Biochemical Defense Responses in Advanced Backcross-derived Rice Genotypes to Nilaparvata lugens (Stal) Infestation

BPH, Nilaparvata lugens (Delphacidae: Homoptera) infestation on most of the resistant and moderately resistant backcross derived rice genotypes and resistant checks (PTB 33 and BM 71) resulted in an increase in the phenolic content in the infested plants leaf sheath. The percentage increase in phenols in resistant and moderately resistant genotypes ranged from 14.8 % to 67.7 %. Upon infestation of BPH there was a decrease in total reducing sugars in all the resistant and moderately resistant genotypes. The highest quantity of reducing sugars was present in healthy susceptible check TN1 compared to all the resistant and moderately resistant backcross derived rice genotypes. The ascorbic acid content in the resistant and moderately resistant genotypes decreased after BPH infestation and percentage decrease ranged from 16% to 36%. The total N content in the infested resistant and moderately resistant genotypes decreased over healthy genotypes. Decrease in the N content was highest in the susceptible check TN1 (35.2%). In the resistant checks slight decrease in the N content was observed. Potassium and Phosphorous (%) increased in the resistant genotypes and resistant checks, but not in susceptible check TN1. The plants responded defensively upon infestation, resulting in production of higher amount of phenolics, potassium, phosphorous and reduced level of nitrogen, reducing sugars and ascorbic acid.