Phenotypic Screening of M₄ Generation of Rathu Heenati for Brown Planthopper (Nilaparvata lugens Stål) Resistance

Brown planthopper (BPH), Nilaparvata lugens Stål, a destructive monophagous insect pest, is one of the main biotic constraints in rice, causing huge yield losses in Asian rice growing areas every year. The BPH cause direct damage by feeding and indirectly transmitting viruses, which cause ragged and grassy stunt diseases. Developing resistant rice cultivars is generally considered to be the most economic and effective way for controlling BPH. A total of 42 M₄ families from Rathu Heenati were used in the present experiment to access the level of resistance to BPH by means of Modified Seedbox Screening technique (MSST). MSST screening results revealed that, among the 42 mutant families eleven were between 1.00 and 3.00, sixteen were between 3.00 and 5.00 and the remaining fifteen had the damage score above 5.00. The susceptible checks, TN1 and BPT5204 possessed the damage score of 9.00 and the resistant check PTB33 showed a damage score of 2.00. Thus indicating that gamma ray irradiated four families of Rathu Heenati within the range of 1 to2 implies highly resistance BPH.