Vol. 10, Issue 9 (2021)

Author(s):
M Udayasree, P Rajanikanth, NRG Varma and M Sreedhar

Abstract:
Thirteen elite rice genotypes were evaluated for their antibiosis and tolerance resistance mechanisms against Brown Planthopper, Nilaparvata lugens under polyhouse conditions using standard susceptible (TN1) and resistant checks (PTB-33). Nymphal survival, nymphal developmental period and growth index were studied under antibiosis mechanism of resistance while days to wilt was studied under tolerance mechanism. Among the thirteen rice genotypes significant lowest nymphal survival of 40.0 per cent was recorded in rice genotypes RNR-26111 and RNR-21571 followed by RNR-23079 and KNM-2305 (43.33%) which were slightly above resistant check PTB-33(36.67%). Highest nymphal developmental period was recorded in RNR-23079 (17.66 days) followed by RNR-21571 and MTU-1010(17.33 days). RNR-26111 and KNM-2305 which recorded lowest nymphal survival also recorded slightly lowest nymphal developmental period (16.33 days) compared to RNR-23079. The resistant check PTB-33 recorded significant highest nymphal developmental period of 20.33 days while the genotype MTU-1010 with 17.33 days was on par with PTB-33. Lowest growth index of 2.09 was recorded on PTB-33 indicating unsuitability of the cultivar for growth and development of BPH followed by RNR-23079 (2.43), RNR-26111 (2.45), MTU-1010 (2.58), KNM-2305 (2.67), RNR-21571 (2.77) and KNM-2307 (2.78). The measure of tolerance of rice genotypes which was based on days to wilt of the BPH infested plants showed among the six rice genotypes which showed good antibiosis mechanism only four genotypes viz., RNR-23079 and RNR-26111 MTU-1010, and KNM -2305 possessed good tolerance against BPH and these genotypes took maximum of 30 and 27 days to wilt which was on par with the resistant check, PTB-33.