. Correlation analysis revealed significant interrelation between various resistance parameters. The study identifies promising BPH-resistant rice lines and elucidates their underlying resistance mechanisms, contributing valuable insights for rice breeding programs in developing durable BPH-resistant cultivars.