Biochemical basis of resistance in rice cultivars to brown plant hopper Nilaparvata lugens (Stal.)

The chemical constituents viz., total phenols, sugars, nitrogen, phosphorous and potassium were estimated in healthy and BPH infested leaf tissue of seven resistant cultures INRC 8815, INRC 7069, INRC 8754, INRC 8712, INRC 7197, INRC 6153, INRC 7040, three moderately resistant cultures viz., INRC 7143, INRC 6165, INRC 7318, one susceptible check (TN₁) and resistant check (Ptb-33). The BPH infestation influenced the phenolic production in most of the resistant and moderately resistant cultures. The total phenols were reduced in susceptible check TN₁, whereas it was increased in the resistant check Ptb-33 after BPH infestation. Significant differences were observed in the sugar and nitrogen contents of healthy leaf tissues of rice cultures. Total sugars were significantly highest in TN₁, and lowest in Ptb-33 before infestation. The depletion of total sugars in TN₁ after infestation was significantly higher, while no marked differences in sugars was observed between healthy and BPH infested resistant and moderately resistant cultures. Significant increase in the potassium content was observed in resistant and moderately resistant cultures, while it remained the same in susceptible TN₁ after BPH Infestation. There was not much difference in phosphorous content among the resistant and susceptible cultures and between healthy and infested plants.