Impact of Silicon Induced Physiological Factors Against Rice Stem Borer (Scirphophaga incertulas)

The present investigation was undertaken to study the resistance induced through silica nutrition and their impact rice stem borer. Field experiment was conducted in AC & RI, Madurai for document the effect of silicon nutrition. Further Laboratory experiments were conducted to analyze the physiological factors such as Silicon content and enzyme activities viz., Polyphenol oxidase (PPO) and Phenylalanine ammonia lyase (PAL). The results revealed that the rice plants treated with silica nutritions significantly reduced the incidence and damage by stem borer as compared to untreated check. Basal application of inorganic sources of silica fertilizer namely calcium silicate 200kg/ha with foliar spray of 0.25% sodium meta silicate (SMS) significantly reduced the incidence of rice stem borer to a tune of 73.98 respectively. The physiological factors analyzed in the leaf and leaf sheath of plants treated with silica nutrients revealed that as the age of the plant increased, the physiological factors viz., silica content, polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) activity proportionately increased in plants. Basal application of calcium silicate 200kg/ha with foliar spray of 0.25% SMS recorded more silica content (12.16%), polyphenol oxidase (55.38^“_495nm/mg⁻¹ g⁻¹) and phenylalanine ammonia lyase (70.38 ^“_290nm/μmol m⁻¹ ml⁻¹ gm⁻¹). It was found that the occurrence of stem borer was negatively correlated with polyphenol oxidase, phenylalanine ammonia lyase and silica content.